Intermittent moisture supply induces drought priming responses in some heat-tolerant chickpea genotypes

Heat and drought stresses are two abiotic factors that often occur simultaneously and are predicted to increase, consequently hampering plant growth. Response of different species to either stresses is well documented but information on the response of the same genotypes to both stresses in chickpea (Cicer arietinum L.) is limited. We aimed to determine whether previously noted heat-stress-tolerant genotype (Acc#7) is drought tolerant, that heat-sensitive genotype (Acc#8) is drought sensitive, and whether intermittent moisture supply at vegetative stage would induce priming effect to later drought at flowering. At vegetative stage, plants were divided into three groups, nonstressed (watered to 75% field capacity [FC], severe water stress (moisture withholding for 14 d), and treated to 40% FC throughout the experiment (mild stress), with recovery for the severely stressed plants after which they were stressed (double stress) at flowering. Drought treatments at vegetative and flowering growth stages decreased physiological parameters and biomass accumulation in both genotypes except low water supply at 40% FC that decreased biomass in Acc#7 but not Acc#8. Double-drought stress resulted in priming effect in Acc#7, having higher biomass, chlorophyll fluorescence, stomatal conductance (g_s), net photosynthesis, and relative water content (RWC) vs. the introduction of stress only at flowering growth stage as well as in comparison with Acc#8. These results showed that both Acc#7 and Acc#8 are sensitive to drought, whereas after priming, Acc#7 is better acclimated to drought than Acc#8 associated with osmotic adjustment on leaf RWC and higher capacity to protect photosynthetic activity, making Acc#7 potentially ideal for areas associated with intermittent drought spells.