Modeling the effects of agronomic factors and physiological and climatic parameters on the grain yield of hulled and hulless oat

Oat is a functional resource in food processing, medical, and cosmetic industries. The aim of this study was to compare the influence of agronomic factors and physiological and climatic parameters on the grain yield of hulled and hulless oat. The following variables were evaluated in a three-year experiment: (i) agronomic factors – nitrogen fertilization, plant protection, and oat morphotypes, (ii) environmental conditions – days after sowing, growing degree days, and accumulated precipitation until the achievement of vegetative, transition, and reproductive phases of plant growth and development, and (iii) physiological indicators of plant growth and development – net photosynthetic rate, transpiration rate, plant nitrogen status, leaf area index, and plant water potential. The physiological indicators of plant growth and development were similar in both oat morphotypes. Variability in morphological traits, yield components, and grain yield was affected mainly by the net photosynthetic rate in hulless oat and by the leaf area index in hulled oat. In both oat morphotypes, nitrogen fertilization was an agronomic factor that induced significant differences in yield, whereas the effects of plant protection were similar. A significant increase in yield was observed in response to the N rate of 60 kg ha⁻¹, by 41 % in hulless oat and by 35 % in hulled oat. A further increase in the nitrogen rate to 120 kg ha⁻¹ increased the grain yield by 11 % in hulless oat and by 13 % in hulled oat. In hulled and hulless oat, nitrogen use efficiency was determined at 20 and 15 kg of grain per 1 kg of N, respectively, and it contributed to a considerable difference in grain yield, which reached 5.8 Mg ha⁻¹ in hulled oat and 4.2 Mg ha⁻¹ in hulless oat. The modeled results indicate that plant height and yield components are the most important yield-related traits in oat cultivation, with significant potential for further improvement in performance.