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Effects of planting time and cultivar on dry matter yield and estimated total digestible nutrient content of forage rice in southwestern Japan
Field Crops Research 105 (2008) 116–123 www.elsevier.com/locate/fcr
Effects of planting time and cultivar on dry matter yield and estimated total digestible nutrient content of forage rice in southwestern Japan Hiroshi Nakano *, Satoshi Morita, Ikuo Hattori, Kenji Sato National Agricultural Research Center for Kyushu Okinawa Region, Chikugo, Fukuoka 833-0041, Japan Received 12 June 2007; received in revised form 24 August 2007; accepted 25 August 2007
Abstract We examined the effects of planting time and cultivar on dry matter yield of forage rice in southwestern Japan. The cultivar Tachiaoba produced a 81.1% higher dry weight per tiller but a 40.5% fewer tillers per square meter than Hinohikari, thus producing a 9.0% higher dry matter yield. Nishiaoba produced almost the same dry matter yield as Hinohikari. Early transplanted plants produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. Early transplanted Tachiaoba produced the highest dry matter yield in the experiment. We also examined the effects of planting time and cultivar on estimated total digestible nutrient (TDN) content. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blades. Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 1 of the 2 years. However, early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Early transplanted plants had a 4.7% higher estimated TDN content in leaf sheath plus stem than normally transplanted plants. These results suggest that early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because of the higher estimated TDN content in leaf sheath plus stem. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari. Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants. Early transplanted Tachiaoba produced the highest estimated TDN yield in this experiment. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and estimated TDN yields. # 2007 Elsevier B.V. All rights reserved. Keywords: Dry matter yield; Estimated total digestible nutrient (TDN) content; Forage rice; Oryza sativa L.; Planting time
1. Introduction The production of forage rice (Oryza sativa L.) is increasing in Japan because of improved control of rice grain production and increasing demand for domestic forage (Sakai et al., 2003). In general, high dry matter yield and high total digestible nutrient (TDN) content are required for forage rice. There are three main cropping systems for forage rice in southwestern Japan: forage rice single cropping (very early planting), forage rice–Italian ryegrass (Lolium multiflorum Lam.) cropping (early planting), and forage rice–wheat (Triticum aestivum L.) or forage rice–barley (Hordeum vulgare L.) cropping (normal planting). We previously examined the effect of twice harvesting (i.e., ratoon cropping) of forage rice, with the first harvest at the full heading stage, on total dry
* Corresponding author. Tel.: +81 942 52 0670; fax: +81 942 53 7776. E-mail address: [email protected] (H. Nakano). 0378-4290/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.fcr.2007.08.005
matter yield of four cultivars transplanted very early (i.e., late April) in southwestern Japan (Nakano and Morita, 2007). Taporuri produced the highest total dry matter yield (22.7 t ha1), with a value 60% higher than that of Hinohikari. Manipulating the time of first harvest, the total amount of nitrogen, and the nitrogen application method increased this cultivar’s total dry matter yield to 27.1 t ha1 (Nakano and Morita, 2008). However, twice harvesting is not feasible for early and normal plantings because it requires long growth duration. In addition, Taporuri generally lodge during ripening in early and normal planting. Recently, the new cultivars Nishiaoba and Tachiaoba, which perform acceptably as forage rices in southwestern Japan, were developed by the National Agricultural Research Center for Kyushu Okinawa Region (Sakai et al., 2007; Tamura et al., 2007). When farmers grow forage rice, they must decide on the planting time and cultivar in order to maximize the dry matter yield and TDN content. Although several studies have reported techniques for the cultivation of forage rice (Yamaguchi and
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
Matsumura, 2004; Kobayashi et al., 2006a,b), information on the effects of planting time and cultivar on dry matter yield and estimated TDN content of forage rice in southwestern Japan is limited. Using enzymatic analysis, organic matter (OM) content in forage can be fractioned into organic cellular content (OCC) and organic cell wall (OCW) contents by a-amylase and actinase (Chalupa, 1968). OCW is further fractioned into organic a (Oa, high digestibility fibre) and organic b (Ob, low digestibility fibre) contents by cellulase. Estimated TDN content in forage rice can be calculated from these components. Our objective in the present study was to determine the effects of planting time and cultivar on dry matter yield and estimated TDN content of forage rice grown in southwestern Japan. 2. Materials and methods 2.1. Crop management The study was conducted on a Grey Lowland soil at the National Agricultural Research Center for Kyushu Okinawa Region (338120 N latitude, 1308300 E longitude, 10 m asl), Chikugo, Fukuoka, Japan, in 2004 and 2005. The previous crop grown in the field was rice, and the same field was used for the experiments in both years of the study. The mean temperature during late August in 2005 was 2.1 8C lower than that in 2004, whereas mean temperature during late September, early October, and mid-October in 2005
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was 2.2, 2.4, and 2.5 8C higher, respectively, than that in 2004 (Fig. 1). Solar radiation during early and mid-July in 2005 was 11.3 and 6.1 MJ m2 d1 lower, respectively, than that in 2004, whereas solar radiation during late June and late September in 2005 was 6.0 and 7.4 MJ m2 d1 higher, respectively, than that in 2004. Therefore, the mean temperature and solar radiation during the early growth stage in 2004 was generally higher than those in 2005, whereas mean temperature and solar radiation during the late growth stage in 2005 was generally higher than those in 2004. The experiment had a 2 (planting time) 3 (cultivar) factorial design arranged in a randomized complete block with three replicates. The planting times were early and normal. The three cultivars were Tachiaoba and Nishiaoba, which were developed as forage rices, and Hinohikari, which is normally grown as food rice in southwestern Japan. Germinated seeds were sown in nursery boxes in late April for early planting or in late May for normal planting and grown in a greenhouse. Seedlings were transplanted to the paddy field by hand in late May for the early transplanted treatment or in late June for the normally transplanted treatment. The mean number of fully expanded leaves on the main culm at transplanting was 4.2. The field received 30 kg N, 13 kg P, and 25 kg K ha1 in the form of chemical fertilizer broadcast by hand 3 days before transplanting, and the fertilizer was incorporated into the soil in such a way as to allow puddling. Plants received 30 kg N ha1 in the form of ammonium sulfate just after transplanting, at the maximum tiller number stage,
Fig. 1. Mean temperature and solar radiation in 2004 (*), 2005 (&), and normal (~) at Chikugo. Normal data is the mean of 30 years (from 1971 to 2000).
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and at 20 and 10 days before heading, respectively. These supplemental applications were broadcast by hand on the plot surface but were not incorporated into the soil. After trimming, each plot was 1.5 m 9.0 m with a mean of 22.2 hills m2 (3 seedlings hill1, 30 cm 15 cm). Twenty hills (0.9 m2) were mowed by hand to ground level at the yellow ripe stage (for the early transplanted treatment, the yellow ripe stages of Tachiaoba, Nishiaoba, and Hinohikari were late September, late September, and mid-September, and for the normally transplanted treatment, mid-October, early October, and late September, respectively), and the number of tillers per square meter was measured. Plants from 2 hills with an average number of tillers were divided into leaf blade, leaf sheath plus stem, and panicle, and then dried at 80 8C in a ventilated oven for 2 days with the plants from the other18 hills to determine their dry weight.
