Effect of source - sink relationship on causal relationship between grain yield and its components in spring wheat genotypes in Ahvaz

This expriment was carried out to evalute the effect of changing in sink- source relationship and grain yield of some wheat genotypes by path analyses. The exprimental arrangment was split plot in RCB design with three replication conducted in research field of agricultural and natural resources research of Khouzestan. Main plot were consists of six spring wheat genotypes and sub plot included flag leaf remove, flag leaf remove + spike covering, spike covering and control.  Significant differences were found between genotypes and treatments of grain yield, number of spike/m2 and number of spikelet per spike at 1% stataistics level. The interaction effect was significant for grain yield, biological yield, harvest index, 1000 grain weight, number of grain per spike, number of grain per m2, number of spike per m2 and number of spikelet per spike at 1% stataistics level.it should be noted that results showed the high genetic diversity existed among wheat genotypes and the number of grain per m2 was the most effective and most important trait that influenced the grain yield.