Evaluating Agronomic Responses of Camelina to Seeding Date under Rain-Fed Conditions

Abstract

The potential to use camelina (Camelina sativa L.) as a bioenergy crop has increased the need to develop management practices that would improve sustainable production. Th is study evaluated the effects by cultivars (Blaine Creek, Pronghorn, and Shoshone) and three spring seeding dates on the performance of camelina grown under rain-fed conditions in northern Wyoming. Results showed significant effects of cultivar and/or seeding dates on camelina establishment, phenology, yield, seed protein, oil content, and estimated biodiesel yield. Growing degree-day (GDD) requirements for plant emergence, flowering, and maturity were 34, 417, and 998, respectively. Among the three cultivars studied, Blaine Creek and Pronghorn had better establishment and subsequent seed yield in both years. Averaged across the 2 yr, seed yield of Blaine Creek and Pronghorn were 931 and 963 kg ha–1, respectively, greater than that of Shoshone (826 kg ha–1). Seeding date had no effect on seed yield in 2013. However, in 2014, early seeding increased camelina seed yield. Early seeding in 2014 resulted in a general increase in plant height, harvest index, protein yield, oil content, and estimated biodiesel yield, but reduced protein content. Our findings showed seeding camelina early resulted in good plant establishment, increased seed yield, oil content, and the estimated biodiesel yield. Nonetheless, early seeding could be restrained by wet field conditions prevalent in the spring in most regions of the Great Plains. Hard frost can also be problematic for young spring camelina seedlings.

Full text

Agronomy Journal • Volume 108, Issue 1 • 2016 349
C is an ancient crop believed to have evolved
as a weed in elds planted with ax, hence the name
“false ax” (Budin et al., 1995; Gugel and Falk, 2006).
According to Matthäus and Zubr (2000), camelina was cul-
tivated for oil in Europe during the Bronze and Iron Ages;
however, its production dwindled during the Middle Ages.
ere has been recent interest in camelina production because
of increased demand for biofuel and other industrial applica-
tions from non-edible oilseeds. Several attractive features
of camelina make it a potential oilseed crop. It is a low-cost
bioenergy crop and the oil has been used successfully as fuel
for diesel transport engines (Bernardo et al., 2003). According
to Shonnard et al. (2010), when camelina jet fuel was ight
tested, it met all the requirements for engine performance.
In addition, greenhouse gases emitted during combustion of
camelina-based fuels were lower than that of petroleum based
fuel. Pinzi et al. (2009) indicated that cold weather aects
the performance of most biofuels; however, fuel derived from
camelina is able to withstand lower temperatures because of
its high polyunsaturated fatty acid content. Besides biodiesel
potential, camelina seeds have an average oil content of 350 to
450 g kg–1, and the proportion of unsaturated fatty acid in the
oil is approximately 900 g kg–1 (Gugel and Falk, 2006). e
high content of unsaturated fatty acid makes camelina oil fast-
drying which is useful for making environmentally friendly
polymers, varnishes, paints, cosmetics, and dermatological
products (Zaleckas et al., 2012).
Agronomically, camelina has wide environmental adaptation
because it can grow under dierent climatic and soil conditions
(Zubr, 2003). According to Moser and Vaughn (2010), cam-
elina is able to grow well in semiarid regions and in low-fertile
and saline soils. Camelina requires low agricultural inputs and
its production cost is relatively low (Budin et al., 1995; Moser
and Vaughn, 2010). ough camelina ts well in crop produc-
tion systems in the semiarid regions in the Great Plains, there
Crop Economics, Production & Management
Evaluating Agronomic Responses of Camelina to Seeding
Date under Rain-Fed Conditions
Henry Y. Sintim, Valtcho D. Zheljazkov,* Augustine K. Obour, Axel Garcia y Garcia, and Thomas K. Foulke
Published in Agron. J. 108:349–357 (2016)
doi:10.2134/a g ronj2015 . 0153
Received 30 Mar. 2015
Accepted 16 Oct. 2015
Available freely online through the author-supported open access option
Copyright © 2016 by the American Society of Agronomy
5585 Guilford Road, Madison, WI 53711 USA
All rights reserved
ABSTRACT
e potential to use camelina (Camelina sativa L.) as a bioen-
ergy crop has increased the need to develop management prac-
tices that would improve sustainable production. is study
evaluated the eects by cultivars (Blaine Creek, Pronghorn, and
Shoshone) and three spring seeding dates on the performance
of camelina grown under rain-fed conditions in northern Wyo-
ming. Results showed signicant eects of cultivar and/or seed-
ing dates on camelina establishment, phenology, yield, seed
protein, oil content, and estimated biodiesel yield. Growing
degree-day (GDD) requirements for plant emergence, ower-
ing, and maturity were 34, 417, and 998, respectively. Among
the three cultivars studied, Blaine Creek and Pronghorn had
better establishment and subsequent seed yield in both years.
