Determination and evaluation of genetic coefficients of peanut lines for breeding applications

Application of a crop simulation model as a plant breeding tool requires cultivar-specific coefficients for a large number of breeding lines which are commonly not available. These cultivar coefficients are normally estimated from field experiments conducted under optimum conditions over several environments, that include a combination of multiple planting dates or locations. However, it is difficult to adhere to this recommendation when many genotypes are involved, such as in plant breeding applications. The objective of this study was to derive genetic coefficients of two groups of advanced peanut breeding lines based on experimental data collected during two growing seasons. The two groups investigated included 12 lines of the large-seeded Virginia type and 14 lines of the small-seeded Spanish type which were under multi-location evaluation at the regional yield trial stage in Thailand in 1998-1999. These lines were grown during the early-rainy season of 1999 and the dry season of 2000 at Khon Kaen University (KKU) in Northeast Thailand. Data were collected on plant development and growth characteristics, soil characteristics, weather and management as required for determining genetic coefficients of a new peanut cultivar. The data were then used for model calibration, using a stepwise procedure to derive the 15 genetic coefficients of the individual lines and cultivars required for the CROPGRO-Peanut model. The results showed that the derived genetic coefficients provided simulated values of various development and growth parameters that were in good agreement with their corresponding observed values for almost all parameters. Model evaluation with an independent data set of four peanut lines grown during the rainy and dry seasons of 2001 and 2002 gave similar results. The differences among breeding lines were also expressed through differences in the derived genetic coefficients. These results suggest that the genetic coefficients of peanut lines obtained from detailed experimental data for two distinct seasons are sufficiently accurate for further evaluation of the CROPGRO-Peanut model in breeding applications.