Abstract:
Climate change under future scenarios is a serious challenge for agriculture sector. Aim of this study is to quantify the impacts of climate change on phenology and yield of wheat. under future scenarios by using APSIM. The data for the crop phenology, biomass and yield was obtained from National Agriculture Research Centre, Islamabad (rainfed), Barani Agriculture Research Institute (BARI), Chakwal (rainfed) and Ayub Agriculture Research Institute (AARI), Faisalabad (irrigated). The baseline and future periods were acquired from Pakistan Meteorological Department and CORDEX-SA regional climate models. APSIM was calibrated and validated for 2007-2008 and 2008-2009, 2011-2012, over irrigated regions, while, during 2016-2017 and 2017-2018, over rainfed regions. The climate change impacts on crop phenology and yield were examined by replacing current climate data with the CORDEX-SA RCM-projections in the model. Subsequently, adaptation strategies for sowing dates (S1: 10 and S2: 20 days earlier than current), irrigation (I1: 15% and I2: 30% additional) and combination of both were also studied. The least number of days, in future periods, when T>25 °C are 9 for RCP4.5 and 13 for RCP8.5 in Islamabad. Iirrigated regions showed higher decline in precipitation than rainfed regions. It was observed that both sowing adaptations responded to yield increase during 2030s with higher rise for sowing-2 than sowing-1that is 0.23 ton/ha (8.9%). However, adaptations showed a decline in yield during 2060s and 2090s -0.57 ton/ha (-18.3 %) and -8.4 ton/ha (27.77%) respectively under RCP4.5. Irrigated regions showed improvement for sowing-2 + Irrigation-2 (S2+I2) under both RCPs. The same combination showed increase in the yield for irrigated region under RCP4.5 with maximum rise of 0.703 t/ha (28.4%), 0.88 t/ha (51.3%) and 0.81 t/ha (49.86%) during 2030s, 2060s and 2090s, respectively. Overall, it observed that the RCP8.5 responded strongly to the climate change in comparison to RCP4.5 over both study regions.
