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Growth of spring camelina (Camelina sativa) under deficit irrigation in Western Nebraska
Industrial Crops and Products 83 (2016) 118–123
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Growth of spring camelina (Camelina sativa) under deficit irrigation in Western Nebraska A.D. Pavlista a,∗ , G.W. Hergert a , J.M. Margheim a , T.A. Isbell b a b
University of Nebraska, PREC, Scottsbluff, NE 69361, USA USDA-ARS, Peoria, IL 61604, USA
a r t i c l e
i n f o
Article history: Received 2 October 2015 Received in revised form 3 December 2015 Accepted 9 December 2015 Available online 4 January 2016 Keywords: Oilseed Biodiesel Omega-3 Omega-9
a b s t r a c t The High Plains of the U.S.A. is subject to periodic drought where low-water using crops are desired. Camelina is a potential biofuel crop that may be suitable for this region. The objective was to determine the growth, seed yield, and oil characteristic of camelina exposed to four levels of applied water in western Nebraska. The cultivar Cheyenne was exposed to rain-fed only (RF), and irrigated with 10 (LI), 20 (MI), and 30 (HI) cm water. Irrigation increased plant growth as measured by canopy height, stem length, and canopy weight. Maximum height (70–80 cm) was reached by 10 weeks after planting (WAP) with a total of 23 cm of applied water or 13 cm of irrigation. By 13 WAP, canopy and pod fresh weights were increased by 40–50% by the MI and HI irrigations. Likewise, at harvest (13 WAP), plant dry weight was increased by 50% by the two higher irrigation levels. Seed yields were increased by each incremental increase in irrigation from 890 kg/ha for RF to 2540 for HI, a 2.85-fold increase. Oil content was not affected by irrigating at the LI or MI but was increased only by the HI irrigation level. The fatty acid profile was altered by irrigation with an increase in the major constituent, linolenic acid, and a corresponding decrease in two other large constituents, oleic and linoleic acids. There also was a slight increase in the minor constituent of erucic acid. The growth pattern of camelina showed that 23 cm of applied water would be required for healthy plant growth but as much as 43 cm would be needed for maximum yield. The results indicate that camelina could be grown successfully in western Nebraska, supplying oil for fuel and cooking. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Western Nebraska is well-known for its low rainfall and periodic, long and severe droughts causing declining water availability for agriculture (Basara et al., 2013) and decreasing irrigation allocations (Bleed and Babbitt, 2015). In NE, KS and CO, legislation has been passed to manage groundwater, which impacts irrigation water allocations. This simply means less water and the need to find low water-using crops. Several major crops have been studied in the High Plains and the findings suggest that applying limited water provides more profit potential and has less impact on the local economy than reverting some land to dryland agriculture (Schneekloth et al., 2001). Under deficit irrigation, less water is applied than is required to meet full evapo-transpiration demand. The crop grows under continuous, but not severe, water stress. However, proper deficit irrigation management may not reduce
∗ Corresponding author. E-mail address: [email protected] (A.D. Pavlista). http://dx.doi.org/10.1016/j.indcrop.2015.12.017 0926-6690/© 2015 Elsevier B.V. All rights reserved.
yield as much as might be expected with corn, soybean or wheat when grown at North Platte, NE (Hergert et al., 1993; Klocke et al., 2004). Deficit irrigation is a way of optimizing irrigation during drought-sensitive stages in crops such as corn (maize) (Zea mais), cotton (Gossypium hirusutum), potato (Solanum tuberosum), soybean (Glycine max), and wheat (Triticum aestivum) (Geerts and Raes, 2009). Real-world use of deficit irrigation on corn, cotton and wheat showed that under conditions where water is scarce, the optimum strategy might be to reduce irrigation by 25–60% (English and Raja, 1996). Pavlista (2015) demonstrated that for marketable yield of potato timing of deficit irrigation is crucial. However, under some circumstances, deficit irrigation may not be economically advantageous (Trout et al., 2010). Although spring camelina is an old crop dating back millenia (Budin et al., 1995; Putnam et al., 1993), recent interest has been observed due to its potential use as an alternate biofuel (Bernardo et al., 2003; Frohlich and Rice, 2005; Moser and Vaughn, 2010; Zaleckas et al., 2012). Camelina may even be used as avaition fuel (Shonnard et al., 2010). An advantage of camelina as a biodiesel is its low greenhouse gas emission, 75–80% less than petrofuels (Moser,
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2010). However, high unsaturated levels of fatty acids resulting in poor oxidative stability will limit camelina methyl esters as a standalone biodiesel (Frohlich and Rice, 2005; Moser and Vaughn, 2010; Zaleckas et al., 2012). As a blend component, camelina esters may be indistinguishable from soybean esters (Moser, 2010) and be comparable to soybean biodiesel (Soriano and Narani, 2012). Camelina is considered a non-food crop, therefore would not disrupt food production, although camelina meal can be used as an animal feed (Pilgeram et al., 2007). It would be suitable for production incorporated into a wheat-fallow rotation in the upper Great Plains of the USA (‘High Plains’) as recently reviewed by Obour et al. (2015). Keske et al. (2013), using an economic analysis, demonstrated that at the farm level, growing camelina for biodiesel and using the meal as a feedstock for livestock could be profitable in the western USA. There has been considerable research reported on producing spring camelina under dryland (rain-fed) conditions in the Great Plains as reviewed by Obour et al. (2015). Emergence under cold temperature (Allen et al., 2014), planting dates (Pavlista et al., 2011a; Shonnard et al., 2010) and planting methods (Aiken et al., 2015; Schillinger et al., 2012) have been reported. Studies on camelina and its irrigation needs are limited, and in the USA are reported primarily for Arizona using surface irrigation to achieve various levels of soil water depletion (French et al., 2009; Hunsaker et al., 2013) and Nebraska using sprinkler irrigation to achieve various levels of available water (Hergert et al., 2011). In AZ under their hot and arid climate, camelina was planted in January while in NE, under a semi-arid climate, it was planted in April. From these studies, water use efficiency and ET were calculated for these two very different climates (Hergert et al., 2011; Hunsaker et al., 2013). Pavlista et al. (2012) compared growth patterns of camelina to canola (Brassica napus) and brown mustard (Brassica juncea) under low irrigation. However, the objective of this study was to identify the effects of various levels of irrigation on growth, yield and oil of camelina in western Nebraska at two location over two years.
Table 1 Dates, physiological days and precipitation, means and standard errors of four camelina trials, Scottsbluff and Sidney, NE, 2007 and 2008.
2. Materials and methods
2.2. Irrigation regimes
2.1. Field trial conditions
Weather stations were located near the trial fields, and rainfall and temperature were monitored by the High Plains Climate Center (Changnon et al., 1990). Irrigation was applied through an overhead, linear-move system. Four irrigation levels were applied to plots and replicated three times in a randomized complete block design. The check was no irrigation or rain-fed only referred to as RF. The three irrigated levels were LI whose targeted seasonal irrigation level was 10 cm, MI targeted at 20 cm, and HI targeted at 30 cm of added irrigation. Irrigation was not adjusted for rainfall, therefore, RF received 15.8 cm rain during the season while HI received 43.1 cm (Table 1). Distribution of irrigation was based on the weather stations and HI was not ET-limited, while actual ET was used to calculate water use (Hergert et al., 2011). LI (10 cm), irrigations were timed to coincide with flowering and early grain fill. MI (20 cm) irrigations were applied through vegetative growth to flowering and early grain fill. Full irrigation (HI) was season long.
