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Planting date and nitrogen fertilization effects on lesquerella production
INDUSTRIALCROPS AND PRODUCTS AN INTERNATIONAL
ELSEVIER
Industrial
JOURNAL
Crops and Products 5 (1996) 217-222
Planting date and nitrogen fertilization effects on lesquerella production John M. Nelson a,*, David A. Dierig b, Francis S. Nakayama b nDepartment of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA ’ USDA-ARS.
U.S. Water Conservation
Laboratory,
Phoenix, AZ 85040, USA
Received 1 September 1995; accepted 30 November 1995
Abstract Lesquerella (Lesquerella fendleri (Gray) Wats.) produces seed containing hydroxy fatty acids similar to castor oil and has good commercial potential. An important step in the commercialization of this plant for the southwestern desert regions of the United States is the development of an efficient agronomic production system. Field experiments were conducted during the 1991-1992, 1992-1993, and 1993-1994 growing seasons at the University of Arizona, Maricopa Agricultural Center, Maricopa, Arizona to determine the effect of planting date and nitrogen fertility on lesquerella seed yield. Results indicate that fall plantings are necessary to obtain high seed production. September plantings generally produced higher yields than the October or November plantings. February plantings produced low yields and appear to be too late for a growing season that ends in June in central Arizona. In all years, lesquerella responded to nitrogen (N) fertilizer. The addition of 60 to 120 kg N/ha increased biomass and seed yields. Nitrogen fertilizer did not affect lOOO-seed weight, but decreased seed oil content in the 1993-1994 planting. There is evidence that increasing the N application rate decreases seed oil content in lesquerella. Keywords: Lesquerella
(Lesquerella fendleri); Seed oil; Hydroxy fatty acid; Nitrogen fertilization
1. Introduction
waxes, nylons, plastics, lubricants, cosmetics, (Dierig al., 1993; 1990; et 1991). The species currently being domesticated grows from Arizona Texas as at from to 1800 with precipitation from 250 400 mm and Barclay, Research that lesquerella can grown as winter annual Arizona in cropping similar to and other grains (Dierig 1993). southern Oregon with cool climate, lesquerella can grown as summer annual et al., and
Lesquerella fendleri (Gray) Wats.), member of Brussicaceae, the potential to provide industry with a source hydroxy acid. Presently, castor and its derivatives are only commercial source these fatty Lesquerella seed is high lesquerolic similar to acid, dominant fatty acid castor. Lesquerella and its derivatives can used in wide range products *
Fax: (520) 568-2556.
PII SO926-6690(96)000023-4
J.M. Nelson et al. /Industrial Crops and Products 5 (1996) 217-222
218
Agronomic research on lesquerella has been in progress since the mid-1980’s. Studies have provided information on seed bed preparation, plant population, water requirement, irrigation timing, weed control, and harvesting (Coates, 1994; Dierig et al., 1993; Roetheli et al., 1991; Thompson et al., 1989). Preliminary results indicate that planting in October may be optimal for central Arizona production (Dierig and Thompson, 1993; Dierig et al., 1993). Harvest in such semi-arid locations has been done in May or June (Dierig and Thompson, 1993). Although lesquerella appears to respond to nitrogen (N) fertilization in cultural studies, no information is available on the nitrogen requirement of this plant. The objective of this research was to determine the effect of planting date and nitrogen fertility on the growth and yield of lesquerella. 2. Materials and methods Experiments were conducted in the 1991-1992, 1992-1993, and 1993-1994 seasons on different, but adjacent field sites at the University of Arizona, Maricopa Agricultural Center, Maricopa, Arizona, USA. The soil is a variable Mohall sandy loam (fine-loamy, mixed hyperthermic, Typic Haplargid). For each year, field preparations prior to planting included discing, land levelling, and incorporating concentrated superphosphate fertilizer (45% PzOs) at a rate of 44 kg/ha of P. In mid-September of each year, the soil N content was determined to a depth of 1.2 m in 30 cm increments at five locations within the experimental site (Table 1). In all years, seed was planted with a spreader-cultipacker type planter. Nitrogen application rates of 0, 60, and 120 kg N/ha
