The Effects of Limitation of Source and Sink on Yield and Yield Components of

In order to study the effect of limitation of source and sink on yield and yield components of cumin, an experiment was conducted in complete randomized block design in Research Field of Agriculture Faculty of Ferdowsi University of Mashhad during the years 2006-2007. The treatments were control, defoliation of 100% of leaves, defoliation of 50% of leaves and removing of 50% of umbrellas. The result indicated that in first sampling (10 days after treatments), dry matter and green area of plant significantly influenced by removing of leaves and umbrellas, in a way that increasing in defoliation cause reduction of dry matter accumulation and total green area of plant. In second sampling (24 days after treatments) defoliation of leaves and umbrellas imposed a significant effect on dry matter and total green area of plant. Leaf weight, stem weight and reproductive organs weight influenced by defoliation and umbrellas removing and in each three component the highest amount was observed in control treatment. In maturity stage, only the number of umbrellas per plant influenced by defoliation and umbrellas treatments. In control and defoliation of 50% of umbrellas, there was no significant difference between grain yield and biological yield. The highest grain weight and harvest index obtained at control and removing 50% of umbrellas. The lowest grain yield observed in 50% of umbrellas removing, whereas, the lowest biological yield observed in 100% defoliation. Moreover, the results indicated that when plant exposed with complete defoliation, accumulates more dry matter in reproductive organs and when exposed with half of umbrellas removing, dry matter partitioning pattern shift to vegetative organs.