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Key message: The ClLOG gene encoding a cytokinin riboside 5ʹ-monophosphate phosphoribohydrolase determines trichome length in watermelon, which is associated with its promoter variations. Trichomes, which are differentiated from epidermal cells, are special accessory structures that cover the above-ground organs of plants and possibly contribute to biotic and abiotic stress resistance. Here, a bulked segregant analysis (BSA) of an F2 population with significant variations in trichome length was undertaken. A 1.84-Mb candidate region on chromosome 10 was associated with trichome length. Resequencing and fine-mapping analyses indicated that a 12-kb structural variation in the promoter of Cla97C10G203450 (ClLOG) led to a significant expression difference in this gene in watermelon lines with different trichome lengths. In addition, a virus-induced gene silencing analysis confirmed that ClLOG positively regulated trichome elongation. These findings provide new information and identify a potential target gene for controlling multicellular trichome elongation in watermelon. [ABSTRACT FROM AUTHOR]

[Display omitted] • The SAS around the Danjiangkou Reservoir shows a clear spatial distribution. • Landscape and environmental factors and soil properties synergistically influence SAS. • Orchards displayed higher SAS compared to paddy fields and uplands. • SAS can be enhanced by reducing LPI and increasing landscape heterogeneity. Soil aggregate stability (SAS) plays a crucial role in determining the soil's resistance to erosion. Conducting a spatial variability analysis of SAS in the reservoir area, which is highly susceptible to soil degradation and erosion, can yield valuable insights for agricultural practices, landscape planning, and environmental management in this region. Nevertheless, existing research remains constrained in its capacity to accurately map and forecast soil aggregates at a spatial level. This study aims to investigate the spatial distribution of SAS in the Danjiangkou reservoir area, as well as to explore the intrinsic linkage mechanisms between changes in soil properties, environmental factors and landscape patterns and SAS. Results revealed significant spatial variations in SAS within the vicinity of the Danjiangkou reservoir area. Notably, soil properties (including clay, available potassium, soil organic matter, and available phosphorus), environmental factors (such as digital elevation model, slope, land surface temperature difference between seasons (ΔLST)), and landscape pattern (largest patch index (LPI), shannon's diversity index (SHDI), edge density (ED)) significantly affected the spatial variability of SAS, explaining 18.91%, 8.22%, and 8.17% of the total variability of soil SAS, respectively. Structural equation modeling results indicated that altering soil properties serves as the primary approach to enhance SAS. Furthermore, interventions targeting landscape factors such as LPI, SHDI, and ED, alongside environmental factors like ΔLST and slope, exert direct influences on SAS, while also indirectly impacting it through their effects on soil properties. These findings contribute to the design of land planning and soil and water conservation measures in the reservoir watershed, promoting its protection of soil structure and its ecological service function. [ABSTRACT FROM AUTHOR]

Soil, water, and nutrients depletion may affect sustainable agriculture in some resource-poor areas. Implementing cover crops as a conservation management strategy mitigates the loss of water, soil, nitrogen (N), and phosphorus (P) by introducing vegetation during non-crop seasons or in the spaces between rows instead of leaving the land bare. This study aimed to compare water, soil, various carbon (C) forms, N, and P losses through leaching and surface runoff in orchard fields that were managed with either no-cover crop (NC) or cover crops, including natural grass (NG), Legume grass (LG), Gramineae grass (GG), and a mixture of Legume and Gramineae grass (MG). The findings indicate that cover crop fields exhibited a significant reduction in the runoff by 33–60 %, leaching amount by 33–51 %, soil loss by 30–53 %, and total C, N, and P by 30–48 %, 30–49 %, and 30–38 %, respectively compared to NC fields. Additionally, implementing artificial grass, particularly MG, demonstrated more significant efficacy in mitigating water and soil losses and associated N and P losses. Specifically, MG fields exhibited a 40 % and 18 % reduction in runoff and leaching as well as a reduction in total C, N, and P loss by 7 %, 12 %, and 7 %, respectively, compared to NG fields. The LG field experienced a 50 % more significant N loss than the MG field, whereas the GG runoff exhibited an increase of more than 70 %. Implementing MG coverage has significantly reduced soil erosion and consequent nutrient loss, establishing it as a viable and uncomplicated approach to conserving soil and water in orchards. • Artificial grass has greater effect on mitigating soil loss than natural grass. • Sowing mode affects the ability of cover crops to reduce soil loss and runoff. • The mixed coverage of crops improves the effectiveness of soil and water loss. • Gramineae-Legumes mixed efficiently reduce soil and water losses. [ABSTRACT FROM AUTHOR]