Ohnishi and Horie (1999). Dried samples were ground in a vibrating sample mill (TI-100, Heiko Seisakusho, Tokyo, Japan). About 500 mg of each was placed in a pressure bottle with 30 ml of distilled water and then boiled on a hot plate for 30 min at 100 8C and then for 20 min at 180 8C. After it cooled, we added 20 ml of sodium phosphate–phosphoric acid buffer (pH 7.4) containing 1.5 mg of a-amylase, 0.5 mg of amyloglucosidase, and 0.5 mg of sodium azide. Each sample was incubated with continuous shaking for 24 h at 40 8C and then filtered through a filter paper (No. 5A, Advantec, Tokyo, Japan). The residues were dried at 135 8C for 4 h to determine their dry weights. NSC content was estimated as follows:
2.2. Estimation of total digestible nutrients
2.4. Statistical analysis
Each dried sample was ground in a Wiley mill (WT-100, Ikemoto Scientific Technology, Tokyo, Japan) and passed through a 1-mm screen. About 500 mg of each sample was placed in a filter bag (F57, Ankom Technology, Macedon, NY, USA), soaked in boiling water for 5 min, and then incubated in 2 L of sodium acetate–acetic acid buffer (pH 5.8) containing 100 mg of a-amylase, 800 mg of actinase, and 70 mg of calcium acetate in a digestion vessel (DAISYII Incubator, Ankom Technology) for 16 h at 40 8C. Each sample residue was rinsed twice with boiling water for 5 min and then twice with cold water for 5 min in a digestion vessel (ANKOM200 Fiber Analyzer, Ankom Technology) and then used for measurement of Ob content, which is resistant to cellulase treatment, and OCW content. For measurement of Ob content, sample residue after treatment with a-amylase and actinase was incubated in 2 L of sodium acetate–acetic acid buffer (pH 4.0) containing 20 mg of cellulase in a digestion vessel (DAISYII Incubator) for 4 h at 40 8C, rinsed twice with boiling water for 5 min and cold water for 5 min in a digestion vessel (ANKOM200 Fiber Analyzer), soaked in acetone for 15 min, dried at 135 8C for 2 h to determine its dry weight, and then burnt at 600 8C for 2 h to determine its ash (CA) content. For measurement of OCW content, sample residue after treatment with a-amylase and actinase was soaked in acetone for 15 min, dried at 135 8C for 2 h to determine its dry weight, and then burnt at 600 8C for 2 h to determine its CA content. TDN content was estimated according to Hattori et al. (2005), as follows:
We used analysis of variance to test differences among treatments. When the F-test of the analysis of variance exceeded the 0.05 level of probability, treatment effects were compared by using the LSD.
TDN ¼ 5:45 þ 0:89ðOCC þ OaÞ þ 0:45OCW; OCC ¼ 100 ðOCW þ CAÞ; OM ¼ 100 CA
Oa ¼ OCW Ob;
2.3. Estimation of nonstructural carbohydrate content in leaf sheath plus stem The nonstructural carbohydrate (NSC) content of leaf sheath plus stem was estimated according to the method of
NSC ¼
sample weight residual weight 100 sample weight
3. Results 3.1. Duration of vegetative growth The duration of vegetative growth differed significantly (P < 0.05) between planting times and among cultivars (Table 1). Early transplanted plants generally had a longer vegetative growth duration (91 days averaged over both years) than normally transplanted plants (72 days) (Tables 2 and 3). Tachiaoba generally had the longest vegetative growth duration (89 days), followed by Nishiaoba (80 days) and Hinohikari (76 days). 3.2. Dry matter yield and its components The dry matter yield differed significantly (P < 0.05) between planting times (Table 1). Early transplanted plants produced a 14.9% higher dry matter yield (16.0 t ha1 averaged over both years) than normally transplanted plants (13.9 t ha1) (P < 0.05) (Tables 2 and 3). Among the components of yield, early transplanted plants produced a 5.5% fewer tillers per square meter than normally transplanted plants in 2004 (P < 0.05), but there was no difference in 2005. Early transplanted plants produced a 21.1% higher dry weight per tiller than normally transplanted plants (P < 0.05). The dry matter yield differed significantly (P < 0.05) between cultivars (Table 1). Tachiaoba produced a 10.2% higher dry matter yield (15.9 t ha1 averaged over both years) than Nishiaoba (14.4 t ha1), and a 9.0% higher than Hinohikari (14.6 t ha1) (P < 0.05) (Tables 2 and 3). Tachiaoba and Nishiaoba produced 40.5% and 21.2% fewer tillers per square meter than Hinohikari, respectively (P < 0.05). Tachiaoba and Nishiaoba produced 81.1% and
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
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Table 1 Analysis of variance of vegetative growth, dry matter yield, dry matter yield components, and estimated TDN content in 2004 and 2005a Vegetative growth (days)b
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tilled1)
Panicle ratio (%) c
Whole plant (%) c
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
Yield (t ha1)
2004 Planting time (A) Cultivar (B) AB
** ** *
** * NS
** ** NS
** ** **
** ** **
** ** *
NS NS NS
** NS NS
NS * NS
** * NS
2005 Planting time (A) Cultivar (B) AB
** ** **
** ** NS
NS ** NS
** ** **
** NS *
NS NS NS
* NS NS
** NS NS
NS NS NS
** ** NS
a b c
Estimated TDN content
*, ** Significant at the 0.05 and the 0.01 levels, respectively. The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
25.6% higher dry weights per tiller than Hinohikari, respectively (P < 0.05).
Tachiaoba and Nishiaoba had 5.2% and 4.2% lower ratios (41.9% and 42.9%, respectively) than Hinohikari (47.1%), respectively, in 2004.
3.3. Ratio of panicle to total dry weight 3.4. Estimated total digestible nutrient content The ratio of panicle to total dry weight differed significantly (P < 0.05) between planting times in both years and among cultivars in 2004 (Table 1). Early transplanted plants had a 5.9% lower ratio (42.5% averaged over both years) than normally transplanted plants (48.4%) (Tables 2 and 3).
The estimated TDN content in the whole plant differed significantly (P < 0.05) between planting times and among cultivars in 2004 (Table 1). Early transplanted plants had a 1.0% higher estimated TDN content (56.6%) than normally
Table 2 Effects of planting time and cultivar on dry matter yield, dry matter yield components, and estimated TDN content in 2004
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05) AB Early planting Tachiaoba Nishiaoba Hinohikari Normal planting Tachiaoba Nishiaoba Hinohikari LSD (0.05) a b
Vegetative growth (days)a
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tiller1)
Panicle ratio (%) b
Whole plant (%)
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
90 72
16.2 13.6
330 348
5.13 4.09
42.3 45.6
56.6 55.6
40.7 40.8
47.4 42.6
72.0 71.9
9.2 7.6
0
0.5
12
0.08
0.6
0.5
NS
0.3
89 79 75
15.6 14.5 14.7
260 335 422
6.01 4.33 3.50
41.9 42.9 47.1
55.4 55.4 57.4
70.9 72.6 72.3
8.6 8.0 8.4
0
0.7
15
0.10
0.7
0.7
1.3
0.4
98 88 84
16.9 15.7 16.0
251 329 410
6.74 4.78 3.89
40.0 42.1 44.8
80 70 65
14.2 13.2 13.5
269 341 435
5.29 3.88 3.10
NS
NS
0.15
1
Estimated TDN content
NS
1.3
Yield (t ha1)
41.2 40.1 41.0
45.7 43.8 45.5
NS
NS
56.0 56.4 57.2
41.2 40.2 40.7
48.6 46.2 47.4
70.4 73.3 72.2
9.5 8.9 9.1
43.8 43.6 49.5
54.9 54.4 57.5
41.1 40.0 41.3
42.7 41.4 43.7
71.3 72.0 72.4
7.8 7.2 7.7
1.0
0.9
NS
NS
NS
The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
NS
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Table 3 Effects of planting time and cultivar on dry matter yield, dry matter yield components, and estimated TDN content in 2005 Vegetative growth (days)a
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tiller1)
Panicle ratio (%)b
Whole plant (%)
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
91 72
15.7 14.2
334 340
5.08 4.35
42.7 51.2
57.9 57.7
42.8 41.0
48.1 43.5
73.3 72.2
9.1 8.2
LSD (0.05)
0
0.5
NS
0.17
1.7
1.5
2.0
NS
0.4
Cultivar (B) Tachiaoba Nishiaoba Hinohikari
88 81 77
16.1 14.3 14.4
251 334 427
6.45 4.31 3.38
45.5 47.9 47.4
57.7 58.8 57.0
43.2 41.3 41.2
45.5 45.8 46.1
72.8 74.6 70.8
9.3 8.4 8.2
LSD (0.05)
0
0.6
29
0.20
NS
NS
NS
NS
NS
0.5
98 90 87
17.1 14.9 15.3
241 317 445
7.08 4.70 3.46
40.1 45.4 42.5
57.6 59.6 56.6
44.3 42.5 41.5
48.6 47.4 48.3
73.0 76.1 70.8
9.8 8.9 8.7
79 71 67
15.2 13.8 13.5
261 350 410
5.83 3.93 3.30
50.9 50.4 52.4
57.7 58.0 57.4
42.0 40.1 40.9
42.4 44.3 43.8
72.6 73.1 70.8
8.8 8.0 7.8
NS
NS
0.29
3.0
NS
NS
NS
NS
Planting time (A) Early planting Normal planting
AB Early planting Tachiaoba Nishiaoba Hinohikari Normal planting Tachiaoba Nishiaoba Hinohikari LSD (0.05) a b
1
Estimated TDN content
NS
Yield (t ha1)
NS
The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
transplanted plants (55.6%) (Table 2). Tachiaoba and Nishiaoba had a 2.0% lower estimated TDN content (55.4% each) than Hinohikari (57.4%). The estimated TDN content in leaf sheath plus stem differed significantly (P < 0.05) between planting times (Table 1). Early transplanted plants had a 4.7% higher estimated TDN content (47.8% averaged over both years) than normally transplanted plants (43.1%) (Tables 2 and 3). The estimated TDN content in panicles was generally 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade (Tables 2 and 3).