Camelina cv. Cheyenne was grown in four field trials, two in 2007 and two in 2008. Two trials were conducted each year, one at Scottsbluff, NE, and the other in Sidney, NE. The trials at Scottsbluff, NE, were at the Panhandle Research and Extension Center (41◦ 89 N, 103◦ 68 W with an elevation of 1189 m) on a Tripp fine sandy loam soil at pH 8.1 with an organic matter content of about 1.0%. The trials at Sidney, NE, were at the High Plains Ag Lab (41◦ 23 N, 103◦ 02 W with an elevation of 1247 m) on a Keith silt loam soil at pH 6.8 and organic matter content of about 2%. Plots consisted of 38 rows spaced 0.2 m apart and 9.1 m long or an area of 69 m2 of which 6 rows 9 m long, an area of 10.8 m2 , was harvested. Previous crops were dry edible beans (Phaseolus vulgaris) at Scottsbluff in both years, and at Sidney, it was winter wheat in 2007 and foxtail millet (Setaria italica) in 2008. Nitrogen was applied based on soil tests using guidelines and practices adapted from recommendations on canola in the region (Boyles et al., 2006). Total residual N in the top 0.9 m was: >130 kg/ha at Scottsbluff in both years and >110 kg/ha at Sidney for both years. The maximum root depth for camelina was previously determined to be between 0.9 and 1.06 m in the High Plains. In Scottsbluff, a starter fertilizer was added pre-plant incorporated at 34 kg N/ha and 39 kg S/ha; in Sidney, the starter fertilizer was added at 50 kg N/ha, 28 kg P2 O5 and 22 kg S/ha. The starter was incorporated with 1.25 cm of water within 6 h of application. The total N for camelina coincides with the range of 120–160 kg N/ha recently reported for the Maritime Provinces of Canada (Jiang et al., 2013).
RFa WAPb
DAPb
P-daysc
4 6 8 10 12 13
31 ± 1 43 ± 1 57 ± 1 71 ± 1 88 ± 2 94 ± 4
114 ± 8 151 ± 24 216 ± 16 313 ± 18 443 ± 8 486 ± 13
LI
MI
HI
Precipitationd (cm) 2.9 ± 0.1 6.6 ± 1.4 9.4 ± 2.7 10.8 ± 3.4 14.2 ± 3.4 15.8 ± 3.3
4.8 ± 0.8 8.5 ± 1.0 13.0 ± 0.6 17.5 ± 2.2 24.1 ± 3.5 25.7 ± 3.3
5.6 ± 0.3 11.0 ± 1.6 17.7 ± 3.7 23.4 ± 3.7 32.3 ± 2.7 34.4 ± 3.3
7.0 ± 0.9 12.3 ± 2.2 19.1 ± 3.2 27.1 ± 2.9 40.4 ± 1.5 43.1 ± 2.7
a Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI representing full irrigation with a target of 30 cm. b WAP = target week after planting; DAP = actual days after planting. c P-days were calculated as described in Sands et al., 1979. d Precipitation is the sum of rainfall plus irrigation. Irrigation level RF represents rainfall alone.
Trifluralin at 0.58 kg AI/ha (Treflan HFP at 1.2 l/ha) was applied pre-plant incorporated. Unlike canola (B. napus), fleabeetle and birds are not an issue with camelina (Pavlista et al., 2011a). Downy mildew (Hyaloperonospora camelinae) (Harveson et al., 2011) did not appear on camelina in these trials. Therefore, neither insects or pathogens presented themselves as a problem in either location in 2007 and 2008. Planting was in mid-April at both locations and in both years as recommended by Pavlista et al. (2011a) and Schillinger et al. (2012). Camelina seed was planted at 4–5 kg/ha at about 770,000 seed/kg as generally recommended for this region (Obour et al., 2015) with a no-till drill at a depth of 1.2 cm (Aiken et al., 2015; Schillinger et al., 2012). All trials were harvested in mid-July, about 13 weeks after planting (WAP) with a small plot combine (Table 1). Camelina seed was considered mature and ready for harvest when the pods desiccated and hardened, and the seed color changed from green to cinnamon orange. Seed moisture was determined and yields adjusted to an 8% moisture basis.
2.3. Data collection and analysis Plant growth data, i.e., canopy height and weight, stem nodes and length, were taken every 2–3 weeks starting at 4 WAP (Table 1) following the procedure of Pavlista et al. (2012). Canopy height and width was measured with a meter-stick three times in the center rows of each plot and averaged. Canopy weight was determined by cutting four plants at the base in each plot, stem length was measured with a meter stick and the number of nodes on the stem were counted. The next day, the plants were weighed with pods (silicles), if present, separated from the main stem and branches.
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Table 2 Canopy height as affected by irrigation level and time, mean of four camelina trials. WAPa P-daysb
4 110
6 150
8 220
10 310
13 490
Irrigationc RF LI MI HI p-valuef
Canopy height (cm) 13 dd 12 d 13 d 12 d NS
29 c 29 c 30 c 29 c NS
46 Be ,b 56 A, b 59 A, b 62 A, b <0.01
60 C, ab 72 B, a 75 AB, a 80 A, a <0.01
63 C, a 72 B, a 83 A, a 84 A, a <0.01
time, canopy height reached a plateau by 10 WAP (Table 2) corresponding to a P-day between 295 and 331 (Table 1). Stem length was also measured at 10 WAP and gave corresponding results as canopy height (data not shown). Canopy width was measured at 10 WAP and showed no significant difference between irrigation levels (data not shown). Plant weight was observed periodically. Irrigation level did not affect the fresh weight of the above-ground plant at 8 WAP but differences were observed three weeks later. As the irrigation level increased the above-ground fresh weight increased (Table 3). Flowers appeared about 8 WAP and showed no irrigation effect. Pods (silicles) matured about 13 WAP; differences in pod fresh weight due to irrigation were measured at that time. Pod fresh weight of the two higher irrigation levels (MI and HI) were significantly higher than the RF and LI (Table 3). Total above-ground fresh weight corresponded to that of the stem and branches. Dry weights followed a similar pattern at harvest (Table 4).
p-value <0.01 <0.01 <0.01 <0.01
a
WAP = weeks after planting. P-days were calculated as described in Sands et al.,1979. c Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level and DAP. d Values in rows (across WAP) followed by the same ordinal letter were not significantly different at p < 0.05 based on least significant differences. e Values in columns (across irrigation levels) followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. f There were no significant interactions between irrigation level and plant height in either year or location. b
3.2. Yield The 10-cm increments in irrigation affected camelina seed yield. Each irrigation increase resulted in a significant yield increase (Table 4). Just irrigating with 10 cm of water increased yield by 644 kg/ha or 72% (Table 4). Adding another 10 cm of irrigated water increased yield by 549 kg/ha and full irrigation, adding 27 cm of water to rainfall raised yield by 1653 kg/ha over rain-fed yields (186% increases) to a total 2543 kg/ha (Table 4). Therefore, adding 27 cm of water to the 16 cm of rainfall resulted in a nearly 3-fold seed yield increase. At harvest, the dry weight of the above-ground portion of a sub-sample of plants was measured. There was no significant effect by adding 10 cm of irrigation, but adding 18.6 or 27.3 cm increased the dry weight by 35% (Table 4).
Then, the plants were dried in an oven set at 50 ◦ C for 7–10 days and re-weighed. Weights were averaged per plot. Seeds were harvested directly and yields were weighed. Plot yields were adjusted per area and presented as kg/ha. Seed sub-samples were sent to the USDA lab in Peoria, IL. Fatty acid and oil content analyses were conducted on harvested seed according to Pavlista et al. (2011a). Data were analyzed using Proc ANOVA in SAS with means separated using least significant differences and inferences based on a 5% significance level (SAS Inst., 2003) when p < 0.05. There were no significant interactions between growth or harvest data with either year or location, therefore the data from the four trials were combined and presented.
