摘要：Although seed oil production and composition
are genetically controlled, changes of oil level and oil composition across
genotypes and environments such as drought and temperature were observed. The
mechanisms of how genotypes interact with environment, affecting oil production
and composition, are still not well understood. The objective of this research
was to investigate the effect of drought/water stress and temperature on
soybean genotypes. Two soybean genotypes of maturity group (MG) II (PI 597411 B
and PI 597408) and two of MG VI (Arksoy and PI 437726) were used. A repeated
greenhouse experiment to study the effect of water stress and a repeated growth
chamber experiment to study the effect of temperature were conducted. The
results showed that both water stress and high temperature altered seed oil
composition by increasing oleic acid and decreasing linoleic and linolenic acid
concentrations. Severe water stress (soil water potential between -150 to -200
kPa) or high temperature (40/33℃, day/night) resulted in higher
palmitic acid and lower stearic acid. Genotypes differed in their responses to
water stress or temperature. Analyses of seed carbohydrates (glucose, fructose,
sucrose, raffinose, and stachyose) showed a significant decline of glucose, fructose,
and sucrose and a significant increase of stachyose concentration by water
stress and high temperature. Analyses of natural abundance of δ15N
and δ13C
isotopes showed changes in sources of nitrogen and carbon fixation, possibly
affecting nitrogen and carbon metabolism pathways. The research demonstrated
that both water stress and high temperature altered oil production and composition, and this could be partially related to limited availability and
movement of carbohydrates from leaves to seed. Further research to investigate
the enzymes controlling fatty acids conversion and nitrogen and carbon
metabolism is needed.
