Recent Progress in Plant Nutrition Research and Plant Physiology

Climate change has intensified the increase in irrigated crops to solve frequent droughts, but part of the stress continues due to heat waves, and for these systems, there is a lack of in-depth discussion about their damage and strategies to minimize this damage. The damage caused by high temperatures may be exacerbated in crops with a nutritional disorder of nitrogen, but optimized management of this nutrient can help mitigate the effects of this stress. This merits further debate, as it would be a sustainable strategy without risk to the environment and at the same time could induce greater plant tolerance to heat stress. This review will address the relevance of rising temperatures and their isolated effects on crop nutrition and productivity and the role of optimized nitrogen use in mitigating this stress and propose future perspectives for this research that could help researchers improve thermotolerance. Nitrogen plays an essential role in plant metabolism, inducing the production of proteins from photosynthesis, boosting primary and secondary plant metabolism and, consequently, the production and defense systems of the plant. Studies indicate that adequate nitrogen supplementation can increase plant resilience to high temperatures, improving water use efficiency and promoting the synthesis of heat shock proteins. In addition, new strategies in nitrogen fertilizer management, such as the use of nitrification inhibitors and biofertilizers, have demonstrated greater efficiency in the use of nitrogen, reducing environmental losses, and, consequently, they could have an impact on stress mitigation. Although nitrogen can mitigate the negative effects of heat waves on plants, there are still gaps in the knowledge about the underlying biochemical and physiological mechanisms involved and whether the doses of N used in research are really optimal for maximizing the plant’s defense system against stress. The future outlook is that optimal N management will become important not only to guarantee high yields but also to minimize heat wave losses by strengthening the plant’s defense mechanisms to deal with this stress. In the context of climate change, a better understanding of the benefits of N will help to better manage heat stress towards more sustainable agriculture. Full article

Grain chalkiness adversely affects rice quality, and the positional variation of grain chalkiness within a rice panicle presents a substantial obstacle to quality improvement in China. However, the molecular mechanism underlying this variation is unclear. This study conducted a genetic and physiological analysis of grains situated at distinct positions (upper, middle, and bottom primary branches of the rice panicle, denoted as Y1, Y2, and Y3) within a rice panicle using the Yangdao 6 variety. The results indicated that the percentage of chalky grains (PCG) in Y1 was the highest, i.e., 17.12% and 52.18% higher than that of Y2 and Y3, respectively. Y2 exhibited the highest degree of grain chalkiness (DGC), attributable to its greater area of endosperm chalkiness (AEC) than the others. Y3 demonstrated the lowest PCG and DGC. Additionally, Y1 and Y2 were characterized by lower amylose and protein contents, as well as looser starch granule morphology, in comparison to Y3. Compared with Y3, both the average and maximum filling rates of Y1 and Y2 increased markedly; however, the active filling duration was notably reduced by 7.10 d and 5.56 d, respectively. The analysis of genomic expression levels indicated an enrichment of starch and sucrose metabolism in Y1-vs.-Y2, Y2-vs.-Y3, and Y1-vs.-Y3, with 7 genes (5 up-regulated and 2 down-regulated), 53 genes (12 up-regulated and 41 down-regulated), and 12 genes (2 up-regulated and 10 down-regulated) in the Y1-vs.-Y2, Y2-vs.-Y3, and Y1-vs.-Y3. The majority of these genes were down-regulated, linking metabolic activity to grain filling and contributing to the occurrence of grain chalkiness in rice panicles. In conclusion, the metabolic processes associated with sucrose and starch play a crucial role in regulating grain filling and the formation of chalkiness in rice. Full article

Green mold caused by Penicillium digitatum is a major post-harvest disease in citrus fruits. Therefore, the search for sustainable and low-environmental-impact alternatives for the management of these fungi is of utmost importance. Physalis peruviana L. is a native fruit of the Peruvian Andes with rich bioactive components present throughout the plant. Its antifungal activity stands out, attributed to its high content of phenols, coupled with its antioxidant capacity and antimicrobial activity. Plants were cultivated aeroponically under a combination of red, mixed (50% red, 50% blue), and green LED lights. Additionally, in vitro-habituated roots free of plant growth regulators were also cultivated. An ethanol extraction assisted by ultrasound for 30 min followed by maceration for 72 h was performed, and the extract was filtrated and evaporated in an extraction hood. Antioxidant activity was assessed using the DPPH method, total polyphenols were measured using the Folin–Ciocâlteu method, and an antifungal test in vitro by the poisoned food method was conducted against P. digitatum. In vitro assays revealed that extracts from leaves, roots, and fruits exerted a significant inhibitory effect on the growth of P. digitatum, as evidenced by a reduction in colony radius when cultured employing the poisoned food method, with IC₅₀ values of 62.17, 53.15, and 286.34 µg·mL⁻¹, respectively, compared to 2297 µg·mL⁻¹ for the commercial fungicide Captan 50WP. Although leaves had higher total polyphenol content, no direct correlation with antifungal activity was found. Colored LEDs enhanced phenol accumulation, antioxidant capacity, and antifungal properties in plant parts compared to white LEDs and in vitro roots. These findings suggest P. peruviana as a new alternative biological production system to provide natural compounds for post-harvest disease management. Full article

