EFFECT OF LEVELS OF APPLIED NITROGEN ON NITRATE REDUCTASE ACTIVITY AND GRAIN PROTEIN IN MAIZE (Zea mays L.)

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Date
1988-09
Authors
SHEIKH, ALIYU USMAN
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Abstract
The patterns of activity «f nitrate reductase (NR) in leaves and the development of crude protein in grains (GPC) were studied in tv/o genotypes of maize (HYBRID 8321-21 and TZB Farz-21) under four levels of soil-applied N (0, 80, 120, 160 kgN/ha), two N-sourceS(UREA and CAN) and at various stages of plant growth. ' Plants v/ere raised in completely randomized plots. The plants were sampled fortnightly for leaf nitrate reductase activity (NRA), weekly for ear leaf NRA during grain filling, and at 10 days intervals for grain protein. Results were analysed using Analysis of Variance for 2 x 2 x 4 x 9 x 3 factorial design. There were no significant differences in NRA between the two varietes. The TZB however had significantly higher GPC at 0 and 80KgN/ha. Urea treated plants had a significantly higher NRA than CAN treatments, whereas their difference in effect on GPC was not significant on GPC. In both varieties, \ both NRA and GPC were found to increase with increase in soil-applied N-level; the increase being significant in NRA while it was not significant in GPC at 120 and 160 KgN/ha regardless of N-source and sampling date, NRA tended to increase with increase in vegetative growth up to flov/ering after which it became erratic. The ear leaf contained a lower NRA than the vegetative leaf in both varieties, and its (ear leaf's) NRA was not a direct function of N-level. The difference in GPC at 10, 20, and 30 days after anthesis was not significant in both varieties but a peak was observed ft, ; midway during filling. GPC was significantly correlated with NRA at nil the three stages of grain frilling in both varieties at all sampling dates for NRA, and hence the latter could be used effectively to predict grain quality in the two varieties.
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Submitted in Partial Fulfillment for the Award of M.Sc. (Botany) Degree at Ahmadu Bello University, Zaria.
Keywords
EFFECT,, LEVELS,, APPLIED,, NITROGEN,, NITRATE,, REDUCTASE,, ACTIVITY,, GRAIN,, PROTEIN,, MAIZE,, Zea mays L.
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