Averaged across the 2 yr, seed yield of Blaine Creek and Prong-
horn were 931 and 963 kg ha–1, respectively, greater than that
of Shoshone (826 kg ha–1). Seeding date had no eect on seed
yield in 2013. However, in 2014, early seeding increased cam-
elina seed yield. Early seeding in 2014 resulted in a general
increase in plant height, harvest index, protein yield, oil con-
tent, and estimated biod iesel yield , but reduced protein content.
Our ndings showed seeding camelina early resulted in good
plant establishment, increased seed yield, oil content, and the
estimated biodiesel yield. Nonetheless, early seeding could be
restrained by wet eld conditions prevalent in the spring in
most regions of the Great Plains. Hard frost can also be prob-
lematic for young spring camelina seedlings.
H.Y. Sintim, and V.D. Zheljazkov, Univ. Wyoming, Dep. Plant Sci.,
and Sheridan Res. and Ext. Center, Laramie, W Y 82071; H.Y. Sintim,
Washington State Univ., Dep. Crop Soil Sci., Puya llup Res. Ext.
Center, 2606 West Pioneer, Puyallup, WA 98371; V.D. Zheljazkov,
Oregon State Univ., Columbia Basin Agric. Res. Center, P.O. Box 370,
Pendleton, OR 97801; A.K . Obour, Kansas State Univ., Agric. Res.
Center-Hays, 1232 240th Ave., Hays, KS 67601; A. Garcia y Garcia,
Univ. Minnesota, Dep. Agronomy and Plant Genetics, Southwest
Research and Outreach Center, 23669 130th St., Lamberton, MN
56152; T.K. Foulke, Univ. Wyoming, Dep. Ag ric. and Appl. Econ.,
1000 E. University Avenue, Laramie, W Y 82071. *Corresponding
author (valtcho.jeliazkov@oregonstate.edu; valtcho.pubs@gmail.com).
Abbreviations: DAP, days aer planting; DOY, day of year; GDD,
growing degree-days.
Published November 23, 2015

350 Agronomy Journal • Volume 108, Issue 1 • 2016
are limited production recommendations for camelina in the
region. is suggests the need for information on management
practices such as seeding dates, nutrient requirements, seeding
rates, weed control, and best cultivars for specic locations to
improve sustainable production.
Seeding date is an important management practice that
could be adapted to minimize the adverse eects of late frost,
moisture stress, and high temperature eects during critical
stages of crop growth. Nevertheless, frosts in early spring pose
potential threats to crop growth and development. is is typi-
cal for regions with variable weather conditions such as north-
ern Wyoming that usually experience temperatures below 0°C
in March through early May. Allen et al. (2014) indicated that
camelina can perform well even at temperatures below 0°C;
however, limited eld access as a result of wet soil conditions
can still impede early seeding.
Researchers have reported varying eects of seeding dates
on camelina growth and seed production under rain-fed con-
ditions. ese discrepancies in the literature may be due to
varying site-specic environmental conditions and edaphic
factors. Berti et al. (2011) observed signicant eects of seed-
ing dates on plant growth and yield of camelina cultivated on
ve locations in Chile. Conversely, Urbaniak et al. (2008) did
not observe any impact of seeding dates on plant emergence,
height, yield, or oil content of camelina grown in the Atlantic
region of Canada. Conceptually, early seeding is generally a
good practice. However, for a short-season crop such as cam-
elina (85–100 d; McVay and Lamb, 2008), the crop might be
able to compensate for slight delays in seeding without any
signicant impact on growth, yield, and quality by completing
its life cycle before the usual summer drought periods, depend-
ing on the type of cultivar used.
Crop cultivars dier in their absorption and translocation
of soil moisture, plant nutrients, photosynthates, and most
importantly, interactions with environmental factors. In addi-
tion, crop cultivars tolerate extreme temperatures, drought,
and toxicity and deciency of some nutrients dierently due
to genetic variability (Baligar et al., 2001). Camelina cultivars
were reported to dier in their response to temperature (Allen
et al., 2014) and nutrient assimilation (Jiang et al., 2013; Fujita
et al., 2014). It would therefore be benecial for growers to
identify camelina cultivars that will perform well in a specic
location. e objective of this study was to evaluate the eects
of cultivar and three spring-seeding dates on the growth, yield,
seed protein, and oil content of camelina for the environmental
conditions of northern Wyoming.
MATERIALS AND METHODS
Experimental Site
e eld experiment was conducted at the Sheridan Research
and Extension Center (ShREC), University of Wyoming, 15 km
west of Sheridan, WY (44°48¢48² N, 106°46¢26² W, 1154 m
elevation). e soil at the experimental site was a Wyarno series
(ne, smectitic, mesic Ustic Haplargid), characterized as very
deep well drained, <0.5% slope, clay loam (31% sand, 36% silt,
and 33% clay). Soil samples collected in the top 0 to 15 cm in
2013 and 2014 were analyzed for soil chemical properties (at
Olsen’s Agricultural Laboratory, Inc., McCook, NE) follow-
ing standard soil test procedures. Soil pH (6.7 and 7.2); organic
matter (2.2 and 2.3%); nitrate N (5.0 and 3.6 kg ha–1); P (22.8
and 27.5 mg kg–1); and K (323 and 333 mg kg–1) for 2013 and
2014, respectively, were similar. e average rainfall distribution
during the 2 yr of the experiment deviated slightly from 30-yr
average (normal; Table 1). Total rainfall in April, May, and July
was greater in 2013 than in 2014, and vice versa for June and
August. In general, total rainfall during the summer months
(June–August) in both years were slightly higher than normal.
