Effect of application of cycocel growth regulator on grain yield and stem reserves in wheat cultivars

Stems water soluble carbohydrates are one of the major sources of assimilates for seed filling in photosynthesis limitaton and drought stress. The objective of this study was to evaluate stem reserves accumulation capacity and its relationship with yield of wheat cultivars under cycocel (cycocel) treatments. 22 wheat cultivars were cultivated in a split plot design with three replications, cycocel foliar application and control (no cycocel) being main plots and wheat cultivars were sub plots. The amount of accumulation was estimated by measuring stem weight and stem soluble carbohydrates content (WSC). Significant variation among cultivars was observed under both cycocel and control treatments. Cycocel foliar application reduced stem length by 3.9% and increased stem specific weight by 6%. An increase in WSC content was observed in some cultivars with cycocel application. Cycocel, not only affected the distribution of photosynthetic assimilates between structural and soluble compounds in the stem, but also increased grain yield and number of seeds per spike. Cycocel increased the number of seeds per spike by 6% and grain yield by 8.2%. According to the results of cluster analysis, in both control and cyclool application treatments, Shabrang and Pishgam cultivars were the best cultivars in terms of studied traits. In conclusion, foliar application of cycocel in the second node emergence stage of wheat had a positive effect on grain yield and number of grains per spike and it aslo improved WSC accumulation capacity especially in taller cultivars.