Soil salinization adversely affects agricultural productivity. Mitigating the adverse effects of salinity represents a current major challenge for agricultural researchers worldwide. The effects of exogenously applied glycine betaine (GB) and salicylic acid (SA) on mitigating sodium toxicity and improving the growth of cotton seedlings subjected to salt stress remain unclear. The treatments in a phytotron included a control (CK, exogenously untreated, non-saline), two NaCl conditions (0 and 150 mM), four exogenous GB concentrations (0, 2.5, 5.0, and 7.5 mM), and four exogenous SA concentrations (0, 1.0, 1.5, and 2.0 mM). The shoot and roots exposed to 150 mM NaCl without supplementation had significantly higher Na⁺ and reduced K⁺, Ca²⁺, and Mg²⁺ contents, along with lowered biomass, compared with those of CK. Under NaCl stress, exogenous GB and SA at all concentrations substantially inversed these trends by improving ion uptake regulation and biomass accumulation compared with NaCl stress alone. Supplementation with 5.0 mM GB and with 1.0 mM SA under NaCl stress were the most effective conditions for mitigating Na⁺ toxicity and enhancing biomass accumulation. NaCl stress had a negative effect on plant growth parameters, including plant height, leaf area, leaf water potential, and total nitrogen (N) in the shoot and roots, which were improved by supplementation with 5.0 mM GB or 1.0 mM SA. Supplementation with 5.0 mM exogenous GB was more effective in controlling the percentage loss of conductivity (PLC) under NaCl stress.

The optimization of irrigation and fertilization indexes for peanuts with drip irrigation is urgently needed in Xinjiang. A field experiment was conducted during the 2021 peanut growing season at Urumqi, Xinjiang, in Northwestern China, to evaluate the effects of different water and nitrogen treatments on the growth, yield, and water and nitrogen utilization of peanuts. In field experiments, we set up three irrigation levels (irrigation water quotas of 22.5, 30, and 37.5 mm, respectively, for W₁, W₂, and W₃), two nitrogen application levels (77.5 and 110 kg·ha⁻¹, recorded as N₁ and N₂), and a control treatment (W₂N₀) that did not include the application of nitrogen. The results showed that nitrogen application enhanced the growth, physiological indexes, yield, and water use efficiency of the W₁, W₂, and W₃ treatments when the irrigation volume remained the same. In comparison with no nitrogen application (W₂N₀), the peanut growth, physiological indexes, yield, and water use efficiency improved with increasing irrigation amounts in the N₁ and N₂ treatments. With an increase in the irrigation volume, the water use efficiency grew; the W₃N₂ treatment had the highest water use efficiency, which was 1.32 kg·m⁻³. The total water consumption and reproductive-stage water consumption of the peanuts in all treatments increased with the irrigation volume, and a high yield was achieved at 402.57 mm, which was 5.2974 Mg·ha⁻¹. In the W₁, W₂, and W₃ treatments, the nitrogen partial factor productivity significantly decreased as the nitrogen application increased, with the nitrogen partial factor productivity in the W₃N₁ treatment being the highest, at 60.61 kg·kg⁻¹. A comprehensive evaluation based on principal component analysis assigned W₃N₂ the higher score. These findings suggest that irrigation water quotas of 37.5 mm should be coupled with 110 kg·ha⁻¹ nitrogen applications for peanuts using drip irrigation in mulch film in Xinjiang.

During four consecutive growing seasons (2014–2018), field experiments were conducted in the North China to determine winter wheat production function. The field experiments were carried out using winter wheat subjected to four N levels (N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀) and three irrigation levels (I_f, I_0.8f, and I_0.6f). The main aims were to characterize winter wheat productivity, drought response factor K_y, and the winter wheat grain yield production functions in relation to water supply under the different N fertilizer levels. The amount of water supply (rain + irrigation) were 326–434, 333–441, 384–492, and 332–440 mm in 2014–2015, 2015–2016, 2016–2017, and 2017–2018 growing seasons, respectively. Similarly, the values of ET_a (including the contribution from soil water storage) were 413–466, 384–468, 401–466, and 417–467 mm in 2014–2015, 2015–2016, 2016–2017, and 2017–2018, respectively. ET_a increased as the amount of irrigation increased. The average values of I_f, I_0.8f, and I_0.6f over the four growing seasons were 459–465, 432–446, and 404–413 mm, respectively. For the same amount of irrigation, there was only small difference in ET_a among different nitrogen levels; for the three irrigation levels, the values of ET_a in N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀ ranged from 384 to 466, 384 to 466, 385 to 467, and 407 to 468 mm, respectively. Water productivity values ranged from 1.69 to 2.50 kg m⁻³ for (rain + irrigation) and 1.45 to 2.05 kg·m⁻³ for ET_a. The K_y linearly decreased with the increase in nitrogen amount, and the values of r were greater than 0.92. The values of K_y for winter wheat in N₁₂₀, N₁₈₀, N₂₄₀, and N₃₀₀ were 1.54, 1.41, 1.28, and 1.25, respectively. The mean value of K_y for winter wheat over the three irrigation levels and the four nitrogen levels was 1.37 (r = 0.95). In summary, to gain higher grain yield and WUE, optimal combination of N fertilizer of 180–240 kg·ha⁻¹ and irrigation quota of 36–45 mm per irrigation should be applied for winter wheat with drip fertigation in the North China Plain.