As a new type of pollutant, microplastics (MPs) are an increasingly prominent threat to terrestrial ecosystems. However, the distribution, sources and influencing factors of MPs need to be further studied, especially in reservoir surrounding soil, a hot zone for MPs accumulation and a source of MPs in the watershed. Here, we detected MPs in 120 soil samples collected around Danjiangkou reservoir, with their amount ranging from 645 to 15,161 items/kg. The topsoil layer at 0–20 cm had lower levels of MPs (mean 3989 items/kg) than subsoils at 20–40 cm (mean 5620 items/kg). The most commonly detected types of MPs were polypropylene (26.4%) and polyamide (20.2%), with sizes ranging from 0.05 to 0.5 mm. With regard to shape, most MPs (67.7%) were fragmented, while fibers make up 25.3% of the MPs. Further analysis revealed that the number of villages had the highest driving force for the abundance of MPs with 51%, followed by pH 25% and land use types 10%. The water and sediment of reservoirs are important sources of agricultural soil microplastics. Paddy lands showed higher microplastics levels than orchards and dry croplands. The polymer risk index indicated that the agricultural soil near Danjiangkou reservoir had the highest MPs risk. This study highlights the importance of assessing MPs contamination in the agroecosystems surrounding reservoirs and provides valuable insight into clarify the ecological risks of MPs in the reservoir area. [Display omitted] • Agricultural soils were investigated for MPs in Danjiangkou Reservoir, China. • Habitats adjacent to the reservoir were widely contaminated by MPs. • Paddy land had higher MPs concentrations compared to orchards and dry croplands. • Microplastic contamination was positively related with number of village settlements. • Assessing fate of MPs in reservoir areas is vital for agroecosystem and food security. [ABSTRACT FROM AUTHOR]

The application of potassium (K) in conjunction with nitrogen (N) has been shown to enhance N use efficiency. However, there is still a need for further understanding of the optimal ratios and molecular regulatory mechanisms, particularly in soil-cotton systems. Here, a field trial was conducted, involving varying rates of N and K, alongside pot and hydroponic experiments. The objective was to assess the impact of N-K interaction on the absorption, transport and distribution of N in cotton. The results showed that K supply at 90 and 240 kg ha−1 had a beneficial impact on N uptake and distribution to both seed and lint, resulting in the highest N use efficiency ranging from 22% to 62% and yield improvements from 20% to 123%. The increase in stem and root diameters, rather than the quantify of xylem vessels and phloem sieve tubes, facilitated the uptake and transport of N due to the provision of K. At the molecular level, K supply upregulated the expression levels of genes encoding GhNRT2.1 transporter and GhSLAH3 channel in cotton roots to promote N uptake and GhNRT1.5/NPF7.3 genes to transport N to shoot under low-N conditions. However, under high-N conditions, K supply induced anion channel genes (GhSLAH4) of roots to promote N uptake and genes encoding GhNRT1.5/NPF7.3 and GhNRT1.8/NPF7.2 transporters to facilitate NO 3 - unloading from xylem to mesophyll cell in high-N plants. Furthermore, K supply resulted in the upregulation of gene expression for GhGS2 in leaves , while simultaneously downregulating the expression of GhNADH-GOGAT, GhGDH1 and GhGDH3 genes in high-N roots. The enzyme activities of nitrite reductase and glutamine synthetase increased and glutamate dehydrogenase decreased, but the concentration of NO 3 - and soluble protein exhibited a significant increase and free amino acid decreased in the shoots subsequent to K supply. • Combination of N and K improved N utilization and cotton yield. • K enhanced N uptake by promoting xylem and saprophyte area but not quantity. • K induced low-affinity N transporters to promote N uptake at high N levels. • K promoted N uptake by high-affinity N transporters at low N levels. • K upregulated GhNRT2.1 , GhSLAH3 under low N, and GhSLAH4 under high N. [ABSTRACT FROM AUTHOR]

