Yield Performance of Summer Season Sunflower under N-Rate by Change in Climate of Northwest of Pakistan

Sunflower (Helianthus annuus L.), a non-conventional oil seed crop, can successfully be fit in the cropping system as spring or summer season crop. However, its planting in summer is at risk of the moon-soon outbreak duration in the season. Present study was aimed to quantify delay-sowing response with increasing N-rate on crop productivity at Agronomy Research Farm, University of Agriculture Peshawar Pakistan. Sunflower (cv. Hysun-33) was planted on different dates i.e. Jul. 1, 11 and 21 treated with different N-rates starting from 40 kg ha^-1 with a 40 kg increment to the maximum of 160 (kg ha^-1) including a control treatment in a randomized complete block (RCB) design in four replications. Sowing date (SD) were main plot and N-rate subplot treatments. Mean results of replications revealed a significant reduction in days to flowering and maturity by delay SD. However, positive responses were observed by increase in N-rate. Early planting showed maximum biomass and yield at 120 kg N ha^-1 which was due to reflecting higher leaf area, plant height and stem diameter (cm). Traits e.g. the head diameter, grain head-1 and grains weight were indicators contributing towards grain yield by early sowing compare to late sowing or increasing N-rate (40 to 120 kg ha^-1). The oil content and oil yield was naturally contributed well to early sowing date in season. However, a decrease in oil content with increasing N was observed. Oil yield (kg ha^-1), the net returns per unit area, is of interest of the crop cultivation and observed the maximum at 120 kg N ha^-1. The study suggests that delay sowing of summer sunflower crop in the region either by monsoon rains or any other circumstances decreased production drastically. Moreover, an increase of N from 120 kg ha^-1 is not of much value under these circumstances but have the potential to investigate for increasing production of the sunflower crop in the region.