Peanut Yield as a Result of Fifty Years of Breeding

Breeding for increased yield is known to indirectly alter other plant characteristics in many crop species, including peanut (Arachis hypogaea L.). This 2-yr, field study examined growth and dry matter allocation to various plant organs of 10 Virginia-type peanut genotypes bred for increased yield in North Carolina, Genotypes representing the period from 1944 to the present were grown in 1988 and 1989. Growth was measured on five dates in each year. Genotypes expressed as the minimum number of breeding cycles from an indigenous germplasm exhibited a yield increase of 30 g m₂ per breeding cycle. Genotypes developed from a greater number of breeding cycles tended to have smaller vegetative mass and shorter main stem lengths. However, concurrent increases in reproductive allocation, measured as pod mass and reproductive-to-vegetative ratios (RVR), were evident. Correlation analysis at 133 d after planting (DAP) between the number of breeding cycles and measurements of main stem length, total dry weight (DW), vegetative DW, stem DW, leaf area index (LAI) and RVR resulted in significant correlation coefficients of -0.67,0.38, -0.67, -0.71, -0.42, and 0.74 respectively. At 71 DAP, reproductive growth, measured as peg number, pod number, pod mass, and RVR was correlated with the number of breeding cycles, with significant correlation coefficients of 0.53, 0.52, 0.46, and 0.46, respectively. Reproductive to vegetative ratio continued to be positively related to both breeding cycle number and year of cultivar release throughout reproductive growth. The data indicate greater reproductive dry matter allocation by more recently released genotypes. Further, the allocation in reproductive growth appears related to an earlier transition from vegetative to reproductive development The research reported herein was funded by the North Carolina Agric. Res. Ser.