Some Quality Components of Four Chia (Salvia hispanica L.) Genotypes Grown under Tropical Coastal Desert Ecosystem Conditions
A chia (Salvia hispanica L.) trial in the Santa Elena Peninsula of Ecuador consisted of 4 genotypes (Tzotzol, Iztac 1, Iztac 2 and Miztic) sown on January 15, 2007 in replicated plots to assess production and composition. Seed yield was affected by genotype, with Miztic and Tzotzol producing significantly (p<0.05) greater yields than the Iztac II genotype, but not more than Iztac I which was not significantly (p<0.05) different from Iztac II. Iztac II had the highest protein content (24.43%), however the difference was significantly (p<0.05) different only from Iztac I. Neither Iztac II nor Iztac I were significantly (p<0.05) different from either the Tzotzol or Miztic genotypes. No significant difference (p<0.05) in lipid content was found among genotypes. Miztic and Iztac II, with 20.23% and 20.03%, respectively had significantly (p<0.05) higher linoleic fatty acid percentages than the 19.23% of the Iztac I genotype. Iztac I had the highest α-linolenic fatty acid percentage (61.73) and this was significantly (p<0.05) different than the 58.37% found for the Iztac II genotype. All of the genotypes showed a similar relationship among compounds, that being caffeic acid>chlorogenic acid> quercetin>kaempherol. In summary, the effect of genotype was more evident on seed yield than protein content, oil content, fatty acid composition and phenolic compounds, hence yield needs to be the main factor when considering establishment of chia as a crop in the area.
Coronary Heart Disease (CHD) causes 1 of every 5 deaths in the United States
and now is the greatest killer of American males and females and this year it
is estimated that 700,000 Americans will suffer from CHD and about 500,000 will
have a recurrence of the disease (American Heart Association,
2007). Coronary Heart Disease also is the leading cause of disability in
the US labor force, accounting for 19% of all disability payments made by the
Social Security Administration (American Heart Association,
2004). The estimated direct and indirect costs of CHD for 2007 are $ 151.6
billion (American Heart Association, 2007). Coronary Heart
Disease is caused by arteriosclerosis and can be prevented if people make healthier
dietary choices. Increased intake of saturated and polyunsaturated ω 6
fatty acids have been shown to exacerbate the risk of CHD. Conversely, increased
intake of ω 3 fatty acids, including α-linolenic fatty acid and its
metabolites EPA and DHA, reduce the risk of suffering CHD (Baylin
et al., 2003; Lorgeril et al., 1996).
Unfortunately Western populations are consuming foods low in ω 3 fatty
acids, hence consumption needs to increase to decrease the risk of CHD (American
Heart Association, 2004). The problem is, however, there are very few readily
available ω 3 sources for human or animal consumption and most of these
should only be consumed in moderation, if at all. The reason for this is contaminants
such as dioxin and mercury are present in fish and anti-nutritional compounds
are found in flaxseed (Hamilton et al., 2005;
Bhatty, 1993). Clearly any reliable source of ω
3 fatty acids that can be found which is safe for consumption would be attractive.
Chia (Salvia hispanica L.) contains ω 3 fatty acids and its oil
provides the richest plant source of α-linolenic fatty acid known (Ayerza
and Coates, 2005a). Studies in which chia was used as a dietary source of
α-linolenic fatty acid for rats have shown improved LDL, HDL and TG levels
along with a better blood fatty acid profile (Ayerza and
Coates, 2007, 2005b) which should consequently reduce
the risk of suffering CHD. Additionally chia seeds have not shown any of the
problems associated with other ω 3 sources such as flaxseed or marine products
which have introduced a fishy flavor into foods, exhibited immune reactions,
animal weight loss, digestive problems, etc. (Azcona et
al., 2008; Ayerza and Coates, 1999, 2002).
Although, chia was one of the four main crops of the Aztecs along with corn,
beans and amaranth, it was for all practical purposes eliminated as a crop.
This was most likely due to the Aztecs use of it in their religious ceremonies
(Ayerza and Coates, 2005b). Efforts to incorporate chia
into modern agriculture only began in 1991 through the Northwestern Argentina
Regional Project (Ayerza and Coates, 2005b). As a consequence
little information about chia seed production and the compounds within the seed
and how they relate to the environment and genetics is available. Santa Elena
Peninsula is a warm, arid area located along the south-central coast of Ecuador.