Mean temperature and total GDD (calculated with 5°C base
temperature) in 2013 and 2014 compared well to normal year,
except for August where they diered slightly (Table 1).
Plot Management
ree spring camelina cultivars (Blaine Creek, Pronghorn,
and Shoshone) were used in the study. In 2013, the window
for planting was short. is was because the soil was too wet
throughout March and April to perform any eld work. As
such, the seeding dates 122, 129, and 136 DOY were spaced at
1 wk interval. In 2014, camelina was initially seeded on 101,
114, and 125 DOY. However, because of complete loss of the
crops from frost damage (temperature below –4°C) at a critical
emerging stage of growth for the second and third seeding, the
plots were tilled and replanted. erefore, the actual seeding
dates in 2014 were 101, 153, and 160 DOY. e experiments
were set as randomized complete block in a split-plot arrange-
ment with four replications, and eects of year being non-
cumulative by planting at dierent areas situated 50 m apart.
e main plot treatments were the seeding dates, and subplot
treatments were the camelina cultivars.
e experiments were established on a previously fallowed
land under a reduced tillage system. e land was prepared
by one-time disking with a tandem disk (Allis-Chalmer
Co., Milwaukee, WI), followed by one-time harrowing
with an arena groomer (Parma Co., Parma, ID). Subplots
Table 1. Mean temperature, growing degree-days, and total monthly precipitation at Wyarno, Sheridan, WY, in 2013 and 2014.
Month
Mean temperature Total growing degree-days‡ Total precipitation
2013 2014 Normal† 2013 2014 Normal 2013 2014 Normal†
–––––––––––––––– °C –––––––––––––––– ––––––––––––––– mm –––––––––––––––
April –0.70 5.9 6.30 113 175 182 51.9 22.9 33.3
May 10.2 11.7 11.5 455 431 407 90.8 58.6 65.5
June 17.0 16.0 16.8 680 583 678 84.9 99.9 62.2
July 22.6 21.1 21.5 997 946 957 25.6 9.60 30.4
August 22.7 20.0 20.4 1012 862 906 3.2 14.5 16.7
Total 256 205 208
† Normal = 30-yr average.
‡ Growing degree-days were calculated using 5°C base temperature.

Agronomy Journal • Volume 108, Issue 1 • 2016 351
were approximately 1.5 by 6 m, and were seeded at a rate of
5.6 kg ha–1 to a depth of 7 mm using a cone drill seeder. Seed
germination was tested before every seeding to adjust for the
seeding rates. Urea was applied at a rate of 56 kg N ha–1 by
broadcasting. Round-up [glyphosate; isopropylamine salt of
N-(phosphonomethyl) glycine] was applied at 1.8 kg a.i. ha–1
to control weeds prior to seeding. Post-emergence weed control
was performed manually by hand removing the weeds. Flea
beetle (Phyllotreta cruciferae) infestation was observed during
the 2014 cropping season but not in 2013. is observation
could be due to canola (Brassica napus L.) that was cultivated
near the experimental site in 2013, but not in 2014, suggesting
that camelina is possibly an alternate host to ea beetle. Sevin
SL (Carbaryl; 1-naphthol N-methylcarbamate) insecticide was
applied at 1.5 kg a.i. ha–1 to control ea beetle on 3 June 2014.
e ea beetle damage was rated visually on a 1 to 10 point
scale for the rst seeding date before applying the insecticide.
e cultivars did not dier in ea beetle infestation, showing
an average of 16% damage.
Data Collection
Before seeding, the 1000-seed weights (adjusted to 8%
moisture content) of the camelina cultivars were measured.
Plant establishment data were collected at the 2 to 3 leaf stage
by counting the number of camelina seedlings within a 1-m
row at 10 randomly selected locations within a plot. e data
was used to calculate the average number of plants per meter
square. e percentage of plant emergence was computed as the
ratio of plants emerged to the total number of seeds planted
multiplied by 100. Flowering date was recorded when 50% of
the plants were at anthesis and the pod date when 50% of the
pods were formed. Flowering period referred to the number
of days between date of anthesis and pod date, and the days to
maturity represented the number of days between seeding to
when the plants were harvested. e GDD of plant emergence,
owering, and maturity were calculated as:
max min
base
GDD
2
j
i
TTT
+
=-
å
[1]
where Tmax and Tmin are daily maximum and minimum air
temperature, respectively, and Tbase was the base temperature.
e GDD was calculated with 5°C base temperature (Aiken et
al., 2015).
