Dry matter yield and quality evaluation at two phenological stages of forage triticale grown in the Po Valley and Sardinia, Italy

Field Crops Research 74 (2002) 207±215

Dry matter yield and quality evaluation at two phenological stages of forage triticale grown in the Po Valley and Sardinia, Italy G. Delogua,*, N. Faccinia, P. Facciolia, F. Reggiania, M. Lendinib, N. Berardoc, M. Odoardid a

Istituto Sperimentale per la Cerealicoltura, Sezione di Fiorenzuola d'Arda, Via S. Protaso 302, I-29017 Fiorenzuola d'Arda (PC), Italy b Centro Regionale Agrario Sperimentale, Viale Trieste 111, I-09100 Cagliari, Italy c Istituto Sperimentale per la Cerealicoltura, Sezione di Bergamo, Via Stezzano 24, I-24100 Bergamo, Italy d Istituto Sperimentale per le Colture Foraggere, Sezione di Chimica, Viale Piacenza 29, I-26900 Lodi, Italy Received 5 July 2001; received in revised form 15 October 2001; accepted 6 December 2001

Abstract Autumn-sown cereals are a very important source of nutrients for livestock. Moreover, the harvesting of the entire plant at milk-dough stage makes a double-cropping approach possible resulting in higher yields per unit area. Of the various winter cereals, triticale is particularly interesting due to its quality±quantity potential as whole-plant silage. Given the broad range of triticale cultivars available today and the important role played by the environment on the nutritional value of forages, the present study was undertaken to establish the adaptability of modern cultivars to different locations for high quality whole-plant production at two growing stages. Our results indicate the yield potential of triticale as silage both in irrigated or in rainfed Mediterranean areas. Regarding quality of the forage the best performance was recorded in Sardinian environments where plant growth was characterised by a gradual temperature increase. Thus, in Mediterranean areas, triticale could represent a viable source of livestock feed during the summer period offsetting the dearth of fresh forage typical in these environments. # 2002 Elsevier Science B.V. All rights reserved. Keywords: Triticale; Varieties; Environments; Dry matter yield; Quality

1. Introduction Autumn-sown cereals supply an important part of livestock nutrient requirements in that, in addition to using the grain as the basic portion of the standard *

Corresponding author. Tel.: ‡39-0523-983758; fax: ‡39-0523-983750. E-mail address: [email protected] (G. Delogu).

dietary regime, the entire plant can now be ensiled when harvested at the milk-dough stage of ripening. Such silage is best exploited in environments with low summer rainfall, which are ill-suited to a spring± summer crop. On the other hand, harvesting the entire plant at the milk-dough stage in environments marked by high fertility and good water supply makes it possible to maximise yields per unit area via double-cropping (winter cereal ‡ summer crop) (Delogu

0378-4290/02/$ ± see front matter # 2002 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 - 4 2 9 0 ( 0 2 ) 0 0 0 0 2 - 3

208

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

et al., 1979, 1990; Stanca, 1984; Siefers and Bolsen, 1997). A number of studies that have focused on the yield and quality potential of various cereal species earmarked for whole-plant silage production (Bonari, 1976; Gentinetta et al., 1983; Stanca et al., 1984; Bocchi et al., 1996) have found that their high variability in yield and nutritive value are linked to year and environment. Indeed, it is a known fact that the nutritional value of forages is dependent largely on seasonal temperature, light and rainfall trends, soil type, energy inputs applied over the growing cycle (Van Soest, 1994) and, to a lesser extent, to the cultivar within the species. Of the various winter cereals, triticale (X. Triticosecale Wittmark) has been studied widely for its quality±quantity potential as whole-plant silage since its introduction into many parts of the world (Sapra et al., 1973; Bishnoi and Walker, 1976; Brown and Almodares, 1976; Gentinetta et al., 1983). Comparative trials involving various cultivars have shown the biomass yield potential of triticale to be similar to, or greater than other small grain cereals. However, the data on quality appear to be more contradictory because this parameter is linked mainly to ripening stage at harvest (Cherney and Marten, 1982; Gentinetta et al., 1983; Brignall et al., 1988; Carnide et al., 1988; Jedel and Salmon, 1994; McCartney and Vaage, 1994; Siefers and Bolsen, 1997). While whole-plant triticale has been used traditionally as feed for dairy and beef cattle, its use as feed for sheep and goats in pasture-based systems is beginning to spread. Given these trends and the fact that a broader range of triticale cultivars are now available, the present study was undertaken to establish the adaptability to environments in the Po Valley in northern Italy, and in Sardinia of modern cultivars for whole-plant production of high quality forage at two growth stages. 2. Material and methods The trials were conducted over the 2-year period from 1993 to 1994 employing the nine Italian registered triticale varieties ``Antares'', ``Boccale'', ``Campo'', ``Catria'', ``Magistral'', ``Mizar'', ``Rigel'', ``Torpedo'' and ``Trica''. They were situated in six districts, three in

