The current study evaluated the canopy cover competition for light and heat in a jujube–cotton intercropping system to measure the growth and yield performance of cotton, and the optimal cotton planting configuration. In this study, a two-year field experiment (2020 and 2021) was studied with different spacing configuration modes designed as follows: two rows of cotton (CM1) planted 1.4 m apart, four rows of cotton (CM2) planted 1.0 m apart, and six rows of cotton (CM3) planted 0.5 m apart, spacing intercropped jujube trees, respectively. The control treatment consisted of monocultured cotton (CK). The light-response curve was plotted using an LI-6400 XT photosynthesis instrument. Based on the modified rectangular hyperbola model, the photosynthetic characteristics were fitted, and the dry matter distribution characteristics and yield were compared. The results showed that with the increase in photosynthetically active radiation, the net photosynthetic rate (Pn) of each growth phase decreased first and then increased rapidly in the range of 0–200 μmol·m⁻²·s⁻¹ and then decreased slightly after the inflection point (light saturation point). The light-response curves of stomatal conductance and transpiration rate showed a linear relationship. The trend in the intercellular CO₂ concentration response curve was opposite to that of Pn. The maximum Pn (Pmax) of intercropped cotton was significantly impacted by configuration modes, of which CM2 treatment generated 1.8% and 22.8% higher Pmax than the CM1 and CM3 treatments. The cotton yield in the two years ranked as CK > CM3 > CM2 > CM1, and the average land equivalent ratio of CM2 was significantly higher than that of CM3 (22.4%) and CM1 (95.9%). The six-row configuration resulted in greater competition with the trees, which affected the accumulation of below-ground dry matter, while the four-row configuration formed a reasonable canopy structure, which ensured that more photosynthetic substances were distributed to the generative organs. The reasonable four-rows configuration mode may improve the photosynthetic efficiency of intercropped cotton economic yield.

Soil aggregates play an important role in affecting the structural stability of the soil, and it is important to understand the relationship between soil aggregate stability and crop yield in herbage-fruit tree intercropping systems. In this study, we determined the optimal spacing configurations for improving aggregate stability while increasing crop yields in alfalfa-jujube intercropping systems. The treatments included three intercropping patterns, i.e., the distances between alfalfa and jujube at 0.5 m (IP_0.5m), 1 m (IP_1m), and 1.45 m (IP_1.45m), along with monoculture alfalfa (CK_AL) and jujube (CK_JU). The results showed that IP_0.5m, IP_1m, IP_1.45m, and CK_JU effectively improved soil aggregate structure compared to CK_AL. The IP_1m spacing significantly increased the amounts of macro-aggregates (8.2%), and improved soil mechanical properties and aggregate stability among the other treatments, which was partly attributable to increased mean weight diameter (13.6%) and decreased soil aggregate destruction rate of water-stable aggregates (2.9%). The results of the principal component analysis showed that IP_1m treatments had a positive effect on PC1. The one-meter spacing of jujube-to-alfalfa intercropping optimized the soil structure while improving the yield (8.3%); thus, it can be considered the most suitable intercropping spacing configuration for growing alfalfa in jujube plantations.

Topping is an essential step in cotton cultivation in Xinjiang, China, which can effectively increase the number of bolls per plant and optimize the yield and quality. Paclobutrazol, as a common chemical topping agent for cotton, faces challenges such as unstable topping effect and limited leaf surface absorption during application. In this study, paclobutrazol was used as the ligand and a zinc complex was synthesized by the thermosolvent method to replace paclobutrazol and improve the topping effect on cotton. The structure of the complex was characterized using FTIR, UV-vis, TG, and XRD analyses. The results confirmed that each zinc ion coordinated with four nitrogen atoms from the triazole rings of paclobutrazol and two oxygen atoms from nitrate ions, forming an octahedral geometry. Surface tension measurement and analysis revealed that the complex had a surface tension reduction of 12.75 mN/m compared to paclobutrazol, thereby enhancing the surface activity of the complex in water systems and improving its absorption efficiency on plant leaves. Two-year field trials indicated that the foliar application of the complex at a dosage of 120 g·hm⁻² in inhibiting cotton plant height was more stable to that of paclobutrazol or mepiquat chloride. It also shortened the length of fruiting branches, making the shape of cotton plants compact, thereby indirectly improving the ventilation and light penetration of the cotton field and the convenience of mechanical harvesting. Yield data showed that, compared with artificial topping, the complex at a dosage of 120 g·hm⁻² treatment increased cotton yield by approximately 4.6%. Therefore, the paclobutrazol–zinc complex is a promising alternative to manual topping and have great application potential in future mechanized cotton production.