Average plant height was determined by measuring the
length of 10 randomly selected plants from the soil surface to
the highest point on the plant at the time of maturity. Plant
stand at maturity was determined the same as to plant stand
at emergence. Plants were harvested when 75% of the silicles
were ripe (Sintim et al., 2015a). Entire plots were harvested
with a hedge trimmer at the soil surface (taking care to avoid
shattering) and the total aboveground biomass weighed before
threshing with a portable stationary thresher, cleaned, and
then weighed to determine seed weight. e crop harvest index
was calculated as dry seed weight divided by dry weight of total
aboveground biomass at harvest. Seed yields were adjusted to
8% moisture content.
Camelina Seed Protein and Oil Content
Analysis and Biodiesel Estimation
Seed protein and oil concentration were determined using
Fourier transform near-infrared spectroscopy and a specic
calibration derived for a scanning monochromater (Perten
DA-7200, Perten Instruments, Hägersten, Sweden) according
to McVay and Khan (2011). e seeds were air-dried, and the
moisture content measured before the oil analysis. Oil con-
tent in the seed was adjusted to 8% seed moisture. Biodiesel
yield was estimated according to Sintim et al. (2015b). e
estimation assumed 80% extraction eciency (Kemp, 2006),
10% postharvest loss, and oil yield conversion of 1 kg ha–1 to
0.439 L volume biodiesel.
Statistical Analysis
Data analysis was performed separately for each year because
the seeding dates were very dierent. e PROC MIXED
procedure in SAS 9.4 (SAS Institute, 2013) was used for the
analysis. Seeding date and cultivar were treated as xed eects,
and then block was considered as random eects. Mean separa-
tions were conducted at P < 0.05, using the least squares means
(LSMEA NS) and adjusted Tukey multiple comparison procedure.
Validity of equal variance, normality, and independence assump-
tions on the error terms were conrmed by assessing the residuals.
RESULTS AND DISCUSSION
Phenological Growth Parameters
Seeding date × cultivar interaction was not signicant on all
measured phenological growth parameters for both years. Early
seeding prolonged the days to plant emergence, owering, and
maturity in both years. In addition, early seeding resulted in
longer owering period or pod formation. However, GDD for
the growth stages were not signicantly dierent among the
seeding date treatments (Table 2). In the central Great Plains
region of Nebraska, Pavlista et al. (2011) observed a reduction in
days to plant emergence but later owering date when camelina
and canola were late seeded. Similar results have been reported
previously (Zheng et al., 1994; Kirkland and Johnson, 2000).
According to Nykiforuk and Johnson-Flanagan (1994), pro-
longed days to emergence with early seeding is a result of low
soil temperature. Despite observing an eect of seeding date on
emergence and owering dates, Pavlista et al. (2011) reported no
dierence in the maturity date, contrary to what we observed.
Previous studies indicated camelina matures between 85 and
100 d aer seeding, when grown in the northern Great Plains
of Montana (McVay and Lamb, 2008). However, depending
on year and seeding date, camelina matured earlier or later
(75–112 d) in our current study (Table 2) than what was previ-
ously reported. e lack of dierence in GDD in this study to
seeding dates, even though calendar days varied signicantly,
emphasizes that accumulation of heat units is the impor-
tant factor for determining growth stages of plants. As such,
specifying number of days in which emergence, owering, or
maturity is expected to occur will not be relevant depending
on prevailing weather conditions. Photoperiod has also been
reported to inuence days to owering of camelina (Gesch
and Cermak, 2011). In the present study, the average GDD
for emergence, owering, and maturity were 34, 417, and 998,
respectively. e GDD for owering was lower than what was

352 Agronomy Journal • Volume 108, Issue 1 • 2016
reported by Gesch and Cermak (2011) for two winter camelina
cultivars near Morris, MN. e authors observed 540 and
555 GDD (under no-till and chisel plowed, respectively) for
camelina cultivar BSX-WG I and 577 and 584 GDD (under
no-till and chisel plowed, respectively) for cultivar Joelle in the
2007–2008 cropping season. e lower GDD in the present
study compared to that reported by Gesch and Cermak (2011)
may be due to the dierent base temperature (5 vs. 4°C) and
cultivar (spring vs. winter type).
ough early seeding prolonged the number of days to vari-
ous growth stages, early seeded plots emerged, owered, and
matured at an earlier calendar date relative to delayed seeding.