the Po Valley, namely Fiorenzuola (448560 N, 128270 E, altitude 76 m a.s.l.), acronymus F93 and F94, and Lonigo (458300 N, 118310 E, altitude 36 m a.s.l.), acronymus L94, marked by high fertile soils and continental regime rainfall (850 mm annual average), and three in the Mediterranean climate of Sardinia, i.e. Ussana (398260 N, 9850 E, altitude 110 m a.s.l.), acronymus U93 and U94, and Prato Sardo (408190 N, 98170 E, altitude 450 m a.s.l.), acronymus PS94, marked by 400 mm average annual rainfall mainly occurring in autumn and winter. The trials were carried out on soils characterised by 2±2.2% OM content in the upper layers at Fiorenzuola (soil type: ®ne silty, mixed, mesic Udic Ustochrepts) and Lonigo (soil type: clay loam, ®ne mixed Ustochrepts) and by 0.7 and 1.6% OM content in the upper layers, respectively, at Ussana (soil type: Typic Haploxerlf) and Prato Sardo (soil type: Typic Xerochrept). The experimental design at each site was a randomised complete block, with eight replications and each plot measured 10 m2: four earmarked for whole-plant harvest at heading and four at the milkdough stage. Sowing was carried out in late October at the Po Valley sites, at a density of 350 viable seeds m 2, and in early December at the Sardinian sites, at 300 viable seeds m 2. The basic pre-sowing fertilisation rates for all plots were 30 kg N/ha, 35 kg P/ha and 33 kg K/ha; a top dressing of 140 and 100 kg N/ha, respectively, was applied to the Po Valley and Sardinian plots as follows: 50% of total N at the 3±4 leaf stage and the remainder at the early stem-elongation stage. The different levels of nitrogen fertiliser applied in the Po Valley and Sardinian locations were established on the basis of previous experiments (Bianchi and Delogu, 1994). Plots were harvested at heading and at the milkdough stage by cutting the plants about 10 cm above ground level. Fresh biomass production from each plot (10 m2) was determined at harvest and is reported in MT (metric tonnes) of dry matter (DM) per hectare; a 500 g sample was also taken for the chemical assays. The samples were dried to constant weight at 65 8C in a forced-air oven. After cooling and weighing, the samples were ground to pass a 1 mm screen. The samples were subsequently re-ground in a Cyclotec mill (Tecator' Hoganas, Sweden) through a 1 mm sieve. All samples were analysed by NIRS (near

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

infrared re¯ectance spectroscopy) using equations developed by Bocchi et al. (1996), after testing the goodness-of-®t of the developed equations via a set of samples on which wet chemical analyses were carried out: for ash content by ashing at 550 8C for 6 h; for crude protein (CP), neutral detergent ®bre (NDF), acid detergent ®bre (ADF), acid detergent lignin (ADL), organic matter (OM) according to AOAC methods and milk feed units (MFU) after the energy production equations of Chase (1981). All chemical parameters determined in duplicate are expressed as g kg 1 of DM. Forage spectra were collected by means of an NIRSystems 5000 scanning monochromator (NIRSystems, Silver Spring, MD) with a rotating ring-cup sample cell. Samples were scanned at 2 nm intervals in the wavelength range between 1100 and 2500 nm. Spectral data were processed using ISI NIRS2 software (ISI, Port Matilda, PA). In addition to quantity and quality traits, each cultivar was rated for frost damage on a 0±9 scale (0: no damage; 9: all plants killed) after Rizza et al. (1997); heading date is expressed as days after 1 April and plant height, excluding the spike, in centimetres. The data were statistically analysed for each harvest using a factorial model that included environments, environment groups (Po Valley and Sardinia) and cultivars. 3. Results