Background: Xinjiang, with unique favorable conditions for cotton growth, faces challenges like water scarcity and soil salinization. The dry sowing and wet emergence (DSWE) water regulation technology may alleviate regional water shortages, but its impacts on soil water-salt dynamics, soil desalination rate (SDR), cotton root growth, yield, and irrigation water production efficiency (IWPE) in saline-alkali land remain poorly documented. Methods: A two-year field trial was conducted during 2023 and 2024, involving three different seedling irrigation amounts (W1, 22.5 mm, W2, 37.5 mm, and W3, 45.0 mm) and two drip irrigation frequencies (F1: one-time irrigation and F2: two-time irrigation), resulting in a total of six irrigation combinations, and a local spring irrigation amount was conducted as CK. Results: Results demonstrated that under the same emergence water amount, F2 treatment exhibited higher soil moisture content and lower soil salt content compared to F1. Increased irrigation frequency and enhanced emergence water amount (W2F2 and W3F2) had greater root length density (RLD) and root vitality, but a lower root-shoot ratio. The W2F1 and W3F1 treatments significantly increased the activities of peroxidase (POD), superoxide dismutase (SOD), and the content of malondialdehyde (MDA) in cotton roots. In contrast, the activities of POD, SOD, and catalase (CAT), as well as the MDA content in cotton roots under the W2F2 and W3F2 treatments were comparable to those in the CK, indicating no obvious physiological stress. Compared with F1, F2 significantly increased cotton boll number and seedcotton yield by 23.3% and 23.5%, respectively. Notably, however, there were no significant differences in boll number and seedcotton yield among the CK, W2F2, and W3F2 treatments, suggesting that increasing water amount did not further improve yield. Conclusion: In conclusion, DSWE technology maintains optimal soil moisture levels, thereby improving root system development, while simultaneously leaching salts from the rhizosphere and reducing oxidative stress. Under the current experimental conditions, the W2F2 treatment emerges as the most effective strategy for regulating seedling emergence water, effectively integrating water conservation, salinity reduction, and seedling vigor enhancement.

Chemical topping involves using plant growth regulators to facilitate the rapid transition of cotton into reproductive growth, similar to manual topping (MT), thereby enhancing cotton yield. Despite its benefits, high-temperature stress following cotton topping often reduces cotton yield. Therefore, developing an effective formula capable of not only inhibiting cotton top growth but also alleviating high-temperature stress is of critical importance. In this study, chlormequat chloride salicylic acid ionic liquids (CSILs) were synthesized via the acid–base neutralization of salicylic acid (SA) and 2-chloro-N,N,N-trimethyl ethanaminium hydroxide, obtained from the reaction between potassium hydroxide and chlormequat chloride (CCC). The resulting CSILs were characterized using various techniques, including nuclear magnetic resonance (NMR), Fourier transformation infrared spectroscopy (FTIR), and ultraviolet-visible light (UV-vis) spectroscopy. The characterization results confirmed the successful synthesis of CSILs as a novel water-soluble cotton-topping agent. Notably, compared with CCC treatment, CSILs at the same concentration exhibited a more sustainable and stable inhibition effect on cotton tip growth, resulting in an 11% increase in cotton yield. These findings suggest that CSILs have a greater potential for use in cotton chemical topping compared with CCC. Furthermore, compared with MT, the MDA content of cotton leaves treated with CSILs was reduced, and the activities of POD and SOD were increased under high-temperature stress. Moreover, these effects became more pronounced with an increasing CSIL concentration, highlighting the positive impact of CSILs in alleviating high-temperature stress on cotton. Notably, no significant difference in cotton yield was observed between the CSIL treatment at 120 g AI ha⁻¹ and the MT treatment. Thus, this study underscores the significant potential of CSILs in both cotton topping and enhancing resistance to high-temperature stress.

Jujube/cotton intercropping is a typical ecological ecosystem, and water is the dominant factor limiting the system productivity. However, it is not clear if and how irrigation rate affects soil bacterial diversity and lint yield in a jujube/cotton intercropping system. To explore the effects of irrigation rate on soil bacterial diversity and enzymatic activities in a jujube/cotton intercropping system, four water stress treatments were applied in 2017 and 2018 in Xinjiang, Northwest China: (1) W1, 3750 m³/ha; (2) W2, 4500 m³/ha; (3) W3, 5250 m³/ha; (4) W4, 6000 m³/ha. In the intercropping field, cotton yield in W2 and W3 treatment was higher than that in W1 and W4 treatments, and significant increases were also observed in soil available phosphorus and potassium, as well as soil alkaline phosphatase and urease activities. The richness and diversity of soil bacterial communities in W2 and W3 treatments were higher than in other treatments, and the abundance of Pseudomonas bacteria was highest under W2 and W3 treatments. Overall, soil nutrient levels and soil enzymatic activities influenced soil bacterial community structure in intercropping system, indicating that soil environment was effectively improved and the best farmland income was obtained when the irrigation rate was controlled at 4500 to 5250 m³/ha.