THE RESPONSE OF DWARF WHEAT VARIETIES ( T r i t i c u m a e s t i v u m L.) TO DIFFERENT WATER STRESS LEVELS, DATES OF SOWING AND NITROGEN FERTILIZATION

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Abstract:

Two field experiments involving (a) Sowing date x Water Stress x Variety and (b) Nitrogen level and Water stress were conducted at the Irrigation Research Station, Kadawa (11° 39’N, 08° 02’E and 500m above sea level), Institute for Agricultural Research, Ahmadu Bello University, Zaria. The Irrigation station is located in the Sudan Savanna ecological zone of northern Nigeria. The investigations were carried out for three consecutive years during 1983/84 to 1985/86 dry seasons (October to March) to study the effect of time of planting, water stress on two varieties in the first experiment and nitrogen fertilization and water stress in the second experiment. A supporting experiment was also conducted under growth chamber condition at the Hydrotechnical Laboratory of Royal Veterinary and Agricultural University, Copenhagen (Denmark) to monitor crucial parameters related to soil and plant water status. Delay in sowing wheat from 10th November to 1st and 22nd December significantly reduced grain yield by 14.8 and 20.8 percent, respectively. Grain yield and yield components were significantly reduced by increase in water stress using IW/CPE (Irrigation water/Cummulative pan evaporation) ratio of 1.00 (no stress), 0.75 (moderate stress) and 0.50 (severe stress). Moderately and severely stressed crop produced 19.7 and 46.0 viii percent lower grain yield respectively when compared with unstressed control (IW/CPE ratio = 1.0). Response of the grain yield to N fertilization was quadratic. The optimum level of N worked out to be 120kg/ha. Wheat variety ‘Siete Cerros’ significantly outyielded ‘Sonalika’ in terms of grain yield, yield components and water-use efficiency (WUE), which decreased with delay in sowing and with increased water stress. Nitrogent application increased WUE linearly up to 150kg/ha. In the sowing date x water stress experiment, there was a positive and very close association between grain yield with 1000-grain weight followed by spikes/m2 and number of grains/spike. Whereas in nitrogen x water stress experiment, a high association was observed between grain yield with number of grains/spike followed closely by spikes/m2. The correlation between the grain yield and 1000-grain weight was not as strong compared with the other two components Except in one experiment, in both sowing date and water stress treatments, there was a negative linear response between the grain yield and the two treatments, whereas in nitrogen x water stress treatment a quadratic response was found to be significant for nitrogen in all the 3 years and combined data analysis. The response to water stress level was quadratic in the first two seasons and linear in the third season and combined analysis.

THE RESPONSE OF DWARF WHEAT VARIETIES ( T r i t i c u m a e s t i v u m L.) TO DIFFERENT WATER STRESS LEVELS, DATES OF SOWING AND NITROGEN FERTILIZATION

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