3.5. Contents of fractions obtained by enzymatic analysis of leaf sheath plus stem The OM, OCC, OCW, and Ob contents in leaf sheath plus stem differed significantly (P < 0.05) between planting times (Table 4). Early transplanted plants had 1.8% higher OM and 6.7% higher OCC contents in leaf sheath plus stem (85.9% and 20.3% averaged over both years, respectively) than normally transplanted plants (84.1% and 13.6%) (Tables 5 and 6). Early transplanted plants had 4.8% lower OCW and 6.0% lower Ob contents in leaf sheath plus stem (65.7% and
Table 4 Analysis of variance of contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2004 and 2005a OMb (%)
OMb
OCWb
NSCb (%)
OCCb (%)
OCWb (%)
Oab (%)
Obb (%)
2004 Planting time (A) Cultivar (B) AB
* NS NS
** * NS
** * NS
** ** NS
** NS NS
** ** NS
2005 Planting time (A) Cultivar (B) AB
** NS NS
** NS NS
** NS NS
NS NS NS
** NS NS
** NS NS
a
*, ** Significant at the 0.05 and the 0.01 levels, respectively. OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular content, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively. b
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
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Table 5 Effects of planting time and cultivar on contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2004 OMa (%)
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05)
OMa
OCWa
NSCa (%)
OCCa (%)
OCWa (%)
Oaa (%)
Oba (%)
84.9 83.9
17.9 13.6
67.0 70.3
7.6 4.8
59.4 65.5
20.9 18.0
0.8
1.7
1.9
1.2
2.3
1.8
84.5 84.2 84.6
16.3 16.9 14.1
68.2 67.2 70.6
6.7 4.4 7.5
61.5 62.8 63.1
20.5 21.0 17.0
2.0
2.4
1.5
NS
NS
2.2
a
OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular content, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively.
59.3%) than normally transplanted plants (70.5% and 65.3%). The OCC, OCW, and Oa contents in leaf sheath plus stem differed significantly (P < 0.01) among cultivars in 2004 (Table 4). Tachiaoba and Nishiaoba had 2.2% and 2.8% higher OCC contents (16.3% and 16.9%, respectively) than Hinohikari (14.1%), respectively (Table 5). Tachiaoba and Nishiaoba had 2.4% and 3.4% lower OCW contents (68.2% and 67.2%) than Hinohikari (70.6%). Tachiaoba and Hinohikari had 2.3% and 3.1% higher Oa contents (6.7% and 7.5%) than Nishiaoba (4.4%), respectively, in 2004. 3.6. Nonstructural carbohydrate content in leaf sheath plus stem
3.7. Estimated total digestible nutrient yield The estimated TDN yield differed significantly (P < 0.05) between planting times and among cultivars (Table 1). Early transplanted plants produced a 16.1% higher estimated TDN yield (9.1 t ha1 averaged over both years) than normally transplanted plants (7.9 t ha1) (P < 0.05) (Tables 2 and 3). Tachiaoba and Hinohikari produced 8% and 5% higher estimated TDN yields (8.6 and 8.4 t ha1, respectively) than Nishiaoba (8.0 t ha1), respectively, in 2004, and Tachiaoba produced 10% and 13% higher estimated TDN yields (9.3 t ha1) than Nishiaoba and Hinohikari (8.4 and 8.2 t ha1), 1), respectively, in 2005. 4. Discussion
The NSC content in leaf sheath plus stem differed significantly (P < 0.05) between planting times in both years and among cultivars in 2004 (Table 4). Early transplanted plants had a 6.0% higher NSC content (25.6% averaged over both years) than normally transplanted plants (19.6%) (Tables 5 and 6). Tachiaoba and Nishiaoba had 3.5% and 4.0% higher NSC contents (20.5% and 21.0%) than Hinohikari (17.0%), respectively.
We examined the effects of planting time and cultivar on dry matter yield of forage rice in southwestern Japan. Cultivars with a long vegetative growth duration generally have a higher dry matter yield than those with a short vegetative growth duration (e.g., Saitoh et al., 2000; Nakano and Morita, 2007). Tachiaoba, which had a 13 days’ longer vegetative growth than Hinohikari, produced a 9.0% higher dry matter yield than
Table 6 Effects of planting time and cultivar on contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2005 OMa (%)
OMa
OCWa a
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05) a
a
OCC (%)
OCW (%)
86.9 84.3
22.6 13.6
64.3 70.7
0.9
3.6
3.1
85.1 85.5 86.3
18.2 18.0 18.2
66.9 67.5 68.2
4.4
3.8
NS
a
Oa (%) 5.0 5.6
NSCa (%) a
Ob (%) 59.2 65.1
30.2 21.2
3.2
3.5
5.3 5.5 5.2
61.7 62.0 62.9
26.0 25.1 26.0
1.2
NS
NS
4.3
OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular contents, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively.