Table 1 Soil N03-N in 30 cm increments to a depth of 120 cm in September before lesquerella was planted in 1991-1992, 19921993 and 1993-1994 Soil depth
(Soil NO3-N, kg/ha)
(cm)
1991-1992
1992-1993
1993-1994
o- 30 30- 60 60- 90 90-120 Total (o-120)
8.5 6.3 5.9 3.7 24.4
10.9 9.0 6.5 4.9 31.3
9.7 8.2 7.1 5.1 30.1
were compared each year. Urea fertilizer (46% N) was the source of N. Experimental design was a split plot within a randomized complete block with four replications. The planting date plots (whole plots) were 6.1 m wide by 45 m long and the N plots (split plots) were 6.1 m by 15 m. Seed oil content was determined by pulsed nuclear magnetic resonance (NMR) at the USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL. 2.1. 1991-1992 experiment Lesquerella was planted on 26 September, 17 October, 6 November, 10 December, 1991 and 7 February 1992. On all planting dates, seeds were planted on raised beds spaced 102 cm apart. The seeding rate varied from 5.0 to 6.7 kg/ha. Each planting was furrow irrigated three or four times with a total of 250 to 320 mm of water to provide adequate moisture for germination and emergence. For the 1991 plantings, the N application rate was split with one-half (30 or 60 kg/ha) applied before planting and one-half applied in March 1992. The February 1992 planting received all N fertilizer (60 or 120 kg/ha) preplant. The 1991 plantings were sampled each month February through June to determine above-ground dry weight. The February 1992 planting was sampled April through June. On each sampling date, one-m2 area in each N fertility subplot was handharvested. Plants within the harvested area were counted, clipped off at the soil surface and dried at 65°C. In April, fully developed leaf blades were collected from plants in all replicates of N subplots in the October planting. Total N was determined on the leaf blade tissue dried at 70°C based on Kjeldahl analysis. 2.2. 1992-1993 experiment Lesquerella was planted on 18 September, 16 October, and 16 November in 1992. The October planting was abandoned because of weed problems. In each planting, seed was planted on level land at a rate of 9 kg/ha. Following sowing of seed, each planting was flood-irrigated two to three times to obtain stands.
J.M. Nelson et al. /Industrial
Crops and Producrs 5 (1996) 2 I7-222
The plantings were flood-irrigated once a month in January and February, and then every two or three weeks March through May. Plots receiving N received split applications with one-half (30 or 60 kg/ha) applied preplant and one-half (30 or 60 kg/ ha) applied in mid-March. On 7 June 1993, two samples, each one-m’ in area, were hand-harvested from each N subplot for plant biomass and seed yield determination. The plants were dried at 65°C and weighed for biomass and then seeds were removed by threshing. Seeds were cleaned, weighed and analyzed for oil content. 2.3. 1993-1994
experiment
Lesquerella was planted on 23 September, 19 October, 23 November 1993, and 16 February 1994. In each planting, seed was planted on level land at a rate of 9 kg/ha. Following sowing of seed, each planting was sprinkler irrigated every other day for up to two weeks for stand establishment. After stand establishment, the plantings were irrigated similar to the 1992-1993 experiment. Nitrogen was applied similar to the other experiments. The September and October plantings were sampled periodically from 20 January to 24 June to determine biomass. The November planting was sampled March through June and the February planting was sampled in April and June. On each sampling date through 25 April, one-m* of area was handharvested from each N subplot. Seed yield was determined for samples harvested in April and June. For the June harvest, two areas, each one m* in area, were harvested from each N subplot. 3. Results 3.1. 1991-1992
experiment
The September 1991 planting was abandoned because of poor stands and weed problems. Final plant populations were 531,000, 712,000, 1,352,000, and 1,250,OOO plants/ha for October, November, December, and February plantings, respectively. Low plant populations in the October and November plantings were probably the result of a low seeding rate (5 kg/ha) and a build-up of salt in the center of the beds during emergence irrigations.
