Plant Growth Response of Two Runner Peanut Cultivars to Reduced Seeding Hate !

The ability of peanut plants to adjust to wide plant-toplant spacing and the use of more precise mechanical planters have not been thoroughly exploited to reduce seeding rates. The magnitude of plant growth adjustment of two runner peanut cultivars to reduced seeding rate was studied in 1992 and 1993. A precision vacuum planter was used to plant the cultivars GK-7 and Southern Runner (SR) in single rows per bed at 8,12, and 22 seed/m". Total plant dry matterweight (TD M), leafarea (LA), and main stem height, nodes, and branches were measured six times during each season. Vegetative growth adjustment to reduced seeding rate was detected as early as 52 d after planting (DAP) in 1992 and 42 DAP in 1993. Plants fully adjusted to reduced seeding rate when they began forming pods at 70 DAP in 1992 and 75 DAP in 1993. By this stage, individual plants in the 8 seed/m" treatment accumulated 2 to 2.7 times as much total dry matter (TDM) as plants in the 22 seed/m", and all seeding treatments within each cultivar accumulated equivalent amounts ofTDM on a unit ground area basis. The 8 seed/mtreatment produced Significantlygreater TDM/m and leaf area index (LA!) than the 22 seed/m" treatment by the end of both seasons (132 DAP in 1992 and 152 DAP in 1993). The partitioning of dry weight to pods and leaves was also greatest for the 8 seed/m" seeding treatment. Bythe end of the season, the 8 seedl m seeding treatment produced as much as 30% more pod dry weight (PDW) per m" than the 22 seed/m" treatment. Plants in the 8 seed/m" seeding were signifi'Contrtbution of the Texas Agric. Exp. Sta. and Texas Agric. Ext. SeN. 2USDA-ARS, 810 Highway 12 East, Mississippi State, MS 39762. 3Texas A&M Univ., Agric. Res. and Ext. Ctr., 1619 Gamer Field Rd.,