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Hinohikari (a balance between a 81.1% higher dry weight per tiller and a 40.5% fewer tillers per square meter than Hinohikari) (Tables 2 and 3). However, Nishiaoba, which had a 4 days’ longer vegetative growth than Hinohikari, produced almost the same dry matter yield as Hinohikari (25.6% higher dry weight per tiller but 21.2% fewer tillers per square meter than Hinohikari). Early transplanted plants, which had a 19 days’ longer vegetative growth than normally transplanted plants, produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. Therefore, early transplanted Tachiaoba produced the highest dry matter yield in the experiment. We also examined the effects of planting time and cultivar on estimated TDN content. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade (Tables 2 and 3), because panicles have a higher ratio of starch to dry weight than these other components. Yamaguchi et al. (2007) reported a significant negative correlation between estimated TDN content in whole plants and the ratio of stem and leaf to total dry weight within cultivars. Our study also showed that Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 2004 (Table 2). However, early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% (an average of both years) higher estimated TDN content in the whole plant than normally transplanted plants (Tables 2 and 3). This is because early transplanted plants had a 4.7% higher estimated TDN content, 1.8% higher OM and 6.7% higher OCC contents, and 4.8% lower OCW and 6.0% lower Ob contents in leaf sheath plus stem than normally transplanted plants (Tables 2, 3, 5 and 6). Thus, early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because, although they had a lower ratio of panicle to total dry weight, they had a higher estimated TDN content in leaf sheath plus stem, owing to higher OM and OCC contents than normally transplanted plants. Yamaguchi and Matsumura (2004) reported a significant negative correlation between NSC content in leaf sheath plus stem at maturity and harvest index within cultivars, and Matsumura (2007) reported a significant negative correlation between NSC content in leaf sheath plus stem at maturity and ratio of panicle to total dry weight within cultivars. Our results show that Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had 3.5% and 4.0% higher NSC contents in leaf sheath plus stem than Hinohikari, respectively, in 2004 (Tables 2 and 5). Tsuno and Yu (1988) and Yamaguchi and Matsumura (2004) indicated that competition between sinks (i.e., panicles) and sources (i.e., leaf and stem) resulted in such accumulation of NSC in leaf sheath plus stem. Early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 6.0% higher NSC content in leaf sheath plus stem (Tables 2, 3, 5 and 6). These results suggest that early transplanted plants
accumulated higher NSC in leaf sheath plus stem than normally transplanted plants, because they had a higher ratio of source (i.e., leaf and stem) in the whole plant than normally transplanted plants. Treatment with a-amylase accounted for the highest OCC and NSC contents, which was derived from starch. Therefore, early transplanted plants accumulated higher OCC and NSC contents in leaf sheath plus stem than normally transplanted plants (Tables 5 and 6). As a result, early transplanted plants had a higher estimated TDN content than normally transplanted plants (Tables 2 and 3). However, they had a lower ratio of panicle to dry weight, and the panicles had a higher estimated TDN content than leaf sheath plus stem and leaf blade, compared to normally transplanted plants. Overall, then, early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari, because it produced a 10.2% higher dry matter yield than Nishiaoba and a 9.0% higher than Hinohikari, and it and Nishiaoba produced 1.3% and 0.2% lower estimated TDN contents in the whole plant than Hinohikari, respectively (Tables 2 and 3). Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants, because they had a 14.9% higher dry matter yield and a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Thus, early transplanted Tachiaoba produced the highest estimated TDN yield in the experiment. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and estimated TDN yields in southwestern Japan. Forage rice is gaining more attention not only in Japan but also in Korea (Seo, 2005). Although this study was conducted in southwest Japan, our findings should be applicable to Korea, which is almost the same climate as Japan, and temperate area. In Japan, although combine harvesters have been developed to harvest forage rice (Urakawa and Yoshimura, 2003), they drop grain. Furthermore, grain is not often digested by cows because it is covered with hull (Nakui et al., 1988). Therefore, depending on the leaf sheath plus stem instead of the panicle for nutrition can reduce the loss of nutrition when forage rice is harvested by combine harvester and digested by cows. 5. Conclusion The cultivar Tachiaoba produced a 81.1% higher dry weight per tiller but a 40.5% fewer tillers per square meter than Hinohikari, thus producing a 9.0% higher dry matter yield. Nishiaoba produced almost the same dry matter yield as Hinohikari. Early transplanted plants produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade. Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 1 of 2 years. However, early transplanted plants, which had a
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Early transplanted plants had a 4.7% higher estimated TDN content in leaf sheath plus stem than normally transplanted plants. These results suggest that early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because of the higher estimated TDN content in leaf sheath plus stem. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari. Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and TDN yields in southwestern Japan. Acknowledgements This study was supported by a grant of the Integrated Research for Developing Japanese-style Forage Feeding System to Increase Forage Self-support Ratio from the Ministry of Agriculture, Forestry and Fishers of Japan. The authors thank Mr. Akitoshi Honbu, Ms. Fujiko Komiya, and Ms. Fumie Tsuru, National Agricultural Research Center for Kyushu Okinawa Region, for their invaluable help and cooperation in the field. References Chalupa, W., 1968. Problem in feeding urea to ruminants. J. Dairy Sci. 27, 207– 219. Hattori, I., Sato, K., Kobayashi, R., Ishida, M., Yoshida, N., Ando, S., 2005. Estimation of total digestible nutrients content of paddy rice silage. Jpn. J. Grassland Sci. 51, 269–273. Kobayashi, R., Sato, K., Hattori, I., 2006a. Evaluation of cv. ‘‘Sprice’’ as forage rice in a ratoon cropping system. Jpn. J. Grassland Sci. 52, 133–137 (in Japanese with English synopsis). Kobayashi, R., Sato, K., Hattori, I., 2006b. Optimizing fertilizer application rate, planting density, and cutting time to maximize dry matter yield by ratoon cropping in forage rice (Oryza sativa L.). Jpn. J. Grassland Sci. 52, 138–143 (in Japanese with English synopsis).
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Matsumura, O., 2007. Varietal characteristics about nonstructural carbohydrate accumulation in the stem of rice plant for rice forage use. Jpn. J. Crop Sci. 76 (Extra issue 1), 50–51 (in Japanese with English title). Nakano, H., Morita, S., 2007. Effects of twice harvesting on total dry matter yield of rice. Field Crop Res. 101, 269–275. Nakano, H., Morita, S., 2008. Effects of time of first harvest, total amount of nitrogen, and nitrogen application method on total dry matter yield in twice harvesting of rice. Field Crop Res. 105, 40–47. Nakui, T., Masaki, S., Aihara, T., Yahara, N., Takai, S., 1988. The making of rice whole crop silage and an evaluation of its value as forage for ruminants. Bull. Tohoku Natl. Agric. Exp. Stn. 78, 161–174 (in Japanese with English summary). Ohnishi, M., Horie, T., 1999. A proxy analysis of nonstructural carbohydrate in rice plant by using the gravimetric method. Jpn. J. Crop Sci. 68, 126–136 (in Japanese with English abstract). Saitoh, K., Ohnaka, T., Kuroda, T., 2000. Effect of dark respiration on dry matter production of field-grown rice cultivars—growth efficiency of early, medium, and rate-maturing cultivars. Jpn. J. Crop Sci. 69, 380–390 (in Japanese with English abstract). Sakai, M., Iida, S., Maeda, H., Sunohara, Y., Nemoto, H., Imbe, T., 2003. New rice varieties for whole crop silage use in Japan. Breed. Sci. 53, 271–275. Sakai, M., Okamoto, M., Tamura, K., Kaji, R., Mizobuchi, R., Hirabayashi, H., Yagi, T., Nishimura, M., Fukaura, S., 2007. A new rice variety for whole crop silage use ‘‘Tachiaoba’’. Breed. Res. 9 (Extra issue 1), 50 (in Japanese with English title). Seo, S., 2005. Forage production and animal husbandry in Korea. Grassland Sci. 51, 21–25. Tamura, K., Okamoto, M., Kaji, R., Hirabayashi, H., Mizobuchi, R., Yagi, T., Yamashita, H., Nishiyama, H., Motomura, H., Takita, T., Saitoh, K., 2007. A new rice variety for whole crop silage, ‘‘Nishiaoba’’. Bull. Natl. Agric. Res. Cent. Kyushu Okinawa Reg. 48, 31–48. Tsuno, Y., Yu, L.W., 1988. Factors affecting the ripening process of different rice cultivars. Jpn. J. Crop Sci. 57, 119–131 (in Japanese with English abstract). Urakawa, S., Yoshimura, Y., 2003. Development of the cutting roll baler for the rice whole crop silage. Jpn. J. Grassland Sci. 49, 43–48 (in Japanese with English synopsis). Yamaguchi, H., Matsumura, O., 2004. The re-accumulation of starch in the stem of rice at harvest viewed from a sink-source relationship as a characteristic of whole crop silage. Jpn. J. Crop Sci. 73, 402–409 (in Japanese with English abstract). Yamaguchi, H., Kimura, S., Yaji, Y., 2007. Growth and yield of forage rice indirect seeding with uncoated seeds in cold region. Jpn. J. Crop Sci. 76 (Extra issue 1), 48–49 (in Japanese with English title).
