RESUMEN
Introduction: Planting without mulching can eliminate the residual film pollution caused by the long-term use of plastic film covers, but it will increase soil moisture evaporation and heat loss and severely reduce water use efficiency and cotton productivity in cotton (Gossypium hirsutum L.) fields in arid regions. It is unclear whether the advantages of subsurface drip irrigation and nighttime irrigation can be leveraged to reduce the amount of irrigation applied in fields, improve the soil and leaf hydrothermal environments, and increase the synchronicity of yield and water use efficiency (WUE). Methods: Therefore, in a two-year field experiment (2019-2020), cotton was grown under different irrigation treatments (I5, 3753 m3 ha-1; I4, 3477 m3 ha-1; I3, 3201 m3 ha-1; I2, 2925 m3 ha-1; and I1, 2649 m3 ha-1). The soil volumetric moisture content, soil temperature, leaf relative water content (RWC), daily changes in gas exchange parameters, lint yield, and WUE were evaluated. Results and discussion: The results showed that reducing irrigation can reduce the soil volumetric moisture content (0-40 cm soil layer), increase the soil temperature and soil temperature conductivity, and increase the leaf temperature, intercellular carbon dioxide concentration (Ci), and WUE; however, reducing irrigation is not conducive to increasing the leaf RWC, net photosynthetic rate (Pn), stomatal conductance (Gs), or transpiration rate (Tr). There was no significant difference in WUE between the I3 and I4 treatments from 8:00 to 20:00, but the lint yield in these treatments increased by 2.8-12.2% compared to that in the I5 treatment, with no significant difference between the I3 and I4 treatments. In addition, a related analysis revealed that the positive effects of the leaf hydrothermal environment on the Pn and soil temperature on the WUE occurs during the same period (10:00-16:00). Overall, an irrigation amount of 3201-3477 m3 ha-1 applied with a subsurface nighttime irrigation system without mulching can enhance the soil moisture content and soil temperature, maintain a high photosynthetic capacity, and increase the lint yield and WUE. These results revealed that the negative impacts of plastic film contamination in arid areas can be alleviated.
RESUMEN
Excessive fertilization, low nutrient utilization rate, and continuous deterioration of cotton field environment have adversely affected the sustainable development of cotton in Xinjiang province of China. To overcome these issues, we hypothesized that an appropriate combination of liquid organic fertilizer and chemical fertilizer (CF) would effectively reduce the input of CF without sacrificing the quality and yield of cotton. A 2-year field experiment explores the effects of three fertilization treatments on the growth, biomass accumulation, and yield of cotton. The three fertilization treatments, namely, no application of fertilizer (CK), the single application of CF, and the combined application of organic liquid fertilizer and CF (F0.6-F1.4), were set up in five ratios. Compared with CF treatment, the combined application of organic liquid fertilizer and CF treatments (F0.6-F1.2) speeded the growth period of cotton by 2-7 days with increased plant height, stem diameter, functional leaf width, and more number of branches, with 9.7-23.5 and 8.4-28.5% higher total plant biomass (TPB) and reproductive organs biomass (ROB), respectively. Compared with CF treatment, the rapid growth duration and maximum accumulation rate of reproductive organs were the highest in F0.8 treatment, with an average increase of 4.6 days and 20.3%. Increment in biomass accumulation contributed to an average increase of 21.8 and 18.9% in cotton boll number and yield, respectively, under F0.8 treatment. Principal component analysis shows that the total biomass, ROB, and total bolls per unit area were positively correlated with the yield, while stem diameter and vegetative organ biomass are negatively correlated with the yield. In conclusion, under film mulching with drip irrigation, organic liquid fertilizer combined with CF reduced by 20% (F0.8 treatment: N, P2O5, and K2O were 182, 104, and 76 kg hm-2, respectively) can sustain the normal growth, promote the accumulation rate of ROB, and lead to efficient cotton production.
RESUMEN
In order to explore the physiological responses of root system of different drought-resistant cotton varieties to drought and their relationships with biomass, we examined the effects of drought stress on root vigor, antioxidant enzyme activities and anatomic structure (duct diameter, number) and biomass of different drought-tolerant varieties, including the drought-inolerant variety 'Xinluzao 17' (L17) and the drought-tolerant variety 'Xinluzao 22' (L22). Both varieties were grown under soil column cultivation conditions, with conventional irrigation (CK), mild drought (W1) and moderate drought (W2) treatments. The results showed that drought stress caused significant reductions in soluble protein (SP) content, root vigor (RV), the number of cork layers, the number of rhizome ducts, the diameter of the ducts in both varieties. The higher root MDA content, CAT, POD and SOD activities in response to drought led to reduction of aboveground dry mass. Compared with that of L17, SP content, 0-40 cm and 80-120 cm soil layer RV, the number of cork layers, the number of rhizome ducts, the diameter of ducts, and the aboveground dry mass of L22 all signi-ficantly increased. Under the W2 treatment, the RV decrease of L22 was 26.2% lower than that of L17, and CAT, POD, SOD activities and the thickness of cortex were 43.6%, 6.9%, 25.4%, 19.9% higher than that of L17. There were positive correlations between dry mass and RV, SOD, POD, the number of cork layers, the diameter and number of rhizome ducts. Therefore, cotton variety with strong drought tolerance could maintain higher root activity, cork layer number, the diameter of rhizome ducts, and number under drought conditions, and thus promote the accumulation of aboveground biomass, which was the physiological mechanism for their stronger drought tolerance.