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Cotton is a major cash crop grown worldwide primarily for fiber and oil seed. As the most important cultural practices for cotton production, single pre-plant irrigation and basal fertilization for cotton plant growth and yield are well documented, but their coupling effects are poorly understood in arid regions. A 2-year outdoor pot trial was conducted to unravel the effects of pre-plant irrigation and basal fertilization on leaf area, root growth, biomass accumulation, and capacity of leaf area and root in cotton plant. Two pre-plant irrigations (i.e., W 80 , well-watered and W 0 , not watered) and two basal dressing fertilizations (F 10 , surface application and F 30 , deep application) were used in the experiments. The aboveground and reproductive biomass were highest in W 80 F 10 after 69 days after emergence. Furthermore, W 80 F 10 increased the root length in the 0-40 cm soil layer and the leaf area and improved the loading boll capacity of the effective root length and leaf area. The effective root length and leaf area had substantial direct effects on the aboveground and root biomass, respectively. Our data suggest that basal fertilizer surface application under adequate pre-plant irrigation is an effective strategy for optimal cotton production, which improves the coordination of water-nutrient absorption and photosynthetic areas and promotes assimilated distribution to the reproductive structures.

Deep drip irrigation combined with high‐density planting is one of the most economical and effective ways to address residual film pollution. This study aimed to explore the photosynthetic potential of and achieve water‐saving and high‐yielding filmless cotton (Gossypium hirsutum L.) by optimizing the irrigation amount. We analyzed the effect of source leaf activity on leaf nitrogen allocation and photosynthetic nitrogen utilization efficiency (PNUE) under different irrigation amounts (mm, 375 (W5), 348 (W4), 320 (W3), 293 (W2), and 265 (W1)) in a 2‐year field experiment under this planting mode. The photosynthetic pigment content, leaf mass per area, and light compensation point all decreased with increasing amounts of irrigation, while the apparent quantum yield of photosynthesis, light saturation point, maximum carboxylation rate (Vcmax), maximum electron transport rate (Jmax), triose phosphate utilization rate (VTPU), nitrogen content in the electron transfer component (NB), and nitrogen content in the carboxylation component (NC) showed opposite trends. At the later full boll stage, the W3 and W4 treatments increased the leaf area of a whole plant (LA) by 10.4% and 19.4%, respectively, compared to that in the W1 treatment, while the PNUE increased by 20.2% and 20.8%, respectively, compared to that in the W5 treatment. In addition, principal component analysis found that the factor variables total nitrogen content in the photosynthetic apparatus (NT), net photosynthetic rate (Pn), stomatal conductance (Gs), light‐saturated net photosynthetic rate (Amax), NC, and Vcmax had higher loadings and were all positively correlated with PNUE; LA had a higher loading and was positively correlated with reproductive organ biomass. Therefore, we recommend using an irrigation rate of 320 mm in this cultivation system to increase nitrogen in carboxylation and electron transport components, enhance photosynthetic capacity, and thereby improve PNUE to increase reproductive organ biomass and reduce the irrigation amount in arid areas. Core Ideas: Optimizing the irrigation amount can enhance the source leaf activity of filmless cotton.The content of nitrogen in carboxylation and electron transport components is the key to improve photosynthetic rate.Increasing the leaf area of a whole plant can increase reproductive biomass.The optimal irrigation system rate is 320 mm under deep drip irrigation without film. [ABSTRACT FROM AUTHOR]

Limitations of soil water and nitrogen (N) are factors which cause a substantial reduction in cotton (Gossypium hirsutum L.) yield, especially in an arid environment. Suitable management decisions like irrigation method and nitrogen fertilization are the key yield improvement technologies in cotton production systems. Therefore, we hypothesized that optimal water-N supply can increase cotton plant biomass accumulation by maintaining leaf photosynthetic capacity and improving root growth. An outdoor polyvinyl chloride (PVC) tube study was conducted to investigate the effects of two water-N application depths, i.e., 20 cm (H20) or 40 cm (H40) from soil surface and four water-N combinations [deficit irrigation (W55) and no N (N0) (W55N0), W55 and moderate N (N1) (W55N1), moderate irrigation (W75) and N0 (W75N0), W75N1] on the roots growth, leaf photosynthetic traits and dry mass accumulation of cotton crops. H20W55N1 combination increased total dry mass production by 29-82% and reproductive organs biomass by 47-101% compared with other counterparts. Root protective enzyme and nitrate reductase (NR) activity, potential quantum yield of photosystem (PS) II (Fv/Fm), PSII quantum yield in the light [Y(II)] and electron transport rate of PSII were significantly higher in H20W55N1 prior to 82 days after emergence. Root NR activity and protective enzyme were significantly correlated with chlorophyll, Fv/Fm, Y(II) and stomatal conductance. Hence, shallow irrigation (20 cm) with moderate irrigation and N-fertilization application could increase cotton root NR activity and protective enzyme leading to enhance light capture and photochemical energy conversion of PSII before the full flowering stage. This enhanced photoassimilate to reproductive organs. [ABSTRACT FROM AUTHOR]