219
Large differences among planting dates were present in above-ground biomass production (Table 2). The 17 October planting date resulted in the highest dry matter yield on all sampling dates except April. Planting lesquerella in February greatly reduced dry matter yield. The greatest growth period for fall-planted lesquerella was March through June. For the October planting, over 95% of dry matter was produced between 20 February and 19 June. A final harvest to determine seed yield was planned for mid June; however, on 28 May 1992 a heavy rain and hailstorm caused a high percentage of the seed pods (siliques) to open resulting in severe seed shattering. The February planting had the lowest seed loss because fewer of the pods in this planting were mature when the rainstorm occurred. No seed yields are reported for this experiment. Nitrogen application rate had a marked effect on biomass production. The highest N rate (120 kg/ha) resulted in significantly higher dry matter yields than the lowest rate (0 kg/ha) at the final sampling date (Table 3). Nitrogen treatments appeared to influence the N content of leaf tissue. Leaf blades collected in April from the October planting averaged 2.2, 2.6 and 3.0% total N in the 0, 60, and 120 kg N/ha treatments, respectively. The concentration of nitrogen in lesquerella leaf blades may be used to determine the sufficiency of the nitrogen supply for crop growth and as an aid in estimating fertilizer needs. 3.2. 1992-1993
experiment
Final plant populations were 1,450,OOO and 1,740,OOO plants/ha for the September and November plantings, respectively. The September planting produced significantly higher biomass and seed yields than the November planting (Table 4). As expected, there was a significant linear relationship between biomass production and seed yield (y = 69.7 + 0.14 (biomass), r* = 0.99, P < 0.01). The highest seed yield obtained in this experiment was 1260 kg/ha in the September planting at the highest N rate. No differences were present between planting dates in seed oil content or lOOO-seed weight. As in 1991- 1992, lesquerella responded to N fertilizer. In both plantings, the highest N applica-
J.M. Nelson et al. /Industrial
Table 5 Effect of planting Planting
date and sampling
23 September 19 October 23 November 16 February LSD (P = 0.05)
Table 6 Effect of planting Planting
date on biomass production
Sampling
date
Crops and Products 5 (1996) 217-222
of lesquerella,
1993-1994
221
experiment
date (kg/ha)
20 January
17 February
24 March
2.5 April
24 June
2840 460
3960 1600
_ 160
1970
5520 3560 1660 _ 1380
6590 5160 4290 690 920
8850 7040 6900 5140 1080
_
date and harvest date on seed yield, lOOO-seed weight, and seed oil content of lesquerella,
date
23 September 19 October 23 November 16 February LSD (P = 0.05) BNS = not statistically
25 April Harvest
1993-1994
experiment
24 June Harvest
Seed yield
1000~Seed weight
Oil
Seed yield
loo&Seed
(kg/ha)
(g)
(%)
(kg/ha)
(g)
(%)
350 320 110 _
0.36 0.34 0.31
120
NSa
16.8 14.7 6.6 _ 8.0
1200 1020 1100 760 180
0.60 0.58 0.60 0.51 0.01
26.3 26.9 26.1 24.6 0.9
-
weight
Oil
significant.
The September planting had the highest biomass yields at all sampling dates (Table 5). As in 19911992, a high percentage of biomass production for the October and November plantings occurred after mid-February. Biomass production in the February planting was low through April, but started to increase in June, the end of the growing season for fall-planted lesquerella. A significant linear relationship (y = 99.1 + 0.13 (biomass), r2 = 0.92, P < 0.05) was present between biomass production and seed yield similar to the 1992-1993 experiment. Seed yields were low when harvest was made in April (Table 6). The lOOO-seed weight and seed oil content were also low in April, probably indicating that the immature seeds were not effectively separated from mature seed during the seed cleaning operation. At the final harvest in June, no significant differences existed among the September, October and November planting dates in seed yield, IOOO-seed weight or seed oil content. However, the February planting date had a much lower seed yield and yield components than the earlier planting dates. Plants in this February planting were still growing
and flowering in June and many seed pods were not mature at harvest. As in the previous experiments, lesquerella responded to N fertilizer. The highest N rate resulted in the highest biomass yield (data not shown). The N rate did not have a significant effect on seed yield in the April harvest, but the 60 kg N/ha rate increased yield for the June harvest (Table 7). In June, seed oil content was reduced as the N rate was increased resulting in a negative correlation (r* = 0.38, P -c0.05) between N rate and oil content. This negative effect of N fertilizer on oil content of lesquerella was also observed in a separate N fertility experiment conducted in 1993-1994 (unpublished data). 4. Discussion These experiments indicate that fall plantings are necessary for lesquerella production in central Arizona to obtain high seed yields. September plantings generally produced higher yields than the October or November plantings, although the differences were small. However, early fall plantings are difficult to
J.M. Nelson et al. /Industrial Crops and Products 5 (1996) 217-222
222
Table 7 Effect of N treatment and harvest date on seed yield, lOOO-seedweight, and seed oil content of lesquerella, 1993-1994 experiment N treatment (kg/ha)
0 60 120 LSD (P = 0.05)
25 April Harvest
24 June Harvest
Seed yield (kg/ha)
lOOO-Seedweight (8)
Oil (%)
Seed yield (kg/ha)
1000~Seed weight (g)
Oil (%)
190 210 280 NSa
0.36 0.33 0.30 0.02
16.1 11.9 10.0 3.4
790 1080 1190 120
0.58 0.57 0.57 NS
26.9 26.1 25.0 0.4
a NS = not statistically significant.