209

Table 1 Days from sowing to cutting at heading and milk-dough stages of triticale in six environments and total rainfall (mm) Environment

Sowing to cutting Heading stage

Milk-dough stage

Days

Rainfalla (mm)

Days

Rainfallb (mm)

Po Valley F93 F94 L94

167 176 181

412 421 389

197 201 206

473 475 455

Mean

175

407

201

468

Sardinia U93 U94 PS94

125 115 141

208 131 285

157 140 168

298 194 340

Mean

127

208

155

277

a b

Total rainfall from sowing to heading. Total rainfall from sowing to milk-dough stage.

earlier than in the former, when the maximum and minimum temperatures reached 15.5 and 5.5 8C, and 23.5 and 10.5 8C, respectively. In contrast, these two stages occurred in the Po Valley at average values of temperature of 21.5/8.0 and 29.0/15.3 8C, respectively, with notable increases of the minimum temperature only from the end of March.

3.1. Weather conditions Total growing season rainfall and days to the two harvest dates in the various environments are shown in Table 1. Rainfall was clearly higher in the Po Valley (north) than in Sardinia (south): the northern crops had 389±421 mm up to heading date and 455±475 mm up to the milk-dough stage, whereas the Sardinian crops had 131±285 and 194±340 mm, respectively, up to both harvest dates. Fig. 1 shows the minimum and maximum air temperatures (averaged over 10 days) from 1 January to harvest date, as mean values of the three environments of Po Valley and three of Sardinia. The mean ranges of temperature clearly differentiate the Po Valley and Sardinia sites. Indeed, the mean heading and milkdough stage dates in the latter occur 25 and 23 days

Fig. 1. Minimum (square and circle open) and maximum (square and circle closed) air temperatures (8C) per 10-day period during the growing season (days from 1 January to harvest dates) as mean values of the environment groups (circle: Po Valley; square: Sardinia).

210

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

3.2. Dry matter yield The environments and environment groups were the largest source of variation in all characters studied, while the mean squares for the `environment  variety' and `group of environments  variety' interactions appeared very small compared to those associated with the main effect. Overall, the mean DM concentrations at the heading and milk-dough harvests were, respectively, 20 and 37%. On the other hand, the DM percentage at heading in the six trial environments ranged between 18% in F94 and 24% in PS94; at milk-dough it ranged between 34% in the Po Valley and 44% in Sardinia. Average DM yield across cultivars and environments was 7.6 and 13.2 MT ha 1 for harvests at the heading and milk-dough stages, respectively (Table 2). DM production at both harvest dates largely depended on environments. At the early heading stage it ranged between 10.7 MT ha 1 in L94 and 5.7 MT ha 1 in U94; at the milk-dough stage it ranged from

16.3 MT ha 1 in F94 to 10.6 MT ha 1 in PS94. The average yield capacity for the trial environments was 35% higher at the heading stage and 20% higher at milk-dough stage in the Po Valley than in Sardinia. The single environments registered a high variation for both growth stages, the intervals being markedly greater amongst those of the Po Valley than for those in Sardinia. For all six trial sites and at both harvest dates, the F93 and U93 environments differ notably. The former produced signi®cantly less DM at heading onset than the other two Po Valley environments, and does not differ signi®cantly from U93 in Sardinia. At the milkdough stage production is even lower than for U93. This ®nding can be explained by frost damage at the F93 site, which registered an index of 6 (Table 2). Average DM production per cultivar (Table 3) at heading and milkdough harvests, respectively, ranged between 8.4 and 14.9 MT ha 1 for Rigel. For Boccale and Campo cultivars the range was 6.6±6.8 and 11.4±11.6 MT ha 1,

Table 2 Mean DM yield (MT ha 1) of whole-plant triticale cut at the heading and milk-dough stages; heading date (days from 1 April) and plant height (cm) in six environments (mean of nine varieties), two environment groupings (mean of three environments of Po Valley and three of Sardinia) and frost damage Po Valleya