Effects of planting time and cultivar on dry matter yield and estimated total digestible nutrient content of forage rice in southwestern Japan Hiroshi Nakano *, Satoshi Morita, Ikuo Hattori, Kenji Sato National Agricultural Research Center for Kyushu Okinawa Region, Chikugo, Fukuoka 833-0041, Japan Received 12 June 2007; received in revised form 24 August 2007; accepted 25 August 2007
Abstract We examined the effects of planting time and cultivar on dry matter yield of forage rice in southwestern Japan. The cultivar Tachiaoba produced a 81.1% higher dry weight per tiller but a 40.5% fewer tillers per square meter than Hinohikari, thus producing a 9.0% higher dry matter yield. Nishiaoba produced almost the same dry matter yield as Hinohikari. Early transplanted plants produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. Early transplanted Tachiaoba produced the highest dry matter yield in the experiment. We also examined the effects of planting time and cultivar on estimated total digestible nutrient (TDN) content. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blades. Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 1 of the 2 years. However, early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Early transplanted plants had a 4.7% higher estimated TDN content in leaf sheath plus stem than normally transplanted plants. These results suggest that early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because of the higher estimated TDN content in leaf sheath plus stem. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari. Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants. Early transplanted Tachiaoba produced the highest estimated TDN yield in this experiment. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and estimated TDN yields. # 2007 Elsevier B.V. All rights reserved. Keywords: Dry matter yield; Estimated total digestible nutrient (TDN) content; Forage rice; Oryza sativa L.; Planting time
1. Introduction The production of forage rice (Oryza sativa L.) is increasing in Japan because of improved control of rice grain production and increasing demand for domestic forage (Sakai et al., 2003). In general, high dry matter yield and high total digestible nutrient (TDN) content are required for forage rice. There are three main cropping systems for forage rice in southwestern Japan: forage rice single cropping (very early planting), forage rice–Italian ryegrass (Lolium multiflorum Lam.) cropping (early planting), and forage rice–wheat (Triticum aestivum L.) or forage rice–barley (Hordeum vulgare L.) cropping (normal planting). We previously examined the effect of twice harvesting (i.e., ratoon cropping) of forage rice, with the first harvest at the full heading stage, on total dry
* Corresponding author. Tel.: +81 942 52 0670; fax: +81 942 53 7776. E-mail address: [email protected] (H. Nakano). 0378-4290/$ – see front matter # 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.fcr.2007.08.005
matter yield of four cultivars transplanted very early (i.e., late April) in southwestern Japan (Nakano and Morita, 2007). Taporuri produced the highest total dry matter yield (22.7 t ha1), with a value 60% higher than that of Hinohikari. Manipulating the time of first harvest, the total amount of nitrogen, and the nitrogen application method increased this cultivar’s total dry matter yield to 27.1 t ha1 (Nakano and Morita, 2008). However, twice harvesting is not feasible for early and normal plantings because it requires long growth duration. In addition, Taporuri generally lodge during ripening in early and normal planting. Recently, the new cultivars Nishiaoba and Tachiaoba, which perform acceptably as forage rices in southwestern Japan, were developed by the National Agricultural Research Center for Kyushu Okinawa Region (Sakai et al., 2007; Tamura et al., 2007). When farmers grow forage rice, they must decide on the planting time and cultivar in order to maximize the dry matter yield and TDN content. Although several studies have reported techniques for the cultivation of forage rice (Yamaguchi and
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
Matsumura, 2004; Kobayashi et al., 2006a,b), information on the effects of planting time and cultivar on dry matter yield and estimated TDN content of forage rice in southwestern Japan is limited. Using enzymatic analysis, organic matter (OM) content in forage can be fractioned into organic cellular content (OCC) and organic cell wall (OCW) contents by a-amylase and actinase (Chalupa, 1968). OCW is further fractioned into organic a (Oa, high digestibility fibre) and organic b (Ob, low digestibility fibre) contents by cellulase. Estimated TDN content in forage rice can be calculated from these components. Our objective in the present study was to determine the effects of planting time and cultivar on dry matter yield and estimated TDN content of forage rice grown in southwestern Japan. 2. Materials and methods 2.1. Crop management The study was conducted on a Grey Lowland soil at the National Agricultural Research Center for Kyushu Okinawa Region (338120 N latitude, 1308300 E longitude, 10 m asl), Chikugo, Fukuoka, Japan, in 2004 and 2005. The previous crop grown in the field was rice, and the same field was used for the experiments in both years of the study. The mean temperature during late August in 2005 was 2.1 8C lower than that in 2004, whereas mean temperature during late September, early October, and mid-October in 2005
117
was 2.2, 2.4, and 2.5 8C higher, respectively, than that in 2004 (Fig. 1). Solar radiation during early and mid-July in 2005 was 11.3 and 6.1 MJ m2 d1 lower, respectively, than that in 2004, whereas solar radiation during late June and late September in 2005 was 6.0 and 7.4 MJ m2 d1 higher, respectively, than that in 2004. Therefore, the mean temperature and solar radiation during the early growth stage in 2004 was generally higher than those in 2005, whereas mean temperature and solar radiation during the late growth stage in 2005 was generally higher than those in 2004. The experiment had a 2 (planting time) 3 (cultivar) factorial design arranged in a randomized complete block with three replicates. The planting times were early and normal. The three cultivars were Tachiaoba and Nishiaoba, which were developed as forage rices, and Hinohikari, which is normally grown as food rice in southwestern Japan. Germinated seeds were sown in nursery boxes in late April for early planting or in late May for normal planting and grown in a greenhouse. Seedlings were transplanted to the paddy field by hand in late May for the early transplanted treatment or in late June for the normally transplanted treatment. The mean number of fully expanded leaves on the main culm at transplanting was 4.2. The field received 30 kg N, 13 kg P, and 25 kg K ha1 in the form of chemical fertilizer broadcast by hand 3 days before transplanting, and the fertilizer was incorporated into the soil in such a way as to allow puddling. Plants received 30 kg N ha1 in the form of ammonium sulfate just after transplanting, at the maximum tiller number stage,
Fig. 1. Mean temperature and solar radiation in 2004 (*), 2005 (&), and normal (~) at Chikugo. Normal data is the mean of 30 years (from 1971 to 2000).
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H. Nakano et al. / Field Crops Research 105 (2008) 116–123
and at 20 and 10 days before heading, respectively. These supplemental applications were broadcast by hand on the plot surface but were not incorporated into the soil. After trimming, each plot was 1.5 m 9.0 m with a mean of 22.2 hills m2 (3 seedlings hill1, 30 cm 15 cm). Twenty hills (0.9 m2) were mowed by hand to ground level at the yellow ripe stage (for the early transplanted treatment, the yellow ripe stages of Tachiaoba, Nishiaoba, and Hinohikari were late September, late September, and mid-September, and for the normally transplanted treatment, mid-October, early October, and late September, respectively), and the number of tillers per square meter was measured. Plants from 2 hills with an average number of tillers were divided into leaf blade, leaf sheath plus stem, and panicle, and then dried at 80 8C in a ventilated oven for 2 days with the plants from the other18 hills to determine their dry weight.
