Kholik Allanov

Balanced cotton nutrition is fundamental to sustaining crop productivity, enhancing nutrient-use efficiency, and maintaining environmental stability. A field experiment was conducted over two consecutive growing seasons (2024–2025) at the experimental station of Tashkent State Agrarian University, Uzbekistan, to evaluate the effects of foliar nutrition in combination with basal fertilization rates on cotton yield and nutrient-use efficiency parameters. The experiment was established using a split-plot design with three replications. Three basal fertilization rates (N₁₅₀P₁₀₅K₇₅, N₂₀₀P₁₄₀K₁₀₀, and N₂₅₀P₁₇₅K₁₂₅) were considered the main-plot factor, while the sub-plot treatments consisted of foliar urea applications at the true-leaf, bud-formation, and flowering stages of cotton, using three regimes (3:5:7, 5:7:9 and 7:9:11 kg ha⁻¹). The results demonstrated that cotton yield increased with increasing basal fertilization rates up to the moderate fertilization rate; however, a decline in yield was observed under the highest fertilizer application rate (N₂₅₀P₁₇₅K₁₂₅). This response suggests that excessive nutrient inputs may have adversely affected crop growth and productivity, potentially due to nutrient imbalance, increased osmotic stress, or reduced nutrient use efficiency. The highest cotton yield was observed at the moderate (N₂₀₀P₁₄₀K₁₀₀) inorganic fertilization norm in tandem with the 7:9:11 kg ha⁻¹ foliar nutrition regime, averaging 21.5% higher than the same fertilization regime without foliar feedings. Under the moderate fertilization regime, foliar application further increased cotton yield to 3.87 Mg ha⁻¹, 4.15 Mg ha⁻¹, and 4.45 Mg ha⁻¹, depending on foliar treatment intensity, corresponding to 17.6%, 26.1%, and 35.3% increases, respectively. However, increasing the basal fertilization rate to N₂₅₀P₁₇₅K₁₂₅ did not yield further improvement in maximum cotton output. Cotton seed and fiber quality indicators also increased significantly in response to the applied agronomic interventions, demonstrating the beneficial effect of balanced nutrition on quality traits. These findings suggest that foliar nutrition can effectively improve cotton productivity and nutrient-use efficiency, thereby reducing reliance on excessive basal fertilization and supporting more sustainable crop production in fragile dryland ecosystems.

Land degradation is a serious problem in arid regions, including in Central Asian countries. Soybean symbiosis with rhizobia microbes has an essential role in improving crop productivity and sustaining soil fertility in an arid environment. An experiment was conducted in light straw-colored sierozem soils in the Syrdarya region of Uzbekistan (41.4° N, 64.6° E) under arid conditions over the 2016–2017 and 2017–2018 growing seasons. This study aimed to assess the beneficial N fixation (BNF) ability of soybean in association with the Bradyrhizobium R6 strain and the Bradyrhizobium japonicum USDA110 strains and their combined effect on soil fertility and crop yield. The residues of winter wheat and soybean improved soil structure, i.e., soil humus and N and P contents, significantly differing from those on the soybean followed by summer fallow treatment. Furthermore, soybean in association with dual inoculation had the highest N derived from the atmosphere (Ndfa) (62.9 kg N ha⁻¹), followed by individual soybean treatments with the R6 and USDA110 strains at 51.9 and 40.6 kg N ha⁻¹, respectively. Improved soil quality positively impacted crop output, increasing winter wheat and soybean yields by 36.5% and 34.6%, respectively. Likewise, the yield parameters, i.e., the number of pods, weight of grain per pods, and 1000 seeds were significantly higher in the inoculated treatment with the highest value observed in the dual-inoculated treatment. These results suggest the insertion of soybean with symbiotic bacteria into the cropping system has considerable potential to contribute to sustainable land management practices in arid zones.

Water deficiency restricts plant productivity, while excessive soil moisture may also have an adverse impact. In light of this background, field trials were conducted in secondary saline soil (EC 6.5 dS m⁻¹) at the experimental station of Tashkent State Agrarian University (TSAU), Uzbekistan to determine drought tolerance of licorice (Glycyrrhiza glabra) by exposure to four levels of water deficit, namely control (70–80%), moderate (50–60%), strong (30–40%) and intense (10–20%) relative water content (WC) in the soil. The moderate drought stress exhibited positive effects on the morphological and physiological parameters of licorice, and was considered to be the most suitable water regime for licorice cultivation. Plant growth under the 50–60% WC treatment was slightly higher as compared to 70–80% WC treatment, exhibiting weak water deficit promotes licorice growth, root yield and secondary metabolite production. In particular, secondary metabolites i.e., ash, glycyrrhizic acid, extractive compounds and flavonoids, tended to increase under moderate water deficit, however further drought intensification brought a sharp decline of these values. These results contribute to the development of licorice cultivation technologies in arid regions and the most important consideration is the restoration of ecological and economical functions of the dryland agricultural system.