Multi-model approach to simulate the growth and seed cotton yield of promising cotton cultivars at different planting times and deficit irrigationunder changing licmate scenarios

Abstract

Adaptation has potential to overcome negative impact of climate change in future. Suitable cotton variety selection is imperative to cope with temporal variations and water deficit conditions for yield maximization and sustainability under unpredictable environmental conditions. Field experiments were conducted for promising cotton cultivars sown from 10-March to 21-June with 20 days interval and deficit irrigation regimes (full irrigation, 80% to 40% of full irrigation and rain-fed) for two growing seasons (2012 and 2013) consecutively. Different statistical approaches were used to analyze the data. Cultivar MNH-886 and NIAB-9811 (NIAB-Kiran) planted 30-March to 10-May produced significantly higher seed cotton and lint yield while NIAB-112 also performed reasonably well for late planting (1-June). However higher net monetary return was produced by 21-April planting reasonably well for all cultivars. Seed cotton, lint yield, fiber quality and water use efficiency were found higher with the application of 60% to 80% (565 mm to 645 mm) of full irrigation (720 mm). Water deficit of 20-40% comparative to conventional farmer practice could be used as an alternative deficit irrigation strategy without any significant reduction in cotton yield. CSM-CROPGRO-Cotton and AquaCrop-Cotton models were parametrized well with field data, models performed reasonably well during evaluation with reasonably good statistical indices as RMSE, d-index, MPD, nRMSE and R2 for phenology, growth, seed cotton yield and yield components within the growing years. It is expected that seasonal average temperature would rise 1.52ºC and 2.60ºC in RCP 4.5 and 1.57ºC and 3.37ºC in RCP 8.5 of twenty nine GCMs ensemble (29 GCMs) in near term (2010-2039) and mid-century (2040-2069), respectively as compared with baseline. Mean seed cotton yield would decrease by 8% and 20% in RCP 4.5 scenario, while 10% and 30% reduction would be expected in RCP 8.5 scenario in near term (2010-2039) and mid-century (2040-2069), respectively compared with the baseline (1980-2010). Cultivar NIAB-9811 and NIAB-122 showed lower reduction in yield under future climate scenarios hence these could be used for future cultivation and to develop climate resilient germplasm. Adaptation technology of 20 days earlier planting than current (10-May), 18% and 29% increase in planting density for spreading and erect type cultivars, 25% increase in nitrogen amount, 30% reduction in irrigation and 15% upsurge in genetic potential would reduce the negative impact of temperature and rainfall variability in mid-century climate (2040-2069).