G x E Interaction on Yield Stability of Five Sweet Corn Hybrids Grown under Different Agricultural Systems

Yield stability in sweet corn and its dependence on G x E interaction were investigated in a series of two way experiments. Five Romanian sweet corn hybrids were tested in three years (2008-2010) in three locations of Central Transylvania in different soils 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 (kg/ha, active matter): N0, typical for organic technologies; N50, corresponding to the low-input (sustainable) system; N100 and N150 customary with conventional system of agriculture. Based on ear yield data registered for hybrids in locations x years x cropping system, a phenotypic index (Pi) was computed for each sweet corn hybrid illustrating the stability of their cob yields, with and without husks. The share of genotypic and G x E effects in the total value of Pi have been estimated. In different agricultural systems the tested hybrids were classified differently based on their Pi values. It is concluded that, at least for the time being, the initiation of an organic breeding program for sweet corn, in Romania, is not economically justified since all semiearly and semilate tested hybrids yielded satisfactorily under organic agricultural practices. Moreover, among the recently released sweet corn hybrids one can find certain genotypes highly suitable to organic (i.e. ‘Deliciul verii’, ‘Estival’) or low input (‘Dulcin’, ‘Estival’) agricultural practices. These three hybrids recorded the highes ear yields (with and without husks) over years, locations and agricultural systems.