Sardiniaa

LSD0.01

F93

F94

L94

U93

U94

PS94

6.8 C 10.1±3.2

10.0 B 11.7±8.2 9.2 A

10.7 A 13.3±9.0

6.5 C 7.1±5.9

5.7 D 6.7±5.0 6.0 B

5.9 D 6.8±4.6

0.4** 1.3** 0.2**

12.9 D 15.4±8.3

16.3 A 19.2±13.9 14.6 A

14.6 B 17.7±11.3

13.8 C 15.1±12.5

10.8 B 13.2±8.8 11.7 B

10.6 E 11.6±8.0

0.7** 2.1** 0.4**

Heading (days from 1 April) Mean 41 A Mean

31 B 33 A

28 C

6E

8 DE 8B

10 D

2** 1**

Plant height (cm) Mean Mean

110 B 111

120 A

114 AB

102 C 108

107 bC

7** NSb

3B 4A

3B

0C

0C 0B

0C

2** 1**

DM (MT ha 1) Heading stage Mean Range Mean Milk-dough stage Mean Range Mean

102 C

Frost damage (scale 0±9) Mean 6A Mean a

Data with different letters are signi®cantly different. Not signi®cantly different. ** P < 0:01. b

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

211

Table 3 Mean value and range for DM yield (MT ha 1) of nine varieties of whole-plant triticale cut at the heading and milk-dough stages; heading date (days 1 April) and plant height (cm) (mean of six environments) and frost damage Cultivar

DM (MT ha 1)a Heading stage

Rigel Catria Torpedo Trica Mizar Antares Magistral Boccale Campo LSD0.01

Milk-dough stage

Po Valley

Sardinia

Mean

Po Valley

Sardinia

Mean

10.5 9.4 10.1 9.6 9.3 8.4 8.6 7.9 8.0

6.3 6.6 5.9 5.8 6.0 6.2 6.5 5.2 5.6

8.4 8.0 8.0 7.7 7.6 7.3 7.6 6.6 6.8

17.2 14.8 16.8 14.9 14.4 14.1 13.9 12.3 12.3

12.6 12.8 11.1 12.0 12.4 12.2 11.6 10.5 10.9

14.9 13.9 14.0 13.4 13.4 13.2 12.7 11.4 11.6

A BC AB BC CD C±E C±E E CDE

FGH F FGHI GHI FGH FGH FG I HI

0.7**

A AB AB BC BC CD BC E DE

A B A B B B BC DE DE

0.5**

D CD EFG DEF D DE DEG G FG

1.2**

A B B BC BC BC C D D

0.88**

Headinga (days from 1 April)

Plant heighta (cm)

Frost damagea,b (scale 0±9)

18 18 27 20 22 18 26 19 26

124 108 98 119 106 99 118 97 115

3 5 2 4 5 6 4 7 8

D D A C B D A CD A

1**

A C D AB C D B D B

5**

DE BCD E CDE BD ABC CDE B A

2.6**

a

Data with different letters are signi®cantly different. Value for F93: Fiorenzuola 1993. The frost damage reported is only relative to F93 as only in this environment the damage was very high, with high mortality of plants. ** P < 0:01. b

respectively. The interaction `environment groups  cultivar,' which was highly signi®cant, shows the response of cvs. Rigel, Catria and Torpedo: while the ®rst is high yielding in both groups of environments, Catria proved to be the top-yielder only in Sardinia and Torpedo only in the Po Valley at both harvest dates (Table 3). This response can be linked both to the differing earliness recorded by the three cultivars and to variation in stress tolerance. The importance of cold tolerance in the Po Valley is also underscored by the responses of cvs. Boccale and Campo at both harvest stages: they proved to be the lowest-yielding cultivars in the Po Valley and F93, i.e. at 3.2 and 4.0 MT ha 1, respectively, concomitant with frost injury ratings of 7 and 8 (Table 3). Similar to the trends for yield, the responses for heading date and plant height also showed marked variations linked to both environment and cultivar (Tables 2 and 3). 3.3. Chemical composition and nutritional value of DM 3.3.1. Heading stage Table 4 shows the average chemical composition and nutritional value of triticale forage harvested at

