Simulating the yield, water and nitrogen productivity in wheat as affected by sowing date, cultivar, irrigation regimes and nitrogen levels”
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2013
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ABSTRACT
In view of shrinking water resources and the anticipated effects of climate change on water availability, management interventions need to be refined in respect of planting time, cultivar, irrigation and fertilizer N regimes. This study includes the evaluation and application of DSSAT-Wheat model. In order to evaluate DSSAT-Wheat model, database was generated on two experiments. In the first experiment, sowing dates, cultivars and irrigation regime effects were evaluated on growth and yield of wheat; while in second experiment, interactive effect of irrigation and nitrogen level on crop yields, water and nitrogen uptake was studied. Field experiments were conducted on a sandy loam soil during 2011-12 growing season at research farm of Punjab Agricultural University, Ludhiana (30o54'N, 75o48'E, 247 m above sea level), Punjab, India. The treatments include a combination of three planting dates (D1 25 October, D2 8 November and D3 20 November), two cultivars PBW-621 (V1) and PBW-550 (V2).and two irrigation regimes (IS stage based and I0.9 IW/PAN-E 0.9) for experiment one and wheat (cv. PBW 550) was planted on 20 November under four irrigation regimes (I0.6 IW/PAN-E 0.6, I0.8 IW/PAN-E 0.8, I1.0 IW/PAN-E 1.0, and I1.2 IW/PAN-E 1.2) and four fertilizer N levels (0 (N0), 60 (N60), 120 (N120) and 180 (N180) kg N/ha) for experiment two.
This evaluation analysis has demonstrated that simulation of crop phenology and harvest time biomass or grain yield was reasonable with normalized RMSD of 10 - 20 % between measured or simulated values, while simulation seasonal water use was fair (normalized RMSD of 20–30 %).Simulated total N uptake had normalized RMSD of 25-35% for measured values of the two sets of data, while grain N uptake had greater variance. Scenario analysis based on 20 years of weather data showed that potential grain yield of V1 had a tendency to increase with shift in planting from Oct 25 to Nov 10 and Nov 25. Interaction effects of irrigation and nitrogen demonstrated that N response of yield was greater under full than under limited irrigation. Water productivity increased with N rates and decreased with increase in irrigation; while NUE had reverse trends.