Partial root zone drying irrigation in papaya (Carica papaya L.) for enhanced water use efficiency under limited water situations

Abstract

Field experiments were conducted during 2015-17 at ICAR-Indian Institute of Horticultural Research, Hessaraghatta, Bengaluru, to standardize the partial root zone drying irrigation in papaya with 12 treatments in RBD design. The results indicated that better soil moisture in the root zone could be maintained under drip irrigation by shifting laterals on either side at fortnightly intervals as compared to fixed laterals with thesame amount of water. Significantly more primary roots (16.5/plant) were observed when irrigation was scheduled on one side with single emitter meeting 60% of the evaporative demand. PRD irrigation through shifting of laterals recorded significantly higher transpiration rate especially at 50% of ER (8.05 m mol m-2 s-1) as compared to the control (3.95m mol m-2 s-1). Further, the same treatment recorded significantly lower fruit cavity index (0.26) with relatively higher fruit volume (1388 cm3 ). Irrigating papaya only on one side with single emitter resulted in significantly higher T.S.S (13.0%). Higher water productivity (23.7 kg/m3 ) could be obtained by scheduling the irrigation at 40% evaporation replenishment through shifting of laterals with saving of substantial water (1285m3 /ha) resulting in higher water use efficiency (237.4 kg/ha.mm).