Yield and fruit quality of Nagpur mandarin (Citrus reticulata Blanco) as influenced by evaporation based drip irrigation schedules

To identify the critical stages of irrigation water requirement of bearing Nagpur mandarin through drip irrigation system a field experiment was conducted on 7-9 years old bearing Nagpur mandarin (Citrus reticulata Blanco) based on evaporation replenishment (ER) irrigation scheduling during 2009-12. The plant growing period was divided into 6 stages, 2 months each, starting from January to December and the effect on water use, tree growth, fruit yield and quality was studied. The irrigation water quantity given per day per plant under different treatments in various months varied from 21.3-158.5 liters per plant, 17.5-153.4 liters per plant and 20.9-164.5 liters per plant in different months during 2009-10, 2010-11 and 2011-12. The highest quantity of water was applied under the irrigation scheduled at 80 % evaporation replenishment (ER) treatment and it varied from 46.8-164.5 liters per plant in 2009-12. The average mandarin plant height was 4.57-4.83 m, stock girth was 51.5-56.3 cm and canopy volume 62.4-71.2 m3. The only canopy volume was found significant among the various scheduling treatments. The fruit yield and quality was significantly affected under various evaporation replenishment (ER) based drip irrigation scheduling treatments. The highest fruit yield (17.25 and 21.48 tones per ha) higher TSS, juice percentage and lower acidity was observed under irrigation at 80 % ER in stages I-V and 30 % ER in stage VI during the study period. The highest TSS to acidity ratio (12.7 and 12.4) was found in the irrigation schedule with 80 % ER in stages I-V and 30 % ER in stage VI during 2010-12.