Effect of pulse irrigation scheduling with hybrid station controller on fruit yield and quality of Nagpur mandarin (citrus reticulate blanco)

Abstract

The hybrid station controller based automatic pulse irrigation scheduling field experiment was conducted on 10-12 years old bearing Nagpur mandarin (Citrus reticulata Blanco) at National Research Center for Citrus, Nagpur during 2008-2011. The objective was to study the automatic daily irrigation scheduling as well as alternate day based on time schedule and potential evapo-transpiration through the drip irrigation. The treatments were consisted of Automatic daily irrigation daily with 60 minute interval three times (I₁); Automatic irrigation daily with 90 minute interval two times (I₂); Automatic irrigation at alternate day with 120 minute three times (I₃); and Automatic irrigation at alternate day with 180 minute two times (I₄) with six replications in Randomized Block Design. The automatic hybrid station controller E-6 (Rain Bird, USA) was used for micro-irrigation schedule setting the time for each treatment based on the water need of the plant and average open pan evaporation. The various scheduling treatment timings were programmed in A, B and C programs of the hybrid station controller. The sustainable production of Nagpur mandarin is possible with drip irrigation using automatic scheduling daily or on alternate days.  The water use in October varied from 65.0-72.4 liters/day/plant and during May-June it was 133.0 - 147.7 liters/day/plant. Drip irrigation was scheduled to maintain automatically the soil moisture status above 25% (wet basis) during fruit growing period. The leaf nutrient status was high with automatic alternate day drip irrigation schedule. The canopy temperature was positively influenced with automatic drip irrigation schedules.  The Nagpur mandarin fruit yield was highest (30.91 tones/ha) with irrigation on alternate day 120 minutes three times, followed by irrigation scheduled with 90 minutes interval two times daily (30.11 tones/ha). Fruit weight (154.7 g), TSS (10.22 0Brix) and juice percent (40.77%) was found with automatic irrigation at alternate day with 120 minute three times. The automatic drip irrigation scheduling can be better substitute for manual drip irrigation operation and enhancing the water use efficiency.