Method for improving growth and yield of cotton by adopting saline water irrigation

Abstract

The invention provides a method for improving the growth and yield of cotton through saline water irrigation, and particularly relates to the technical field of crop water and fertilizer management. According to the method, saline water is only irrigated once in the bud stage, the irrigation amount of the saline water is 8.9% of the total irrigation amount, fresh water is adopted for irrigation in the remaining growth stage or saline water is irrigated once in the bud stage and the flowering stage respectively, the irrigation amounts of the saline water in the bud stage and the flowering stage are 8.9% and 11.1% of the total irrigation amount respectively, and saline water of fresh water irrigation is adopted for supplementary irrigation in the remaining growth stage. The growth and yield improvement of the cotton can be obviously promoted, and the reasonable utilization and agricultural sustainable development of salty water resources in the southern Xinjiang region of Xinjiang are also promoted.

Description

Technical Field

[0001] The present invention belongs to the technical field of crop water and fertilizer management, and particularly relates to a method for improving cotton growth and yield by using saline water irrigation. Background Art

[0002] Xinjiang is located in the northwest of China and belongs to a typical arid climate region. Especially in the southern part of Xinjiang, precipitation is scarce and water resources are severely lacking. In terms of agricultural production, agricultural planting in the southern part of Xinjiang mainly relies on irrigation, with a huge demand for water resources. Among them, agricultural water consumption accounts for more than 92%. Especially in the production process of high water-demand crops such as cotton, water shortage has become an important factor restricting the sustainable development of oasis agriculture in the southern part of Xinjiang.

[0003] The salt content in saline water has a complex and significant impact on crop growth, especially on economic crops such as cotton. As an important economic crop and having significant salt tolerance, cotton has a high demand for water, and its sensitivity to water and salt is different at each stage of its growth process. The sensitivity to water and salt is different at different growth stages, and changes in irrigation timing and water-salt concentration may have a significant impact on its growth and development, dry matter accumulation, and seed cotton yield. The impact of saline water on cotton growth and yield not only depends on the salt content of the irrigation water but also is closely related to irrigation timing, frequency, and soil drainage conditions.

[0004] In view of the current situation that fresh water resources are tense during the critical growth period (June - September) of cotton in the southern part of Xinjiang and a large amount of saline water resources are directly used for irrigation, exploring a suitable saline water supplementary irrigation scheme can improve the water resource utilization efficiency while ensuring the stable progress of cotton production, which is an urgent technical problem to be solved in this field. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for improving cotton growth and yield by using saline water irrigation, which can significantly improve cotton growth and yield by using saline water irrigation, and also promote the rational utilization of saline water resources and the sustainable development of agriculture in the southern part of Xinjiang.

[0006] The present invention provides a method for improving cotton growth and yield by using saline water irrigation, where saline water is only irrigated once during the budding stage, and the saline water irrigation amount is 8.9% of the total irrigation amount, and fresh water is used for irrigation in the remaining growth periods.

[0007] The present invention provides a method for improving cotton growth and yield by using saline water irrigation, where saline water is irrigated once during the budding stage and once during the flowering stage, and the saline water irrigation amounts during the budding stage and the flowering stage are 8.9% and 11.1% of the total irrigation amount respectively, and fresh water is used for irrigation in the remaining growth periods.

[0008] Preferably, irrigation is carried out 10 times during the cotton growth period, starting from the budding stage, and the irrigation interval is 7 days.

[0009] Preferably, the total irrigation volume is 4500 m 3 / hm 2 .

[0010] Preferably, the salinity of the saline water ranges from 5.21 to 5.92 g / L.

[0011] Preferably, the first irrigation of saline water during the flowering period is the 5th irrigation after the first irrigation.

[0012] Preferably, Bacillus subtilis is drip-applied with water droplets during the first irrigation, and the application rate of Bacillus subtilis is 40 - 50 kg / hm 2 ; The irrigation method is drip irrigation under plastic film.

[0013] Preferably, the planting adopts the "one film, three pipes, and six rows" planting mode; the "one film, three pipes, and six rows" planting mode includes a plastic film width of 205 cm, and the drip irrigation tape is laid in the narrow row; the distances between the narrow row, the wide row, and the film are 13 cm, 73 cm, and 30 cm respectively.

[0014] Preferably, the cotton is planted in the southern part of Xinjiang, and the variety of the cotton is 'Xinluzhong No. 54'.

[0015] Preferably, the sowing time of the cotton is in the middle of April, and the harvest date is in the late October.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The present invention provides two methods for improving cotton growth and yield by using saline water irrigation. When the fresh water supply is insufficient during the critical growth period of cotton (from June to September), saline water is used for supplementary irrigation. Appropriate amount and suitable saline water are irrigated at the appropriate growth stage, saving some fresh water resources. While improving the water resource utilization efficiency, it also ensures the stable progress of cotton production, improves cotton growth and yield, and provides a theoretical basis for the efficient utilization of saline water resources and the sustainable development of agriculture in the southern part of Xinjiang. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the "one film, three pipes, and six rows" planting mode in the cotton field in Example 1.

