The effect of planting dates in the sum of three components of the genetic structures of sunflower

Abstract

A field trial was conducted at Abu-Ghraib research station , Baghdad, Iraq , The objectives were to study the effect of sowing dates on the performance of three sunflower genotypes . A split-plot lay in a randomized complete block design with three replications were used . Five sowing dates ( 16th Jan , 4th , 14th and 26th of Feb. and the 15th of March ) were assigned to main plots , where as genotypes in sub-plots .Any delay in sowing dates after the 16th Jan . Hastened the physiological processes of the developmental stages of the crop . and reflect , the effects of environmental factors such as ( higher temperature , longer photoperiod and lower relative humidity , consequently the optimum periods of the life cycle of the crop was shortened . Sowing as early as mid of January maximized seed weight 91.3 mg , and number of seed /head 1440 , also the fertility percentage and head size reaches it highest value 97% and 25.3 cm respectively at this planting date.The largest head 24.3 cm and more seed /head 1463.5 gave the genotype Pan 7392 .Interactions between genotypes and sowing dates were also detected.genotypes (Pan7392)gave the highest more seed /head and seed weight 1543.2 and 97.2 mg respectively.