3.3. Oil and fatty acids Seed oil content was significantly higher with full irrigation (HI) compared to the other three moisture levels (Table 4). There were no interactions between either year or locale for any of the harvest data. C18:3 (linolenic acid, ‘omega-3’) was significantly increased to 35.0% under HI (43.1 cm applied water) (Table 5). The other two major constituents were octadecenoic acid (C18:1 9, 94%; C18:1 11, 6% of the octadecenoic acid fraction) and linoleic acid (C18:2 9, 12) (Table 5). Adding irrigation decreased the proportion of C18:1 in the oil from 20.7% for RF to 17.9% for HI (Table 5). Likewise, C18:2 (linoleic acid) decreased in the oil from 20.2% for RF to 18.8% for HI (Table 5). It appears that the increase in C18:3 with irrigation was at the expense of C18:1 and C18:2. The consumption of oleic acid to form linolenic and ercucic acids is expected since the development of oil and fatty acids are farther along the biosynthetic pathway in the development of the seed and those seeds under stress would have delayed production of these components. Another significant increase due to irrigation was observed with
3. Results 3.1. Seasonal growth Emergence occurred 10–12 days after planting at which time Pdays began accumulating and differential irrigation was imposed (Table 1). Growth was followed from about 4 WAP to harvest at about 13 WAP. Irrigation level did not affect the number of nodes on the main stem, but the number did significantly increase over time reaching a maximum of 28 by 6 WAP (data not shown). This corresponded to a P-day of 150 (Table 1). Canopy height was not affected by irrigation until 8 WAP when RF plants were shorter (Table 2). Two weeks later, RF and LI were significantly different from each other and the LI was significantly different from the HI irrigation level. However, by harvest, the two lower irrigations were shorter than both the higher irrigation levels (Table 2). Over
Table 3 Vine, pod and above-ground fresh weight as affected by irrigation level, mean of four camelina trials.
WAP
a
Irrigationb RF LI MI HI p-value* *
Vine fresh weight, g/plant
Pod fresh weight, g/plant
Top fresh weight, g/plant
8
13
8
13
8
13
22 23 24 21 NS
12 C 14 BC 17 AB 18 A 0.01
2.0 2.5 2.4 2.2 NS
20 B 22 B 29 A 29 A <0.01
24 25 28 23 NS
32 C 36 BC 46 AB 47 A <0.01
Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. WAP = weeks after planting. b Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level and WAP. a
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Table 4 Harvesta data as the means of four camelina trials, Scottsbluff and Sidney, NE, 2007 and 2008. Irrigation levelb
Yield, kg/ha e
Plant dry weightc , g/plant
Harvest Indexd (%)
Seed oil content, % dry weight
RF LI MI HI
890 D 1534C 2083 B 2543 A
16 B 19 B 24 A 25 A
2.5 C 3.6 BC 4.0 AB 5.1 A
27.7 B 27.7 B 28.2 B 29.1 A
p-values: Irrigation (I) Year (Y) Locale (L) I*Y I*L
<0.01 <0.01 NS NS NS
<0.01 <0.01 <0.01 NS NS
<0.01 NS <0.01 NS NS
<0.01 <0.01 NS NS NS
Harvests of the four trials were around 17 July (calendar day 198) or about 13 weeks after planting. The mean P-days ± standard error at harvest was 486 ± 13. Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level. c Plant weights were of the total above ground weights; roots were not included. d Harvest index was the % seed dry weight divided by the total dry weight of the above-ground plant. e Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. a
b
Table 5 Profile of major fatty acids in camelina seed, mean of four trials. C18:1b
C18:2
C18:3
C20:1
C22:1
Irrigation level RF LI MI HI
Relative % 20.7 A 19.4 B 18.5 C 17.9 C
20.2 A 19.7 AB 19.3 BC 18.8C
32.1 C 32.7 BC 33.7 B 35.0 A
12.3 12.7 12.6 12.5
3.2 B 3.5 AB 3.6 A 3.6 A
p-values Irrigation (I) Year (Y) Locale (L) Ic Y Ic L
<0.01 NS <0.01 NS NS
<0.01 0.01 0.01 NS NS
0.02 0.01 0.03 NS NS
NS NS NS NS NS
0.02 0.01 NS NS NS
a
a Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level. b Seed oil and fatty acid profile were determined by the method described in Pavlista et al., 2011a,b. C18:1 = oleic acid (‘omega-9’); C18:2 = linoleic acid; C18:3 = linolenic acid (‘omega-3’); C20:1 = eicosenoic acid; and C22:1 = erucic acid. c Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05.
C22:1 (erucic acid) which increased from 3.2% in RF to 3.6% for the MI and HI irrigation treatments (Table 5). The other constituents profiled, C16:0, C18:0, C20:0, C20.0, and C24.0, were less than 6% of the oil and showed no change resulting from irrigation (data not shown). 4. Discussion 4.1. Seasonal growth Although the number of stem nodes was not affected by the amount of applied water, plant growth as measured by canopy height and weight, and stem length was increased with irrigation. Since node number was not affected, increased canopy height and stem length were due to promotion of internode elongation suggesting stimulation by greater gibberellic acid. A difference in applied water of 20 cm was sufficient to reach maximum canopy height (75 cm) by 10 WAP (Table 2). Previous studies of camelina in western Nebraska under low water availability (less than 20 cm) reported a maximum canopy height between 70 and 75 cm reached after 9 WAP (Pavlista et al., 2012). This range was also reported in Arizona as a winter/spring crop (Hunsaker et al., 2013) and slightly less than that reported in Nova Scotia and Prince Edward Island (Urbaniak et al., 2008), but substantially shorter than reported for camelina as a winter annual in Chile (Berti et al., 2011). Main stem
plus branches and pod weights showed the same irrigation effect at 13 WAP, two weeks after maximum canopy height was reached (Table 3). Main stem plus branches and pod fresh weight were 17 and 29 g/plant with greater than 30 cm available water. There heights were greater than that reported with 20 cm available water (Pavlista et al., 2012). Plant dry weight at harvest was increased by MI and HI versus RF and LI (Table 4). 4.2. Yield For every increase in available moisture of about 9 cm in irrigation, seed yield was significantly increased from 890 kg/ha for RF to 2540 kg/ha for HI (Table 4). With 20 cm of seasonal irrigation and rainfall, Pavlista et al. (2011a) reported a yield of about 1300 kg/ha which is about half way between RF and LI treatments reported here (Table 4). The lower amount of applied water in 2005 and 2006 explains the lower yield obtained compared to 2007 and 2008 when irrigation level was tested. Urbaniak et al. (2008) reported their highest yields of mid-May planted camelina between 2300 and 2600 kg/ha planted in Maritime Canada which is similar to that reported here for HI (43 cm available water), but Jiang et al. (2013) reported lower yields (1900–2000 kg/ha) with early May planted camelina in the same Canadian region. In west central Minnesota, Gesch (2014) reported the highest yield of 2300 kg/ha for the camelina cultivar Calena planted in early May (2009). Seed yields reported in Arizona of camelina planted between January and May were 1500–1600 kg/ha receiving about 50 cm of applied water (Hunsaker et al., 2013) which is the range reported here for LI receiving about 26 cm of water. Spring camelina in Idaho reached a high yield value of 1700 kg/ha (Schillinger et al., 2012). In a review, Moser (2010) reported a yield range of 900–2240 kg/ha for camelina. Variations in yield could be due to location climate and soil conditions as well as cultivars and planting dates used. In North America, western Nebraska shows excellent potential for spring-planted camelina production (Obour et al., 2015). Winter camelina yields have been reported to be as high as 2900 kg/ha in Idaho (Schillinger et al., 2012) and 1320 kg/ha in Minnesota (Gesch and Cermak, 2011). In Chile, the highest yields of camelina as a winter crop were about 2300 kg/ha at Osorno and about 1900 kg/ha at Los Angeles in 2008 (Berti et al., 2011). 4.3. Oil and fatty acids The percent oil in seed on a dry weight basis was raised by HI (43.1 cm moisture) to 29.1% from 27.7% in the lower two levels and 28.2% in MI. These oil contents were less than the range of 30–34% reported earlier in western Nebraska (Pavlista et al., 2011a,
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2012) under lower irrigation. Spring camelina may behave similar to spring canola in the High Plains where there was an inverse relation between seed yield and seed oil content (Pavlista et al., 2011b). High temperature may also play a major factor in oil content in the High Plains as observed with spring canola (Pavlista et al., 2011b). The oil content range reported for Maritime Canada was 36–40% (Jiang et al., 2013; Urbaniak et al., 2008) and over 40% in Minnesota (Gesch, 2014). However, Jiang et al. (2013) reported that increasing soil N resulted in decreasing oil content. This could explain the low oil content here as N levels, above 120 kg/ha, were present. Camelina oil content in Minnesota has been reported at 31% (Putnam et al., 1993) and between 29 and 39% (Budin et al., 1995). Oil content greater than 40% have been reported in Arizona (Hunsaker et al., 2013), and in Europe (Zubr, 2003) and in South America (Chile) (Berti et al., 2011). The fatty acid profile was altered by adding water during the season. Linolenic acid (C18:3), the main constituent was increased with irrigation from 32 to 35% while the amount of oleic acid (C18:1) and linoleic acid (C18:2) decreased from 21 to 18% and 20 to 19%, respectively (Table 5). Earlier studies in western Nebraska showed linolenic acid at 36% with 36 cm applied water (Pavlista et al., 2011a) and 31% with 20 cm (Pavlista et al., 2012). The range of linolenic acid in camelina has been reported between 31 and 38% (Budin et al., 1995; Putnam et al., 1993; Zukr, 2003; Zukr and Matthaus, 2002). The ranges reported by these authors for oleic acid, linoleic acid, and eicosenoic acid (C20:1) were 13–19%, 15–23%, and 12–15%, respectively. The values reported here are in line with these. Erucic acid (C22:1) is generally undesirable. Its content showed a slight increase with irrigation from 3.2 to 3.6%. An erucic acid content of about 3% was typically reported by the above authors. Compared to many oilseed crops, camelina contained more linolenic acid (‘omega-3’) with the exception of flax (Budin et al., 1995; Putnam et al., 1993; Zubr, 2003). Unlike canola, camelina does contain about 3% erucic acid and ranges from 2 to 4% which is below the acceptable limit for vegetable oils used for human consumption (Zubr, 2003). However, the fatty acid profile of camelina is suitable for conversion to biodiesel and more importantly has been successfully converted to renewable jet fuel where full scale conversion and testing on commercial aircraft engines has been completed (Li and Mupondwa, 2014).
