Value and contribution of assimlate remobilization in grain production of wheat cultivars under terminal drought stress

Stem water soluble carbohydrates are one of the major sources of assimilates for seed filling in photosynthesis limitation conditions. The objective of this study was to evaluate the remobilization potential of wheat varieties by potassium iodide. 22 wheat cultivars as sub plots were cultivated in a split plot design with three replications in two growing seasons 2015- 2017 and application and no application of potassium iodide (KI) were main plots. Yield, the number of seed per spike, remobilization, and contribution of remobilization in grain yield were estimated. Significant genotypic variation among cultivars was observed under both normal and KI application. Current photosynthesis elimination decreased the average seed weight per spike by 46%. Grain yield per spike in some cultivars such as Shoosh, Pishgam and Arta and Zare was decresed significantly (up to 65%). The average of grain number per spike was 38 in control, but the application of potassium iodide reduced it to 24% (29 grain per spike). The results of this study showed that the inhibition of current photosynthesis increased the remobilization of assimilate from 3% to 44% in different cultivars. According to the results of cluster analysis, Karim, Shebrang, Hamoon, Pishgam and Dena cultivars had high and also Zare, Chamran and Shush cultivars had low remobilization potentials.