establish; air temperatures are high at planting time and frequent irrigations may be required for stand establishment. In addition, summer weeds emerge and compete with the lesquerella. Later fall plantings generally escape summer weed problems, but usually have to contend with winter weeds. Vigorous winter annual weed growth is highly competitive against the slower growing lesquerella seedlings during the winter. February plantings do not appear feasible for central Arizona production. Even though winter plantings produce rapid growth in the spring and summer months, the total growing season is too short to obtain commercially acceptable seed yields. The growing season cannot be extended, since it appears that lesquerella must be harvested during June. Lesquerella will continue to grow and flower in July or later, but there is an increased risk of rainstorms and crop damage during this period. Lines presently available are subject to seed shattering by heavy rain or hail when the seed pods are mature. The best strategy for lesquerella production in Arizona is to provide adequate water and N fertilizer to keep the plants actively growing and fruiting through mid June and then to terminate growth using a desiccant or by cutting and wind-rowing the plants. Harvesting should be completed by the end of June. Lesquerella responds well to N fertilizer. The addition of 60 to 120 kg N/ha resulted in increased dry matter production and seed yields. However, increasing N will result in a decrease in seed oil content. Additional experiments are being conducted to determine precisely the optimum amount and timing for N fertilizer applications.
Acknowledgements This research was partially funded by the US DOD through the USDA-CSRS program ‘Advanced Materials from Renewable Resources, Program Area 3 (Functional Fluids)’ under cooperative agreement 93-COOP-1-9527. References Coates, W., 1994. Mechanical harvesting of lesquerella. Ind. Crops Prod., 2: 245-250. Dierig, D. and Thompson, A.E., 1993. Vernonia and Lesquerella potential for commercialization. In: J. Janick and J. Simon (Editors), New Crops. Proceedings of the Second National Symposium on New Crops, 6-9 October 1991, Indianapolis, IN, pp. 362-367. Dierig, D.A., Thompson, A.E. and Nakayama, ES., 1993. Lesquerella commercialization efforts in the United States. Ind. Crops Prod., 1: 289-293. Gentry, H.S. and Barclay, A.S., 1962. The search for new industrial crops III: Prospectus of Lesquerella fendleri. Econ. Bot., 16: 206-211. Kleiman, R., 1990. Chemistry of new industrial oilseed crops. In: J. Janick and J.E. Simon (Editors), Advances in New Crops. Timber Press, Inc., Portland, OR, pp. 196-203. Roetheli, J.C., Carlson, K.D., Kleiman, R., Thompson, A.E., Dierig, D.A., Glaser, L.K., Blase, M.G. and Goddell, J., 1991. Lesquerella as a source of hydroxy fatty acids for industrial products. USDA-CSRS Office of Agricultural Materials, Growing Industrial Materials Series (unnumbered). Washington, DC. Thompson, A.E., Dierig, D.A. and Johnson, E.R., 1989. Yield potential of Lesquerella fendleri (Gray) Wats., a new desert plant resource for hydroxy fatty acids. J. Arid Environ., 16: 331-336.
