No abstract

How agricultural ecosystems adapt to climate change is one of the most important issues facing agronomists at the turn of the century. Understanding agricultural ecosystem responses requires assessing the relative shift in climatic constraints on crop production at regional scales such as the temperate zone. In this work we propose an approach to modeling the growth, development and yield of Triticum durum Desf. under the climatic conditions of north-eastern Poland. The model implements 13 non-measurable parameters, including climate conditions, agronomic factors, physiological processes, biophysical parameters, yield components and biological yield (latent variables), which are described by 33 measurable predictors as well as grain and straw yield (manifest variables). The agronomic factors latent variable was correlated with nitrogen fertilization and sowing density, and biological yield was correlated with grain yield and straw yield. An analysis of the model parameters revealed that a one unit increase in agronomic factors increased biological yield by 0.575. In turn, biological yield was most effectively determined by climate conditions (score of 60–62) and biophysical parameters (score of 60–67) in the 2nd node detectable stage and at the end of heading. The modeled configuration of latent and manifest variables was responsible for less than 70% of potential biological yield, which indicates that the growth and development of durum wheat in north-eastern Europe can be further optimized to achieve high and stable yields. The proposed model accounts for local climate conditions and physiological processes in plants, and it can be implemented to optimize agronomic practices in the cultivation of durum wheat and, consequently, to expand the area under T. durum to regions with a temperate climate.

Agronomic treatments and environmental conditions of cultivation affect the nutritional value and technological quality of durum-wheat-based products. The aim of this study was to determine the effect of 18 agronomic treatments that differed in nitrogen rate, sowing density, and growth regulator application on variability in the quality and milling parameters of durum wheat grain, and the interrelationships between these parameters. The study demonstrated that the investigated parameters were modified by the agronomic treatments. However, environmental variance resulting from differences in soil characteristics and climatic conditions dominated in most cases (44–93%). The percentage of variance induced by differences between treatments in total variance was distinctly higher only in the case of the gluten index (59%). The treatments without nitrogen fertilization and with or without the application of the growth regulator, and the treatments with the application of the growth regulator and the nitrogen rate of 120 kg N ha−1, discriminated between the milling parameters associated with sifting (bran, type 1 semolina) and grading of milling products (flour, type 2 semolina, and type 3 semolina), respectively.