5. Conclusion Camelina needed about 23 cm of applied water (rain plus irrigation) to achieve maximum plant growth. However, maximum seed yield was reached when at least 43 cm of water was applied. This is within the range reported in a recent review of growing camelina in the Great Plains (Obour et al., 2015), and the amount of water required in Arizona (Hunsaker et al., 2013) and in the Pacific Northwest (Schillinger et al., 2012). Hergert et al. (2011) reported early findings that 46 cm of water was needed in western Nebraska to achieve a camelina seed yield of about 2500 kg/ha. Schillinger et al. (2012) estimated that there is a seed yield gain of 2.8 kg/ha for each mm of water applied. Camelina could be grown successfully under the semi-arid conditions of western Nebraska where seasonal rainfall averages about 15 cm. An advantage of some irrigation is the increase of the beneficial fatty acid, omega-3, for human consumption. Camelina would readily fit into the wheat-fallow rotation in the U.S. Great Plains (Obour et al., 2015). Cultivars may also differ considerably in their growth, seed yield and oils (Budin et al., 1995; Gesch, 2014; Urbaniak et al., 2008); therefore more information is needed on potential cultivars for use in the production of biodiesel or for livestock feed.
Acknowledgments The authors are grateful for the technical support of Allison Hazen and the assistance of summer interns. I give special appreciation for the financial support of the USDA Risk Management Assessment program. References Aiken, R., Baltensperger, D., Krall, J., Pavlista, A., Johnson, J., 2015. Planting methods affect emergence, flowering and yield of spring oilseed crops in the U: S. Central High Plains. Ind. Crops Prod. 69, 273–277. Allen, B.L., Vigil, M.F., Jabro, J.D., 2014. Camelina growing degree hour and base temperature requirements. Agron. J. 106, 940–944. Basara, J.B., Maybourn, J.N., Peirano, C.M., Tate, J.E., Brown, P.J., Hoey, J.D., Smith, B.R., 2013. Drought and associated impacts in the Great Plains of the United States—a review. Int. J. Geosci. 4, 72–81. Bernardo, A., Howard-Hildige, R., O’Connell, A., Nichol, R., Ryan, J., Rice, B., Roche, E., Leahy, J.J., 2003. Camelina oil as a fuel for diesel transport engines. Ind. Crops Prod. 17, 191–197. Berti, M., Wilckens, R., Fischer, S., Solis, A., Johnson, B., 2011. Seeding date influence on camelina seed yield, yield components, and oil content. Ind. Crops Prod. 34, 1358–1365. Bleed, J.B., Babbitt, C.H., 2015. Nebraska’s Natural Resources Districts: An Assessment of a Large-Scale Locally Controlled Water Governance Framework. Policy Report 1. In: Robert Daugherty, B. (Ed.). Water for Food Institute, University of Nebraska–Lincoln, 155 pp. Boyles, M.T., Peeper, T., Stamm, M., 2006. Great Plains Canola Handbook. Kansas State University, MF-2734. Budin, J.T., Breene, W.M., Putnam, D.H., 1995. Some compositional properties of camelina (Camelina sativa L. Crantz) seed and oils. J. Am. Oil Chem. Soc. 72, 309–315. Changnon, S.A., Lamb, P., Hubbard, K.G., 1990. Regional climate centers: new institutions for climate services and climate-impact research. Bull. Am. Meteorol. Soc. 71, 527–537. English, M., Raja, S.N., 1996. Perspectives on deficit irrigation. Agric. Water Manag. 32, 1–14. French, A.N., Hunsaker, D., Thorp, K., Clarke, T., 2009. Evapotranspiration over a camelina crop at Maricopa, Arizona. Ind. Crops Prod. 29, 289–300. Frohlich, A., Rice, B., 2005. Evaluation of Camelina sativa oil as a feedstock for biodiesel production. Ind. Crops Prod. 21, 24–31. Geerts, S., Raes, D., 2009. Deficit irrigation as an on-farm strategy to maximize crop water productivity in dry areas. Agric. Water Manag. 96, 1275–1284. Gesch, R.W., 2014. Influence of genotype and sowing date on camelina growth and yield in the north central U.S. Ind. Crops Prod. 54, 209–215. Gesch, R.W., Cermak, C., 2011. Sowing date and tillage effects on fall-seeded camelina in the norther Corn Belt. Agron. J. 103, 980–987. Harveson, R.M., Santra, D.K., Pavlista, A.D., Putnam, M.L., Curtis, M., 2011. A new report for downy mildew ((Hyaloperonospora camelinae Gäum.) Goker, Voglmayr, Riethm., M. Weiss & Oberw.) of camelina (Camelina sativa (L.)) Crantz in the High Plains of the United States. Plant Health Prog., http://dx.doi. org/10.1094/php-2011-1014-01-br. Hergert, G.W., Klocke, N.L., Petersen, J.L., Nordquist, P.T., Clark, R.T., Wicks, G.A., 1993. Cropping systems for stretching limited irrigation supplies. J. Prod. Agric. 6, 520–529. Hergert, G.W., Margheim, J., Pavlista, A., Burgener, P., Lyon, D., Hazen, A., Martin, D., Supalla, R., Thompson, C., 2011. Yields and ET of deficit to fully irrigated spring canola and camelina. In: Proceeding of the 23nd Annual Central Plains Irrigation Conference, Burlington, CO, USA, pp. 190–198. Hunsaker, D.J., French, A.N., Thorp, K.R., 2013. Camelina water use and seed yield response to irrigation scheduling in an arid environment. Irrig. Sci. 31, 911–929. Jiang, Y., Caldwell, C.D., Falk, K.C., Lada, R.R., MacDonald, D., 2013. Camelina yield and quality response to combined nitrogen and sulfur. Agron. J. 105, 1847–1852. Keske, C.M.H., Hoag, D.L., Brandess, A., Johnson, J.J., 2013. Is it economically feasible for farmers to grow their own fuel? A study of Camelina sativa produced in the western United States as an on-farm biofuel. Biomass Bioenergy 54, 89–99. Klocke, N.L., Schneekloth, J.P., Melvin, S.R., Clark, R.T., Payero, J.O., 2004. Field scale limited irrigation scenarios for water policy strategies. Appl. Eng. Agric. 20, 623–631. Li, X., Mupondwa, E., 2014. Life cycle assessment of camelina oil derived jet fuel in the Canadian Prairies. Sci. Total Environ. 481, 17–26. Moser, B.R., 2010. Camelina (Camelina sativa L.) oil as a biofuel feedstock: golden opportunity or false hope? Lipid Technol. 22, 270–273. Moser, B.R., Vaughn, S.F., 2010. Evaluation of alkyl esters from Camelina sativa oil as biosiesel and as blend components in ultra low-sulfur diesel fuel. Bioresour. Technol. 101, 646–653. Obour, A.K., Sintin, H.V., Obeng, E., Jeliazkov, V.D., 2015. Oilseed camelina (Camelina sativa L. Crantz): production systems, prospects and challenges in the USA Great Plains. Adv. Plants Agric. Res. 2, 1–10. Pavlista, A.D., 2015. Scheduling reduced irrigation on ‘Atlantic’ potato for minimal effect. Am. J. Potato Res. 92, 673–683.
