Influence of spermine on pigment,carbohydrate and some yield traits in three wheat cultivars (Triticum aestivum L.) during drought exposure in post-anthesis stage

Water deficit is a major threat for yield cereals during the origin of impregnation phase, especially. In the meantime, application of hormonal treatment is one of the ways to yield increment in plants when environmental stresses as drought appeared. Therefore, the pot experiment as completely randomized designs with for replications was conducted to study of exogenous application of spermine (25mgl-1) on flag leaf chlorophyll and total soluble carbohydrate in related to weight of thousand grains and grain yield in three wheat cultivars differing in post-anthesis drought tolerance Gaspard (drought-sensitive), Sabalan (drought-semi tolerant) and Pishtaz (drought-tolerant)- in field capacities of 100% and 50% (drought stress) from grain filling starting stage until spike maturity. Samples separated to flag leaves and spike and biochemical and yield traits were analyzed. Statistical analysis was performed using analysis of variance (ANOVA). Significant differences were determined at P≤0.05, according to Turkey‟s HSD multiple comparison test. Results showed that chlorophyll a, b and a+b of Gaspard cultivar showed more significant reduction as regards two other cultivars under drought stress, although the significant decrease of carotenoid and chlorophyll a/b was only showed in the sensitive cultivar. Also, the significant decline of flag leaf total soluble carbohydrate, starch and total soluble carbohydrate/starch ratio in Gaspard and Sabalan cultivars was showed under drought stress. The weight of thousand grains and grain yield decreased significantly under drought stress with regard to well-watered that was more insensitive cultivar (39% and 33% reduction of weight of thousand grains and grain yield, respectively). It was only showed a significant correlation between soluble carbohydrate and pigment reduction with the weight of thousand grains (R= 0.56) and grain yield (R= 0.24) insensitive cultivar. Results showed that exogenous application of spermine caused more increment of flag leaf chlorophyll a, b, a+b and total soluble carbohydrate as compared with a partial elevation of starch content in all cultivars under drought stress that was higher in the tolerant cultivar. Hormonal treatment of spermine resulted in the significant increment of soluble carbohydrate/starch, although it had not the significant effect on chlorophyll a/b. In a total conclusion; despite improvement of flag leaf pigment stability and increment of carbohydrate sink, the exogenous application of spermine caused only raise of the weight of thousand grains in semi-tolerant and tolerant cultivars. Also, the spermine treatment did not cause significant correlation between the weight of thousand grains and grain yield.

Keywords:

Correlation , Flag leaf , Hormonal treatment , Carbohydrate , Weight of thousand grains