Mineral Nitrogen Fertilization of Sweet Corn in Central Transylvania II. In Organic Agricultural System

Abstract

Five Romanian sweet corn hybrids (Prima, Dulcin, Estival, Deliciul verii and T-145) were tested in three years (2008-2010) in three locations of Central Transylvania with obviously different soil and climatic conditions. The experiments were organized in a split-plot design in which, on a general level of organic fertilization (40 t/ha manure), four levels of mineral N fertilization were applied: N0, N50, N100 and N150. Ear yield (with and without husk) was registered each year and location and a superiority index (Pi) was computed according to the procedure suggested by Lin and Binns (1988). The shares of G and G x E effects in the total value of Pi were also computed and thus the tested hybrids were classified on the basis of their yield stability expressed by Pi index, ear yield level in the organic agricultural system and the prevalence of G or G x E effects in the total value of Pi. Quite expectedly, the poorest ear yields were recorded, in all tested hybrids, when no mineral N was applied. Fertilization with N100 and N150 had significant and very significant effects on ear yield in all semiearly and semilate hybrids. Prima cv. reacted very poorly to increasing rates on mineral N, most probably due to its earliness. Deliciul verii and Estival were classified as most stable and high yielding hybrids under organic N fertilization practices while Prima showed the lowest stability of its rather poor ear yield.