The Effects of Irrigation Level and Genotype on Pod-Filling Related Traits in Peanut (Arachis hypogaea)

In peanut (Arachis hypogaea), pod-filling is an important biological stage that is strongly influenced by the availability of water. It also has genetic component; since genotypes vary considerably in their pod-filling potential. We studied the effects of irrigation level, genotype and the Irrigation Level × Genotype interaction on pod-filling and other pod-related traits of peanut. Four peanut genotypes, including three Virginia-types and one Peruvian-type which differ considerably in their pod-filling potential, were examined under field conditions. Four irrigation treatments were applied (60%, 80%, 100% and 120%) in a factorial experimental design. A significant irrigation-treatment effect was observed for the two main pod-filling related traits, meat content and dead-end ratio, in all of the genotypes studied. The irrigation level significantly affected gross pod weight, 100-pod weight and 100-seed weight, but did not have any significant effects on pod yield per plot or pod size distribution. Therefore, our study suggests that reduction in irrigation directly influence the developing pods, as a result of low water availability/potential in the pod’s surrounding environment. The effect of irrigation was most significant at the lowest irrigation level (60%); whereas a milder effect was observed in the 80% irrigation treatment, indicating that, in some cases, it is possible to reduce irrigation down to 80% without affecting the pod-filling components. Although the Irrigation × Genotype interaction was not statistically significant, some genotypes were found to be more strongly affected by the low-irrigation treatments. Also, irrigation level significantly affected the incidence of pod wart and the pod color variables, suggesting that higher irrigation should be applied in order to address these marketing-related traits. This trial serves as a fundamental study for understanding the pod-filling components that are influenced by the irrigation level in peanut.