Crop Production Supply Research Articles

Investigation of the long-term supply–demand relationships of ecosystem services at multiple scales under SSP–RCP scenarios to promote ecological sustainability in China's largest city cluster

Ensuring ecological sustainability in urbanizing mega-regions like the Yangtze River Middle Reaches (YRMR) city cluster is crucial. Distinct dynamics in ecosystem service supply and demand (ESSD) have emerged due to land use changes, climate shifts, and policy drivers. Addressing potential imbalances and mismatches necessitates strategic ESSD regulation. However, it remains unclear how the future ESSD relationship will evolve under the combined impact of climate change and rapid urbanization. To improve demand simulation, this study examined causal links between socio-economic factors, land use, and ES demands from 2000 to 2018 using a system dynamics model. Six ES supplies and demands were simulated under the SSP-RCP scenarios in 2018–2050. Imbalances and mismatches in ESSD were assessed at grid, city, and sub-city cluster scales. The results showed sizable deficits in crop production (CP) and nature access (NA) services at three scales. A synergistic relationship between CP supply and water yield (WY) demand suggested that increased agricultural production could strain water resources. Growing demand for carbon storage (CS) and WY would worsen ESSD imbalance. To maintain long-term ESSD balance, strict carbon policies, land-use restrictions, cross-scale collaboration are needed. A tiered zoning approach based on supply-demand bundles can enhance ecosystem management in a socio-ecological context.

Identification of Loci Through Genome-Wide Association Studies to Improve Tolerance to Sulfur Deficiency in Rice.

Sulfur (S) is an essential nutrient for plant growth and development; however, S supply for crop production is decreasing due to reduced inputs from atmospheric deposition and reduced application of S-containing fertilizers. Sulfur deficiency in soil is therefore becoming a widespread cause of reduced grain yield and quality in rice (Oryza sativa L). We therefore assessed the genotypic variation for tolerance to S deficiency in rice and identified loci associated with improved tolerance. Plants were grown in nutrient solution with either low (0.01 mM) or high (1.0 mM) supply of S. Plants grown under low-S treatment showed a reduction in total biomass, mainly due to a marked reduction in shoot biomass, while root biomass and root-to-shoot ratio increased, relative to plants under high-S treatment. Genome-wide association studies (GWAS) identified loci associated with root length (qSUE2-3, qSUE4, and qSUE9), and root (qSUE1, qSUE2-1, and qSUE3-1 and qSUE3-2) or total dry matter (qSUE2, qSUE3-1, and qSUE11). Candidate genes identified at associated loci coded for enzymes involved in secondary S metabolic pathways (sulfotransferases), wherein the sulfated compounds play several roles in plant responses to abiotic stress; cell wall metabolism including wall loosening and modification (carbohydrate hydrolases: beta-glucosidase and beta-gluconase) important for root growth; and cell detoxification (glutathione S-transferase). This study confirmed the existence of genetic variation conferring tolerance to S deficiency among traditional aus rice varieties. The advantageous haplotypes identified could be exploited through marker assisted breeding to improve tolerance to S-deficiency in modern cultivars in order to achieve sustainable crop production and food security.

The importance of early season phosphorus nutrition

A review of studies conducted in a range of plant species indicated the importance of an adequate supply of P during early crop growth and outlined plant adaptations for accessing early season P. Potential implications of the requirement for early season P in the development of management practices to optimize P supply for crop production were also discussed. Phosphorus plays a critical role in energy reactions in the plant. Deficits can influence essentially all energy requiring processes in plant metabolism. Phosphorus stress early in the growing season can restrict crop growth, which can carry through to reduce final crop yield. Deficiencies during early growth generally have a greater negative influence on crop productivity than P restrictions imposed later in growth. Plants respond to P deficiencies by adaptations that increase the likelihood of producing some viable seed. The adaptations increase the ability of the plant to access and accumulate P and include modification of rhizosphere pH, diversion of resources to root production, increased root proliferation in high-P regions, and formation of associations with vesicular arbuscular mycorrhizae. Plants differ in strategies adopted and in efficiency of P absorption. Effective nutrient management for optimal crop production must ensure that P is supplied to the crop in adequate amounts early in the growing season. It is important that we develop methods to accurately predict the early season P supply from the soil, in order to avoid either over-fertilization or crop deficiencies. Practices to provide adequate P early in plant growth include placement of P fertilizer in or near the seed-row and maintenance of adequate concentrations of plant-available P in the soil through a long-term nutrient management strategy. Other possible management practices could include enhancement of seed concentrations of P, manipulation of tillage system and crop sequence, improved activity of mycorrhizae and other microbiological agents such as Penicillium bilaii to increase phytoavailability of soil P, or genetic selection of crops with an enhanced ability for early season uptake of P from both soil and fertilizer sources. As plants differ in relative abilities to access P from the soil and fertilizer applications, nutrient management must be tailored to the specific crop, in order to optimize P supply and crop productivity. By restricting fertilizer applications to situations where P supply is limiting to crop production and by use of effective P management practices, we can optimize the economic of fertilizer use while avoiding negative impacts on environmental quality. Key words: Crop, fertilizer, placement, nutrient, management