Flowering before the usual summer heat and drought period
can help prevent pod abortion or other forms of stresses that
cause premature senescence (Adamsen and Coelt, 2005;
Chen et al., 2005). According to Clayton et al. (2004), heat
and moisture stress as a result of late seeding can hasten crop
maturity. Hence, the shorter owering time on late seeding
might be due to a more rapid accumulation of GDD under
warmer conditions that the late seeded plants may have expe-
rienced. Wang et al. (2003) indicated that plants respond to
harsh temperatures through physiological adaptations.
e cultivars used in this study emerged at similar times,
but Pronghorn owered and matured earlier than Blaine
Creek and Shoshone in both years (Table 3). Low protability
of wheat (Triticum aestivum L.)–fallow system in dry areas
of the Great Plains has raised the need to replace the fallow
phase with an alternative crop (DeVuyst and Halvorson, 2004;
Obour et al., 2015). e crop must be well adapted to the
region and possess unique qualities that will t into the crop-
ping system. Identifying short growing camelina cultivars such
as Pronghorn in this study will be important for successful
incorporation of camelina into dryland wheat-based produc-
tion systems. is is because shorter growing cultivars will
Table 2. The number of calendar days and growing degree-days required for emergence, owering, and maturity of camelina as affected
by seeding date in 2013 and 2014.
Seeding date Emergence Emergence Flowering Flowering
Flowering
period Maturity Maturity
DOY† DAP GDD‡ DAP GDD‡ days DA P GDD‡
2013
122 7.1 ± 0.23a§ 30.6 ± 1.66a 50 ± 0.37a 402 ± 4.69a 13.0 ± 0.21a 79 ± 1.16a 1005 ± 21.4a
129 3.3 ± 0.13b 31.9 ± 1.45a 43 ± 0.48b 392 ± 11.1a 12.1 ± 0.19b 79 ± 0.71a 997 ± 11.1a
136 3.2 ± 0.13b 32.5 ± 1.04a 42 ± 0.36b 402 ± 5.61a 12.6 ± 0.15ab 76 ± 0.43b 1000 ± 7.3a
P value <0.001 0.734 <0.001 0.621 0.013 <0.001 0.244
2014
101 13 ± 0.34a 37.5 ± 0.29a 72 ± 1.23a 406 ± 14.1a 13.3 ± 0.33a 112 ± 1.37a 970 ± 23.6a
153 2.5 ± 0.15b 35.2 ± 1.42a 41 ± 0.39b 441 ± 6.52a 11.3 ± 0.36b 84 ± 0.58b 1019 ± 8.51a
160 2.3 ± 0.13b 38.6 ± 1.31a 38 ± 0.43b 459 ± 7.56a 10.6 ± 0.28b 79 ± 0.43c 996 ± 4.75a
P value <0.001 0.431 <0.001 0.101 0.003 <0.001 0.384
† DOY, day of year; DAP, days after planting; GDD, growing degree-days.
‡ GDD was calculated using 5°C base temperature.
§ Within column and year, means followed by the same letter(s) are not signicantly different using the least squares means (LSMEANS) and adjusted
Tukey multiple comparison procedure (P < 0.05). Data are averaged across three camelina cultivars and four replications (n = 12), followed by the
standard error of the mean.
Table 3. Cultivar effects on the number of calendar days and growing degree-days required for emergence, owering, and maturity of
camelina in 2013 and 2014.
Cultivar Emergence Emergence Flowering Flowering
Flowering
period Maturity Maturity
DAP† GDD‡ DAP GDD days DAP GDD
2013
Blaine C. 4.6 ± 0.60a§ 31.7 ± 1.30a 45 ± 1.13a 399 ± 5.05ab 12.6 ± 0.19b 80 ± 0.57a 1025 ± 2.54a
Pronghorn 4.5 ± 0.56a 31.4 ± 1.28a 44 ± 1.16b 386 ± 10.2b 12.0 ± 0.17c 75 ± 0.28b 939 ± 7.37b
Shoshone 4.5 ± 0.56a 31.7 ± 1.29a 46 ± 1.14a 410 ± 5.14a 13.1 ± 0.15a 80 ± 0.75a 1037 ± 7.42a
P value 0.387 0.305 <0.001 0.022 <0.001 <0.001 <0.001
2014
Blaine C. 5.7 ± 1.42a 37.1 ± 1.21a 50 ± 4.82a 441 ± 9.89a 12.1 ± 0.29a 93 ± 4.54a 1006 ± 17.1b
Pronghorn 5.8 ± 1.45a 37.1 ± 1.23a 48 ± 4.55b 413 ± 12.2b 10.7 ± 0.40b 90 ± 4.37b 971 ± 16.0c
Shoshone 5.8 ± 1.50a 37.6 ± 1.34a 51 ± 4.76a 452 ± 10.6a 12.6 ± 0.45a 93 ± 4.73a 1010 ± 11.5a
P value 0.195 0.348 <0.001 <0.001 <0.001 0.001 0.003
† DAP, days after planting; GDD, growing degree-days.
‡ GDD was calculated using 5°C base temperature.
§ Within column and year, means followed by the same letter(s) are not signicantly different using the least squares means (LSMEANS) and adjusted
Tukey multiple comparison procedure (P < 0.05). Data are averaged across three seeding dates and four replications (n = 12), followed by the standard
error of the mean.