A.D. Pavlista et al. / Industrial Crops and Products 83 (2016) 118–123 Pavlista, A.D., Isbell, T.A., Baltensperger, D.D., Hergert, G.W., 2011a. Planting date and development of spring-seeded irrigated canola, brown mustard and camelina. Ind. Crops Prod. 33, 451–456. Pavlista, A.D., Santra, D.K., Isbell, T.A., Baltensperger, D.D., Hergert, G.W., Krall, J., Mesbach, A., Johnson, J., O’Neil, M., Aiken, R., Berrada, A., 2011b. Adaptability of irrigated spring canola oil production to the US High Plains. Ind. Crops Prod. 33, 165–169. Pavlista, A.D., Baltensperger, D.D., Isbell, T.A., Hergert, G.W., 2012. Comparative growth of spring-planted canola, brown mustand and camelina. Ind. Crops Prod. 36, 9–13. Pilgeram, A.L., Sands, D.C., Boss, D., Dale, N., Wichman, D., Lamb, P., Lu, C., Barrows, R., Kirkpatrick, M., Thompson, B., Johnson, D.L., 2007. Camelina sativa, a Montana omega-3 and fuel crop. In: Janick, J., Whipkey, A. (Eds.), Issues in New Crops and New Uses. ASHS Press, Alexandria, VA, pp. 129–131. Putnam, D.H., Budin, J.T., Field, L.A., Breene, W.M., 1993. Camelina: a promising low-input oilseed. In: Janick, J., Simon, J.E. (Eds.), New Crops. Wiley, NY, pp. 314–322. Sands, P.J., Hackett, C., Nix, H.A., 1979. A model of the development and bulking of potatoes (Solanum tuberosum L.). I. Derivation from well-managed field crops. Field Crops Res. 2, 309–331. SAS Institute, 2003. SAS System for Windows. Release 9.1. SAS Institute Inc., Cary, NC. Schillinger, W.F., Wysocki, D.J., Chastain, T.G., Guy, S.O., Karow, R.S., 2012. Camelina: planting date and method effects on stand establishment and seed yield. Field Crops Res. 130, 138–144.
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Schneekloth, J.P., Norton, N.A., Clark, R.T., Klocke, N.L., 2001. Irrigating for Maximum Economic Return with Limited Water. Univ. NE NebGuide, G01-1422. Shonnard, D.R., Williams, L., Kalnes, T.N., 2010. Camelina-derived jet fuel and diesel: sustainable advanced biofuels. Environ. Prog. Sustain. Energy 29, 382–392. Soriano, N.U., Narani, A., 2012. Evaluation of biodiesel derived from Camelina sativa oil. J. Am. Oil Chem. Soc. 89, 917–923. Trout, T., Bausch, W., Buchleiter, G., 2010. Does deficit irrigation give more crop per drop? In: Proceedings of the 22nd Annual Central Plains Irrigation Conference, Kearney, NE, USA, pp. 36–40. Urbaniak, S.D., Caldwell, C.D., Zheljazkov, V.D., Lada, R., Luan, L., 2008. The effect of cultivar and applied nitrogen on the performance of Camelina sativa L. in the maritime provinces of Canada. Can. J. Plant Sci. 88, 111–119. Zaleckas, E., Makareviciene, V., Senzikiene, E., 2012. Possibilities of using Camelina sativa oil for producing biodiesel fuel. Transport 27, 60–66. Zubr, J., 2003. Dietary fatty acids and amino acids of Camelina sativa seed. J. Food Qual. 26, 451–462. Zukr, J., Matthaus, B., 2002. Effects of growth conditions on fatty acids and tocopherols in Camelina sativa oil. Ind. Crops Prod. 15, 155–162.
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Industrial Crops and Products journal homepage: www.elsevier.com/locate/indcrop
Growth of spring camelina (Camelina sativa) under deficit irrigation in Western Nebraska A.D. Pavlista a,∗ , G.W. Hergert a , J.M. Margheim a , T.A. Isbell b a b
University of Nebraska, PREC, Scottsbluff, NE 69361, USA USDA-ARS, Peoria, IL 61604, USA
a r t i c l e
i n f o
Article history: Received 2 October 2015 Received in revised form 3 December 2015 Accepted 9 December 2015 Available online 4 January 2016 Keywords: Oilseed Biodiesel Omega-3 Omega-9
a b s t r a c t The High Plains of the U.S.A. is subject to periodic drought where low-water using crops are desired. Camelina is a potential biofuel crop that may be suitable for this region. The objective was to determine the growth, seed yield, and oil characteristic of camelina exposed to four levels of applied water in western Nebraska. The cultivar Cheyenne was exposed to rain-fed only (RF), and irrigated with 10 (LI), 20 (MI), and 30 (HI) cm water. Irrigation increased plant growth as measured by canopy height, stem length, and canopy weight. Maximum height (70–80 cm) was reached by 10 weeks after planting (WAP) with a total of 23 cm of applied water or 13 cm of irrigation. By 13 WAP, canopy and pod fresh weights were increased by 40–50% by the MI and HI irrigations. Likewise, at harvest (13 WAP), plant dry weight was increased by 50% by the two higher irrigation levels. Seed yields were increased by each incremental increase in irrigation from 890 kg/ha for RF to 2540 for HI, a 2.85-fold increase. Oil content was not affected by irrigating at the LI or MI but was increased only by the HI irrigation level. The fatty acid profile was altered by irrigation with an increase in the major constituent, linolenic acid, and a corresponding decrease in two other large constituents, oleic and linoleic acids. There also was a slight increase in the minor constituent of erucic acid. The growth pattern of camelina showed that 23 cm of applied water would be required for healthy plant growth but as much as 43 cm would be needed for maximum yield. The results indicate that camelina could be grown successfully in western Nebraska, supplying oil for fuel and cooking. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Western Nebraska is well-known for its low rainfall and periodic, long and severe droughts causing declining water availability for agriculture (Basara et al., 2013) and decreasing irrigation allocations (Bleed and Babbitt, 2015). In NE, KS and CO, legislation has been passed to manage groundwater, which impacts irrigation water allocations. This simply means less water and the need to find low water-using crops. Several major crops have been studied in the High Plains and the findings suggest that applying limited water provides more profit potential and has less impact on the local economy than reverting some land to dryland agriculture (Schneekloth et al., 2001). Under deficit irrigation, less water is applied than is required to meet full evapo-transpiration demand. The crop grows under continuous, but not severe, water stress. However, proper deficit irrigation management may not reduce
∗ Corresponding author. E-mail address: [email protected] (A.D. Pavlista). http://dx.doi.org/10.1016/j.indcrop.2015.12.017 0926-6690/© 2015 Elsevier B.V. All rights reserved.
