Sensitivity analysis of erucic acid free cultivars of rapeseed-mustard under nutrient application

A field experiment was conducted on three better performing cultivars of rapeseed-mustard selected on the basis of seed yield and fatty acid composition of oil. The cultivars included two erucic acid free, viz. Brassica napus L. cv. Hyola PAC-401 and Brassica juncea L. Czern. & Coss. cv. TERI (0E) M21Swarna and one locally popular high yielding, Brassica juncea L. Czern. & Coss. cv. Rohini as a check. These were grown with the five graded combinations of soil-applied N (urea) and P (diammonium phosphate), viz. (i) 0 kg N +0 kg P ha⁻¹, (N₀P₀) (ii) N₃₀P₁₀, (iii) N₆₀P₂₀, (iv) N₉₀P₃₀ and (v) N₁₂₀P₄₀, along with 30 kg K ha⁻¹. Growth and physiological and biochemical parameters were studied at 45 and 60 days after sowing and yield characteristics and fatty acid composition of oil, at harvest. Application of N₉₀P₃₀ proved best for most of the parameters studied. For example, this treatment increased net assimilation rate by 98.7%, seed yield by 78.6% and oil yield by 72.7% over N₀P₀ (control). Cultivar Hyola PAC-401, followed by TERI (0E) M21-Swarna, proved best particularly on the basis of high seed and oil yield and low erucic acid content. The oil of Hyola PAC-401 and TERI (0E) M21-Swarna contained almost negligible erucic acid (0.40% and 0.59% respectively) compared with that of Rohini (35.5%). Interaction N₉₀P₃₀ x Hyola PAC-401 proved best for most parameters.