Effect of planting dates on stages and some characteristics of growth of four sunflower hybrids [Helianthus annus L.]

ABSTRACT

This work was designed to study the effect of planting dates on the growth stages and some growth characteristics of four sunflower hybrids [Helianthus annus L.]. An experiment was conducted at Nasser's Faculty of Agricultural Sciences in Tuban Delta, Lahej Governorate,Yemen,during each of the two agricultural seasons 2002/2003 and 2003/2004. Each experiment contained twelve treatments which were the combination of three planting dates [10 September, 10 December and 10 February] and four sunflower hybrids [Aranda, Sunbro, Sunloca and Melody].A split-plots design with three replications was utilized. Plating dates were allotted to the main plots, while hybrids of sunflower were devoted to the sup-plots The experimental unit of the area was of 7.2m[2], containing 6 rows [2m long and 60 cm apart].The experimental results revealed the following finding: there were significant effects of planting dates and sunflower hybrids on the growth stages at two growing seasons. In context, the results indicated that planting dates at either 10 September or 10 February led to significantly decreased number of days from plating to 50% appearing of head-flower, days to 50% flowering, days to 50% physiological maturity and harvest in two seasons. In contrast, results mentioned that planting dates at 10 September and 10 February gave significant increase in plant height and number of leaves per plant at two growing seasons, while stem diameter was significantly increased in the second seasons only. With respect to sunflower hybrids the results showed that all sunflower hybrids had significant effect on the number of days to 50% appearing of head-flower [capitulum's], flowering physiological maturity and harvest in two seasons. Noteworthy, the results showed that Sunbro and Sunloca of sunflower hybrids gave the earlier plant growth stage compared with other hybrids at both growing seasons. The interaction effect between planting dates and sunflower hybrids was significantly affected in all different stages of plant growth except days to 50% flowering stages in both seasons, while the interaction effect between planting dates and sunflower hybrids could not reach the level of significance with respect to plant, stem diameter and number of leaves per plant. The interaction of the Sunloca and Sunbro sunflower hybrids planted 10 February gave the earlier days from planting to 50% appearing of head-flower, 50% flowering, 50% physiological maturity and harvest in both growing seasons