Agronomy Journal • Volume 108, Issue 1 • 2016 353
mature early, allowing enough time for soil moisture recharge
when adopted in wheat–fallow cropping systems. Dierences
in GDD for owering and maturity among cultivars in the
present study may be attributed to varying photoperiod sensi-
tivity similar to that reported for winter camelina cultivars by
Gesch and Cermak (2011).
Plant Emergence and Stand at Maturity
Plant emergence and stand at maturity was not aected by
seeding date; however, they diered signicantly among the
cultivars (Table 4). Average plant emergence was 27 and 23%,
respectively, for 2013 and 2014. Plant emergence (20–28%) was
similar to what was reported in Nova Scotia and considerably
lower (45–72%) compared to Prince Edward Island Provinces
in Canada (Urbaniak et al., 2008). In contrast to our current
study, seeding date was observed to aect camelina emergence
at four sites in the Pacic Northwest (Lind, WA; Pendleton,
OR; Moscow, ID; and Corvallis, OR) from 2008 to 2010,
except for 2010 at Pendleton (Schillinger et al., 2012). ough
the seeding dates analyzed in this study showed no dierence
in plant emergence, complete loss of initial second and third
seeding in 2014 due to low temperatures in this study, suggests that
seeding date can play a signicant role in emergence of camelina.
Blaine Creek and Pronghorn had better emergence and stand
at maturity than Shoshone. Plant stand at maturity was consider-
ably lower than it was at emergence, implying some of the plants
that emerged thinned-out during crop growth. On average,
43, 44, and 35% for Blaine Creek, Pronghorn, and Shoshone,
respectively, in 2013 and 42, 43, and 29% for Blaine Creek,
Pronghorn, and Shoshone, respectively, in 2014 of the plants that
emerged thinned-out. Loss in plant stand from emergence to
crop maturity was not unprecedented because of the small seed
size and increased competition for water, nutrient sources, and
light (Leach et al., 1999). Not surprising, Shoshone with the least
plant emergence had fewer plants thinned-out.
Plant Height, Seed Yield, and Harvest Index
ere was a signicant interaction eect of seeding date and
cultivar on plant height in 2014 but not in 2013 (Fig. 1). Early
seeding resulted in taller plants among the cultivars. Blaine
Creek was generally the tallest cultivar, except when planted on
153 DOY in 2014 where the cultivars had similar plant height.
Average plant height ranged from 64 to 76 cm in 2013 and 59 to
77 cm in 2014. is was comparable to camelina plant height of
64 to 72 cm reported by Pavlista et al. (2011). ere was no seed-
ing date × cultivar interaction eect on seed yield and harvest
index. Seeding date had no signicant eect on the seed yield
in 2013. However, seeding date aected camelina seed yield in
the 2014 growing season. Delayed seeding in 2014 (153 and 160
DOY) resulted in decreased seed yield compared to when cam-
elina was seeded early (101 DOY; Fig. 2). Our results are in agree-
ment with the ndings of previous studies (Berti et al., 2011;
Schillinger et al., 2012) that showed that early seeding enhanced
camelina performance and increased seed yields. However,
under irrigated conditions in Scottsblu, NE, Pavlista et al.
(2011) reported no seed yield advantage in planting camelina
early. is indicated that signicant yield benet of early seeding
under rain-fed conditions may be attributable to soil moisture
availability. In dryland agriculture, moisture availability plays a
signicant role in crop performance and seeding camelina late
could result in moisture stress during reproductive stages of crop
growth due to untimely rainfall distribution. Under dry condi-
tions plants shed their leaves, which limits source (photosyn-
thate) for seed yield (Gan et al., 2004). However, camelina was
able to compensate for slight delays in seeding without signi-
cant eect on seed yield in this study. is was observed in 2013
when seeding dates were spaced at 1 wk intervals.
It is imperative to note that timely seeding, not necessarily
early seeding is the important factor in camelina production.
is is because frost at temperature of –4.4°C completely
damaged young camelina seedlings at critical emerging stages
when seeded on 114 and 125 DOY. Even the late seeded plots
(166 DOY) produced seed yield of 509 kg ha–1; whereas
those seeded earlier (114 and 125 DOY) produced nothing.
Camelina seedlings planted on 101 DOY were able to with-
stand the low temperatures because they were well established
before onset of the frost.
Among the three cultivars studied, Blaine Creek and
Pronghorn showed promise for higher seed production under
rain-fed conditions in drier areas of the Great Plains such as
Wyoming (Table 4). Yields were generally higher in 2013 than
in 2014. e reason is because yields are averaged across seeding
Table 4. Plant emergence, plant stand at maturity, seed yield, and harvest index in 2013 and 2014 as affected by camelina cultivar.