early heading in the six trial environments. Expressed as whole-plant CP, NDF, ADF and ADL, the average chemical pro®le is 108, 585, 362 and 37 g kg 1 DM, respectively; its corresponding estimated nutritional value is 0.72 MFU kg 1 DM. The observed variation in chemical composition appears largely linked to the environmental effect, although for all assayed parameters except CP content the signi®cant differences were registered amongst cultivars (Tables 4 and 5). While CP content (Table 4) varies over environments, ranging from 128 (F93) to 88 g kg 1 DM (PS94), it was on average signi®cantly higher in the Po Valley than in Sardinia (118 against 98 g kg 1 DM). Cell-wall contents of NDF, ADF and ADL in U93, U94 and PS94 environments in Sardinia (Table 4) were decidedly lower than those recorded for the Po Valley sites, with values of MFU kg 1 DM (0.79, 0.82 and 0.81, respectively) being accordingly higher. Amongst cultivars, although the variation in the NDF, ADF, ADL and MFU values was signi®cant, it appears limited when compared to environments (Tables 4 and 5). The cvs. Catria, Mizar, Rigel and Torpedo have the lowest ADF values (353±358 g kg 1 DM), which are accompanied by higher MFU average values (0.74±0.73 kg 1 DM).

212

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

Table 4 Chemical composition and nutritional value of whole-plant triticale (mean of nine varieties) cut at the heading stage in six environments of Italy Environment

CPa (g kg

F93 F94 L94 U93 U94 PS94

128 118 107 101 104 88

Mean LSD0.01

108 8**

585 13**

362 9**

37 2**

0.72 0.02**

Po Valley mean Sardinia mean LSD0.01

118 A 98 B 5**

643 A 527 B 8**

416 A 308 B 5**

42 A 31 B 1**

0.64 B 0.81 A 0.01**

a

1

DM)

A B C C C D

NDFa (g kg 603 650 676 516 522 544

1

DM)

C B A E E D

ADFa (g kg 392 432 425 318 296 309

1

DM)

B A A C E D

ADLa (g kg 44 37 45 32 28 34

1

DM)

A B A C D C

MFUa (kg 0.68 0.61 0.62 0.79 0.82 0.81

1

DM)

C D D B A AB

Data with different letters are signi®cantly different. P < 0:01.

**

from 303 to 392 g kg 1 DM at U94 and F94; and ADL ranges from 41 to 52 g kg 1 DM at U93 and L94 (Table 6). On average, the Sardinian sites corroborate that DM composition values are lower than those in the Po Valley in CP, NDF and ADF contents, in the order of 24, 7 and 18%. The forage nutritional value, expressed as MFU kg 1 DM, was on average 0.75 MFU kg 1 DM and showed notable variations linked mainly to environment groups (Po Valley: 0.69 MFU kg 1 DM; Sardinia: 0.81 MFU kg 1 DM). As with heading date harvest, CP content showed no signi®cant differences between cultivars (Table 7). At

3.3.2. Milk-dough stage The DM chemical composition at the milk-dough stage is reported in Tables 6 and 7. In general, with respect to the heading harvest, there is an expected drop in the values of all assayed parameters except for ADL content, which shows a notable increase (‡21%). At this stage, too, the effect of the environments on the expression of the individual traits is dominant with respect to cultivar and amongst sites. CP content varies between 55 and 87 g kg 1 DM at sites PS94 and F93; NDF varies from 548 and 616 g kg 1 DM at the U94 and L94 sites; ADF ranges

Table 5 Chemical composition and nutritional value of nine varieties of whole-plant triticale (mean of six environments) cut at the heading stage Cultivar

CP (g kg

Catria Rigel Torpedo Mizar Magistral Antares Boccale Campo Trica

107 112 111 104 110 113 107 108 106

LSD0.01

NSb

a

1

DM)

NDFa (g kg 576 580 593 592 576 591 593 595 598

1

C BC AB ABC C ABC AB AB A

16**

Data with different letters are signi®cantly different. Not signi®cantly different. ** P < 0:01. b

DM)

ADFa (g kg 353 355 358 358 365 367 367 367 373

D CD BCD BCD ABC AB AB AB A

10**

1

DM)

ADLa (g kg 38 36 37 38 34 38 38 35 37

A ABC AB A C A A BC AB

3**

1

DM)

MFUa (kg 0.74 0.73 0.73 0.73 0.71 0.71 0.71 0.71 0.70

A AB AB AB BC BC BC BC C

0.02**

1

DM)

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

213

Table 6 Chemical composition and nutritional value of whole-plant triticale (mean of nine varieties) cut at the milk-dough stage in six environments in Italy Environment

