Nitrogen nutrition and water stress effects on growth, yield and water use efficiency of wheat (Triticum aestivum L.)

Waraich, E.A.; Ahmad, R.; Saifullah ; Sabir, M.

Pakistan Journal of Agricultural Sciences 44(1): 64-73

2007


ISSN/ISBN: 0552-9034
Accession: 014118917

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Abstract
A field experiment was conducted on sandy loam soil in Faisalabad, Pakistan, during 2002-03 and 2003-04 to study the effects of N (urea) on the growth, yield, and water use efficiency of wheat (cv. Inqlab 91) under adequate and limited water supply. The treatments consisted of 4 levels of irrigation (I1, one irrigation at the tillering stage; I2, irrigation each at the tillering and anthesis stages; I3, irrigation each at the tillering, anthesis and grain development stages; and I4, irrigation each at the tillering, stem elongation, anthesis and grain development stages) in main plots and 4 N levels (0, 50, 100 and 150 kg N ha-1) in subplots. The increase in the number of irrigations from 1 to 4, and the increase in the N level from 0 to 150 kg ha-1 significantly (p<=0.05) increased the average leaf area index (LAI), crop growth rate (CGR), yield attributes, and grain yield over the control (I0 and N0) in both the seasons. The highest LAI and CGR, which were obtained with the highest levels of irrigation and N, were recorded at 73-88 days after sowing. Regression analysis revealed that LAI estimates with biological yield were 92 and 38% during 2002-03 and 2003-04, respectively. The mean grain yields under 4, 3 and 2 irrigation treatments increased by 47, 23 and 9% during 2002-03, and by 91, 84 and 23% in 2003-04, respectively, relative to irrigation once. Water deficit reduced the number of spikes m-2. In both years, the average reduction in number of spikes m-2 under maximum irrigation deficit (one irrigation) at all N levels was 24%. The number of grains per spike was reduced by water deficit by 36%, on average. The mean water use efficiency (WUE) at all N levels was 41% higher under one irrigation than under 4 irrigations. A higher WUE was obtained with 150 kg N ha-1 at all irrigation treatments. WUE decreased with increasing number of irrigation. N application significantly improved WUE.