Ohnishi and Horie (1999). Dried samples were ground in a vibrating sample mill (TI-100, Heiko Seisakusho, Tokyo, Japan). About 500 mg of each was placed in a pressure bottle with 30 ml of distilled water and then boiled on a hot plate for 30 min at 100 8C and then for 20 min at 180 8C. After it cooled, we added 20 ml of sodium phosphate–phosphoric acid buffer (pH 7.4) containing 1.5 mg of a-amylase, 0.5 mg of amyloglucosidase, and 0.5 mg of sodium azide. Each sample was incubated with continuous shaking for 24 h at 40 8C and then filtered through a filter paper (No. 5A, Advantec, Tokyo, Japan). The residues were dried at 135 8C for 4 h to determine their dry weights. NSC content was estimated as follows:
2.2. Estimation of total digestible nutrients
2.4. Statistical analysis
Each dried sample was ground in a Wiley mill (WT-100, Ikemoto Scientific Technology, Tokyo, Japan) and passed through a 1-mm screen. About 500 mg of each sample was placed in a filter bag (F57, Ankom Technology, Macedon, NY, USA), soaked in boiling water for 5 min, and then incubated in 2 L of sodium acetate–acetic acid buffer (pH 5.8) containing 100 mg of a-amylase, 800 mg of actinase, and 70 mg of calcium acetate in a digestion vessel (DAISYII Incubator, Ankom Technology) for 16 h at 40 8C. Each sample residue was rinsed twice with boiling water for 5 min and then twice with cold water for 5 min in a digestion vessel (ANKOM200 Fiber Analyzer, Ankom Technology) and then used for measurement of Ob content, which is resistant to cellulase treatment, and OCW content. For measurement of Ob content, sample residue after treatment with a-amylase and actinase was incubated in 2 L of sodium acetate–acetic acid buffer (pH 4.0) containing 20 mg of cellulase in a digestion vessel (DAISYII Incubator) for 4 h at 40 8C, rinsed twice with boiling water for 5 min and cold water for 5 min in a digestion vessel (ANKOM200 Fiber Analyzer), soaked in acetone for 15 min, dried at 135 8C for 2 h to determine its dry weight, and then burnt at 600 8C for 2 h to determine its ash (CA) content. For measurement of OCW content, sample residue after treatment with a-amylase and actinase was soaked in acetone for 15 min, dried at 135 8C for 2 h to determine its dry weight, and then burnt at 600 8C for 2 h to determine its CA content. TDN content was estimated according to Hattori et al. (2005), as follows:
We used analysis of variance to test differences among treatments. When the F-test of the analysis of variance exceeded the 0.05 level of probability, treatment effects were compared by using the LSD.
TDN ¼ 5:45 þ 0:89ðOCC þ OaÞ þ 0:45OCW; OCC ¼ 100 ðOCW þ CAÞ; OM ¼ 100 CA
Oa ¼ OCW Ob;
2.3. Estimation of nonstructural carbohydrate content in leaf sheath plus stem The nonstructural carbohydrate (NSC) content of leaf sheath plus stem was estimated according to the method of
NSC ¼
sample weight residual weight 100 sample weight
3. Results 3.1. Duration of vegetative growth The duration of vegetative growth differed significantly (P < 0.05) between planting times and among cultivars (Table 1). Early transplanted plants generally had a longer vegetative growth duration (91 days averaged over both years) than normally transplanted plants (72 days) (Tables 2 and 3). Tachiaoba generally had the longest vegetative growth duration (89 days), followed by Nishiaoba (80 days) and Hinohikari (76 days). 3.2. Dry matter yield and its components The dry matter yield differed significantly (P < 0.05) between planting times (Table 1). Early transplanted plants produced a 14.9% higher dry matter yield (16.0 t ha1 averaged over both years) than normally transplanted plants (13.9 t ha1) (P < 0.05) (Tables 2 and 3). Among the components of yield, early transplanted plants produced a 5.5% fewer tillers per square meter than normally transplanted plants in 2004 (P < 0.05), but there was no difference in 2005. Early transplanted plants produced a 21.1% higher dry weight per tiller than normally transplanted plants (P < 0.05). The dry matter yield differed significantly (P < 0.05) between cultivars (Table 1). Tachiaoba produced a 10.2% higher dry matter yield (15.9 t ha1 averaged over both years) than Nishiaoba (14.4 t ha1), and a 9.0% higher than Hinohikari (14.6 t ha1) (P < 0.05) (Tables 2 and 3). Tachiaoba and Nishiaoba produced 40.5% and 21.2% fewer tillers per square meter than Hinohikari, respectively (P < 0.05). Tachiaoba and Nishiaoba produced 81.1% and
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
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Table 1 Analysis of variance of vegetative growth, dry matter yield, dry matter yield components, and estimated TDN content in 2004 and 2005a Vegetative growth (days)b
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tilled1)
Panicle ratio (%) c
Whole plant (%) c
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
Yield (t ha1)
2004 Planting time (A) Cultivar (B) AB
** ** *
** * NS
** ** NS
** ** **
** ** **
** ** *
NS NS NS
** NS NS
NS * NS
** * NS
2005 Planting time (A) Cultivar (B) AB
** ** **
** ** NS
NS ** NS
** ** **
** NS *
NS NS NS
* NS NS
** NS NS
NS NS NS
** ** NS
a b c
Estimated TDN content
*, ** Significant at the 0.05 and the 0.01 levels, respectively. The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
25.6% higher dry weights per tiller than Hinohikari, respectively (P < 0.05).
Tachiaoba and Nishiaoba had 5.2% and 4.2% lower ratios (41.9% and 42.9%, respectively) than Hinohikari (47.1%), respectively, in 2004.
3.3. Ratio of panicle to total dry weight 3.4. Estimated total digestible nutrient content The ratio of panicle to total dry weight differed significantly (P < 0.05) between planting times in both years and among cultivars in 2004 (Table 1). Early transplanted plants had a 5.9% lower ratio (42.5% averaged over both years) than normally transplanted plants (48.4%) (Tables 2 and 3).
