Influence of sowing time and nitrogen fertilization on Alternaria leaf blight and oil yield of Sesame cultivars

Two sesame cultivars (Sesamum indicum L.) were evaluated using various 3 different sowing dates (20 th June, 10 th and 30 th July) and four nitrogen levels (0, 40, 80 and 120 kg N ha -1 ) at the New Developmental Farm of The University of Agriculture, Peshawar, Pakistan during summer 2012. The experiment was laid out in randomized complete block design (RCBD) with split plot arrangement using four replications each. Sowing dates and sesame cultivars (local black and local white) were allotted to the main plots, while nitrogen levels were allotted to subplots. Results exhibited that plants sown on 20 th June had significantly higher oil yield (522 kg ha -1 ), seed yield (1135 kg ha -1 ) and nitrogen use efficiency (15%) while 10 th July sowing showed higher Alternaria leaf blight incidence (77%) and severity (45%) as compared with other sowing dates. Local black cultivar had significantly more oil content (47%), oil yield (335 kg ha -1 ), seed yield (696 kg ha -1 ) and Nitrogen Use Efficiency (NUE) (12%) as compared with local white cultivar which showed higher Alternaria leaf blight incidence (46%) and severity (28%). Plots treated with 120 kg N ha -1 produced maximum Alternaria leaf blight incidence (49%), disease severity (31%), oil content (52%), oil yield (433 kg ha -1 ) and seed yield (833 kg ha -1 ) but higher NUE (15%) was obtained when plots were treated with 40 kg N ha -1 . The interaction among sowing dates, cultivars and nitrogen level revealed that sesame cultivar local black sown on 20 th June and supplied nitrogen @ of 120 kg ha -1 had produced higher oil content, oil yield and seed yield but NUE was significantly higher when plots were treated with 40 kg N ha -1 . Local black cultivar sown on 20 th June and treated with 120 kg N ha -1 produced the best results in terms of oil content, oil yield, seed yield and minimum Alternaria leaf blight disease incidence and severity percentage.