Precipitation varies within the region from 112 mm year-1 in Salinas,
up to 550 mm year-1 in Chongon. In this area, as is true all along
the Ecuadorian coast, the El Niňo phenomenon affects rainfall patterns
dramatically. At irregular periods, in general every seven years, El Niňo
is much stronger and brings heavy rains which causes flooding that destroys
the basic infrastructure of the area including roads, bridges, houses and crops
(Ministerio del Ambiente, 2004; Cornejo,
2003). This periodic destruction of crops is one of the major obstacles
to cultivation of perennial species which need 3-4 years to fruit. In the 1990s
the Government of Ecuador began work on an irrigation system designed to provide
water for up to 23,000 has of the approximately 540,000 has which comprise the
Santa Elena Peninsula (Ministerio del Ambiente, 2004;
Cornejo, 2003). This study has not met expectations and
only 6,512 has are now cultivated (Cornejo, 2003). One
of the problems has been an absence of data which can be used to identify crops
that should do well in the area (C. Noel, 2006, Salinas, Guayas, Ecuador, personal
communication). Obviously any crop for which there is a market and which appears
adapted to the region, would be attractive. The objective of this study was
to plant 4 genotypes of chia in the region to determine which is the best in
terms of seed yield (kg ha-1), amount of protein (%), oil content
(%) and phenolic compounds (quercetin, kaempherol, chlorogenic acid, caffeic
acid as molecular weight in g kg-1 of seed produced), as well as
fatty acid composition (%).
MATERIALS AND METHODS
The research plot was established on the Santa Marta farm, located at 020
18 00" South, 800 37 00" West, 48 m above sea level.
The soil type is Entic Haplustoll according to the USDA Soil Classification
System (Cornejo, 2003). Meteorological data showed that
an annual mean precipitation of 220 mm year-1 evaporation of 1,627
mm year-1 and an average temperature of 25.7°C with remarkable
uniformity occurring from year to year (Cornejo, 2003).
For the test an average temperature of 26.5°C was recorded over the last
30 days of the crop cycle, with data being recorded on site using a portable
weather station. Experimental design was a randomized complete block with 3
replications. Plots consisted of 3 rows, 10 m in length, spaced 1.6 m apart.
Seeding rate was 5 kg ha-1. The plots were maintained using conventional
cultural and drip-irrigation practices. No insect problems or plant diseases
were encountered. Sowing was done on January 15/ 2007 and harvested on April
30/2007. Four genotypes were planted: Tzotzol, Iztac 1, Iztac 2 and Miztic.
A 1 m long section from the center of the middle row of each plot was hand-harvested,
cleaned and weighed for yield determination following procedures used by the
researchers in similar chia studies. A sub-sample from each genotype and each
replication was obtained to determine 1000-seed weight and to conduct the laboratory
analysis. Crude nitrogen was determined by a standard micro-Kjeldahl method
(Guebel et al., 1991) and converted into protein
content using a 5.71 conversion factor.
Lipids were extracted and converted into fatty acid methyl esters using the
IRAM 5-560II method (Instituto Argentino de Racionalización de Materiales
(IRAM), 1982). Fatty acid methyl esters were separated
and quantified by an automated gas chromatograph (Model 6890, GC; Hewlett Packard
Co., Wilmington, DE, 20006) equipped with flame ionization detectors and a 30
mx530 μm i.d. capillary column (Model HP-FFAP; Hewlett Packard Co., Wilmington,
DE, USA). Phenol compounds were extracted using an Ultraturrax homogenizer (IKA
Works Inc., Wilmington, NC, USA). A methanol:water solution of 90:10 was utilized,
with this being filtered through a 0.45 μm membrane prior to analysis.
