Optimizing growth, yield and water use efficiency (WUE) in Nagpur mandarin (Citrus reticulata) under drip irrigation and plastic mulch

The field experiment was conducted during 2005–08 to assess the response of various drip irrigation regimes, viz 40, 60, 80 and 100 per cent of cumulative pan evaporation on alternate day (Ecp) with black polyethylene mulch versus basin irrigation method in three year old Nagpur mandarin (Citrus reticulata) trees budded on Rough lemon (Citrus jambhiri) root stock. All the drip irrigation regimes with plastic mulch produced a significantly higher annual increase in tree height (0.47–0.64 m), canopy volume (0.53–0.99 kg plant⁻¹ m³), fruit yield (9.2–15.0 kg plant⁻¹) and water use efficiency (0.015–0.036 kg plant⁻¹ mm⁻¹) over basin irrigation method. However, drip irrigation at 60 per cent Ecp with plastic mulch produced the highest magnitude of plant growth parameters, fruit yield and water use efficiency. Among different fruit quality parameters (juice percentage, TSS and acidity), significantly higher juice content (39.8%) was observed in drip irrigation at 60 per cent Ecp with plastic mulch over control (36.5%). Analysis of leaf nutrients (N, P, K, Fe, Mn, Cu, and Zn) indicated that the drip irrigation at 60 per cent Ecp with plastic mulch produced a significantly higher leaf N (2.56%), K (1.88%), and Fe (112.6 ppm) over basin irrigation.