Agronomy

Efficient nutrient management is vital to sustaining rice production in the sandy soils of Northeast Thailand, where zinc (Zn) deficiency and low organic matter often constrain yield. This study evaluated the effects of Zn fertilization on the growth, yield, and Zn use efficiency (ZUE) of rice (Oryza sativa L. cv. Chai Nat 1) grown under greenhouse conditions in contrasting soil textures (loamy sand and clay). Four Zn rates were applied: 0, 5, 10, and 15 kg ZnSO₄·7H₂O ha⁻¹ (0, 0.013, 0.026, and 0.039 g ZnSO₄·7H₂O pot⁻¹). Clay soil, with higher organic matter, nitrogen, and available Zn, supported greater vegetative growth, biomass, and yield than loamy sand. Zinc fertilization significantly increased plant height, tiller number, chlorophyll content, biomass, panicle number, grain number, and filled grain weight. Yield improvement in loamy sand was associated mainly with reproductive efficiency, whereas in clay it was driven by vegetative vigor, biomass accumulation, and Zn uptake. Thousand-grain weight was not affected by Zn. ZUE peaked at 5 kg ha⁻¹ in loamy sand and 10 kg ha⁻¹ in clay, with clay showing a greater overall increase in ZUE across Zn rates and loamy sand exhibiting diminishing returns at higher application rates, reflecting differences in Zn availability and retention capacity. Correlation, PCA, and SEM analyses confirmed soil-specific yield mechanisms. Overall, Zn fertilization improved rice productivity and tissue Zn concentration, with optimal rates differing by soil texture. These findings highlight the importance of site-specific Zn management in enhancing yield, nutrient efficiency, and biofortification in rice-based systems of Northeast Thailand.

Guar (Cyamopsis tetragonoloba (L.) Taub.) is a legume crop valued for the gum (carbohydrate galactomannan) found in its seeds, which is widely used in the oil and mining industries. In this study, we assessed changes in seed metabolite content caused by drought stress in three guar genotypes (tolerant, neutral, and sensitive to drought) in order to gain an insight into molecular mechanisms of guar tolerance to drought. The most intense response to drought was observed in seeds of the tolerant genotype. In response to drought, the content of sugars and their derivatives in the seeds of all three genotypes changed: monosaccharide content increased and glycoside content decreased. However, the tolerant genotype accumulated a specific set of sugars and their derivatives, including galactinol, and demonstrated higher levels of tocopherols. The neutral genotype was characterized by higher content of glycosides and pentoses, while the sensitive genotype had higher accumulation of some specific sugars and derivatives, major phytosterols, and unsaturated C18 fatty acids. Overall, the accumulation of galactinol, phytol, and alpha-tocopherol in seeds was associated with guar drought tolerance. This finding expands the understanding of the molecular mechanisms of drought tolerance in guar and paves the way for breeding drought-tolerant guar varieties.

As a versatile shrub, sea buckthorn (Hippophae rhamnoides L.) plays a significant role in restoring degraded ecosystems and supporting regional economies. However, its cultivation faces increasing risks from climate change and pest infestations, particularly from Rhagoletis batava and Cossus cossus. This study aimed to evaluate potential suitable planting areas for H. rhamnoides under current and future climate conditions while accounting for pest risks. The MaxEnt model was employed to predict species distributions and their overlap with pest habitats across multiple climate scenarios (SSP126, SSP245, and SSP585) for the periods 2041–2060 and 2081–2100. The results indicate that currently, 61.95% of the suitable areas for H. rhamnoides face threats from pests. Under future scenarios, the total suitable area showed an increasing trend under SSP126 and SSP245, but a significant decrease under SSP585 by the 2090s. Notably, the area severely threatened by both pests was projected to reduce dramatically, by up to 85.40% under the high-emission scenario (SSP585–2090s), suggesting a potential ecological window for cultivation expansion in certain regions. The study introduces a dual-constraint model incorporating both climate and pest variables, providing a more accurate assessment of optimal planting areas. These findings offer critical insights for the sustainable management of H. rhamnoides cultivation by highlighting regions where pest control strategies should be prioritized and informing future policy and management decisions.

Agricultural water resources face growing pressure from rising food demand and environmental changes. In large agricultural irrigation areas, water and land use is closely linked to energy consumption, carbon emissions, and food production. Therefore, regulating the water–land–energy–food–carbon nexus under multiple external changes is essential for achieving sustainable agriculture. This study aims to optimize water and land allocation in large agricultural irrigation areas to enhance yields and reduce carbon emissions under different external environments and production conditions. A spatial–temporal synergistic optimization and regulation model for water and land resources in large agricultural irrigation zones is developed. Based on 191 representative irrigation districts in Heilongjiang Province, multiple scenarios are constructed, including water-saving irrigation, climate change and low-carbon irrigation energy transitions. Optimal solutions are identified using the Non-dominated Sorting Genetic Algorithm Ⅲ. The results indicate that, after optimization in the current scenario, crop production increased by 2.13%, carbon emissions decreased by 1.23%, and irrigation energy productivity rose by 9.33%. Concurrently, water-saving irrigation should be prioritized in western regions. This study provides an efficient water management pathway for major food production regions.