Quantification and determination of the various phenolics in the crude extract
were carried out using a TSP (Thermo Separation Products Inc., Piscataway, NJ,
USA) chromatograph equipped with a quaternary pump, a degasses and diode array
detector (L 3000). Phenolic compounds were separated using a ODS-Hypersil C18
column, 250x4.6 mm i.d. and particle of 5 μm (Knauer, Berlin, Germany)
and a Lichrospher RP-18 pre-column (Merck KgaA, Darmstadt, Germany). The column
temperature was 25°C, with injection volume for the chia seed extracts and
standards set at 20 μL following procedures used by the researchers in
earlier chia trials. The system was run with a linear gradient of a two solvent
mix according to Vitract et al. (2002). The phenolic
concentrations were determinated by comparison with standard calibration curves
developed using the same chromatographic system and seven concentration levels
of each compound. As insufficient seed for each replication was available for
phenol analysis only one sample, made by combining the three replications, was
analyzed for the Iztac I, Tzotzol and Miztic genotypes. Phenol analysis was
not performed on the Iztac II genotype, since insufficient seed was available.
Each variable was compared by analysis of variance. When the F-value was significant
(p<0.05), means were separated using Duncans new multiple range test
(Cohort Stat, 2006).
RESULTS AND DISCUSSION
Seed yield was affected by genotype. The Miztic and Tzotzol genotypes produced
significantly (p <0.05) higher seed yields than the Iztac II genotype, but
not more than Iztac I which was not significantly (p<0.05) different from
Iztac II. Tzotzol and Miztic genotypes, with 1.30 and 1.22 g/1000 seeds, respectively,
had higher seed weights, followed by Iztac I and Iztac II genotypes with 1.20
g/1000 seeds each (Table 1). As seed weights were not replicated,
no statistical significance for the differences could be established. Iztac
II had the highest protein content (24.43%), however, the difference was significantly
(p<0.05) different only from Iztac I. Neither Iztac II nor Iztac I were significantly
(p<0.05) different from either the Tzotzol and Miztic genotypes. No significant
difference (p<0.05) in lipid content was found among genotypes, however palmitic
and stearic fatty acid percentages were significantly (p<0.05) different
|| Crop cycle, seed yield and seed weights of four chia genotypes
|1Means within each column did not differ significantly
(p<0.05) according to Duncan´s multiple range test; 2Not replicated
and 3Least significant difference for p<0.05
Total saturated fatty acid percentage, was significantly (p<0.05) lower
for Iztac I compared to the Miztic and Iztac II genotypes. Miztic and Iztac
II, with 20.23 and 20.03%, respectively, had significantly (p<0.05) higher
linoleic fatty acid percentages than the 19.23% of the Iztac I genotype. Iztac
I had the highest α-linolenic fatty acid percentage (61.73) and this was
significantly (p<0.05) different than the 58.37% found for the Iztac II genotype
(Table 2). Total polyunsaturated fatty acid (PUFA), calculated as the sum of
linoleic and α-linolenic fatty acids, was significantly (p<0.05) higher
for Iztac I, compared to Iztac II. The ω 6:ω 3 and SAT:PUFA fatty
acid ratios were significantly (p<0.05) lower for Iztac I compared to Iztac
II, with the ω 6:ω 3 ratio for Iztac I also being significantly lower
than the Miztic as well. Four phenolic compounds were detected in all genotypes
namely, quercetin, kaempherol, chlorogenic acid and caffeic acid. Individual
and total phenolic contents varied among genotypes, however as the analysis
were not replicated, statistical significance of the differences could not be
established (Table 3). However, all of the genotypes showed a similar relationship
among compounds, that being caffeic acid>chlorogenic acid>quercetin>kaempherol.
The sum of the chlorogenic and caffeic acids comprised 98.4, 98.6 and 97.7%
of the total phenolic compounds found in the Miztic, Iztac I and Tzotzol, genotypes,
Significant (p<0.05) differences between the Miztic and Tzotzol yields and
that of Iztac II show a strong genotype effect on seed yield under the environmental
conditions in which the experiment was conducted. However, the seed yields measured
herein were lower than those reported in other experiments. Maximum yields of
1,355, 938 and 862 kg ha-1 with growth cycles of 148, 173 and 174
days, respectively, were reported for three other experimental fields. The first
2 were in the Sub Humid Chaco ecosystem and the other, which was irrigated,
was in the Semiarid Chaco ecosystem.
|| Means of the protein and oil contents and fatty acid composition
in four chia genotypes
|1Means in a column within a group with the same
letter(s) are not statistically different (p<0.05) according to Duncan´s
multiple range test; 2Least significant difference for p<0.05;
3SAT: Saturated fatty acids; 4PUFA: Polyunsaturated
|| Phenolic content and composition in the chia genotypes
Additionally yields were less than the 1,602 and 1,188 kg ha-1,
with crop cycles of 166 and 151 days, respectively, for commercially irrigated
fields established in 2 locations in the Semiarid Chaco ecosystem (Coates
and Ayerza, 1996). Yields of 1,171 and 1,047 kg ha-1, with cycle
durations of 124 and 140 days, respectively, were reported for two other irrigated
commercial fields located in the Semiarid Chaco ecosystem (Coates
and Ayerza, 1998).
