Evaluation of a Crop Growth Model for Sweet Potato Over a Set of Agro-Climatic Conditions in India

A study was conducted to evaluate the wider applicability of sweet potato growth model, 'SPOTCOMS' for simulating the phenology and yield over a set of agroclimatic conditions in India. The model simulated the phenology of the crop as a function of growing degree days. The genetic coefficients required for the model were estimated from the field experiments conducted with sweet potato variety, Sree Bhadra and other local varieties at the study locations. The model simulated the yield of the sweet potato well and the statistical indices calculated between the simulated and observed yields stated the reliability of the model simulations. The agreement index (D-index) for Sree Bhadra ranged from 0.55 to 0.99, and the D-index for local varieties ranged from 0.51 to 1.00. The calculated values of normalized objective function ranged from 0.01 to 0.10 for Sree Bhadra and 0.00 to 0.22 for other local varieties, and indicated better agreement of simulated and observed yields. The normalized root mean square error ranged from 0.80% to 10.40% for Sree Bhadra and 0.00% to 22.44% for other varieties, and these results suggested the wider applicability of the model with excellent to good simulations. The model also simulated dry matter distribution in tubers pertaining to different stresses such as water, nitrogen and potassium. The study revealed that the simulation model 'SPOTCOMS' can be used for simulating the yield as well as to manage the stresses during the crop growth period and to optimize best management practices for the crop cultivation irrespective of the agroclimatic conditions.