Nutrient management: as a panacea to improve the caryopsis quality and yield potential of durum wheat (Triticum turgidum L.) under the changing climatic conditions

The increasing human population and the changing climate, which have given rise to frequent drought spells, pose a serious threat to global food security, while identification of high-yielding drought-tolerant genotypes coupled with nutrient management remains a proficient approach to cope with these challenges. An increase in seasonal temperature, recurring drought stress, and elevated atmospheric CO2 are alarmingly affecting durum wheat production, productivity, grain quality, and the human systems it supports. An increase in atmospheric carbon dioxide can improve wheat grain yield in a certain amount, but the right amount of nutrients, water, and other required conditions should be met to realize this benefit. Nutrients including nitrogen, silicon, and sulfur supply could alleviate the adverse effects of abiotic stress by enhancing antioxidant defense and improving nitrogen assimilation, although the effects on plant tolerance to drought stress varied with nitrogen ionic forms. The application of sewage sludge to durum wheat also positively impacts its drought stress tolerance by triggering high accumulation of osmoregulators, improving water retention capacity in the soil, and promoting root growth. These beneficial effect of nutrients contribute to durum wheat ability to withstand and recover from abiotic stress conditions, ultimately enhance its productivity and resilience. While these nutrients can provide benefits when applied in appropriate amounts, their excessive use can lead to adverse environmental consequences. Advanced technologies such as precision nutrient management, unmanned aerial vehicle-based spraying, and anaerobic digestion play significant roles in reducing the negative effects associated with nutrients like sewage sludge, zinc, nanoparticles and silicon fertilizers. Hence, nutrient management practices offer significant potential to enhance the caryopsis quality and yield potential of durum wheat. Through implementing tailored nutrient management strategies, farmers, breeders, and agronomists can contribute to sustainable durum wheat production, ensuring food security and maintaining the economic viability of the crop under the changing climatic conditions.

Chlorophyll Meter: A Precision Agricultural Decision-Making Tool for Nutrient Supply in Durum Wheat (Triticum turgidum L.) Cultivation under Drought Conditions

How crop biodiversity adapts to drought conditions and enhances grain yield became the most important issue facing agronomists and plant breeders at the turn of the century. Variations in genetic response, inadequacy of nutrients in the soil, and insufficient access to nutrients are factors that aggravate drought stressors. The development of screening tools for identifying drought tolerance is important in the deployment of durum wheat varieties suited to drought-prone environments. An experiment was conducted to evaluate durum wheat varieties under a range of nutrient supplies in naturally imposed drought conditions. The treatments consisting of two nitrogen regimes (i.e., control and 60 kg ha−1), four durum wheat varieties, and three types of nutrients (control, sulfur, and zinc) that were arranged in a split-split plot design with three replications. Both foliar-based sulfur and zinc fertilization were employed at the flag leaf stage, at a rate of 4 and 3-L ha−1, respectively. The results showed a significant (p < 0.05) genetic variation in chlorophyll concentration, grain protein content, tillering potential, and leaf area index. Varieties that contained better leaf chlorophyll content had improved grain yield by about 8.33% under 60 kg/ha nitrogen. A combined application of nitrogen and zinc at flag leaf stage significantly improved grain yield of Duragold by about 21.3%. Leaf chlorophyll content was found to be a more important trait than spikes per m2 to discriminate durum wheat varieties. Foliar application of sulfur increased the grain yield of drought-stressed plants by about 12.23%. Grain yield and protein content were strongly correlated with late-season SPAD readings. Significant (p < 0.05) correlation coefficients were obtained between normalized difference vegetation index, leaf area index, grain yield, and protein content with late-season chlorophyll content, revealing the importance of chlorophyll content in studying and identifying drought-tolerant varieties.

Changes in Plant and Grain Quality of Winter Oat (Avena sativa L.) Varieties in Response to Silicon and Sulphur Foliar Fertilisation under Abiotic Stress Conditions

In order to investigate the abiotic stress (drought) tolerance of oat (Avena sativa L.) with silicon and sulphur foliar fertilisation treatments, and monitor the effect of the treatments on the physiology, production, stress tolerance, plant, and grain quality of winter oat varieties, a field experiment was conducted in the growing season of 2020-2021. As a continuation of our article, published in another Special Issue of Plants, in this publication we evaluate the effect of silicon and sulphur treatments on the quality of winter oats. The whole grain sulphur content was significantly different between varieties. The foliar fertiliser treatments caused greater differences in both the carbon and nitrogen, and sulphur contents in the green plant samples, compared to the differences measured in the grain. Foliar treatments had a significant effect on the sulphur content of both plant samples and grains. Significant differences in the Al, Ba, Ca, Cu, Fe, K, Mn, Mo, Na, Ni, P, Pb, Sr, and Zn contents of oat grains were measured, both between treatments and between varieties. Winter oat varieties did not respond equally to the foliar fertiliser treatments in terms of either macronutrient or micronutrient content. When P, K, Ca, Mg, and S were summarised, the highest values were in the control plots. Significant differences in protein content were identified between winter oat varieties in response to the treatments, but the varieties did not respond in the same way to different foliar fertiliser treatments. Based on our results, we recommend the use of foliar fertilisation in oats in drought-prone areas.