Abstract

A Field experiment was carried out at the experimental farm of Nasser's Faculty of Agricultural Sciences, University of Aden; during 2011 - 2012 and 2012 - 2013 growing seasons to study the effect of nitrogen and phosphorus fertilization on some vegetative growth of three sunflower (Heliathus annus L.) cultivars. The experiment included twenty one treatments which were the combination between three cultivars of sunflwer: Demazen , Saha53 and Giza102 , and seven levels of fertilization: N0P0 , N30P30 , N30P60 , N60P30 , N60P60 , N90P30 and N90P60 kg / ha . Split– plot design in randomized complete blocks, with four replications, was used. The obtained results might be summarized as follows:
The study Saka53 cultivar, significain all growth characteristics increased both seasons gave the plant height (152.43, 152.91 cm), Stem diameter (1.62, 1.67 cm), Number of leaves (25.88, 25.94 leave / plant) and Leaf area / plant (3160, 3116 cm2) in both seasons.
The results indicated that increasing the rate of nitrogen and phosphorus fertilization increased none significantly plant height (cm), Stem diameter (cm) and Number of leaves / plant in the both seasons.
The level fertilization (N90P30kg/ha) gave the highest mean significant differences found on Leaf area / plant (2760, 2750 cm2) in both seasons. A significant interaction was found between the cultivars and fertilization ( NP ) , the saka53 cultivar with ( N30P30 kg/ha ) gave the plant height ( 161.32cm) in the second season only, and the height Leaf area (cm2) with ( N90P30 kg/ ha ) ( 2720 and 2645 cm2 ) in both seasons.