Abstract
Supplies of nitrogen in saffEcient quantlties is inevitable for better carp ykld anti improved quality of citrus fruits. Since the losses of N after applica-tion are quite high, therefore, its judicious application Is essential. A short term study was con ducted on four years old Feutrelle Early trees to verify the validity of the recommended time of application of nitrogen fertilizers which is fifteen days in the case of NO3 nitrogen and one month for NH4 nitrogen, ahead of flowering. In this experiment two fertilizers, i. e. atrim onitm sulphate and ammonium nitrate representing ammonium alanc and amm-onium plus nitrate sources of nitrogen respectively were applied. The quantity f nitrogen supplied was 350 g per plant. Both the fertilizers were applied in the third week of February. For leaf analysis, 4-7 mouths old leaves gr4re sarn?le i oa VI!: day or fer-tilizers application, ten days after and thz:t after every third day until middle of March. Total nitrogen was estimated by lvlic..bro-Kjeldhals method. It was revealed through leaf analysis that the trees supplied with ammoni-um nitrate showed a signiticantiy higher nitrogen level of leaves tea days after application and maintained higher nitrogen throughout the period of study (bloom duration) than the trees fertilized with am llonium sulphate. There was an immediate decline in the leaf nitrogen concentration afterwards but thes:iiisi-factory range was prolonged in treys fertilized with ammonium nitrate while such a range could not be maintained in trees treated with am major's sulphate (Table 1). The lower leaf N values were responsible for the poor fruit setting nitrate d. wh.. and lower yield of citrus. It is, therefore, suggests that siatmottium. supplies both NO and NH4 sources of nitrogen may be better for citrus orchards as it maintained higher levels of leaf nitrogen for longer periods when applied ten days ahead of flowering instead of one mouth as recommended,
