Impact of nitrogen fertilization on nitrate reductase activity in spring barley (Hordeum vulgare L.) leaves under drought stress
Krcek, M.(Slovak Univ. of Agriculture in Nitra (Slovak Republic). Tr. A. Hlinku 2, 949 76 Nitra, Slovak Republic | Olsovska, K. | Brestic, M. | Slamka, P.
Effect of nitrogen rates on NRA (nitrate reductase activity) in leaves of spring barley (variety Kompakt) was investigated in pot vegetation experiment at atmospheric conditions. There were applied the following rates of N per pot: 0.0 g (treat. 1, control), 1.0 g (treat. 2), 2.0 g (treat. 3). Plants were grown under optimum water moisture regime (60% of full water retention capacity- FWRC) and drought stress was applied during the duration of growth stage of tillering, shooting and earing, respectively. During stress period the water content in soil was maintained on the average level of 15-20% of FWRC. After finishing respective stress period the plants were further grown under optimal water regime until the end of growing season. Samples of material were taken after stress finishing in respective growth stages and NRA was determined by Jaworski (1971) method in Barker (1974) modification. Achieved results show that NRA was in all fertilized and unfertilized treatments significantly higher under optimal water regime than in respective treatments which were exposed to drought stress. Applied nitrogen fertilization particularly higher rate of N alleviated adverse effect of applied drought stress during investigated growth stages in comparison to unfertilized control. The most drought stress sensitive growth stage seems to be shooting where NR activity was not stimulated significantly by N-fertilizing. However, if the moisture conditions during this growth stage were optimum, effect of N-fertilization resulted in the highest values of NR activity.
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