Journal of Applied Horticulture. 2001: 3(2): 91-94

Changes in the activity of nitrogen utilizing enzymes during development of malformed and normal panicles of mango (Mangifera indica L.).

Singh, V K; Saini, J P; Misra, A K

Central Institute for Subtropical Horticulture, Rehmankhera, PO. Kakori, Lucknow - 227 107, India.

The activity of nitrogen-utilizing enzymes, i.e. nitrate reductase (NR), glutamine synthetase [glutamate-ammonia ligase] (GS), glutamate synthase (GOGAT), and glutamate dehydrogenase (GDH), during the development of healthy and malformed panicles of mango cultivars Amrapali and Dashehari was studied in Lucknow, Uttar Pradesh, India, during 1995-97. Healthy and malformed panicles were evaluated at stages I (fully developed apical bud), II (flower bud at inception), III (fully grown panicles prior to full bloom), and IV (fully developed panicle at the full bloom stage). NR activity was significantly reduced in normal panicles from stage I to IV in both cultivars. Nonsignificant changes were observed in the malformed panicles of Amrapali. In general, the activity of GS and GOGAT followed the same trend. Contrary to the activity of NR, GS, and GOGAT, a sharp increase in GDH activity was observed in malformed panicles at the early stage of panicle development. GDH activity, which was highest at stage II in both cultivars, declined gradually during stage III and IV. The higher activity of GDH in malformed panicles indicated the shift of primary route of ammonia assimilation (GS/GOGAT) at the early stage of panicle development. Total nitrogen, protein, and nitrate contents declined with the age of healthy panicle in both cultivars. However, their level remained higher at the later stage of malformed panicle development.