The effects of exogenous cytokinin application on sink size in bread wheat (Triticum aestivum)

Abstract

To study the effect of exogenous cytokinin application on wheat yield, an experiment was conducted in 2005 - 2006. Three varieties of wheat (Azadi cross, Darab 2 and Niknezhad) and four levels of BAP (N6- benzyl amino purin) (0, 2, 4 and 6 mg/L) that were applied at the stage of ear emergence had been used. The results showed that treatments to which 4 and 6 PPM of BAP were applied had the highest flag leaf area duration (LAD), chlorophyll index, number of endosperm cells, seed weight, seed filling duration (SFD), lowest dry weight of stem, dry weight of flag leaf and seed growth rate (SGR) in all the three varieties. Conclusively, application of BAP in early stage of seed filling (stage of cell division in endosperm) could decrease the limitation of sink by increasing the size of source through increasing flag leaf area duration, chlorophyll index and seed filling duration and ultimately, grain yield.   Key words: Wheat, source-sink relationship, SGR, SFD, Benzylamino purin.