The estimated TDN content in the whole plant differed significantly (P < 0.05) between planting times and among cultivars in 2004 (Table 1). Early transplanted plants had a 1.0% higher estimated TDN content (56.6%) than normally
Table 2 Effects of planting time and cultivar on dry matter yield, dry matter yield components, and estimated TDN content in 2004
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05) AB Early planting Tachiaoba Nishiaoba Hinohikari Normal planting Tachiaoba Nishiaoba Hinohikari LSD (0.05) a b
Vegetative growth (days)a
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tiller1)
Panicle ratio (%) b
Whole plant (%)
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
90 72
16.2 13.6
330 348
5.13 4.09
42.3 45.6
56.6 55.6
40.7 40.8
47.4 42.6
72.0 71.9
9.2 7.6
0
0.5
12
0.08
0.6
0.5
NS
0.3
89 79 75
15.6 14.5 14.7
260 335 422
6.01 4.33 3.50
41.9 42.9 47.1
55.4 55.4 57.4
70.9 72.6 72.3
8.6 8.0 8.4
0
0.7
15
0.10
0.7
0.7
1.3
0.4
98 88 84
16.9 15.7 16.0
251 329 410
6.74 4.78 3.89
40.0 42.1 44.8
80 70 65
14.2 13.2 13.5
269 341 435
5.29 3.88 3.10
NS
NS
0.15
1
Estimated TDN content
NS
1.3
Yield (t ha1)
41.2 40.1 41.0
45.7 43.8 45.5
NS
NS
56.0 56.4 57.2
41.2 40.2 40.7
48.6 46.2 47.4
70.4 73.3 72.2
9.5 8.9 9.1
43.8 43.6 49.5
54.9 54.4 57.5
41.1 40.0 41.3
42.7 41.4 43.7
71.3 72.0 72.4
7.8 7.2 7.7
1.0
0.9
NS
NS
NS
The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
NS
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H. Nakano et al. / Field Crops Research 105 (2008) 116–123
Table 3 Effects of planting time and cultivar on dry matter yield, dry matter yield components, and estimated TDN content in 2005 Vegetative growth (days)a
Dry matter yield and its components Yield (t ha1)
Tillers per square meter (tillers m2)
Dry weight per tiller (g tiller1)
Panicle ratio (%)b
Whole plant (%)
Leaf blade (%)
Leaf sheath puls stem (%)
Panicle (%)
91 72
15.7 14.2
334 340
5.08 4.35
42.7 51.2
57.9 57.7
42.8 41.0
48.1 43.5
73.3 72.2
9.1 8.2
LSD (0.05)
0
0.5
NS
0.17
1.7
1.5
2.0
NS
0.4
Cultivar (B) Tachiaoba Nishiaoba Hinohikari
88 81 77
16.1 14.3 14.4
251 334 427
6.45 4.31 3.38
45.5 47.9 47.4
57.7 58.8 57.0
43.2 41.3 41.2
45.5 45.8 46.1
72.8 74.6 70.8
9.3 8.4 8.2
LSD (0.05)
0
0.6
29
0.20
NS
NS
NS
NS
NS
0.5
98 90 87
17.1 14.9 15.3
241 317 445
7.08 4.70 3.46
40.1 45.4 42.5
57.6 59.6 56.6
44.3 42.5 41.5
48.6 47.4 48.3
73.0 76.1 70.8
9.8 8.9 8.7
79 71 67
15.2 13.8 13.5
261 350 410
5.83 3.93 3.30
50.9 50.4 52.4
57.7 58.0 57.4
42.0 40.1 40.9
42.4 44.3 43.8
72.6 73.1 70.8
8.8 8.0 7.8
NS
NS
0.29
3.0
NS
NS
NS
NS
Planting time (A) Early planting Normal planting
AB Early planting Tachiaoba Nishiaoba Hinohikari Normal planting Tachiaoba Nishiaoba Hinohikari LSD (0.05) a b
1
Estimated TDN content
NS
Yield (t ha1)
NS
The duration of vegetative growth is the number of days from transplanting to the heading stage. Panicle ratio is ratio of panicle to total dry weight.
transplanted plants (55.6%) (Table 2). Tachiaoba and Nishiaoba had a 2.0% lower estimated TDN content (55.4% each) than Hinohikari (57.4%). The estimated TDN content in leaf sheath plus stem differed significantly (P < 0.05) between planting times (Table 1). Early transplanted plants had a 4.7% higher estimated TDN content (47.8% averaged over both years) than normally transplanted plants (43.1%) (Tables 2 and 3). The estimated TDN content in panicles was generally 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade (Tables 2 and 3).
3.5. Contents of fractions obtained by enzymatic analysis of leaf sheath plus stem The OM, OCC, OCW, and Ob contents in leaf sheath plus stem differed significantly (P < 0.05) between planting times (Table 4). Early transplanted plants had 1.8% higher OM and 6.7% higher OCC contents in leaf sheath plus stem (85.9% and 20.3% averaged over both years, respectively) than normally transplanted plants (84.1% and 13.6%) (Tables 5 and 6). Early transplanted plants had 4.8% lower OCW and 6.0% lower Ob contents in leaf sheath plus stem (65.7% and
Table 4 Analysis of variance of contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2004 and 2005a OMb (%)
OMb
OCWb
NSCb (%)
OCCb (%)
OCWb (%)
Oab (%)
Obb (%)
2004 Planting time (A) Cultivar (B) AB
* NS NS
** * NS
** * NS
** ** NS
** NS NS
** ** NS
2005 Planting time (A) Cultivar (B) AB
** NS NS
** NS NS
** NS NS
NS NS NS
** NS NS
** NS NS
a
*, ** Significant at the 0.05 and the 0.01 levels, respectively. OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular content, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively. b
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
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Table 5 Effects of planting time and cultivar on contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2004 OMa (%)
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05)
OMa
OCWa
NSCa (%)
OCCa (%)
OCWa (%)
Oaa (%)
Oba (%)
84.9 83.9
17.9 13.6
67.0 70.3
7.6 4.8
59.4 65.5
20.9 18.0
0.8
1.7
1.9
1.2
2.3
1.8
84.5 84.2 84.6
16.3 16.9 14.1
68.2 67.2 70.6
6.7 4.4 7.5
61.5 62.8 63.1
20.5 21.0 17.0
2.0
2.4
1.5
NS
NS
2.2
a
OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular content, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively.
59.3%) than normally transplanted plants (70.5% and 65.3%). The OCC, OCW, and Oa contents in leaf sheath plus stem differed significantly (P < 0.01) among cultivars in 2004 (Table 4). Tachiaoba and Nishiaoba had 2.2% and 2.8% higher OCC contents (16.3% and 16.9%, respectively) than Hinohikari (14.1%), respectively (Table 5). Tachiaoba and Nishiaoba had 2.4% and 3.4% lower OCW contents (68.2% and 67.2%) than Hinohikari (70.6%). Tachiaoba and Hinohikari had 2.3% and 3.1% higher Oa contents (6.7% and 7.5%) than Nishiaoba (4.4%), respectively, in 2004. 3.6. Nonstructural carbohydrate content in leaf sheath plus stem
3.7. Estimated total digestible nutrient yield The estimated TDN yield differed significantly (P < 0.05) between planting times and among cultivars (Table 1). Early transplanted plants produced a 16.1% higher estimated TDN yield (9.1 t ha1 averaged over both years) than normally transplanted plants (7.9 t ha1) (P < 0.05) (Tables 2 and 3). Tachiaoba and Hinohikari produced 8% and 5% higher estimated TDN yields (8.6 and 8.4 t ha1, respectively) than Nishiaoba (8.0 t ha1), respectively, in 2004, and Tachiaoba produced 10% and 13% higher estimated TDN yields (9.3 t ha1) than Nishiaoba and Hinohikari (8.4 and 8.2 t ha1), 1), respectively, in 2005. 4. Discussion
The NSC content in leaf sheath plus stem differed significantly (P < 0.05) between planting times in both years and among cultivars in 2004 (Table 4). Early transplanted plants had a 6.0% higher NSC content (25.6% averaged over both years) than normally transplanted plants (19.6%) (Tables 5 and 6). Tachiaoba and Nishiaoba had 3.5% and 4.0% higher NSC contents (20.5% and 21.0%) than Hinohikari (17.0%), respectively.
We examined the effects of planting time and cultivar on dry matter yield of forage rice in southwestern Japan. Cultivars with a long vegetative growth duration generally have a higher dry matter yield than those with a short vegetative growth duration (e.g., Saitoh et al., 2000; Nakano and Morita, 2007). Tachiaoba, which had a 13 days’ longer vegetative growth than Hinohikari, produced a 9.0% higher dry matter yield than
Table 6 Effects of planting time and cultivar on contents of fractions obtained by enzymatic analysis in leaf sheath plus stem in 2005 OMa (%)
OMa
OCWa a
Planting time (A) Early planting Normal planting LSD (0.05) Cultivar (B) Tachiaoba Nishiaoba Hinohikari LSD (0.05) a
a
OCC (%)
OCW (%)
86.9 84.3
22.6 13.6
64.3 70.7
0.9
3.6
3.1
85.1 85.5 86.3
18.2 18.0 18.2
66.9 67.5 68.2
4.4
3.8
NS
a
Oa (%) 5.0 5.6
NSCa (%) a
Ob (%) 59.2 65.1
30.2 21.2
3.2
3.5
5.3 5.5 5.2
61.7 62.0 62.9
26.0 25.1 26.0
1.2
NS
NS
4.3
OM, OCC, OCW, Oa, Ob, NSC represent organic matter, organic cellular contents, organic cell wall, organic a, organic b, and nonstructural carbohydrate, respectively.