ELSEVIER
Industrial
JOURNAL
Crops and Products 5 (1996) 217-222
Planting date and nitrogen fertilization effects on lesquerella production John M. Nelson a,*, David A. Dierig b, Francis S. Nakayama b nDepartment of Plant Sciences, University of Arizona, Tucson, AZ 85721, USA ’ USDA-ARS.
U.S. Water Conservation
Laboratory,
Phoenix, AZ 85040, USA
Received 1 September 1995; accepted 30 November 1995
Abstract Lesquerella (Lesquerella fendleri (Gray) Wats.) produces seed containing hydroxy fatty acids similar to castor oil and has good commercial potential. An important step in the commercialization of this plant for the southwestern desert regions of the United States is the development of an efficient agronomic production system. Field experiments were conducted during the 1991-1992, 1992-1993, and 1993-1994 growing seasons at the University of Arizona, Maricopa Agricultural Center, Maricopa, Arizona to determine the effect of planting date and nitrogen fertility on lesquerella seed yield. Results indicate that fall plantings are necessary to obtain high seed production. September plantings generally produced higher yields than the October or November plantings. February plantings produced low yields and appear to be too late for a growing season that ends in June in central Arizona. In all years, lesquerella responded to nitrogen (N) fertilizer. The addition of 60 to 120 kg N/ha increased biomass and seed yields. Nitrogen fertilizer did not affect lOOO-seed weight, but decreased seed oil content in the 1993-1994 planting. There is evidence that increasing the N application rate decreases seed oil content in lesquerella. Keywords: Lesquerella
(Lesquerella fendleri); Seed oil; Hydroxy fatty acid; Nitrogen fertilization
1. Introduction
waxes, nylons, plastics, lubricants, cosmetics, (Dierig al., 1993; 1990; et 1991). The species currently being domesticated grows from Arizona Texas as at from to 1800 with precipitation from 250 400 mm and Barclay, Research that lesquerella can grown as winter annual Arizona in cropping similar to and other grains (Dierig 1993). southern Oregon with cool climate, lesquerella can grown as summer annual et al., and
Lesquerella fendleri (Gray) Wats.), member of Brussicaceae, the potential to provide industry with a source hydroxy acid. Presently, castor and its derivatives are only commercial source these fatty Lesquerella seed is high lesquerolic similar to acid, dominant fatty acid castor. Lesquerella and its derivatives can used in wide range products *
Fax: (520) 568-2556.
PII SO926-6690(96)000023-4
J.M. Nelson et al. /Industrial Crops and Products 5 (1996) 217-222
218
Agronomic research on lesquerella has been in progress since the mid-1980’s. Studies have provided information on seed bed preparation, plant population, water requirement, irrigation timing, weed control, and harvesting (Coates, 1994; Dierig et al., 1993; Roetheli et al., 1991; Thompson et al., 1989). Preliminary results indicate that planting in October may be optimal for central Arizona production (Dierig and Thompson, 1993; Dierig et al., 1993). Harvest in such semi-arid locations has been done in May or June (Dierig and Thompson, 1993). Although lesquerella appears to respond to nitrogen (N) fertilization in cultural studies, no information is available on the nitrogen requirement of this plant. The objective of this research was to determine the effect of planting date and nitrogen fertility on the growth and yield of lesquerella. 2. Materials and methods Experiments were conducted in the 1991-1992, 1992-1993, and 1993-1994 seasons on different, but adjacent field sites at the University of Arizona, Maricopa Agricultural Center, Maricopa, Arizona, USA. The soil is a variable Mohall sandy loam (fine-loamy, mixed hyperthermic, Typic Haplargid). For each year, field preparations prior to planting included discing, land levelling, and incorporating concentrated superphosphate fertilizer (45% PzOs) at a rate of 44 kg/ha of P. In mid-September of each year, the soil N content was determined to a depth of 1.2 m in 30 cm increments at five locations within the experimental site (Table 1). In all years, seed was planted with a spreader-cultipacker type planter. Nitrogen application rates of 0, 60, and 120 kg N/ha