[0019] Figure 2 It is the change result of cotton plant height and stem diameter with time under different treatments in 2023 in Example 1. Among them, A is the change result of cotton plant height under different treatments in 2023, B is the change result of the maximum cotton plant height under different treatments in 2023, C is the change result of cotton stem diameter under different treatments in 2023, and D is the change result of the maximum cotton stem diameter under different treatments in 2023.

[0020] Figure 3 Results of the changes in cotton plant height and stem diameter over time under different treatments in 2024 in Example 1. Among them, A shows the results of the changes in cotton plant height under different treatments in 2024, B shows the results of the maximum cotton plant height under different treatments in 2024, C shows the results of the changes in cotton stem diameter under different treatments in 2024, and D shows the results of the maximum cotton stem diameter under different treatments in 2024.

[0021] Figure 4 Dry matter proportion diagrams of various organs at the boll-opening stage of cotton under different treatments in Example 1. Among them, the left figure is for 2023 and the right figure is for 2024. Detailed implementation methods

[0022] The present invention provides a method for improving cotton growth and yield by using saline water irrigation. Saline water is only irrigated once during the budding stage, and the saline water irrigation amount is 8.9% of the total irrigation amount. Fresh water is used for irrigation during the remaining growth period, or saline water is irrigated once during both the budding stage and the flowering stage. The saline water irrigation amounts during the budding stage and the flowering stage are 8.9% and 11.1% of the total irrigation amount respectively, and fresh water is used for irrigation during the remaining growth period. The single saline water irrigation during the budding stage is the first irrigation during the cotton growth period; the single saline water irrigation during the flowering stage is the 5th irrigation starting from the first irrigation during the cotton growth period. In the present invention, the cotton growth period includes the budding stage, the flowering stage, the boll stage, and the boll-opening stage.

[0023] In the present invention, irrigation is carried out 10 times during the cotton growth period, starting from the budding stage, with an irrigation interval of 7 days; the total irrigation amount is 4500m 3 / hm 2 . As an implementable method, the starting time of the first irrigation during the budding stage is in mid-June. In the present invention, the salinity of the saline water ranges from 5.21 to 5.92 g / L; except for the saline water, local conventional fresh water is used for irrigation, and the salinity range of the conventional fresh water is from 0.5 to 1 g / L.

[0024] In the present invention, Bacillus subtilis is applied with the water droplets during the first irrigation, and the application amount of Bacillus subtilis is 40 - 50 kg / hm 2 ; preferably 42 - 48 kg / hm 2 , more preferably 45 kg / hm 2 . The fertilizer application amount refers to the local level, 350 kg / hm of nitrogen fertilizer (N) 2 , 120 kg / hm of phosphate fertilizer (P2O5) 2 , and 90 kg / hm of potassium fertilizer (K2O) 2 .

[0025] In the present invention, the irrigation method is drip irrigation under plastic film. As an alternative embodiment, the planting adopts the "one film, three pipes and six rows" planting mode; the "one film, three pipes and six rows" planting mode includes a plastic film covering width of 205 cm, and the drip irrigation tape is laid in the narrow row; the distances between the narrow row, the wide row and the film are 13 cm, 73 cm and 30 cm respectively.

[0026] In the present invention, cotton is planted in the southern Xinjiang region, and the cotton variety includes 'Xinluzhong No. 54'. As an alternative embodiment, the cotton variety is 'Xinluzhong No. 54'. The sowing time of the cotton is in the middle of April, and sowing can be carried out when the ground temperature at 5 cm under the plastic film stably reaches 12 °C; the harvest date is in the late October.

[0027] In the present invention, to prevent the appearance of headless cotton caused by thrips damage, when the cotton emergence rate reaches 80%, 55.0 g·hm of 70% imidacloprid wettable powder is sprayed. -2 When the cotyledons are flattened, 30.0 g·hm of mepiquat chloride is sprayed. -2 When there are 2 true leaves, timely intertillage and soil covering are carried out to increase the ground temperature and prevent weed growth. When there are 4 true leaves, 15 g·hm of mepiquat chloride is sprayed to prevent the appearance of tall and slender cotton. At the early flowering stage, chemical regulation is carried out again, and 15 g·hm of mepiquat chloride is sprayed to shape the fruiting branches and prevent the closure of the rows. From the full flowering stage to the boll stage, that is, around July 5, 120 g·hm of mepiquat chloride is sprayed for 1 heavy control, and the distance between the fruiting branches is controlled at 7-8 cm, and the fruiting branches are shaped again. Seven days later, a chemical topping agent is used for topping. -2 -2 -2

[0028] In the present invention, an irrigation method of irrigating salt water only once at the budding stage, with the salt water irrigation amount being 8.9% of the total irrigation amount, or irrigating salt water once at the budding stage and once at the flowering stage, and the salt water irrigation amounts at the budding stage and the flowering stage being 8.9% and 11.1% of the total irrigation amount respectively, significantly improves the growth performance and yield of the planted cotton, effectively increases the biomass and improves the distribution ratio of dry matter, thereby significantly increasing the seed cotton yield and water production efficiency. The growth performance is the maximum plant height and stem diameter of the cotton.

