EFFECT OF MINIMAL AMOUNT OF SUPPLEMENTAL IRRIGATION DURING DROUGHT STRESS ON YIELD AND QUALITY OF GROUNDNUT

A field experiment was conducted for two years to find out the response of groundnut to small quantities of supplemental irrigation through sprinklers. Different depths of irrigation (0, 5, 10, 15 and 20 mm) were applied as protective irrigation during pod filling phase of rain fed groundnut. The results revealed that the leaflets of plants with no irrigation were closed for the entire day due to moisture stress except for brief period of 1.8 hours, while leaflets were in open condition for 10.7 hours/day at 4 days after irrigation (DAI) with 20 mm of irrigation. The leaflets were in open condition for 6 hours/day with 10 mm of water at 7 DAI, while 5.6 hours with 20 mm water at 9 DAI. Soil moisture percentage at 6 DAI did not differ between 0 and 5 mm irrigation but significantly higher with 10 mm and 15 mm of irrigation. Relative water content of leaves at 6 DAI was significantly influenced by the amount of irrigation water. Retranslocation of carbohydrates as observed in dry matter partitioning, occurred from leaves to stem in control and it was from stem to pods with 5 and 10 mm of irrigation water. Application of 20 mm water resulted in higher dry matter in pods. Aflatoxin content was significantly lower with 10 mm of irrigation (5 µg/kg) when compared to control (15.4 µg/kg). Oil and protein contents were not significantly influenced by irrigation levels. Sound mature kernels were significantly higher with 10 mm water (71%) and lowest (44%) with 20 mm water due to addition of new pods. The pod yield was significantly higher over control by 21.7% and 31.8% respectively during first and second years with 10 mm of supplemental irrigation.