The increasing frequency of low-temperature events in spring, driven by climate change, poses a serious threat to wheat production in Northern China. Understanding how low-temperature stress affects wheat yield and its components under varying moisture conditions, and exploring the role of irrigation before exposure to low temperatures, is crucial for food security and mitigating agricultural losses. In this study, four wheat cultivars—semi-spring (YZ4110, LK198) and semi-winter (ZM366, FDC21)—were tested across two years under different conditions of soil moisture (irrigation before low-temperature exposure (IBLT) and non-irrigation (NI)) and low temperatures (−2 °C, −4 °C, −6 °C, −8 °C, and −10 °C). The IBLT treatment effectively reduced leaf wilt, stem breakage, and spikelet desiccation. Low-temperature stress adversely impacted the yield per plant—including both original and regenerated yields—and yield components across all wheat varieties. Furthermore, a negative correlation was found between regenerated and original yields. Semi-spring varieties showed greater yield reduction than semi-winter varieties, with a more pronounced impact under NI compared to IBLT. This suggests that the compensatory regenerative yield is more significant in semi-spring varieties and under NI conditions. As low-temperature stress intensified, the primary determinant of yield loss shifted from grain number per spike (GNPS) to spike number per plant (SNPP) beyond a specific temperature threshold. Under NI, this threshold was −6 °C, while it was −8 °C under IBLT. Low-temperature stress led to variability in fruiting rate across different spike positions, with semi-spring varieties and NI conditions showing the most substantial reductions. Sensitivity to low temperatures varied across spikelet positions: Apical spikelets were the most sensitive, followed by basal, while central spikelets showed the largest reduction in grain number as stress levels increased, significantly contributing to reduced overall grain yield. Irrigation, variety, and low temperature had variable impacts on physiological indices in wheat. Structural equation modeling (SEM) analysis revealed that irrigation significantly enhanced wheat’s response to cold tolerance indicators—such as superoxide dismutase (SOD), proline (Pro), and peroxidase (POD)—while reducing malondialdehyde (MDA) levels. Irrigation also improved photosynthesis (Pn), chlorophyll fluorescence (Fv/Fm), and leaf water content (LWC), thereby mitigating the adverse effects of low-temperature stress and supporting grain development in the central spike positions. In summary, IBLT effectively mitigates yield losses due to low-temperature freeze injuries, with distinct yield component contributions under varying stress conditions. Furthermore, this study clarifies the spatial distribution of grain responses across different spike positions under low temperatures, providing insights into the physiological mechanisms by which irrigation mitigates grain loss. These findings provide a theoretical and scientific basis for effective agricultural practices to counter spring freeze damage and predict wheat yield under low-temperature stress. Full article

Cover crops can be used to accelerate the solubilization process of low-solubility fertilizers; thus, the aim of this study was to evaluate the potential of grasses in solubilizing potassium from phonolite rock powder. With a 2 × 5 factorial scheme, two doses of phonolite rock powder, equivalent to 0 and 8 t ha⁻¹, were combined with four grass species (Urochloa ruziziensis, U. decumbens, U. humidicola, and Andropogon gayanus), besides a control treatment without any cover crop. The dry matter production of the aerial parts of the plants was evaluated at days 40 and 70 post-emergence, and then the concentration of potassium in the plants and the soil was evaluated (exchangeable, non-exchangeable, structural, and total potassium contents). In the soil, the phonolitic rock powder increased the exchangeable, non-exchangeable, structural, and total K contents, favoring the absorption of K and the production of the dry mass of the three Urochloa, but U. decumbens stood out because it promoted greater availability of K in the system compared to the cultivation of other plant species. This research proposes the inclusion of U. decumbens in production systems that receive phonolitic rock, constituting a sustainable strategy to improve its agronomic efficiency. Full article

Nitrogen is one of the most important elements for improving potato yield. However, excessive application of nitrogenous fertilizer not only produces river and other environmental pollution but also increases agricultural production costs. In recent years, to explain the molecular mechanisms of nitrogen metabolites, some vital genes involved have been reported; however, only limited success has been achieved in potato. Here, we report that the expression of cytosolic glyceraldehyde-3-phosphate dehydrogenase 1 (StGAPC1) is increased under low-nitrogen stress. StGAPC1-overexpressing potato seedlings had more biomass and a significant increase in total nitrogen content and root nitrate influx rate compared to the wild type. The overexpression of StGAPC1 also increased the expression of nitrate transporters and increased ROS system activity to reduce hydrogen peroxide content under low-nitrogen stress. Our results provide a foundation for further research on StGAPC1 function in nitrogen absorption and utilization mechanisms in potato. Full article

The global cultivation of blood oranges is experiencing an increase due to their remarkable nutritional properties. Blood orange by-products, especially the peel, have a high concentration of bioactive compounds with exceptional antioxidant potential, making them an ideal choice for incorporation into various food products. This study aimed to determine the morphological parameters and primary and secondary metabolite content of peel of eight blood orange varieties using ¹H NMR and HPLC-ESI-DAD-MSⁿ. “Tarocco Meli” had the highest weight (367.83 g), caliber (94.13 mm and 88.87 mm), peel thickness (6.73 mm), and peel weight (155.0 g). “Tarocco Rosso”, “Sanguinelli”, and “Tarocco Gallo” had the highest levels of total amino acids (25.57 g kg⁻¹ DW), total organic acids (29.99 g kg⁻¹ DW), and total sugars (68.56 g 100 g⁻¹ DW), respectively. The peel of “Moro” had significantly higher concentrations of total anthocyanins, hydroxycinnamic acids, and flavones (650.67, 263.33, and 449.85 mg kg⁻¹, respectively) compared to the other varieties. In conclusion, “Tarocco Meli” had the most interesting values for morphological parameters, “Tarocco Rosso”, “Sanguinelli”, and “Tarocco Gallo” for primary metabolites, and “Moro” for secondary metabolites. With the increasing interest in utilizing co-products, these findings could be useful in developing functional food products that meet consumer demands for healthier and more sustainable food choices. Full article