Evaluation of potassium application effect on grain yield, oil and protein content of brassica (Brassica napus L.)

Potassium response on yield, yield components, oil and protein contents of brassica cultivars was evaluated in a field study at University of Agriculture, Peshawar during winter 2010-11. Three cultivars (Abasin-95, Bulbul-98 and Durr-e-NIFA) and four potassium levels (0, 30, 60, 90 and 120 kg per ha) were compared. Randomized Complete Block design with factorial combination of cultivars and potassium levels was used with four replications. Seed was sown at the rate of 5 kg per ha keeping row to row distance of 35 cm. Nitrogen and phosphorus were applied at the rate of 80 and 60 kg per ha from urea and DAP respectively. Half N was applied at sowing and the other half at the beginning of flowering. Thinning was carried out to maintain uniform population by keeping about 5 cm plant to plant distance. Weeds were controlled manually. The crop was irrigated when needed and at least seven irrigations were given until the physiological maturity. Analysis of data revealed significant difference for the cultivars in grain number silique-1, 1000 grain weight, biological yield, grain yield, harvest index, seed oil yield, seed oil content and protein contents. At par siliques m-2 (9914 and 9878), grain yield (1759 and 1799 kg per ha), oil yield (767 and 784 kg per ha) and harvest indices (13.9 and 13.7%) were recorded for Bulbul-98 and Abasin-95, respectively. Maximum grain number silique-1 (24), 1000 grain weight (3.5 g) and protein content (26.7 %) for Bulbul-98, maximum biological yield (13189 kg per ha) for Abasin-95 and maximum oil content (44.3 %) was recorded for Durr-e-NIFA. K levels affected number of siliques m-2, grains silique-1, 1000 grains weight, biological yield, grain yield, harvest index, seed oil yield, seed oil and protein content. At par harvest indices, biological, grain and oil yields were recorded at K levels of 60, 90 and 120 kg per ha. At par grains siliques-1, 1000 grain weight, seed oil and protein content were recorded at K levels of 90 and 120 kg per ha, and maximum siliques m-2 were recorded at K level of 120 kg per ha. CxK interaction exhibited significant differences for protein content only. It was concluded that Bulbul-98 and Abasin-95 had higher grain yield, seed oil yield and oil contents. Bulbul-98 had more protein content than Abasin-95 and Durr-e-NIFA. On the average, cultivars gave at par grain and oil yield at 60, 90 and 120 kg per ha. However, they produced at par oil and protein content at 90 and 120 kg per ha. In light of the above conclusion Bulbul-98 and Abasin-95 are recommended for higher grain and oil yield for general cultivation in Peshawar valley. Potassium @ 60 kg per ha is recommended for higher grain and oil yield in brassica.