CPa (g kg

1

F93 F94 L94 U93 U94 PS94

87 83 77 66 64 55

Mean LSD0.01

72 6**

576 18**

346 14**

47 4.9**

0.75 0.027**

Po Valley mean Sardinia mean LSD0.01

82 A 62 B 4**

598 A 555 B 11**

381 A 312 B 8**

47 46 NSb

0.69 B 0.81 A 0.02**

DM)

A AB B C C D

NDFa (g kg 591 588 616 565 548 551

1

DM)

B B A C C C

ADFa (g kg 374 392 378 318 303 315

1

DM)

B A AB C D C

ADLa (g kg 47 42 52 41 47 50

1

DM)

B C A C B AB

MFUa (kg 0.70 0.67 0.70 0.80 0.82 0.80

1

DM)

B C B A A A

a

Data with different letters are signi®cantly different. Not signi®cantly different. ** P < 0:01. b

Table 7 Chemical composition and nutritional value of nine varieties of whole-plant triticale (mean of six environments) cut at the milk-dough stage Cultivar

CP (g kg

Catria Rigel Torpedo Antares Boccale Trica Magistral Mizar Campo

76 68 75 70 73 74 70 72 74

LSD0.01

NSb

1

DM)

NDFa (g kg 555 554 588 556 576 574 601 576 606

1

DM)

C C AB C BC BC A BC A

22**

ADFa (g kg 320 336 336 338 344 346 362 363 369

1

DM)

D CD CD C C BC AB AB A

17.7**

ADLa (g kg 44 47 42 45 46 48 49 50 48

cd ab d bcd abcd abc ab a abc

4.6*

1

DM)

MFUa (kg 0.79 0.77 0.77 0.76 0.76 0.75 0.72 0.72 0.71

1

DM)

A AB AB AB AB BC CD CD D

0.03**

a

Data with different letters are signi®cantly different. Not signi®cantly different. * P < 0:05. ** P < 0:01. b

milk-dough stage, the average chemical composition for the tested cultivars, expressed as ®bre fractions, was: NDF ranging from 554 to 606 g kg 1 DM in the cvs. Rigel and Campo; ADF from 320 to 369 g kg 1 DM in Catria and Campo; and ADL from 42 to 50 g kg 1 DM in Torpedo and Mizar. The average nutritional value of the cultivars at milk-dough, expressed as MFU kg 1 DM, was over 0.70 units, the values ranging from 0.71 to 0.79 MFU kg 1 DM, respectively, for Campo and Catria.

4. Discussion 4.1. DM yield The DM yields of triticale forage for both harvest stages were high, with an average 42% increase from early heading to milk-dough, as expected and according to the data reported by Cherney and Marten (1982), Brignall et al. (1988) and Bocchi et al. (1996). This ®nding can be attributed to the

214

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

completion by the plant of its growth cycle and to the storage of newly-formed photosynthates in the grain. The DM that has accumulated by early heading is the determinant factor for the yield capacity of the subsequent growth stage (milk-dough). It is also largely dependent on the soil-climate conditions of the trial environments, as shown in the fertile Po Valley sites by the fact that the yield potential of triticale can be limited because it is inversely proportional to the poor winter frost resistance of certain varieties. This is clearly the case at the F93 site, where the January±February minimum temperatures ranged, respectively, from 8.2 to 1.4 8C. Such conditions induce a marked drop in DM yields, 3.2 and 4.6 MT ha 1, respectively, for Campo and Boccale, the two most cold-susceptible cvs. Rigel showed the best yield performance of all the tested cultivars at both heading (8.4 MT ha 1) and milk-dough (14.9 MT ha 1) harvests. In effect, this cultivar combines a high earliness with good cold tolerance, two traits that adapt it well to both the Po Valley and Sardinian environments. The importance of these two characters in maximising DM yield in both environment groupings is evident from the cvs. Catria and Torpedo, which, respectively, registered average DM yields of 8.0±13.9 and 8.0±14.0 MT ha 1, although the early but poorly cold-resistant Catria performed best in Sardinia and the cold-resistant but later ripening Torpedo best in the Po Valley (at levels similar to Rigel). During the National Trials in Italy for grain yield, all these cultivars were included in the recommended variety list for their high yield capacity in all districts (Bianchi and Delogu, 1994). This suggests that the best cultivars for triticale forage production are those which can also maximise grain yield, in accordance with data reported for barley (Stanca et al., 1984). 4.2. DM chemical composition DM chemical composition at both harvest dates showed, as expected, signi®cant differences. When going from early heading to milk-dough stages, in fact, grain starch accumulation had a signi®cant diluting effect on CP, NDF and ADF contents (West et al., 1991), whereas plant ageing processes induced an increase in ADL (Cherney and Marten, 1982). This results in a general enhancement of DM nutritional value from the former to the latter harvest date, as shown by a decrease in ADF of 4.6%. As with DM

