Relative stability of seed and kernel oil content under moisture stress in sunflower: evolutionary adaptation or physiologically constrained?

Abstract

The effects of soil moisture stress imposed during 41-71 or 58-93 d after sowing (DAS) on both seed and kernel oil contents in 24 sunflower genotypes were examined. Both early (41-71 DAS) and late stress (58-93 DAS) did not adversely affect the seed and kernel oil contents, while the av. seed yield, 100-seed wt and total DM were reduced especially under early stress. The relative stability in the seed oil content of genotypes under moisture stress was explained partly by its relation to the variation in the kernel:hull ratio. The constancy in seed and kernel oil contents is discussed in the context of physiological constraints determining oil biogenesis and the evolutionary significance of seed oil to seedling fitness.