RELATIONSHIPS BETWEEN LEAF WATER POTENTIAL, CWSI, YIELD AND FRUIT-QUALITY OF SWEET LIME UNDER DRIP IRRIGATION

This study was initiated to correlate the leaf water potential and crop water stress index (CWSI) with the yield and yield quality of sweet lime (Citrus limetta, Swing) under drip irrigation with water application based on different fractions of pan evaporation (0.4 E(pan) to 1.0 E(pan)). The lower baseline for CWSI of Idso et al. (1981) was (Tc-Ta) = 3.61-1.74 (VPD), and the upper limit for CWSI calculations was 5.0-degrees-C. The average CWSI during the growing season varied from zero to 0.435 at different irrigation treatments (1.0 E(pan) to 0.4 E(pan). The maximum fruit yield was produced at a pan evaporation fraction of 0.75, corresponding to the CWSI of 0.103 and leaf water potential of -2.03 MPa with maximum water-use efficiency of 26.8 kg/mm. However, the maximum weight of fruit, pulp and juice resulted at higher water application while the total dissolved solid, ascorbic acid and vitamin C were lower. The relationship between the leaf water potential and CWSI was dependent on the air vapor pressure deficit (VPD). Furthermore, a relationship between (Tc-Ta) and VPD was proposed for irrigation scheduling of sweet lime with an infrared thermometer method.