Yield and yield components of facultative wheat are affected by sowing time, nitrogen fertilization and environment

Production of wheat (Triticum aestivum L.) is affected by changing weather conditions, which are difficult to predict especially under climate change. Therefore, facultative varieties can be beneficial, because of their high adaptability in sowing time. Information on yield and yield components of facultative wheat in temperate climate, however, is limited. Therefore, a two-factorial experiment with the factors sowing time (autumn versus spring) and nitrogen fertilization (0, 5, 10, 15 and 20 g m(-2)) was conducted on a chernozem soil under Pannonian conditions in Eastern Austria in two seasons to assess the effects of sowing time, nitrogen fertilization and environment on yield and yield components of one facultative wheat variety. The experimental data were analyzed using principal component analysis and quantitative mixed model analysis. Grain yield of autumn-sown wheat was higher at 0 g N m(-2) and featured a higher increase with additional nitrogen fertilization compared to spring-sowing. At high nitrogen fertilization rates above 15 g m(-2), grain yield showed no response to further nitrogen fertilization. Based on ear density, grains per ear, thousand kernel weight and harvest index, the other yield and yield component parameters investigated in this study can be calculated. Ear density showed an increase with additional nitrogen fertilization, which was higher for autumn-sowing than spring-sowing. Differences in environmental conditions resulted in higher variation of grains per ear and thousand kernel weight for spring-sowing compared to autumn-sowing. Ear density, grains per ear, thousand kernel weight and harvest index featured dependencies among each other and were affected by environmental conditions during relevant developmental stages, e.g., tillering until anthesis for ear density and grains per ear as well as grain filling period after anthesis for thousand kernel weight and harvest index.