The behavior of four varieties of peanuts as affected by calcium and potassium variables

Although certain effects of calcium and potassium on kernel development and yield of large-seeded type peanuts have been determined, the effects of these elements on peanuts of smaller seed size have not been thoroughly investigated. To compare the behavior of four varieties which differed widely in type and seed size to the addition of calcium and potassium, field investigations were undertaken on soils low in these elements. The soils selected represented those commonly encountered in the southern Coastal Plain area of North Carolina. They were somewhat lower in fertility and calcium levels than those characteristic of the older peanut area of this state. The four varieties selected were Virginia Bunch, North Carolina Runner, Spanish 2B, and White Spanish. Four fertilization variables were superimposed on each variety, viz., no treatment, gypsum, gypsum plus potash, and limestone plus potash. The effects of these treatments upon each variety were determined by measuring yield, true shelling percentage, and percentage of the ovarian cavities filled. The most striking feature of the results was the pronounced difference that the four varieties exhibited in their requirements for calcium. Virginia Bunch was found to have by far the highest calcium requirement of any of the varieties used. At one location, for example, yield of this variety was increased nearly six fold by the application of gypsum, that of North Carolina Runner nearly two fold, whereas those of Spanish 2B and White Spanish were not appreciably affected. The effect of calcium on the quality of fruit of each of the varieties at the same location is shown by the following increase in percentage cavities filled which were obtained by the use of gypsum: Virginia Bunch, 35.5; North Carolina Runner, 24.8; Spanish 2B, 19.0; and White Spanish, 4.6. The increases in yield from added potash were small in comparison with those obtained by the use of gypsum. There was little difference in varietal response to potash additions, although North Carolina Runner tended to respond somewhat less than the other varieties. Potassium had no beneficial effect on kernel development and its addition resulted in increased yields through its effect on plant size. This behavior is in marked contrast to that of calcium, in which yields were increased through the beneficial effects of this element on kernel development. The oil content of large and medium kernels was affected comparatively little by fertilization or by variety. In general, however, the kernels from fruit of a high shelling percentage were somewhat higher in oil than those from fruit of lower quality. The yield of oil per acre is essentially a function of pounds of plump kernels produced. When all the results of this study are considered, it is evident that peanut breeding and soil fertility programs are virtually inseparable. Recognition of differences in fertilizer practice and soil characteristics, particularly with respect to calcium, are essential for research in peanut breeding. Furthermore, problems in peanut nutrition cannot be attacked so successfully when differences in varietal behavior are disregarded.