yield as much as might be expected with corn, soybean or wheat when grown at North Platte, NE (Hergert et al., 1993; Klocke et al., 2004). Deficit irrigation is a way of optimizing irrigation during drought-sensitive stages in crops such as corn (maize) (Zea mais), cotton (Gossypium hirusutum), potato (Solanum tuberosum), soybean (Glycine max), and wheat (Triticum aestivum) (Geerts and Raes, 2009). Real-world use of deficit irrigation on corn, cotton and wheat showed that under conditions where water is scarce, the optimum strategy might be to reduce irrigation by 25–60% (English and Raja, 1996). Pavlista (2015) demonstrated that for marketable yield of potato timing of deficit irrigation is crucial. However, under some circumstances, deficit irrigation may not be economically advantageous (Trout et al., 2010). Although spring camelina is an old crop dating back millenia (Budin et al., 1995; Putnam et al., 1993), recent interest has been observed due to its potential use as an alternate biofuel (Bernardo et al., 2003; Frohlich and Rice, 2005; Moser and Vaughn, 2010; Zaleckas et al., 2012). Camelina may even be used as avaition fuel (Shonnard et al., 2010). An advantage of camelina as a biodiesel is its low greenhouse gas emission, 75–80% less than petrofuels (Moser,
A.D. Pavlista et al. / Industrial Crops and Products 83 (2016) 118–123
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2010). However, high unsaturated levels of fatty acids resulting in poor oxidative stability will limit camelina methyl esters as a standalone biodiesel (Frohlich and Rice, 2005; Moser and Vaughn, 2010; Zaleckas et al., 2012). As a blend component, camelina esters may be indistinguishable from soybean esters (Moser, 2010) and be comparable to soybean biodiesel (Soriano and Narani, 2012). Camelina is considered a non-food crop, therefore would not disrupt food production, although camelina meal can be used as an animal feed (Pilgeram et al., 2007). It would be suitable for production incorporated into a wheat-fallow rotation in the upper Great Plains of the USA (‘High Plains’) as recently reviewed by Obour et al. (2015). Keske et al. (2013), using an economic analysis, demonstrated that at the farm level, growing camelina for biodiesel and using the meal as a feedstock for livestock could be profitable in the western USA. There has been considerable research reported on producing spring camelina under dryland (rain-fed) conditions in the Great Plains as reviewed by Obour et al. (2015). Emergence under cold temperature (Allen et al., 2014), planting dates (Pavlista et al., 2011a; Shonnard et al., 2010) and planting methods (Aiken et al., 2015; Schillinger et al., 2012) have been reported. Studies on camelina and its irrigation needs are limited, and in the USA are reported primarily for Arizona using surface irrigation to achieve various levels of soil water depletion (French et al., 2009; Hunsaker et al., 2013) and Nebraska using sprinkler irrigation to achieve various levels of available water (Hergert et al., 2011). In AZ under their hot and arid climate, camelina was planted in January while in NE, under a semi-arid climate, it was planted in April. From these studies, water use efficiency and ET were calculated for these two very different climates (Hergert et al., 2011; Hunsaker et al., 2013). Pavlista et al. (2012) compared growth patterns of camelina to canola (Brassica napus) and brown mustard (Brassica juncea) under low irrigation. However, the objective of this study was to identify the effects of various levels of irrigation on growth, yield and oil of camelina in western Nebraska at two location over two years.
Table 1 Dates, physiological days and precipitation, means and standard errors of four camelina trials, Scottsbluff and Sidney, NE, 2007 and 2008.
2. Materials and methods
2.2. Irrigation regimes
2.1. Field trial conditions
Weather stations were located near the trial fields, and rainfall and temperature were monitored by the High Plains Climate Center (Changnon et al., 1990). Irrigation was applied through an overhead, linear-move system. Four irrigation levels were applied to plots and replicated three times in a randomized complete block design. The check was no irrigation or rain-fed only referred to as RF. The three irrigated levels were LI whose targeted seasonal irrigation level was 10 cm, MI targeted at 20 cm, and HI targeted at 30 cm of added irrigation. Irrigation was not adjusted for rainfall, therefore, RF received 15.8 cm rain during the season while HI received 43.1 cm (Table 1). Distribution of irrigation was based on the weather stations and HI was not ET-limited, while actual ET was used to calculate water use (Hergert et al., 2011). LI (10 cm), irrigations were timed to coincide with flowering and early grain fill. MI (20 cm) irrigations were applied through vegetative growth to flowering and early grain fill. Full irrigation (HI) was season long.
Camelina cv. Cheyenne was grown in four field trials, two in 2007 and two in 2008. Two trials were conducted each year, one at Scottsbluff, NE, and the other in Sidney, NE. The trials at Scottsbluff, NE, were at the Panhandle Research and Extension Center (41◦ 89 N, 103◦ 68 W with an elevation of 1189 m) on a Tripp fine sandy loam soil at pH 8.1 with an organic matter content of about 1.0%. The trials at Sidney, NE, were at the High Plains Ag Lab (41◦ 23 N, 103◦ 02 W with an elevation of 1247 m) on a Keith silt loam soil at pH 6.8 and organic matter content of about 2%. Plots consisted of 38 rows spaced 0.2 m apart and 9.1 m long or an area of 69 m2 of which 6 rows 9 m long, an area of 10.8 m2 , was harvested. Previous crops were dry edible beans (Phaseolus vulgaris) at Scottsbluff in both years, and at Sidney, it was winter wheat in 2007 and foxtail millet (Setaria italica) in 2008. Nitrogen was applied based on soil tests using guidelines and practices adapted from recommendations on canola in the region (Boyles et al., 2006). Total residual N in the top 0.9 m was: >130 kg/ha at Scottsbluff in both years and >110 kg/ha at Sidney for both years. The maximum root depth for camelina was previously determined to be between 0.9 and 1.06 m in the High Plains. In Scottsbluff, a starter fertilizer was added pre-plant incorporated at 34 kg N/ha and 39 kg S/ha; in Sidney, the starter fertilizer was added at 50 kg N/ha, 28 kg P2 O5 and 22 kg S/ha. The starter was incorporated with 1.25 cm of water within 6 h of application. The total N for camelina coincides with the range of 120–160 kg N/ha recently reported for the Maritime Provinces of Canada (Jiang et al., 2013).
RFa WAPb
DAPb
P-daysc
4 6 8 10 12 13
31 ± 1 43 ± 1 57 ± 1 71 ± 1 88 ± 2 94 ± 4
114 ± 8 151 ± 24 216 ± 16 313 ± 18 443 ± 8 486 ± 13
LI
MI
HI
Precipitationd (cm) 2.9 ± 0.1 6.6 ± 1.4 9.4 ± 2.7 10.8 ± 3.4 14.2 ± 3.4 15.8 ± 3.3
4.8 ± 0.8 8.5 ± 1.0 13.0 ± 0.6 17.5 ± 2.2 24.1 ± 3.5 25.7 ± 3.3
5.6 ± 0.3 11.0 ± 1.6 17.7 ± 3.7 23.4 ± 3.7 32.3 ± 2.7 34.4 ± 3.3
7.0 ± 0.9 12.3 ± 2.2 19.1 ± 3.2 27.1 ± 2.9 40.4 ± 1.5 43.1 ± 2.7
a Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI representing full irrigation with a target of 30 cm. b WAP = target week after planting; DAP = actual days after planting. c P-days were calculated as described in Sands et al., 1979. d Precipitation is the sum of rainfall plus irrigation. Irrigation level RF represents rainfall alone.
Trifluralin at 0.58 kg AI/ha (Treflan HFP at 1.2 l/ha) was applied pre-plant incorporated. Unlike canola (B. napus), fleabeetle and birds are not an issue with camelina (Pavlista et al., 2011a). Downy mildew (Hyaloperonospora camelinae) (Harveson et al., 2011) did not appear on camelina in these trials. Therefore, neither insects or pathogens presented themselves as a problem in either location in 2007 and 2008. Planting was in mid-April at both locations and in both years as recommended by Pavlista et al. (2011a) and Schillinger et al. (2012). Camelina seed was planted at 4–5 kg/ha at about 770,000 seed/kg as generally recommended for this region (Obour et al., 2015) with a no-till drill at a depth of 1.2 cm (Aiken et al., 2015; Schillinger et al., 2012). All trials were harvested in mid-July, about 13 weeks after planting (WAP) with a small plot combine (Table 1). Camelina seed was considered mature and ready for harvest when the pods desiccated and hardened, and the seed color changed from green to cinnamon orange. Seed moisture was determined and yields adjusted to an 8% moisture basis.
