Modeling Climate Change Effects on Sweet potato and Okra Yield in Edo State, South Southern Nigeria

Abstract The climate study aims to evaluate the projected effects of changes in climate on sweet potato (Abelmoschus esculentus L.) and okra (Ipomoea batatas) yields for the time slices of 2049-2069 (the 2050s) and 2070-2100 (2080s) relative to the referenced period 1977-2100 (2080s) relative to the referenced period 19772005 under the median and worst-case emission scenarios: representative concentration pathways (RCP 4.5 and RCP 8.5) using statistical downscaled climate datasets from an ensemble of three (3) general circulation models (GCMs) over Edo State, south southern Nigeria. The baseline yield analysis showed that sweet potato (SP) yield decreased with an average of 0.2 ton/ha, while okra (OKR) yield increased by 0.03 ton/ha from 1977-to 2007. Hence, this period corresponded to an annual mean temperature increase of 0.02oC. The outcome of the climate analyses showed that the CCCMA model indicated the highest decrease in SP yield of 22.5% (1.3 ton/ha) and 27.7 % (1.66 tons/ha), while NOAA projected the lowest decrease of 15.2% (0.85 ton/ha) and 18.6% (1.04 tons/ha) for the 2050s and 2080 in comparison with the baseline. Hence, the projected climate has a slight effect on OKR yield compared to SP. The projection showed that NOAA and ICHEC models indicated a lower OKR yield decrease, whereas the CCCMA model projected the highest yield reduction for the 2050s and 2080s under the two RCPs. Therefore, a 30% (35 days) and reduced 10% (10 days) okra growing cycle length (OGCL) were predicted under RCP 8.5 by 2080s from the CCCMA model, while all the GCMs indicated no elongation period for OGCL by 2050s. In conclusion, the crops due to their mild drought tolerance could be considered for the potential for potential climate change adaptation crops.