Green gram yield projections for Kibwezi east subcounty Kenya using the APSIM model under RCP's 4.5 and 8.5

Green gram is widely grown in Kenya for food and income. However, climate change has shown unprecedented effects on its production in Kibwezi East Sub County affecting its yielding capacity. In this study, the Agricultural Production Systems Simulator Model (APSIM) (green gram module) was used to evaluate climate change impacts on its production by simulating the yields under present scenario (2001-2023), Representative Concentration Pathways 4.5 and 8.5 (2041-2071) climate scenarios. The model was parameterized and evaluated using soil data, daily climate data and phenological characteristics for three green gram varieties, Biashara, KS 20 and N26. Yield data was obtained from a field experiment carried out during the October - November – December (OND) planting seasons in 2020 and 2021.The developed models had a Coefficient of Determination (R2) ranging from 0.58 to 0.84 and a Root Mean Square Error (RMSE) ranging 3.0 and 13.3 meaning the models were reliable in simulating future yields. Model predictions showed that performance of green gram under RCP 4.5 and RCP 8.5 would greatly reduce. Varieties KS 20 and Biashara showed relatively high resilience to increased temperatures. This calls for employment of innovative and sustainable strategies for climate change adaptation.