2.3. Data collection and analysis Plant growth data, i.e., canopy height and weight, stem nodes and length, were taken every 2–3 weeks starting at 4 WAP (Table 1) following the procedure of Pavlista et al. (2012). Canopy height and width was measured with a meter-stick three times in the center rows of each plot and averaged. Canopy weight was determined by cutting four plants at the base in each plot, stem length was measured with a meter stick and the number of nodes on the stem were counted. The next day, the plants were weighed with pods (silicles), if present, separated from the main stem and branches.
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Table 2 Canopy height as affected by irrigation level and time, mean of four camelina trials. WAPa P-daysb
4 110
6 150
8 220
10 310
13 490
Irrigationc RF LI MI HI p-valuef
Canopy height (cm) 13 dd 12 d 13 d 12 d NS
29 c 29 c 30 c 29 c NS
46 Be ,b 56 A, b 59 A, b 62 A, b <0.01
60 C, ab 72 B, a 75 AB, a 80 A, a <0.01
63 C, a 72 B, a 83 A, a 84 A, a <0.01
time, canopy height reached a plateau by 10 WAP (Table 2) corresponding to a P-day between 295 and 331 (Table 1). Stem length was also measured at 10 WAP and gave corresponding results as canopy height (data not shown). Canopy width was measured at 10 WAP and showed no significant difference between irrigation levels (data not shown). Plant weight was observed periodically. Irrigation level did not affect the fresh weight of the above-ground plant at 8 WAP but differences were observed three weeks later. As the irrigation level increased the above-ground fresh weight increased (Table 3). Flowers appeared about 8 WAP and showed no irrigation effect. Pods (silicles) matured about 13 WAP; differences in pod fresh weight due to irrigation were measured at that time. Pod fresh weight of the two higher irrigation levels (MI and HI) were significantly higher than the RF and LI (Table 3). Total above-ground fresh weight corresponded to that of the stem and branches. Dry weights followed a similar pattern at harvest (Table 4).
p-value <0.01 <0.01 <0.01 <0.01
a
WAP = weeks after planting. P-days were calculated as described in Sands et al.,1979. c Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level and DAP. d Values in rows (across WAP) followed by the same ordinal letter were not significantly different at p < 0.05 based on least significant differences. e Values in columns (across irrigation levels) followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. f There were no significant interactions between irrigation level and plant height in either year or location. b
3.2. Yield The 10-cm increments in irrigation affected camelina seed yield. Each irrigation increase resulted in a significant yield increase (Table 4). Just irrigating with 10 cm of water increased yield by 644 kg/ha or 72% (Table 4). Adding another 10 cm of irrigated water increased yield by 549 kg/ha and full irrigation, adding 27 cm of water to rainfall raised yield by 1653 kg/ha over rain-fed yields (186% increases) to a total 2543 kg/ha (Table 4). Therefore, adding 27 cm of water to the 16 cm of rainfall resulted in a nearly 3-fold seed yield increase. At harvest, the dry weight of the above-ground portion of a sub-sample of plants was measured. There was no significant effect by adding 10 cm of irrigation, but adding 18.6 or 27.3 cm increased the dry weight by 35% (Table 4).
Then, the plants were dried in an oven set at 50 ◦ C for 7–10 days and re-weighed. Weights were averaged per plot. Seeds were harvested directly and yields were weighed. Plot yields were adjusted per area and presented as kg/ha. Seed sub-samples were sent to the USDA lab in Peoria, IL. Fatty acid and oil content analyses were conducted on harvested seed according to Pavlista et al. (2011a). Data were analyzed using Proc ANOVA in SAS with means separated using least significant differences and inferences based on a 5% significance level (SAS Inst., 2003) when p < 0.05. There were no significant interactions between growth or harvest data with either year or location, therefore the data from the four trials were combined and presented.
3.3. Oil and fatty acids Seed oil content was significantly higher with full irrigation (HI) compared to the other three moisture levels (Table 4). There were no interactions between either year or locale for any of the harvest data. C18:3 (linolenic acid, ‘omega-3’) was significantly increased to 35.0% under HI (43.1 cm applied water) (Table 5). The other two major constituents were octadecenoic acid (C18:1 9, 94%; C18:1 11, 6% of the octadecenoic acid fraction) and linoleic acid (C18:2 9, 12) (Table 5). Adding irrigation decreased the proportion of C18:1 in the oil from 20.7% for RF to 17.9% for HI (Table 5). Likewise, C18:2 (linoleic acid) decreased in the oil from 20.2% for RF to 18.8% for HI (Table 5). It appears that the increase in C18:3 with irrigation was at the expense of C18:1 and C18:2. The consumption of oleic acid to form linolenic and ercucic acids is expected since the development of oil and fatty acids are farther along the biosynthetic pathway in the development of the seed and those seeds under stress would have delayed production of these components. Another significant increase due to irrigation was observed with
3. Results 3.1. Seasonal growth Emergence occurred 10–12 days after planting at which time Pdays began accumulating and differential irrigation was imposed (Table 1). Growth was followed from about 4 WAP to harvest at about 13 WAP. Irrigation level did not affect the number of nodes on the main stem, but the number did significantly increase over time reaching a maximum of 28 by 6 WAP (data not shown). This corresponded to a P-day of 150 (Table 1). Canopy height was not affected by irrigation until 8 WAP when RF plants were shorter (Table 2). Two weeks later, RF and LI were significantly different from each other and the LI was significantly different from the HI irrigation level. However, by harvest, the two lower irrigations were shorter than both the higher irrigation levels (Table 2). Over
Table 3 Vine, pod and above-ground fresh weight as affected by irrigation level, mean of four camelina trials.
WAP
a
Irrigationb RF LI MI HI p-value* *
Vine fresh weight, g/plant
Pod fresh weight, g/plant
Top fresh weight, g/plant
8
13
8
13
8
13
22 23 24 21 NS
12 C 14 BC 17 AB 18 A 0.01
2.0 2.5 2.4 2.2 NS
20 B 22 B 29 A 29 A <0.01
24 25 28 23 NS
32 C 36 BC 46 AB 47 A <0.01
Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. WAP = weeks after planting. b Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level and WAP. a
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Table 4 Harvesta data as the means of four camelina trials, Scottsbluff and Sidney, NE, 2007 and 2008. Irrigation levelb
Yield, kg/ha e
Plant dry weightc , g/plant
Harvest Indexd (%)
Seed oil content, % dry weight
RF LI MI HI
890 D 1534C 2083 B 2543 A
16 B 19 B 24 A 25 A
2.5 C 3.6 BC 4.0 AB 5.1 A
27.7 B 27.7 B 28.2 B 29.1 A
p-values: Irrigation (I) Year (Y) Locale (L) I*Y I*L
<0.01 <0.01 NS NS NS
<0.01 <0.01 <0.01 NS NS
<0.01 NS <0.01 NS NS
<0.01 <0.01 NS NS NS
Harvests of the four trials were around 17 July (calendar day 198) or about 13 weeks after planting. The mean P-days ± standard error at harvest was 486 ± 13. Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level. c Plant weights were of the total above ground weights; roots were not included. d Harvest index was the % seed dry weight divided by the total dry weight of the above-ground plant. e Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05. a
b
Table 5 Profile of major fatty acids in camelina seed, mean of four trials. C18:1b
C18:2
C18:3
C20:1
C22:1
Irrigation level RF LI MI HI
Relative % 20.7 A 19.4 B 18.5 C 17.9 C
20.2 A 19.7 AB 19.3 BC 18.8C
32.1 C 32.7 BC 33.7 B 35.0 A
12.3 12.7 12.6 12.5
3.2 B 3.5 AB 3.6 A 3.6 A
p-values Irrigation (I) Year (Y) Locale (L) Ic Y Ic L
<0.01 NS <0.01 NS NS
<0.01 0.01 0.01 NS NS
0.02 0.01 0.03 NS NS
NS NS NS NS NS
0.02 0.01 NS NS NS
a
a Irrigation levels were: RF representing no irrigation, LI with a target irrigation of 10 cm, MI with a target irrigation of 20 cm, and HI with a target of 30 cm. Refer to Table 1 for actual total precipitation (rainfall + irrigation) for each irrigation level. b Seed oil and fatty acid profile were determined by the method described in Pavlista et al., 2011a,b. C18:1 = oleic acid (‘omega-9’); C18:2 = linoleic acid; C18:3 = linolenic acid (‘omega-3’); C20:1 = eicosenoic acid; and C22:1 = erucic acid. c Values in columns followed by the same capital letter were not significantly different at p < 0.05 based on least significant differences; NS = not significant at p < 0.05.