Due to the changing climate, frequent episodes of drought have threatened cotton lint yield by offsetting their physiological and biochemical functioning. An efficient use of irrigation water can help to produce more crops per drop in cotton production systems. We assume that an optimal drip irrigation with low mepiquat chloride application could increase water productivity (WP) and maintain lint yields by enhancing leaf functional characteristics. A 2-year field experiment determines the response of irrigation regimes (600 (W1), 540 (W2), 480 (W3), 420 (W4) 360 (W5) m3 ha−1) on cotton growth, photosynthesis, fiber quality, biomass accumulation and yield. Mepiquat chloride was sprayed in different concentration at various growth phases (see material section). Result showed that W1 increased leaf area index (LAI) by 5.3–36.0%, net photosynthetic rate (Pn) by 3.4–23.2%, chlorophyll content (Chl) by 1.3–12.0% than other treatments. Improvements in these attributes led to higher lint yield. However, no differences were observed between W1 and W2 in terms of lint and seed cotton yield, but W2 increased WP by 3.7% in both years. Compared with other counterparts, W2 had the largest LAI (4.3–32.1%) at the full boll stage and prolonged reproductive organ biomass (ROB) accumulation by 30–35 d during the fast accumulation period (FAP). LAI, the average (VT) and maximum (VM) biomass accumulation rates of ROB were positively correlated with lint yield. In conclusion, the drip irrigation level of 540–600 m3 ha−1 with reduced MC application is a good strategy to achieve higher WP and lint yield by improving leaf photosynthetic traits and more reproductive organ biomass accumulation. [ABSTRACT FROM AUTHOR]

Subsurface drip irrigation in arid areas has the potential to replace traditional mulched drip irrigation to achieve green and sustainable cotton production. However, the suitable irrigation amount and frequency are still unclear, which seriously limits the ability of this model to improve water productivity and water-saving potential. Therefore, a field experiment was carried out from 2021 to 2023; a split plot experimental design was adopted with two irrigation amounts (W1, 3177 m3 ha−1; W2, 3840 m3 ha−1) and three irrigation frequencies (F1, 9; F2, 8; F3, 7). The effects of different irrigation strategies on the soil microenvironment, moisture content, biomass, and water use efficiency (WUE) of cotton organs were evaluated. The W2 treatment improved the soil moisture content, increased the soil temperature gradient, and reduced the soil conductivity, thereby increasing the moisture content and biomass of various organs. Moreover, compared with the F1 treatment, the F2 and F3 treatments were more likely to increase the soil moisture content, soil temperature gradient, WUE Stem , WUE Leaf and WUE Boll. In addition, the water consumption of the F2 and F3 treatments decreased by 3.9 % and 0.9 %, respectively, compared with that of the F1 treatment. These findings indicate that W2F2 can reduce water consumption while increasing boll biomass and WUE Boll. Further analysis revealed that under W2F2, WUE Boll was positively correlated with soil temperature gradient and soil conductivity and negatively correlated with leaf moisture content (LMC) and water consumption. In summary, with an irrigation amount of 3840 m3 ha−1, delaying the initial irrigation event and increasing the irrigation quota (8 irrigation events) improve the water environment in cotton fields, reducing soil temperature fluctuations and surface salt accumulation and synergistically increasing the boll biomass of cotton organs and WUE Boll. This irrigation strategy represents an effective cotton cultivation method to maximize cotton yield and improve resource utilization efficiency. • Increasing the soil moisture content can reduce the thermal conductivity and surface salinity of the root zone. • The moisture content of cotton organs varies with soil moisture to support biomass. • Increases in cotton root and boll biomass promote boll water use efficiency. • Delaying initial irrigation and increasing quotas on the basis of a 3840 m3 ha−1 irrigation amount increases efficiency. [ABSTRACT FROM AUTHOR]