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Hinohikari (a balance between a 81.1% higher dry weight per tiller and a 40.5% fewer tillers per square meter than Hinohikari) (Tables 2 and 3). However, Nishiaoba, which had a 4 days’ longer vegetative growth than Hinohikari, produced almost the same dry matter yield as Hinohikari (25.6% higher dry weight per tiller but 21.2% fewer tillers per square meter than Hinohikari). Early transplanted plants, which had a 19 days’ longer vegetative growth than normally transplanted plants, produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. Therefore, early transplanted Tachiaoba produced the highest dry matter yield in the experiment. We also examined the effects of planting time and cultivar on estimated TDN content. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade (Tables 2 and 3), because panicles have a higher ratio of starch to dry weight than these other components. Yamaguchi et al. (2007) reported a significant negative correlation between estimated TDN content in whole plants and the ratio of stem and leaf to total dry weight within cultivars. Our study also showed that Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 2004 (Table 2). However, early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% (an average of both years) higher estimated TDN content in the whole plant than normally transplanted plants (Tables 2 and 3). This is because early transplanted plants had a 4.7% higher estimated TDN content, 1.8% higher OM and 6.7% higher OCC contents, and 4.8% lower OCW and 6.0% lower Ob contents in leaf sheath plus stem than normally transplanted plants (Tables 2, 3, 5 and 6). Thus, early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because, although they had a lower ratio of panicle to total dry weight, they had a higher estimated TDN content in leaf sheath plus stem, owing to higher OM and OCC contents than normally transplanted plants. Yamaguchi and Matsumura (2004) reported a significant negative correlation between NSC content in leaf sheath plus stem at maturity and harvest index within cultivars, and Matsumura (2007) reported a significant negative correlation between NSC content in leaf sheath plus stem at maturity and ratio of panicle to total dry weight within cultivars. Our results show that Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had 3.5% and 4.0% higher NSC contents in leaf sheath plus stem than Hinohikari, respectively, in 2004 (Tables 2 and 5). Tsuno and Yu (1988) and Yamaguchi and Matsumura (2004) indicated that competition between sinks (i.e., panicles) and sources (i.e., leaf and stem) resulted in such accumulation of NSC in leaf sheath plus stem. Early transplanted plants, which had a 5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 6.0% higher NSC content in leaf sheath plus stem (Tables 2, 3, 5 and 6). These results suggest that early transplanted plants
accumulated higher NSC in leaf sheath plus stem than normally transplanted plants, because they had a higher ratio of source (i.e., leaf and stem) in the whole plant than normally transplanted plants. Treatment with a-amylase accounted for the highest OCC and NSC contents, which was derived from starch. Therefore, early transplanted plants accumulated higher OCC and NSC contents in leaf sheath plus stem than normally transplanted plants (Tables 5 and 6). As a result, early transplanted plants had a higher estimated TDN content than normally transplanted plants (Tables 2 and 3). However, they had a lower ratio of panicle to dry weight, and the panicles had a higher estimated TDN content than leaf sheath plus stem and leaf blade, compared to normally transplanted plants. Overall, then, early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari, because it produced a 10.2% higher dry matter yield than Nishiaoba and a 9.0% higher than Hinohikari, and it and Nishiaoba produced 1.3% and 0.2% lower estimated TDN contents in the whole plant than Hinohikari, respectively (Tables 2 and 3). Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants, because they had a 14.9% higher dry matter yield and a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Thus, early transplanted Tachiaoba produced the highest estimated TDN yield in the experiment. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and estimated TDN yields in southwestern Japan. Forage rice is gaining more attention not only in Japan but also in Korea (Seo, 2005). Although this study was conducted in southwest Japan, our findings should be applicable to Korea, which is almost the same climate as Japan, and temperate area. In Japan, although combine harvesters have been developed to harvest forage rice (Urakawa and Yoshimura, 2003), they drop grain. Furthermore, grain is not often digested by cows because it is covered with hull (Nakui et al., 1988). Therefore, depending on the leaf sheath plus stem instead of the panicle for nutrition can reduce the loss of nutrition when forage rice is harvested by combine harvester and digested by cows. 5. Conclusion The cultivar Tachiaoba produced a 81.1% higher dry weight per tiller but a 40.5% fewer tillers per square meter than Hinohikari, thus producing a 9.0% higher dry matter yield. Nishiaoba produced almost the same dry matter yield as Hinohikari. Early transplanted plants produced a 14.9% higher dry matter yield and a 21.1% higher dry weight per tiller than normally transplanted plants. The estimated TDN content in panicles was 27.0% higher than that in leaf sheath plus stem and 31.1% higher than that in leaf blade. Tachiaoba and Nishiaoba, which had 5.2% and 4.2% lower ratios of panicle to total dry weight than Hinohikari, respectively, had a 2.0% lower estimated TDN content in the whole plant than Hinohikari in 1 of 2 years. However, early transplanted plants, which had a
H. Nakano et al. / Field Crops Research 105 (2008) 116–123
5.9% lower ratio of panicle to total dry weight than normally transplanted plants, had a 0.6% higher estimated TDN content in the whole plant than normally transplanted plants. Early transplanted plants had a 4.7% higher estimated TDN content in leaf sheath plus stem than normally transplanted plants. These results suggest that early transplanted plants had a higher estimated TDN content in the whole plant than normally transplanted plants because of the higher estimated TDN content in leaf sheath plus stem. Tachiaoba produced a 9.1% higher estimated TDN yield than Nishiaoba and a 7.7% higher than Hinohikari. Early transplanted plants produced a 16.1% higher estimated TDN yield than normally transplanted plants. Therefore, it is effective to plant Tachiaoba early to obtain high dry matter and TDN yields in southwestern Japan. Acknowledgements This study was supported by a grant of the Integrated Research for Developing Japanese-style Forage Feeding System to Increase Forage Self-support Ratio from the Ministry of Agriculture, Forestry and Fishers of Japan. The authors thank Mr. Akitoshi Honbu, Ms. Fujiko Komiya, and Ms. Fumie Tsuru, National Agricultural Research Center for Kyushu Okinawa Region, for their invaluable help and cooperation in the field. References Chalupa, W., 1968. Problem in feeding urea to ruminants. J. Dairy Sci. 27, 207– 219. Hattori, I., Sato, K., Kobayashi, R., Ishida, M., Yoshida, N., Ando, S., 2005. Estimation of total digestible nutrients content of paddy rice silage. Jpn. J. Grassland Sci. 51, 269–273. Kobayashi, R., Sato, K., Hattori, I., 2006a. Evaluation of cv. ‘‘Sprice’’ as forage rice in a ratoon cropping system. Jpn. J. Grassland Sci. 52, 133–137 (in Japanese with English synopsis). Kobayashi, R., Sato, K., Hattori, I., 2006b. Optimizing fertilizer application rate, planting density, and cutting time to maximize dry matter yield by ratoon cropping in forage rice (Oryza sativa L.). Jpn. J. Grassland Sci. 52, 138–143 (in Japanese with English synopsis).
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