Direct and residual effect of nitrogen in high-yielding/hybrid chilli (Capsicum annuum)–radish (Raphanus sativus) system

未知. A field experiment was conducted in a sandy loam soil involving ‘Arka Lohit’, a high-yielding variety and ‘ECL’, an F1 hybrid chilli (Capsicum annuum L.) during 2002–05 using 15N-enriched (1% N abundance) urea as the tracer to evaluate direct and residual of applied nitrogen in chilli–radish (Raphanus sativus L.) system. Response in terms of dry matter production was observed in both the varieties when 100% N dose (120 and 200 kg/ha, respectively) was applied in 3 splits, i e basal + 2 top-dresses. The highest yield ‘Arka Lohit’ was obtained when the same dose was applied in 2 equal splits as basal + top-dress due to its slower growth habit. ‘ECL’ hybrid outyielded other treatments when 100% N dose was applied in 3 splits as basal + 2 top-dresses due to its quick yielding habit. Either deferring the time of application by 10 days or reducing the N dose by 20–40% and increasing the splits from 2 to 3 were not beneficial. A significant residual effect of N was exhibited by ‘Arka Nishant’ radish raised during July-August 2003, in terms of fresh yield, dry matter production and different parameters of N-use efficiency compared with the ‘control’. Response of radish decreased as the dose of N input to chilli decreased. Therefore, the yield and N recovery was higher in radish where ‘ECL’ chilli was raised earlier. The highest overall recovery of residual fertilizer N was observed under 100% N dose applied to chilli crop as 3 splits (basal + 2 top-dresses), followed by the same dose applied in 2 splits (basal + top-dress) and 3 splits (deferred by 3 days) in radish raised after both the chilli varieties. Radish utilized only 0.50 – 2.58% of residual N from fertilizer applied to previous chilli crop, indicating a low recovery which is a common feature in most crops.