Yield, Protein Content and Water-Related Physiologies of Spring Wheat Affected by Fertilizer System and Weather Conditions

Abstract

Technological and climatic factors significantly influence the expression of quality and quantity properties of spring wheat. This study aims to quantify the effects of weather conditions and fertilizer systems on spring wheat yield, quality (protein content), and physiological indicators (leaf vapor pressure deficit, evapotranspiration, surface temperature of the flag leaf) and to identify a suitable spring wheat genotype for the Transylvanian Plain. The experimental factors were: Y represents the year (Y1, 2019; Y2, 2020); F represents the fertilizer variant (F1, a single rate of fertilization: 36 kg ha−1 of nitrogen; F2, two rates of fertilization: 36 kg ha−1 of nitrogen + 72 kg ha−1 of nitrogen; F3, two rates of fertilization: 36 kg ha−1 of nitrogen + 105 kg ha−1 of nitrogen); and S represents the genotype (S1, Pădureni; S2, Granny; S3, Triso; S4, Taisa; S5, Ciprian; and S6, Lennox). This multifactorial experiment with three factors was conducted on Phaeozem soil. Regardless of weather conditions, fertilization with N100–110 at the head swollen sheath (stage 10, Feeks Growth Scale for Wheat) is deemed the most suitable variant because it yields an average grain yield of 5000 kg ha−1 of good quality (13.84% protein) with a considerable flag leaf area (29 cm2) where physiological processes can optimally support the well-being of the spring wheat plants. Beyond this level of fertilization, the average grain yield tends to plateau, but the protein content considerably increases by 13–23%, depending on the genotype. High yields were achieved in the Lennox and Triso genotypes.