Özet:

To assess the nitrogen use efficiency of hybrid sunflower Helianthus annuus L. , an experiment was conducted at New Developmental Farm, Khyber Pakhtunkhwa, Agricultural University Peshawar-Pakistan. Randomized complete block RCB design with split plot arrangement, replicated four times, was used. Sunflower hybrids Suncross, Gulshan-98, Aritar-93, and Peshawar-93 were allotted to main plots while nitrogen levels 0, 45, 90, 135, 180, and 225 kg ha-1 to the sub-plots. Statistical analysis of the data revealed that nitrogen had significant effects P≤0.05 on all parameters under study. Days to button formation and flowering decreased with increase in nitrogen levels. The delayed button formation 35.63 and flowering 52.06 were observed in controlled plots, while earlier button formation 31.94 and flowering 48.56 were noted when 225 kg N ha-1 was applied to the crop. Among hybrids Peshawar-93 took less days 45.29 , while Gulshan-98 took more days 56.42 to flowering. Maximum plant height 87.54 cm , seed yield ha-1 1302.75 kg and leaf area plant-1 9909.5 cm2 was recorded in plots with highest dose of nitrogen 225 kg ha-1 . Maximum leaf area plant-1 8777.53 cm2 has produced by Suncross. Values of nitrogen use efficiency were higher in controlled plots 342 and lower 5.83 in plots with highest dose of nitrogen 225 kg ha-1 . Out of tested hybrids, Suncross produced maximum yield with maximum dose of nitrogen. It is therefore suggested that Suncross should be sown in Peshawar Valley by farmers with N application at the rate of 225 kg ha-1

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