Simulating Cassava Growth Under Rain-Fed Conditions in Nigeria

Accurate assessments of yield potentials of cassava are needed to analyse yield gaps, define yield targets and benchmark actual yields. To that end, we calibrated and evaluated the LINTUL-Cassava model using measured light interception and radiation use efficiency (RUE). On-farm experiments were conducted at six locations in Nigeria across three major cassava growing agro-ecologies of Western Africa in 2016 – 2018. Fertilizer was applied at rates targeting a yield of about 90 t fresh storage root yield ha-1 y-1 (equivalent to 32 t DM ha-1, produced in a growing season of 12 months). Light interception (LI) and canopy measurements were done in 4 week intervals; biomass of stems, storage roots and leaves were determined in two intermediate, and at final harvest and used to calculate the RUE. The measured average fraction of light intercepted was 80 % with a RUE of 2.7 g DM MJ−1 intercepted photosynthetically active radiation (IPAR). The re-calibrated LINTUL-Cassava model described the crop growth and observed patterns of LAI well. Simulated and observed storage root yield were strongly correlated (R2 of 0.92), with a RMSE of 4.93 t DM ha-1 . The measured values for RUE were much higher than those found elsewhere reflecting the high yield potential of cassava in productive environments typical of southern Nigeria. These results confirm that the LINTUL-Cassava model is able to describe the growth of cassava with reasonable accuracy. This work contributes to a better understanding of cassava growth and yield potentials in the tropics.