C22:1 (erucic acid) which increased from 3.2% in RF to 3.6% for the MI and HI irrigation treatments (Table 5). The other constituents profiled, C16:0, C18:0, C20:0, C20.0, and C24.0, were less than 6% of the oil and showed no change resulting from irrigation (data not shown). 4. Discussion 4.1. Seasonal growth Although the number of stem nodes was not affected by the amount of applied water, plant growth as measured by canopy height and weight, and stem length was increased with irrigation. Since node number was not affected, increased canopy height and stem length were due to promotion of internode elongation suggesting stimulation by greater gibberellic acid. A difference in applied water of 20 cm was sufficient to reach maximum canopy height (75 cm) by 10 WAP (Table 2). Previous studies of camelina in western Nebraska under low water availability (less than 20 cm) reported a maximum canopy height between 70 and 75 cm reached after 9 WAP (Pavlista et al., 2012). This range was also reported in Arizona as a winter/spring crop (Hunsaker et al., 2013) and slightly less than that reported in Nova Scotia and Prince Edward Island (Urbaniak et al., 2008), but substantially shorter than reported for camelina as a winter annual in Chile (Berti et al., 2011). Main stem
plus branches and pod weights showed the same irrigation effect at 13 WAP, two weeks after maximum canopy height was reached (Table 3). Main stem plus branches and pod fresh weight were 17 and 29 g/plant with greater than 30 cm available water. There heights were greater than that reported with 20 cm available water (Pavlista et al., 2012). Plant dry weight at harvest was increased by MI and HI versus RF and LI (Table 4). 4.2. Yield For every increase in available moisture of about 9 cm in irrigation, seed yield was significantly increased from 890 kg/ha for RF to 2540 kg/ha for HI (Table 4). With 20 cm of seasonal irrigation and rainfall, Pavlista et al. (2011a) reported a yield of about 1300 kg/ha which is about half way between RF and LI treatments reported here (Table 4). The lower amount of applied water in 2005 and 2006 explains the lower yield obtained compared to 2007 and 2008 when irrigation level was tested. Urbaniak et al. (2008) reported their highest yields of mid-May planted camelina between 2300 and 2600 kg/ha planted in Maritime Canada which is similar to that reported here for HI (43 cm available water), but Jiang et al. (2013) reported lower yields (1900–2000 kg/ha) with early May planted camelina in the same Canadian region. In west central Minnesota, Gesch (2014) reported the highest yield of 2300 kg/ha for the camelina cultivar Calena planted in early May (2009). Seed yields reported in Arizona of camelina planted between January and May were 1500–1600 kg/ha receiving about 50 cm of applied water (Hunsaker et al., 2013) which is the range reported here for LI receiving about 26 cm of water. Spring camelina in Idaho reached a high yield value of 1700 kg/ha (Schillinger et al., 2012). In a review, Moser (2010) reported a yield range of 900–2240 kg/ha for camelina. Variations in yield could be due to location climate and soil conditions as well as cultivars and planting dates used. In North America, western Nebraska shows excellent potential for spring-planted camelina production (Obour et al., 2015). Winter camelina yields have been reported to be as high as 2900 kg/ha in Idaho (Schillinger et al., 2012) and 1320 kg/ha in Minnesota (Gesch and Cermak, 2011). In Chile, the highest yields of camelina as a winter crop were about 2300 kg/ha at Osorno and about 1900 kg/ha at Los Angeles in 2008 (Berti et al., 2011). 4.3. Oil and fatty acids The percent oil in seed on a dry weight basis was raised by HI (43.1 cm moisture) to 29.1% from 27.7% in the lower two levels and 28.2% in MI. These oil contents were less than the range of 30–34% reported earlier in western Nebraska (Pavlista et al., 2011a,
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2012) under lower irrigation. Spring camelina may behave similar to spring canola in the High Plains where there was an inverse relation between seed yield and seed oil content (Pavlista et al., 2011b). High temperature may also play a major factor in oil content in the High Plains as observed with spring canola (Pavlista et al., 2011b). The oil content range reported for Maritime Canada was 36–40% (Jiang et al., 2013; Urbaniak et al., 2008) and over 40% in Minnesota (Gesch, 2014). However, Jiang et al. (2013) reported that increasing soil N resulted in decreasing oil content. This could explain the low oil content here as N levels, above 120 kg/ha, were present. Camelina oil content in Minnesota has been reported at 31% (Putnam et al., 1993) and between 29 and 39% (Budin et al., 1995). Oil content greater than 40% have been reported in Arizona (Hunsaker et al., 2013), and in Europe (Zubr, 2003) and in South America (Chile) (Berti et al., 2011). The fatty acid profile was altered by adding water during the season. Linolenic acid (C18:3), the main constituent was increased with irrigation from 32 to 35% while the amount of oleic acid (C18:1) and linoleic acid (C18:2) decreased from 21 to 18% and 20 to 19%, respectively (Table 5). Earlier studies in western Nebraska showed linolenic acid at 36% with 36 cm applied water (Pavlista et al., 2011a) and 31% with 20 cm (Pavlista et al., 2012). The range of linolenic acid in camelina has been reported between 31 and 38% (Budin et al., 1995; Putnam et al., 1993; Zukr, 2003; Zukr and Matthaus, 2002). The ranges reported by these authors for oleic acid, linoleic acid, and eicosenoic acid (C20:1) were 13–19%, 15–23%, and 12–15%, respectively. The values reported here are in line with these. Erucic acid (C22:1) is generally undesirable. Its content showed a slight increase with irrigation from 3.2 to 3.6%. An erucic acid content of about 3% was typically reported by the above authors. Compared to many oilseed crops, camelina contained more linolenic acid (‘omega-3’) with the exception of flax (Budin et al., 1995; Putnam et al., 1993; Zubr, 2003). Unlike canola, camelina does contain about 3% erucic acid and ranges from 2 to 4% which is below the acceptable limit for vegetable oils used for human consumption (Zubr, 2003). However, the fatty acid profile of camelina is suitable for conversion to biodiesel and more importantly has been successfully converted to renewable jet fuel where full scale conversion and testing on commercial aircraft engines has been completed (Li and Mupondwa, 2014).
5. Conclusion Camelina needed about 23 cm of applied water (rain plus irrigation) to achieve maximum plant growth. However, maximum seed yield was reached when at least 43 cm of water was applied. This is within the range reported in a recent review of growing camelina in the Great Plains (Obour et al., 2015), and the amount of water required in Arizona (Hunsaker et al., 2013) and in the Pacific Northwest (Schillinger et al., 2012). Hergert et al. (2011) reported early findings that 46 cm of water was needed in western Nebraska to achieve a camelina seed yield of about 2500 kg/ha. Schillinger et al. (2012) estimated that there is a seed yield gain of 2.8 kg/ha for each mm of water applied. Camelina could be grown successfully under the semi-arid conditions of western Nebraska where seasonal rainfall averages about 15 cm. An advantage of some irrigation is the increase of the beneficial fatty acid, omega-3, for human consumption. Camelina would readily fit into the wheat-fallow rotation in the U.S. Great Plains (Obour et al., 2015). Cultivars may also differ considerably in their growth, seed yield and oils (Budin et al., 1995; Gesch, 2014; Urbaniak et al., 2008); therefore more information is needed on potential cultivars for use in the production of biodiesel or for livestock feed.
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