Effects of Cultivar, Nitrogen Fertilization and Years on Number of Spikes Variation in Winter Wheat

Abstract

Number of spikes per unit area in yield trials with winter wheat cultivars and two levels of Nitrogen fertilization, was monitored during 2016 to 2018 at the National Agricultural Research and Development Institute at Fundulea. The aim was to estimate the contribution of this yield component to wheat grain yield, and the effects of cultivars, Nitrogen fertilization and years to the variation of spike number in the continental climate of South Romania. The percentages of yield variation that could be explained by the variation of spike number were on average about 28% with N fertilization and almost 0 without N fertilization The main sources of variation in the number of spikes per m-2 were the different conditions of the years, followed by the Nitrogen fertilization and by the differences between cultivars, while none of the interactions were significant. Several cultivars, like Unitar, Ursita and Şimnic 60, were noticed with superior number of spikes in most conditions. Bezostaya 1, the only non Rht-B1b cultivar in the study, showed a much lower yield than could have been expected from its relatively high number of spikes. The numbers of spikes at the two levels of Nitrogen fertilization were highly correlated (r=0.68**), but Şimnic 60 deviated significantly from the general regression, suggesting that it might have the ability to form more spikes at lower Nitrogen availability.