Optimal digging time of peanut in the mid-southern United States

Abstract

Peanut (Arachis hypogaea L.) digging time is critical for achieving optimal grade and yield potential. Growing degree days (GDDs) indices have successfully predicted peanut growth, development, and digging timing in the United States. However, this method was developed for mid-maturing cultivars (∼140 days after planting to harvest maturity) that are no longer cultivated. No study has evaluated the accuracy of GDD models to predict peanut seed maturity for new mid-maturing cultivars in the mid-south. This 3-year study assessed the relationship between maturity indices (MIs), GDD, pod yield, and grade of mid-maturing cultivars Georgia-06G and IPG-914 at two Mississippi locations. The objective was to determine optimal digging time (ODT) for peanuts cultivated at latitudes (33–35° N) in the mid-southern production region. Results showed the ratio of black, brown (maturity index 1), and orange (maturity index 2) colored mesocarps had a weak correlation with peanut grade. Our GDD models indicated ODT for peanut production in Mississippi is ∼1835 GDDs, which corresponded to 72% black, brown, and orange pods. This ODT differed between cultivars, with Georgia-06G having roughly 50 GDDs more ODT than IPG-914. Location and year differences also existed, indicating a favorable cultivation environment can extend growth and development time, resulting in a delayed ODT. These findings provide improved estimates of ODT that can improve peanut yield and grade for peanuts grown at mid-southern US latitudes. Further research should explore contributions of individual color classes to grade and pod yield for new cultivars.