Cultivar Plant emergence Plant stand at maturity Seed yield Harvest index
––––––––––––––––––––––– % ––––––––––––––––––––––– kg ha–1
2013
Blaine C. 35 ± 2.02a† 20 ± 0.98a 1018 ± 49.0a 0.243 ± 0.003a
Pronghorn 32 ± 1.64a 18 ± 0.58a 1068 ± 49.4a 0.246 ± 0.003a
Shoshone 14 ± 1.31b 8.7 ± 0.86b 932 ± 44.7b 0.246 ± 0.003a
P value <0.001 <0.001 <0.001 0.137
2014
Blaine C. 28 ± 2.32a 16 ± 1.44a 843 ± 117a 0.196 ± 0.025b
Pronghorn 26 ± 1.97a 15 ± 1.15a 858 ± 111a 0.239 ± 0.025a
Shoshone 14 ± 1.93b 9.8 ± 1.33b 720 ± 88.7b 0.210 ± 0.020b
P value <0.001 <0.001 0.001 <0.001
† Within column and year, means followed by the same letter(s) are not signicantly different using the least squares means (LSMEANS) and adjusted
Tukey multiple comparison procedure (P < 0.05). Data are averaged across three seeding dates and four replications (n = 12), followed by the standard
error of the mean.

354 Agronomy Journal • Volume 108, Issue 1 • 2016
dates and the two late seeding dates (153 and 160 DOY) in
2014 produced very low yields 698 and 509 kg ha–1, respectively.
However, seed yield when camelina was seeded early in 2014 (101
DOY) was greater (1214 kg ha–1) than the highest yield for 2013
(1174 kg ha–1). Reported camelina seed yield in Lingle, W Y
which is much drier than Sheridan, WY was 410 to 520 kg ha–1
(Aiken et al., 2015). In wetter climates, seed yield of 1338 to
1599 kg ha–1 has been reported in Canada (Urbaniak et al.,
2008) and as high as 2314 kg ha–1 in Chile (Berti et al., 2011).
In 2013, seeding date had no eect on the crop harvest
index, whereas in 2014 harvest index increased with early
seeding, similar to seed yield (Fig. 2). In addition, harvest
index of the cultivars in 2013 was similar but diered in 2014.
Pronghorn (0.239) showed the highest crop harvest index com-
pared to Blaine Creek (0.196) and Shoshone (0.210). In Chile,
Berti et al. (2011) observed signicant eect of seeding date
on crop harvest index of camelina at only one location out of
ve locations studied. Camelina harvest index observed in our
current study (0.159–0.320), compares well with that reported
Fig. 1. Plant height as affected by seeding date. Data are averaged across three camelina cultivars and four replication (n = 12) in 2013;
whereas in 2014, they were averaged across four replication (n = 4). Within year or cultivar, means followed by the same letter(s) are not
significantly different using the least squares means (LSMEANS) and adjusted Tukey multiple comparison procedure (P < 0.05). Error bars
represent 1 SE of the mean.
Fig. 2. Harvest index and seed yield as affected by seeding date. Data are averaged across three camelina cultivars and four replication
(n = 12). Within year, means followed by the same letter(s) are not significantly different using the least squares means (LSMEANS) and
adjusted Tukey multiple comparison procedure (P < 0.05). Error bars represent 1 SE of the mean.

Agronomy Journal • Volume 108, Issue 1 • 2016 355
in the literature (Gesch and Cermak, 2011; Solis et al., 2013;
Liu et al., 2015).
e dierential responses of camelina cultivars to year
or seeding date shows that the cultivars had unique physi-
ological and biochemical adaptations because of genetic vari-
ability, and/or their interactions with environmental factors.
According to Fujita et al. (2014), genetic dierences among
camelina cultivars have a large inuence on their uptake and
ecient utilization of soil nutrients, and subsequent biomass
and grain production. is was conrmed in our current study
as the cultivars showed dierences in plant height, seed yield,
and harvest index.
Camelina Protein, Oil, and Biodiesel
ere was a general reduction in protein content with early
seeding in both years (Tables 5 and 6). However, protein yield
was greatest in the rst seeding dates in both years. Blaine
Creek was the superior cultivar in terms of protein content in
2013; however, in 2014, the cultivars had similar protein con-
tent. In general, protein yield was greater in Blaine Creek and
Pronghorn than in Shoshone. Contrary to seed protein, cam-
elina oil content increased with early seeding. Subsequently, it
translated to higher estimated biodiesel yield since seed yield
increased somewhat when camelina was planted early. is
was more evident in 2013 when seed yield was not aected by
seeding date, but there were signicant dierences in estimated
biodiesel yield. Blaine Creek had the least oil content in both
years, but not the least estimated biodiesel yield because it
yielded more seeds than Shoshone.
Pearson correlation analysis showed an inverse association
between the seed protein and oil concentration of camelina
(Fig. 3), which was consistent with previous studies (Jiang et
al., 2013; Sintim et al., 2015b). According to Canvin (1965),
temperature has profound eects on the oil content of rape-
seed and ax, observing highest oil content in both rapeseed
and ax at low temperatures and a continual decrease as tem-
perature during crop growth increased. Reduction in seed
oil content as a result of increased average daily temperature
during seed development in Cuphea sp. has also been reported
(Berti and Johnson, 2008). Saldivar et al. (2011) indicated that
levels of protein in sunower [Helianthus annuus (L.) Crantz]
decreased by 20 to 60 g kg–1 during the rst 3 to 5 wk aer
owering and gradually increased thereaer until maturity.
ey attributed it to rapid synthesis of oil and starch during
early seed development.