Table 1 Soil N03-N in 30 cm increments to a depth of 120 cm in September before lesquerella was planted in 1991-1992, 19921993 and 1993-1994 Soil depth
(Soil NO3-N, kg/ha)
(cm)
1991-1992
1992-1993
1993-1994
o- 30 30- 60 60- 90 90-120 Total (o-120)
8.5 6.3 5.9 3.7 24.4
10.9 9.0 6.5 4.9 31.3
9.7 8.2 7.1 5.1 30.1
were compared each year. Urea fertilizer (46% N) was the source of N. Experimental design was a split plot within a randomized complete block with four replications. The planting date plots (whole plots) were 6.1 m wide by 45 m long and the N plots (split plots) were 6.1 m by 15 m. Seed oil content was determined by pulsed nuclear magnetic resonance (NMR) at the USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Peoria, IL. 2.1. 1991-1992 experiment Lesquerella was planted on 26 September, 17 October, 6 November, 10 December, 1991 and 7 February 1992. On all planting dates, seeds were planted on raised beds spaced 102 cm apart. The seeding rate varied from 5.0 to 6.7 kg/ha. Each planting was furrow irrigated three or four times with a total of 250 to 320 mm of water to provide adequate moisture for germination and emergence. For the 1991 plantings, the N application rate was split with one-half (30 or 60 kg/ha) applied before planting and one-half applied in March 1992. The February 1992 planting received all N fertilizer (60 or 120 kg/ha) preplant. The 1991 plantings were sampled each month February through June to determine above-ground dry weight. The February 1992 planting was sampled April through June. On each sampling date, one-m2 area in each N fertility subplot was handharvested. Plants within the harvested area were counted, clipped off at the soil surface and dried at 65°C. In April, fully developed leaf blades were collected from plants in all replicates of N subplots in the October planting. Total N was determined on the leaf blade tissue dried at 70°C based on Kjeldahl analysis. 2.2. 1992-1993 experiment Lesquerella was planted on 18 September, 16 October, and 16 November in 1992. The October planting was abandoned because of weed problems. In each planting, seed was planted on level land at a rate of 9 kg/ha. Following sowing of seed, each planting was flood-irrigated two to three times to obtain stands.
J.M. Nelson et al. /Industrial
Crops and Producrs 5 (1996) 2 I7-222
The plantings were flood-irrigated once a month in January and February, and then every two or three weeks March through May. Plots receiving N received split applications with one-half (30 or 60 kg/ha) applied preplant and one-half (30 or 60 kg/ ha) applied in mid-March. On 7 June 1993, two samples, each one-m’ in area, were hand-harvested from each N subplot for plant biomass and seed yield determination. The plants were dried at 65°C and weighed for biomass and then seeds were removed by threshing. Seeds were cleaned, weighed and analyzed for oil content. 2.3. 1993-1994
experiment
Lesquerella was planted on 23 September, 19 October, 23 November 1993, and 16 February 1994. In each planting, seed was planted on level land at a rate of 9 kg/ha. Following sowing of seed, each planting was sprinkler irrigated every other day for up to two weeks for stand establishment. After stand establishment, the plantings were irrigated similar to the 1992-1993 experiment. Nitrogen was applied similar to the other experiments. The September and October plantings were sampled periodically from 20 January to 24 June to determine biomass. The November planting was sampled March through June and the February planting was sampled in April and June. On each sampling date through 25 April, one-m* of area was handharvested from each N subplot. Seed yield was determined for samples harvested in April and June. For the June harvest, two areas, each one m* in area, were harvested from each N subplot. 3. Results 3.1. 1991-1992
experiment
The September 1991 planting was abandoned because of poor stands and weed problems. Final plant populations were 531,000, 712,000, 1,352,000, and 1,250,OOO plants/ha for October, November, December, and February plantings, respectively. Low plant populations in the October and November plantings were probably the result of a low seeding rate (5 kg/ha) and a build-up of salt in the center of the beds during emergence irrigations.