Differences in seed yields between these plots and earlier trials could be
a result of a combination of factors including genetics, environmental conditions,
agronomic practices, seeding dates and their interactions. A decrease in biomass
and seed yield was reported when chia seeding dates were compared. Coates
and Ayerza (1996) determined that both biomass and total seed yields were
significantly (p<0.05) higher for earlier plantings compared to later plantings.
The lower seed yields reported herein could be related to the shorter crop cycle
for the current study, since crop cycle has been reported as an important factor
affecting crop yield (Ellis et al., 1990). In
general high temperatures shorten crop cycles, resulting in a reduction in yield,
decreased fruit set and rate of photosynthesis (Uzun, 2007;
Ellis et al., 1990). Since, chia is a fall-winter
crop in the subtropical Chaco ecosystem, the lower yields found with all four
genotypes could be related to the shorter crop cycle caused by the high summer
temperatures. Another factor contributing to yield differences could be row
spacing. Since, the other studies were sown with 0.70-0.80 m between rows (Coates
and Ayerza, 1996, 1998). This means an approximate
2.3 fold increase in planted area. Another experiment specifically set up to
examine the effect of plant density under irrigated conditions in the Arid Chaco
Ecosystem, found the highest seed yield with a 0.70 m spacing, as compared to
greater separation between rows (Gonzalez Vera et al.,
1996). The significant (p<0.05) differences between yields of the Miztic
and Tzotzol genotypes and Iztac II that were found would tend to indicate that
a strong genotype effect on seed yield exists, at least under the environmental
conditions in which the experiment was conducted. Seed weights found herein
are in agreement with that of the 1.24 g/1,000 seeds reported by Guyot
and Rueda (1996) for chia produced under irrigated conditions in the Arid
Chaco ecosystem. However, the seeds were much heavier than the 0.32-0.53 g/1,000
seeds reported by Coates and Ayerza (1998), for six
samples of a common genotype collected from commercial farms in the Semiarid
Chaco ecosystem and the average of 0.89 g/1,000 seeds (with extremes of 0.79-0.95
g/1,000 seeds) reported by Gonzalez Vera et al. (1996)
for a trial in the Arid Chaco ecosystem. The differences could be a result of
genetics alone, or to a genetic x environment interaction. All but the Iztac
II genotype showed a higher protein content than the maximum value of 23.1%
reported for seed produced in 9 sites located within 6 different tropical and
subtropical ecosystems of South America (Ayerza and Coates,
2004). The higher protein content found herein could be related to the temperature
difference between trials. The average temperature measured over the last 30
days of the crop cycle was 25.7°C, which is 1.5°C higher than that recorded
over the last 30 days of the Ayerza and Coates (2004)
trial. Another trial demonstrated that as altitude decreased, with a subsequent
temperature increase, protein content of chia seed tended to increase (Ayerza
and Coates, 2004). Other crops such as sorghum and soybeans have shown similar
changes in protein content induced by environment (Vollmann
et al., 2000; Mohammed et al., 1987).
The oil contents measured herein were lower than those of chia seeds grown in
other ecosystems. As demonstrated for chia and other oilseed crops, temperatures
affect oil content: high temperatures decrease oil content, while low temperatures
increase oil content (Ayerza, 2001; Yaniv
et al., 1995; Cherry et al., 1985).
