Nutrient management effects on light interception, photosynthesis, growth, dry-matter production and yield of Indian mustard (Brassica juncea)

A field experiment was conducted on sandy loam acidic soil to study the effect of nutrient managements on light interception, photosynthesis, growth, biomass production and yield of Indian mustard [Brassica juncea (L.) Czern & Coss.]. Plant height, number of branches per plant, number of siliqua per plant, number of seeds per siliquae, 1000-seed weight, seed and oil yield of Indian mustard improved at 100 % recommended rates of NPK (N-P-K at 80-17.2-33.2 kg ha(-1)) + 10 t ha(-1) farmyard manure (FYM) (T-3) compared with 100 % NPK rate (T-2). It was also at par with 100 % NPK + 10 kg ha(-1) borax + 20 kg ha(-1) ZnSO4 (T-6) and 50 % NPK + 10 t ha(-1) FYM +10 kg ha(-1) borax + 20 kg ha(-1) ZnSO4 (T-10). The rate of photosynthesis increased due to appropriate nutrient management treatments (T-3, T-6 or T-10) with concomitant increase in photosynthetically active radiation, internal CO2 concentration and rate of transpiration and decrease in stomatal resistance. Consequent upon the higher rate of photosynthesis, dry-matter accumulation increased. The crop receiving nutrient treatment T-3 or T-6 maintained higher light interception ratio (LIR), leaf area index (LAI), biomass production, crop growth rate (CGR) and net assimilation rate (NAR) that resulted in greater rate of photosynthesis, harvest index and seed yield. Similarly, T-10 was equally efficient in registering greater LIR, LAI, CGR, NAR and seed yield of mustard. The average seed yields were 1692, 1683 and 1668 kg ha(-1) in T-3, T-6 and T-10, respectively, and these three treatments were significantly superior to T-2 (1332 kg ha(-1)), control (723 kg ha(-1)) and other treatments. Significantly greater seed oil contents of 41.30, 40.60 and 41.07 % were recorded in T-3, T-6 and T-10, respectively. Thus, significant improvement due to appropriate combination of NPK, FYM, borax and ZnSO4 was observed for uptake of nutrients.