219
Large differences among planting dates were present in above-ground biomass production (Table 2). The 17 October planting date resulted in the highest dry matter yield on all sampling dates except April. Planting lesquerella in February greatly reduced dry matter yield. The greatest growth period for fall-planted lesquerella was March through June. For the October planting, over 95% of dry matter was produced between 20 February and 19 June. A final harvest to determine seed yield was planned for mid June; however, on 28 May 1992 a heavy rain and hailstorm caused a high percentage of the seed pods (siliques) to open resulting in severe seed shattering. The February planting had the lowest seed loss because fewer of the pods in this planting were mature when the rainstorm occurred. No seed yields are reported for this experiment. Nitrogen application rate had a marked effect on biomass production. The highest N rate (120 kg/ha) resulted in significantly higher dry matter yields than the lowest rate (0 kg/ha) at the final sampling date (Table 3). Nitrogen treatments appeared to influence the N content of leaf tissue. Leaf blades collected in April from the October planting averaged 2.2, 2.6 and 3.0% total N in the 0, 60, and 120 kg N/ha treatments, respectively. The concentration of nitrogen in lesquerella leaf blades may be used to determine the sufficiency of the nitrogen supply for crop growth and as an aid in estimating fertilizer needs. 3.2. 1992-1993
experiment
Final plant populations were 1,450,OOO and 1,740,OOO plants/ha for the September and November plantings, respectively. The September planting produced significantly higher biomass and seed yields than the November planting (Table 4). As expected, there was a significant linear relationship between biomass production and seed yield (y = 69.7 + 0.14 (biomass), r* = 0.99, P < 0.01). The highest seed yield obtained in this experiment was 1260 kg/ha in the September planting at the highest N rate. No differences were present between planting dates in seed oil content or lOOO-seed weight. As in 1991- 1992, lesquerella responded to N fertilizer. In both plantings, the highest N applica-
J.M. Nelson et al. /Industrial
Table 5 Effect of planting Planting
date and sampling
23 September 19 October 23 November 16 February LSD (P = 0.05)
Table 6 Effect of planting Planting
date on biomass production
Sampling
date
Crops and Products 5 (1996) 217-222
of lesquerella,
1993-1994
221
experiment
date (kg/ha)
20 January
17 February
24 March
2.5 April
24 June
2840 460
3960 1600
_ 160
1970
5520 3560 1660 _ 1380
6590 5160 4290 690 920
8850 7040 6900 5140 1080
_
date and harvest date on seed yield, lOOO-seed weight, and seed oil content of lesquerella,
date
23 September 19 October 23 November 16 February LSD (P = 0.05) BNS = not statistically
25 April Harvest
1993-1994
experiment
24 June Harvest
Seed yield
1000~Seed weight
Oil
Seed yield
loo&Seed
(kg/ha)
(g)
(%)
(kg/ha)
(g)
(%)
350 320 110 _
0.36 0.34 0.31
120
NSa
16.8 14.7 6.6 _ 8.0
1200 1020 1100 760 180
0.60 0.58 0.60 0.51 0.01
26.3 26.9 26.1 24.6 0.9
-
weight
Oil
significant.
The September planting had the highest biomass yields at all sampling dates (Table 5). As in 19911992, a high percentage of biomass production for the October and November plantings occurred after mid-February. Biomass production in the February planting was low through April, but started to increase in June, the end of the growing season for fall-planted lesquerella. A significant linear relationship (y = 99.1 + 0.13 (biomass), r2 = 0.92, P < 0.05) was present between biomass production and seed yield similar to the 1992-1993 experiment. Seed yields were low when harvest was made in April (Table 6). The lOOO-seed weight and seed oil content were also low in April, probably indicating that the immature seeds were not effectively separated from mature seed during the seed cleaning operation. At the final harvest in June, no significant differences existed among the September, October and November planting dates in seed yield, IOOO-seed weight or seed oil content. However, the February planting date had a much lower seed yield and yield components than the earlier planting dates. Plants in this February planting were still growing
and flowering in June and many seed pods were not mature at harvest. As in the previous experiments, lesquerella responded to N fertilizer. The highest N rate resulted in the highest biomass yield (data not shown). The N rate did not have a significant effect on seed yield in the April harvest, but the 60 kg N/ha rate increased yield for the June harvest (Table 7). In June, seed oil content was reduced as the N rate was increased resulting in a negative correlation (r* = 0.38, P -c0.05) between N rate and oil content. This negative effect of N fertilizer on oil content of lesquerella was also observed in a separate N fertility experiment conducted in 1993-1994 (unpublished data). 4. Discussion These experiments indicate that fall plantings are necessary for lesquerella production in central Arizona to obtain high seed yields. September plantings generally produced higher yields than the October or November plantings, although the differences were small. However, early fall plantings are difficult to
J.M. Nelson et al. /Industrial Crops and Products 5 (1996) 217-222
222
Table 7 Effect of N treatment and harvest date on seed yield, lOOO-seedweight, and seed oil content of lesquerella, 1993-1994 experiment N treatment (kg/ha)
0 60 120 LSD (P = 0.05)
25 April Harvest
24 June Harvest
Seed yield (kg/ha)
lOOO-Seedweight (8)
Oil (%)
Seed yield (kg/ha)
1000~Seed weight (g)
Oil (%)
190 210 280 NSa
0.36 0.33 0.30 0.02
16.1 11.9 10.0 3.4
790 1080 1190 120
0.58 0.57 0.57 NS
26.9 26.1 25.0 0.4
a NS = not statistically significant.
