Water management is critical for wheat production under extreme drought conditions, and the mechanisms by which root dynamics and soil water utilization affect wheat yield are uncertain. This study was conducted in 2023–2024 under a mesophilic semi-arid climate with a two-factor partitioned experimental design, aiming to assess the response of different irrigation amounts in winter wheat crops on root growth and development, soil water utilization, and yields in different soil horizons. The results showed that variety and irrigation volume had significant effects on the spatial and temporal distribution of root and yield components, with irrigation volume having the greatest effect on yield. Compared with CK, deficit-regulated irrigation significantly promoted root penetration to deeper layers and delayed root senescence. DRWD, RLD, RSA, and RV decreased gradually with increasing soil depth, and the peaks of RLD, RSA, and RV appeared at the tassel to flowering stage, respectively; and under deficit-regulated irrigation, the contribution of the A2W4 treatment to stable yield was greater. Therefore, A2W4 is an effective water-saving irrigation method to improve grain yield and water-use efficiency under deficit-regulated irrigation.

Grain yield and quality are critical factors in agricultural production. This study aimed to investigate the impact of sowing time on wheat yield and quality and identify the optimal sowing period for wheat in the Xinjiang region of China. The yield and quality changes of different spring and winter wheat varieties were investigated under different sowing periods. The results showed that late sowing of winter wheat and winter sowing of spring wheat adversely affected wheat yield, especially in spring wheat. For winter wheat, late sowing resulted in higher protein content, wet gluten content, rheological properties, and tensile strength, indicating potential quality improvements with delayed sowing. In contrast, the four spring wheat varieties showed an increase in protein and wet gluten contents under winter sowing treatments. However, the effects of winter sowing on grain quality parameters varied among the four varieties. These findings provide valuable insights for optimizing wheat sowing dates locally to achieve both high yield and quality in wheat production.

To clarify the compensatory effect of increasing density on the yield of extremely late-sown wheat and screen the best combination of the sowing date and density of extremely late-sown wheat in the wheat area of northern Xinjiang, this study set three extremely late-sown dates of October 25 (D1), November 4 (D2), and November 14 (D3) and four densities of 337.5 (M1), 450 (M2), 562.5 (M3), and 675 kg·hm⁻² (M4). Additionally, the effects of the sowing date and density combinations on the formation process of the yield element spike number, spike grain number, and 1000-grain weight were analyzed in detail using the local conventional sowing date and density (25 September, 270 kg·hm⁻²) as the control (CK). The results showed that compared to the CK, increasing the planting density of extremely late-sown wheat compensated for the reduction in the number of harvested spikes due to low emergence rates. The young spikes were stunted due to a reduction in the number of grains per spike, and the grain grouting rate caused a reduction in the defects of the 1000-grain weight in order to increase the number of harvested spikes to improve yield. Under extremely late sowing conditions, D2M2 had the highest post-spring emergence rates, the highest number of harvested spikes, better development of young spikes and grain-filling, and non-significant declines in the number of grains per spike and 1000-grain weight, which balanced the contribution of the number of harvested spikes, number of grains per spike, and 1000-grain weight to the yield and gave the highest yield. After comprehensive yield factor analysis, sowing 450 kg·hm⁻² (1.00 × 10⁶ seeds·hm⁻²) on 4 November (pre-winter cumulative temperature of 47.5 °C) was determined to be the best combination for planting extremely late-sown wheat in the northern Xinjiang wheat area, and the results of this study can provide important theoretical and technical references for guaranteeing the yield of winter wheat in extremely late-sown winter wheat areas.

Soil microbes are crucial in shaping the root-associated microbial communities. In this study, we analyzed the effect of the soil–root niche gradient on the diversity, composition, and assembly of the bacterial community and co-occurrence network of two cotton varieties. The results revealed that the bacterial communities in cotton soil–root compartment niches exhibited a skewed species abundance distribution, dominated by abundant taxa showing a strong spatial specificity. The assembly processes of the rhizosphere bacterial communities were mainly driven by stochastic processes, dominated by the enrichment pattern and supplemented by the depletion pattern to recruit bacteria from the bulk soil, resulting in a more stable bacterial community. The assembly processes of the endosphere bacterial communities were determined by processes dominated by the depletion pattern and supplemented by the enrichment pattern to recruit species from the rhizosphere, resulting in a decrease in the stability and complexity of the community co-occurrence network. The compartment niche shaped the diversity of the bacterial communities, and the cotton variety genotype was an important source of diversity in bacterial communities within the compartment niche. We suggest that the moderate taxa contribute to significantly more changes in the diversity of the bacterial community than the rare and abundant taxa during the succession of bacterial communities in the cotton root–soil continuum.

Seeding depth is a critical factor influencing the uniformity and vigor of wheat seedlings. To address inconsistent seeding depth in wide-row uniform seeding agricultural practices, we performed parameter analysis and optimization experiments on the seeding depth device of a wheat wide-row uniform seeding machine. The structure and working principle of the device were described, soil movement during operation was analyzed, and the models of rotary tiller blades and soil retention plates were investigated, identifying three key factors affecting seeding quality. Using the discrete element method, a model of the seeding depth device was established, and experiments were conducted, yielding the following conclusions: 1. Single-factor experiments were conducted under different seeding rate conditions, and it was found that the effects of various factors on the two indicators, namely the seeding depth qualification rate and the coefficient of variation for seeding uniformity, were regular. 2. A quadratic orthogonal rotated combination experiment with three factors determined the optimal structural parameters: tillage device penetration depth of 120 mm, rotational speed of 310 rpm, and soil retention plate inclination angle of 27°. Under these parameters, the seed depth qualification rate exceeded 90%, and the coefficient of variation for seed distribution uniformity was below 25%. 3. Field validation tests under optimal parameters confirmed a seed depth qualification rate ≥90% and variation for seed distribution uniformity was below ≤20.69%. 4. The error between simulation and field tests was ≤5%, validating the reliability of the discrete element method-based optimization for the seeding depth device.