Table 5. Camelina protein content, protein yield, oil content, and estimated biodiesel yield as affected by seeding date in 2013 and 2014.
Seeding date Protein content Protein yield Oil content Calculated biodiesel yield
DOY† g kg–1 kg ha–1 g kg–1 L ha–1
2013
122 290 ± 2.98b‡ 349 ± 14.6a 354 ± 3.46a 124 ± 4.93a
129 297 ± 2.16b 290 ± 6.71b 339 ± 2.46b 96.5 ± 2.27b
136 310 ± 2.13a 270 ± 8.50b 322 ± 4.48c 82.0 ± 2.84c
P value 0.002 0.007 <0.001 0.001
2014
101 291 ± 3.64b 350 ± 22.5a 326 ± 4.78a 116 ± 9.99a
153 321 ± 2.79a 224 ± 11.3b 312 ± 3.85a 65.0 ± 3.74b
160 322 ± 2.06a 164 ± 7.80b 305 ± 6.11b 45.4 ± 2.56b
P value 0.004 0.004 0.041 0.009
† DOY, day of year.
‡ Within column and year, means followed by the same letter(s) are not signicantly different using the least squares means (LSMEANS) and adjusted
Tukey multiple comparison procedure (P < 0.05). Data are averaged across three camelina cultivars and four replications (n = 12), followed by the
standard error of the mean.
Table 6. Cultivar effects on camelina protein content, protein yield, oil content, and estimated biodiesel yield in 2013 and 2014.
Cultivar Protein content Protein yield Oil content Calculated biodiesel yield
g kg–1 kg ha–1 g kg–1 L ha–1
2013
Blaine C. 304 ± 2.92a† 305 ± 14.3a 324 ± 5.29b 95.8 ± 6.05b
Pronghorn 297 ± 3.89b 320 ± 13.0a 344 ± 3.96a 109 ± 6.38a
Shoshone 298 ± 3.29b 277 ± 11.8b 344 ± 3.99a 94.2 ± 5.38b
P value 0.017 <0.001 <0.001 <0.001
2014
Blaine C. 314 ± 5.79a 257 ± 30.0a 300 ± 4.87c 75.4 ± 11.6ab
Pronghorn 312 ± 5.82a 261 ± 27.5a 330 ± 3.58a 83.4 ± 11.7a
Shoshone 309 ± 3.63a 219 ± 24.1b 318 ± 4.37b 67.8 ± 9.02b
P value 0.066 <0.001 <0.001 0.001
† Within column and year, means followed by the same letter(s) are not signicantly different using the least squares means (LSMEANS) and adjusted
Tukey multiple comparison procedure (P < 0.05). Data are averaged across three seeding dates and four replications (n = 12), followed by the standard
error of the mean.

356 Agronomy Journal • Volume 108, Issue 1 • 2016
CONCLUSIONS
e number of days from seeding to crop maturity was
higher with early seeding. However, early seeded camelina
matured at early dates compared to when it was late seeded.
Early seeding also enhanced plant growth, seed yield, oil con-
tent, and estimated biodiesel yields. Nonetheless, early seed-
ing was restrained by wet eld conditions in 2013. Camelina
is commonly identied as a cold tolerant crop, but in this
study, cold temperatures in the spring of 2014 (temperatures
below –4°C) caused complete loss to camelina seedlings soon
aer plants had emerged. Camelina seedlings withstood the
frost when they were well established. Flea beetle damage
of camelina as a result of the absence of their main host was
also observed and could be a potential challenge to camelina
production.
Among the three cultivars studied, Blaine Creek and
Pronghorn had better establishment and subsequent seed yield
in both years. Pronghorn was the earliest maturing cultivar
and this can provide enough time for soil water recharge when
incorporated in the fallow phase in cropping systems with
wheat. e results indicate that seeding camelina as early as
eld conditions permit in northern Wyoming, while avoiding
the potential for hard frosts, enhances its growth, seed yield,
and oil content. In general, camelina shows promise as a poten-
tial oilseed crop that can be cultivated under rain-fed condi-
tions in water-limited environments.
ACKNOWLEDGMENTS
The study was supported by the USDA-NIFA Biomass Research
and Development Initiative program (Grant no. 2012-10006-20230).
We thank Dr. Kent McVay, Dr. Qasim Khan, and Ms. Kelli Maxwell
of Montana State University, Southern Agricultural Research Center,
Huntley, MT, for helping us with the FT-NIR analysis. We thank Mr.
Dan Smith, and Mr. Jeremiah Vardiman, farm manager and research
associate respectively, at the University of Wyoming’s Sheridan
Research and Extension Center (ShREC), Sheridan, who helped with
the trial set up, management, and harvesting.
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