Potassium Influences Kernel Filling of Large-Seeded Groundnut in Calcareous Soil

Abstract

Saurashtra and Kutch regions of Gujarat comprise the main area for production of exportquality groundnut in India. However, under the prevalent practices of fertilizer application, the largeseeded groundnuts show poor filling resulting in low kernel mass. Experiments were conducted in pots (sand culture) and also in field (calcareous soil) to examine the influence of K and Ca nutrition on pod-filling of large-seeded groundnut. Sand culture, pot experiment revealed that large-seeded groundnut genotypes differed from others and showed shriveled kernels at low levels of both Ca and K. Individual application of increasing levels of Ca or K was not as beneficial as increasing levels of both of these indicating that both K and Ca are to be applied in such proportions which will facilitate optimum uptake of both of these nutrients and in sand culture, the best combination was 100 ppm K + 200 ppm Ca for largeseeded groundnut and 100 ppm K + 50 ppm Ca for other cultivars. In field, application of K (100 kg/ha K2O as muriate of potash) alone increased the pod yield by 20.2% and Ca (100 kg/ha Ca as gypsum) alone by 15 %, whereas combined application of these two increased by 29.5%. Further, the increase in pod yield was also accompanied by improvement in shelling out turn, 100-seed mass as well as proportion of sound mature kernels (SMK). The SMK increased from 78 to 89% in large-seeded genotype (TKG 19A) due to combined application of these nutrients. Thus, it is concluded that K and Ca are important nutrients for proper pod-filling in largeseeded groundnuts. However, in calcareous soils, Ca being present in abundance, K becomes the limiting nutrient and must be applied to produce export quality groundnut