Evaluation of the groundnut model PNUTGRO for crop response to plant population and row spacing

Field experiments were conducted during the 1987, 1991 and 1992 rainy seasons at Patancheru, Andhra Pradesh, to collect data to test and validate the hedgerow version of the groundnut model PNUTGRO for predicting phenological development, light interception, canopy growth, DM production, pod and seed yields of groundnuts as influenced by row spacing and plant population. The model was calibrated using the crop growth and phenology data of groundnut cv. Robut 33-1 obtained from the 1987 and 1991 rainy season experiments. Groundnuts were grown at plant populations ranging from 5 to 45 plants/sq m with and without irrigation. Changes were made in the cultivar-specific coefficients related to the light penetration into the crop canopy and DM production. The model was validated against independent data obtained from a 1992 rainy season experiment. In 1992, groundnuts were grown at plant populations ranging from 10 to 40 plants/sq m and at row spacings of 20, 30 and 60 cm. The model predicted the occurrence of vegetative and reproductive stages, canopy development, total DM production and its partitioning to pods and seed accurately. Maximum LAI observed during the season was significantly correlated with simulated values (sq r = 0.95). In spite of some incidence of diseases and pests, the correlation between simulated and observed pod yield was significant (sq r = 0.61). It is concluded that the hedgerow version of the groundnut model PNUTGRO can be used to quantify groundnut growth and yields as influenced by plant population and row spacin