LAUSR

Abstract Scarcity of water and nutrients in orchards are the major causes of low productivity and decline of citrus in tropics. With a hypothesis that the optimal amount of water and nutrients application through drip irrigation (DI) could save substantial irrigation and fertilizers comparative to that under traditional basin irrigation (BI) with band placement of fertilizer (BPF), this study was conducted in citrus in vertisol of central India. Three DI regimes: I 1 , I 2 and I 3 scheduled at 50% class-A pan evaporation rate (E p ), 75% E p , and 100% E p along with three fertilizer doses: F 1 , F 2 and F 3 at 50% recommended dose of fertilizer (RDF, N:P 2 O 5 :K 2 O=600 g:200 g:100 g), 75% of RDF and 100% of RDF were applied to mandarin plants respectively. BI with band placement of fertilizer (BPF) at 100% RDF was taken for comparison. All the drip-fertigation treatments (except I 1 F 1 ) produced higher plant growth and fruit yield, with better quality fruits compared with BI+BPF. The highest fruit yield (16.39 t ha −1 ), water use efficiency (3.9 kg m −3 ) and fertilizer use efficiency (87.3 kg kg −1 ) were observed in I 2 F 2 . The concentrations of N, K and Fe in leaves were significantly higher in I 2 F 2 compared to other treatments. The leaf photosynthesis, stomatal conductance ( G s ) and transpiration were the highest in I 3 F 3 . However, leaf water use efficiency (LWUE, photosynthesis/transpiration) was the highest in I 2 F 2 . The overall results of this study demonstrated that the application of optimum quantity of water and fertilizers (I 2 F 2 ) through DI could be a productive and water efficient option in citrus production in vertisol.