yield, its chemical components are largely dependent on soil-climate conditions in the various trial districts, thereby corroborating what has been reported for other small grain cereals (Gentinetta et al., 1983; Stanca et al., 1984). The ®ndings from the present study make it possible to highlight the role of temperature amongst the causes contributing to variability in DM chemical composition. It is, in fact, widely known that high temperatures induce a rapid process of growth: they speed up both lignin biosynthesis and the conversion to cell-wall of photosynthetic products, resulting in a reduced pool of metabolites (amino acids, nitrates, carbohydrates) in the cells (Van Soest, 1994). Our results appear to con®rm all this. Indeed, the differences observed in the air temperatures during the growth and maturing stages of the plant (Fig. 1) make it clearly possible to distinguish between the Po Valley environment and that of Sardinia (Mediterranean area). These differences are just as clearly re¯ected in DM chemical composition in both site groupings: in the Po Valley, following the winter stasis which delays the onset of heading to late-April±early-May, the DM accumulation becomes much more rapid with relatively high temperatures; the NDF, ADF and ADL values are decidedly higher than those recorded in Sardinia, where heading occurs about a month earlier under more moderate temperatures. All this means lower NDF, ADF and ADL values at the Sardinian sites than at the Po Valley sites, by 22, 35 and 35%, respectively. The better forage quality from the Sardinian sites with respect to the Po Valley environments harvested at heading is con®rmed by the milk-dough harvest, although the marked differences in NDF and ADF at this stage become less notable but still signi®cant (8 and 22%, respectively). In general, the milk-dough harvest corroborates the role played by grain starch accumulation in diluting the fraction of ®bre components in total DM. In fact, in both the Po Valley and Sardinia environments, where potential grain yield is, respectively, 6.5 and 4.3 MT ha 1 (Bianchi and Delogu, 1994), the ADF content decreases, as expected, to a higher extent at the sites registering higher grain yields (Po Valley). This is countered by the increase in ADL, which is both general and particularly high in the Mediterranean environments (‡33%), indicating that when the milkdough stage is reached here the basal part of the plant is affected by an early senescence, a phenomenon

G. Delogu et al. / Field Crops Research 74 (2002) 207±215

underscored by the increase in NDF content at this stage with respect to heading harvest. Environmental effects on DM chemical composition also affect its nutritional value, estimated in MFU on the basis of the ADF concentration (Chase, 1981). Indeed, this value in the Po Valley districts ranges from 0.64 MFU kg 1 DM at heading to 0.69 MFU kg 1 DM at milk-dough, whereas in Mediterranean sites the MFUs do not substantially vary (0.81). Thus, the yield potential of triticale as silage, whether in the irrigated sites of the Po Valley or in typically Mediterranean ones, is high for both harvest stages. Even the DM chemical composition registers an acceptable quality level: NDF and ADF contents averaged less than 600 and 362 g kg 1 DM, with an average nutritional DM value ranging from 0.72 to 0.75 MFU kg 1 DM at heading and milk-dough, respectively. At both harvest stages, the best quality performance was recorded in the Sardinian environments: plant growth at these sites was accompanied by a gradual temperature increase over time, thereby preventing an abrupt rise in plant ®bre components and working to the advantage of its energy value at both heading and milk-dough stages. Yield per unit of acreage at these two stages, respectively, averaged 4860 and 9558 MFU ha 1, indicating that in the Mediterranean areas triticale represents a viable source of livestock nutrition and can contribute to offsetting the dearth of fresh forage that routinely occurs during the summer in this environment. Acknowledgements This research has been carried out within the P.O.M.-Measure 2 ``Technological innovations and its diffusion'' with grants from the UE (80%) and MiPAF (20%). References Bianchi, A., Delogu, G., 1994. Triticale: scelta varietale. L'Inf. Agr. 50 (35), 29±33. Bishnoi, U.R., Walker, J.C., 1976. Evaluation of existing triticale varieties for growth, yield and forage qualities. Alabama Univ. Ann. Res. Rep. 6, 70±88. Bocchi, S., Lazzaroni, G., Berardo, N., Maggiore, T., 1996. Evaluation of triticale as a forage plant through the analysis of the kinetics of some qualitative parameters from stem

