Munjal, S.V.Patil Shivaji R.2018-08-252018-08-251987http://krishikosh.egranth.ac.in/handle/1/5810069491Winged bean seedlings were grown in soil-filled pots under ftfflfl&~ house conditions of the Department of Agricul tural Chemistry and Soil Science, Flahatma Phule Agricultural University, Rahuri, during the months from April to August 1986^ for standardizing in_ vivo assay conditions for trifoliate leaf NR, Separate experiments were conducted to study the influence of pre-incubation temperature (0°, 15° and 30°C) under dark conditions on iri vivo NR activity and also to monitor the changes in NR activity during plant development. The in, vivo assays for trifoliate leaf NR wee opti mized in respect of n-propanolt Triton-X-100 and substrate concentration. It was noticed that 4 per cent (v/v) n propanol with 0,05 per cent (v/v) Triton-X-100 was found to be optimum for maximum in_ vivo NR activity. The optimum nitrate concentration observed was 100 m*.. A linear rela tionship between NR activity and reaction time was found over a period of 2-hr, When leaf sections (squares) of uppermost just expanded trifollates of winged bean were incubated at 0, 15 and 30°C under dark conditions, the loss of activity was fastest at 30°C and slowest at 0°C. The loss of acti vity was only 15-2 0 per cent at the end of 10 hr incubation at 0°C while the loss was 50 and 80 per cent at 15 and 30°C, '* V~ \ o respectively. The half^(t^) of enzyme at 30 C, was found to be approximately 4 hr while it was 10 hr at 15°C. Nitrate reductase activity profiles within leaf canopy were established upto 45 days of growth period on the 12th,»21st, 30th and 45th days of growth. From studies with changes in NR activity during plant development, it was noticed that the fully expanded uppermost leaves had the higher nitrate reductase activity than the middle and lower leaves. The uppermost just expanded leaves also had higher NR activity during early growth stage and the acti vity gradually declined with the advancement of the age of the leaf.ennullThesis