Potassium (K) fertilizer additions can result in high crop yields of good quality and low nitrogen (N) loss; however, the interaction between K and N fertilizer and its effect on N 2 O emissions and associated microbes remain unclear. We investigated this in a pot experiment with six fertilizer treatments involving K and two sources of N, using agricultural soil from the suburbs of Wuhan, central China. The aim was to determine the effects of the interaction between K and different forms of N on the N 2 O flux and the abundance of nitrifying and denitrifying microbial communities, using static chamber-gas chromatography and high-throughput sequencing methods. Compared with no fertilizer control (CK), the addition of nitrate fertilizer (NN) or ammonia fertilizer (AN) or K fertilizer significantly increased N 2 O emissions. However, the combined application (NNK) of K and NN significantly reduced the average N 2 O emissions by 28.3%, while the combined application (ANK) of K and AN increased N 2 O emissions by 22.7%. The abundance of nitrifying genes amoA in ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) changed in response to N and/or K fertilization, but the denitrifying genes nar G, nir K and nor l were strongly correlated with N 2 O emissions. This suggests that N or K fertilizer and their interaction affect N 2 O emissions mainly by altering the abundance of functional genes of denitrifying microbes in the soil-plant system. The genera Paracoccus, Rubrivivax and Geobacter as well as Streptomyces and Hyphomicrobium play an important role in N 2 O emissions during denitrification with the combined application of N and K. • Potassium addition reduces nitrate-stimulations on soil N 2 O emissions. • NNK treatment lowers the abundance of nirK and norB and most denitrifiers than NN treatment. • Soils with lower N 2 O emissions have a lower norB/nosZ ratio. [ABSTRACT FROM AUTHOR]

The phosphorus (P) content in agricultural soils in catchments of lakes or rivers is an important issue because P is both an essential nutrient for high plant yields and a major contributor to eutrophication of water bodies. Thus, we have assessed the spatial distribution of soil P, impacts of environmental factors on its spatial variation, and associated pollution risks, in farmland around the Danjiangkou Reservoir, China. A total of 217 sites were sampled, including 121, 44 and 52 in dry cropland, paddy land and orchards, respectively. Total phosphorus (TP) contents in the sampled soils ranged from 0.230 to 1.893 g kg−1 and Olsen-P (a measure of available P) from 0.38 to 176 mg kg−1. Soil TP and Olsen-P had moderate and high variability, with coefficients of variation of 40% and 115%, respectively. Geostatistical analysis showed that both TP and Olsen-P had positive nugget effects, but TP had stronger spatial autocorrelations than Olsen-P (nugget-to-sill ratios: 22 and 50%, respectively). Total P was significantly influenced by temperature, elevation, aspect, soil pH, organic matter and precipitation, while Olsen-P was controlled by aspect and land use. The TP in soil was very similar in dry cropland and orchards (0.64 ± 0.19 and 0.61 ± 0.23 g kg−1, respectively), but substantially lower in paddy land (0.15 ± 0.25 g kg−1). Risks for P loss appeared to be very high, high, moderate and low in approximately 10, 40, 15 and 30% of the farmland in the Danjiangkou reservoir area, respectively. Unlabelled Image • Soil total phosphorus and Olsen-P had moderate and high variability, respectively. • Positive nugget effects were obtained for both total phosphorus and Olsen-P contents. • Total phosphorus had stronger spatial autocorrelations than Olsen-P. • Classical kriging performed well in modeling the P pollution risk index. [ABSTRACT FROM AUTHOR]