Physiological determinants for pod yield of Peanut lines
The number of pods per unit area is an important component of pod yield of peanut. The goals of this study were to determine the relationships of (i) pod yield with number of pods per unit area and weight per pod and (ii) number of pods per unit area with crop growth rate (CGR) and duration during the different developmental stages. Fifteen peanut lines were tested at Khon Kaen University in Northeast Thailand during the 2002 and 2003 rainy and the 2003 and 2004 dry seasons. Data were recorded on developmental stages, biomass, pod yield, and yield components. The CGRs were calculated for different developmental periods. Results showed a positive linear relationship between pod yield and number of pods per unit area across genotypes and seasons (R2 = 0.69; P > F < 0.0001), but no relationship was observed between pod yield and weight per pod (R2 = 0.001; P > F = 0.85). A significant relationship between number of pods per unit area and CGR among the test genotypes was found only during the period from R6 to R7 (R2 = 0.44; P > F = 0.007), and the same relationship across seasons was significant (R2 = 0.45; P > F < 0.001) only during the period from planting to R4. These results indicate that number of pods per unit area is the major determinant for pod-yield differences among peanut lines, and that the differences among lines for this trait are influenced by CGR during the period from R6 to R7.