215

elongation to maturity. In: Guedes-Pinto, H., Darvey, N., Carnide, V.P. (Eds.), Triticale: Today and Tomorrow. Kluwer Academic Publishers, The Netherlands, pp. 827±834. Bonari, E., 1976. Alla ricerca di nuove colture foraggere da insilamento per ambienti non irrigui. Primi risultati di una sperimentazione pluriennale con cereali autunno-vernini. Riv. Agron. 10 (1±2), 35±42. Brignall, D.M., Ward, M.R., Whittington, W.J., 1988. Yield and quality of triticale cultivars at progressive stages of maturity. J. Agric. Sci. Camb. 111, 75±84. Brown, A.R., Almodares, A., 1976. Quantity and quality of triticale forage compared to other small grains. Agron. J. 68, 264±266. Carnide, V., Ferreira, A., Guedes-Pinto, H., 1988. A comparative study of triticale lines as a forage crops. In: Proceedings of the EUCARPIA Meeting of the Cereal Section on Triticale, Vol. 266, pp. 591±604. Chase, L.E., 1981. Energy prediction equations in USA at NY DHAI Forage laboratory. Production Agricultural Training School, Ithaca, NY. Cherney, J.H., Marten, G.C., 1982. Small grain crop forage potential. I. Biological and chemical determinants of quality and yield. Crop Sci. 22, 227±231. Delogu, G., Maggiore, T., Stanca, A.M., Lorenzoni, C., Marocco, A., 1979. Produzione di sostanza secca nella doppia coltura orzo-mais per l'insilamento. Riv. Agron. 13, 437±442. Delogu, G., Gatti, A., Terzi, V., Stanca, A.M., 1990. VarietaÁ di orzo (Hordeum vulgare L.) e soia (Glycine max L. Merr.) di diversa precocitaÁ per lo sviluppo della doppia coltura. Riv. Agron. 24 (1), 34±41. Gentinetta, E., Giammona, M., Delogu, G., Lorenzoni, C., Maggiore, T., 1983. Triticale ed altri cereali a semina autunnale: confronto qualitativo del prodotto della pianta intera e delle sue parti. Riv. Agron. 17 (3), 392±396. Jedel, P.E., Salmon, D.F., 1994. Forage potential of Wapiti triticale mixtures in central Alberta. Can. J. Plant Sci. 74 (3), 515±519. McCartney, D.H., Vaage, A.S., 1994. Comparative yield and feeding value of barley, oat and triticale silages. Can. J. Anim. Sci. 74 (1), 91±96. Rizza, F., Baldi, P., Cattivelli, L., Delogu, G., 1997. Cold hardening in triticale in comparison with rye and wheat. Cereal Res. Commun. 25 (4), 947±954. Sapra, V.T., Sharma, G.C., Hughes, J.L., Bradford, R.R., 1973. Triticale: a wheat-hybrid. J. Tenn. Acad. Sci. 48, 59±61. Siefers, M.K., Bolsen, K.K., 1997. Agronomic and silage quality traits of winter cereals. In: Proceedings of the IGC, Manitoba, Saskatchewan, pp. 91±92. Stanca, A.M., 1984. Earliness in barley and dry matter yield in a double-cropping system. In: Gallagher, E.J. (Ed.), Cereal Production. Royal Dublin Society/Butterworths, London, pp. 342±343. Stanca, A.M., Delogu, G., Maggiore, T., Gentinetta, E., Lorenzoni, C., 1984. Composition of the whole-plant in winter barley cultivars. Cereal Res. Commun. 12 (1±2), 59±65. Van Soest, P.J., 1994. Plant, animal, and environment. In: Nutritional Ecology of the Ruminant, 2nd Edition, pp. 77±92. West, C.P., Walker, D.W., Bacon, R.K., Longer, D.E., Turner, K.E., 1991. Phenological analysis of forage yield and quality in winter wheat. Agron. J. 83, 217±224.