Water productivity and fruit yield of brinjal (Solanum melongena L.) as influenced by various levels of nitrogen and irrigation methods

The field experiment was conducted at Research Farm of Punjab Agricultural University Regional Station, Bathinda, India, during 2007-08, 2008-09 and 2010-11 to evaluate the independent and interactive effects of three levels of N and different quantities of water applied through drip as well as furrow irrigation on eggplant fruit yield, agronomic efficiency of N and water productivity: In the present field investigation, ridge planting with each furrow and alternate furrow irrigation were compared with drip irrigation at two levels of water : 100% (CPE 1.0) and 50% (CPE 0.5) of each furrow irrigation (designated as D-1.0 and D-0.5). The three levels of N studied were 90 kg N/ha (75% of recommended dose of nitrogen i. e. N-1), 120 kg N/ha (100% of RDN i. e: N-2) and 150 kg N/ha (125% of recommended dose of nitrogen i. e. N-3). The results revealed that mean fruit yield increased significantly with increasing N level up to N-2 in EF, AF and D-1.0 . However, in D-0.5, there was non-significant reduction in fruit yield with increase in N level from N-1 to N-2 and significant reduction with further increase from N-2 to N-3. The highest fruit yield under drip (D-1) was obtained at N-2, which was statistically at par with that obtained under each furrow irrigation at N-120. The 50% water through drip can be saved by sacrificing 1.9% mean fruit yield as compared to each furrow irrigation. The increase in fruit yield was the result of an increase in the number of fruits per plant. The highest mean WEE was recorded in D-0.5 (667.4 kg/ha-cm) followed by RAF, (565.3 kg/ha-cm) and the lowest in RE, (481.9 kg/ha-cm). In furrow irrigation, the WEE was 605.5 and 503.6 kg/ha/cm under alternate and each furrow irrigation at N-120. Similarly, under drip (D-1) the WEE was 577.3 kg/ha/cm at N-2 level and increased to 682.5 kg/ha/cm in D-2 at same level of nitrogen. The agronomic efficiency of nitrogen (AEN) decreased with the increase in level of nitrogen in all the methods of irrigation. The higher AEN was recorded at N-1 and the lowest in N, level. The results further revealed that application of only 50% water through drip (D-0.5) produced 7.0 and 10.4% higher yield as compared with each furrow irrigation method at N-120 and N-150 levels of N, respectively. These results clearly indicate that there is need to work out amount of water required to be applied through drip at different levels of N for maximizing the benefits under field conditions.