Effect of gibberellic acid spray and basal nitrogen and phosphorus on productivity and fatty acid composition of rapeseed-mustard

Two field experiments were conducted during 1994-95 to study the effect of spray of 10(-5) M GA3 at 40 days after sowing on mustard (Brassica juncea (L.) Czern & Coss.) cv. Varuna grown with basally applied 0, 40, 80 and 120 kg N ha(-1) (Expt. 1) and 0, 15, 30 and 45 kg P ha(-1) (Expt. 2) on pod number per plant, seeds per pod, 1000 seed weight, seed yield, biological yield, harvest index and fatty acid composition of oil. No significant difference between water and GA3 spray was found when basally applied nitrogen was 0 or 40 kg N ha(-1). N-80 proved to be the best for yield characteristics. In another experiment on phosphorus, GA(3) and 30 kg P ha(-1) individually enhanced the yield, but interaction of GA(3) and P remained non-significant. The fatty acid composition of oil in both experiments was significantly affected only by nitrogen and phosphorus treatments for oleic acid and erucic acid. It was found that return in the form of yield was more for every kg applied fertilizer under GA(3) spray treatment. The response was more for N fertilizer in comparison to P. GA(3) at a low level of fertilization significantly increased the return from fertilization.