establish; air temperatures are high at planting time and frequent irrigations may be required for stand establishment. In addition, summer weeds emerge and compete with the lesquerella. Later fall plantings generally escape summer weed problems, but usually have to contend with winter weeds. Vigorous winter annual weed growth is highly competitive against the slower growing lesquerella seedlings during the winter. February plantings do not appear feasible for central Arizona production. Even though winter plantings produce rapid growth in the spring and summer months, the total growing season is too short to obtain commercially acceptable seed yields. The growing season cannot be extended, since it appears that lesquerella must be harvested during June. Lesquerella will continue to grow and flower in July or later, but there is an increased risk of rainstorms and crop damage during this period. Lines presently available are subject to seed shattering by heavy rain or hail when the seed pods are mature. The best strategy for lesquerella production in Arizona is to provide adequate water and N fertilizer to keep the plants actively growing and fruiting through mid June and then to terminate growth using a desiccant or by cutting and wind-rowing the plants. Harvesting should be completed by the end of June. Lesquerella responds well to N fertilizer. The addition of 60 to 120 kg N/ha resulted in increased dry matter production and seed yields. However, increasing N will result in a decrease in seed oil content. Additional experiments are being conducted to determine precisely the optimum amount and timing for N fertilizer applications.
Acknowledgements This research was partially funded by the US DOD through the USDA-CSRS program ‘Advanced Materials from Renewable Resources, Program Area 3 (Functional Fluids)’ under cooperative agreement 93-COOP-1-9527. References Coates, W., 1994. Mechanical harvesting of lesquerella. Ind. Crops Prod., 2: 245-250. Dierig, D. and Thompson, A.E., 1993. Vernonia and Lesquerella potential for commercialization. In: J. Janick and J. Simon (Editors), New Crops. Proceedings of the Second National Symposium on New Crops, 6-9 October 1991, Indianapolis, IN, pp. 362-367. Dierig, D.A., Thompson, A.E. and Nakayama, ES., 1993. Lesquerella commercialization efforts in the United States. Ind. Crops Prod., 1: 289-293. Gentry, H.S. and Barclay, A.S., 1962. The search for new industrial crops III: Prospectus of Lesquerella fendleri. Econ. Bot., 16: 206-211. Kleiman, R., 1990. Chemistry of new industrial oilseed crops. In: J. Janick and J.E. Simon (Editors), Advances in New Crops. Timber Press, Inc., Portland, OR, pp. 196-203. Roetheli, J.C., Carlson, K.D., Kleiman, R., Thompson, A.E., Dierig, D.A., Glaser, L.K., Blase, M.G. and Goddell, J., 1991. Lesquerella as a source of hydroxy fatty acids for industrial products. USDA-CSRS Office of Agricultural Materials, Growing Industrial Materials Series (unnumbered). Washington, DC. Thompson, A.E., Dierig, D.A. and Johnson, E.R., 1989. Yield potential of Lesquerella fendleri (Gray) Wats., a new desert plant resource for hydroxy fatty acids. J. Arid Environ., 16: 331-336.