Altering the enzyme activities for enhancing yield in 'off' year mango (cv. Alphonso) through chemicals and growth regulators.
Vijayalakshmi D., Srinivasan P. S.
Author Affiliation: Department of Crop Physiology, Tamil Nadu Agricultural University, Coimbatore-641 003, India.
Orissa Journal of Horticulture 28 : 1-7
Abstract : To determine the role of the activities of catalase, peroxidase, nitrate reductase and IAA oxidase in manipulating certain physiological processes and bringing about mango yield during the off years, an experiment was initiated in Tamil Nadu, India in September 1995. Ten-year-old mango trees were subjected to the following treatments: single soil drenching with 10 ml paclobutrazol/tree at the root zone (given during the second fortnight of September) and simultaneously, foliar sprays of 1% KNO3, 1% urea, 200 ppm Ethrel [ethephon], 20 ppm NAA and 5000 ppm mepiquat chloride at monthly intervals until January 1996. Observations were recorded at the stages: before spray, new flush formation, bud initiation, flowering and fruiting. For catalase and peroxidase, between the stages of sampling, the enzyme activities registered their peak during flowering, with a gradual decline at the time of harvest. Among all treatments, paclobutrazol favoured catalase and peroxidase activities to the greatest extent (12.57 µmoles H2O2 and 2.94 µg g-1 h-1, respectively). A highly significant positive association was established between catalase and peroxidase activities and the fruit yield. Urea increased nitrate reductase activity (1.35 µg NO2 g-1 h-1). Nitrate reductase activity also exhibited a significant association with the fruit yield. The highest decline in the IAA oxidase activity was observed upon treatment with paclobutrazol (366.67 µg IAA oxidized g-1 h-1). IAA oxidase activity decreased as the crop grew. Moreover, it had a highly significant negative association with fruit yield. In the untreated trees, all the enzyme activities, except for IAA oxidase activity, were the lowest.