The mean oil content and extreme values found for chia produced at nine sites
(Ayerza and Coates, 2004) were 30.7 and 28.5-32.7%,
respectively; while for five other sites in Northwestern Argentina they were
35.9 and 35.6-38.6%, respectively (Ayerza, 1995). Since,
the mean temperature for the current trial was 1.7 and 6.4°C higher than
those measured in the 2 trials noted above, this most likely was the reason
for the lower oil content. In general, SAT and PUFA contents, as well each of
their components, were slightly higher and lower, respectively, compared to
oil from seeds grown under the lower temperatures reported by Ayerza
and Coates (2004) and by Ayerza (1995). A SAT palmitic
fatty acid increase and a PUFA α-linolenic decrease [both significant (p<0.05)
were found to be positively correlated with increased temperatures during the
last 30 days of the crop cycle (Ayerza, 1995). Increased
oil saturation through increased palmitic and stearic acid contents, with concomitant
decreases in linoleic and linolenic acids brought about by increased temperatures
has been reported in soybeans (Thomas et al., 2003).
Lack of a significant (p<0.05) difference in palmitic, stearic and oleic
fatty acid percentages between genotypes and the small, but significant (p<0.05)
difference in linoleic content found between Iztac I and Miztic and Iztac II
and the α-linolenic fatty acid content between Iztac I and Iztac II genotypes
could indicate a relatively close genetic relationship among genotypes. Data
from a trial conducted at 3 sites located between 1,600 and 2,200 m of elevation
showed the Tzotzol and Iztac I genotypes to have similar oil content and fatty
acid compositions, even though significant (p<0.05) differences in seed yield
were recorded (Ayerza and Coates, 2004). Hence, these
data would tend to support the theory of small genetic diversity reported by
Cahill (2004) using RAPD (Random Amplified Polymorphic
DNA) markers for domestic accessions of chia. The current trial, however, did
indicate that some fatty acid differences do exist among genotypes. As a general
recommendation, one way of reducing the risk of CHD is to lower the ω 6:ω
3 ratio in the diet from typical values of 15:1 to no more than 5:1, with an
ideal ratio being 1:1 (British Nutrition Foundation, 1992;
Canada Health and Welfare, 1990). Given this, the significantly
(p<0.05) lower ω 6:ω 3 ratio shown by the Iztac I genotype, compared
to that of the Miztic and Iztac II genotypes, might be considered a nutritional
advantage. Several nutritional studies support a relationship between SAT consumption
and the risk of CHD exists. Hence, there is a need to reduce these fatty acids
in the diet and increase the consumption of PUFAs (Canada
Health and Welfare, 1990). The significantly (p<0.05) lower total SAT
content (up to 12%) along with the lower SAT:PUFA ratio (up to 19%) exhibited
by the Iztac I genotype also makes this genotype appear to be nutritionally
superior. The phenolic compounds found in chia have been shown to possess consistently
strong antioxidant properties (Reyes-Caudillo et al.,
2007; Taga et al., 1984). A number of studies
have shown good oxidative stability of chia seed when used as animal feed or
as a food ingredient, with this being attributed to the high antioxidant activity
of the phenolic compounds it contains (Bautista Justo et
al., 2007; Ayerza et al., 2002; Ayerza
and Coates, 2002, 1999). Interestingly the phenolic
compound analysis did not determine any measurable amount of myricetin, which
was reported earlier by Taga et al. (1984). Whether
this is just an anomaly, or a result of environment is not known. The total
phenolic amounts found herein are lower than the 0.757-0.881 mg g-1
found for 2 chia seed sources as reported by Reyes-Caudillo
et al. (2007). This could be related to environment, since antioxidant
content has been found to be affected by growing season for Artemisia princeps
var. orientalis (Yun et al., 2008).
The effect of genotype is more evident on seed yield than protein content, oil content, fatty acid composition and phenolic compounds. The data herein is consistent with earlier research which has reported that high temperatures reduce oil content and degree of unsaturation, while increasing protein content. The seed yields, which were obtained in only 105 days, indicate that chia seed can be produced in this region with a comparatively, short crop cycle. Additional trials are required to fully assess the potential of chia cultivation in this region, but in general, the data indicate that chia could be an alternative to the traditional crops grown here.
The authors acknowledge support for this study from the Corporation International de Comercio y Servicios S.A, Buenos Aires, Argentina and Hacienda Santa Marta, El Azucar, Ecuador. The authors are also grateful to Ing. Carlos Noel and Agr. Ricardo Weisson and Agr. Fernando Castilla for caring for the experimental plots and assistance throughout the trial and to Dr. Marina Insani for her support with HPLC tests.
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