[0029] In this invention, the experiment was conducted in the cotton fields of Hailou Town, Shaya County, Aksu Prefecture, Xinjiang (41°13′N, 82°46′) from 2023 to 2024. The research area is located in the southwestern part of Xinjiang, in the southeastern part of Aksu, in the northern part of the Tarim Basin, at the southern end of the Weigan River oasis plain. It is bordered by the Tianshan Mountains in the north and the desert in the south. The terrain is high in the north and low in the south, belonging to the temperate continental climate. The average annual rainfall in Shaya County is 81.6 mm, the annual evaporation is more than 2000 mm, the average annual sunshine is up to 3000 hours, and the average annual temperature is 10.7 °C. The climate is dry and mild, with little rainfall, abundant sunlight, sufficient heat, and a large temperature difference between day and night. The tested soil is sandy loam, with medium soil fertility and suitable soil moisture. The average soil bulk density of the 0 - 100 cm soil layer is 1.58 g / cm 3 , and the average volumetric water content of the soil before sowing is 39%. The irrigation water mainly comes from the Weigan River, and the groundwater level is 3.8 m.

[0030] In this invention, the cotton plants are irrigated with saline water once during the budding stage, and the saline water irrigation amount is 8.9% of the total irrigation amount, which is the G1 treatment in Example 1: supplementary irrigation once during the budding stage, 8.9% of the irrigation quota. The cotton plants are irrigated with saline water once during both the budding stage and the flowering stage. The saline water irrigation amounts during the budding stage and the flowering stage are 8.9% and 11.1% of the total irrigation amount respectively, and the total saline water irrigation amount for the two times is 20% of the total irrigation amount, which is the G2 treatment in Example 1: supplementary irrigation once during both the budding stage and the flowering stage, 20% of the irrigation quota.

[0031] In this invention, the Bacillus subtilis was purchased from Weifang Jinfengyang Agrochemical Co., Ltd., in the form of powder, and the content of Bacillus subtilis is 5.2 billion per gram. The specific strain name is Bacillus subtilis, which is preserved in the China General Microbiological Culture Collection Center (CGMCC), with the preservation number CGMCC 1.3376 and the original number DSM 4181, and was preserved on March 1, 2003.

[0032] Unless otherwise specified, the test methods used in the following examples are all conventional methods; the materials, reagents, and fertilizers used, unless otherwise specified, can all be obtained from commercial channels.

[0033] The technical solutions provided by the present invention will be described in detail below in conjunction with the examples, but they should not be construed as limiting the protection scope of the present invention.

[0034] Example 1

[0035] 1.1 Overview of the test area

[0036] The experiment was conducted in the cotton fields of Hailou Town, Shaya County, Aksu Prefecture, Xinjiang (41°13′N, 82°46′) from 2023 to 2024. The study area is located in the southwestern part of Xinjiang, in the southeastern part of Aksu, in the northern part of the Tarim Basin, at the southern end of the Weigan River oasis plain, with the Tianshan Mountains to the north and the desert to the south. The terrain is high in the north and low in the south, belonging to the temperate continental climate. The average annual rainfall in Shaya County is 81.6 mm, the annual evaporation is more than 2000 mm, the average annual sunshine duration is up to 3000 hours, and the average annual temperature is 10.7℃. The climate is dry and mild, with little rainfall, abundant sunlight, sufficient heat, and a large temperature difference between day and night. The tested soil is sandy loam, with medium soil fertility and suitable soil moisture. The average soil bulk density of the 0-100 cm soil layer is 1.58 g / cm 3 , and the average soil volumetric water content before sowing is 39%. The irrigation water mainly comes from the Weigan River, and the groundwater level is 3.8 m.

[0037] 1.2 Experimental design

[0038] The experiment adopted drip irrigation under plastic film. Taking the local conventional fresh water (0.5 - 1 g / L) irrigation treatment as the control (CK), a total of 5 saline water supplementary irrigation schemes were set: G1 (supplementary irrigation once during the budding stage, 8.9% of the irrigation quota), G2 (supplementary irrigation once during the budding stage and once during the flowering stage, 20% of the irrigation quota), G3 (supplementary irrigation twice during the budding stage and once during the boll stage, 28.9% of the irrigation quota), G4 (supplementary irrigation twice during the budding stage, once during the flowering stage and once during the boll stage, 40% of the irrigation quota), G5 (supplementary irrigation twice during the budding stage, once during the flowering stage and twice during the boll stage, 51.1% of the irrigation quota). There were a total of 6 treatments, with 3 replicates for each treatment, and a total of 18 experimental plots. The area of each experimental plot was 30 m 2 (5 m × 6 m), and the irrigation quota was 4500 m 3 / hm 2 , which was consistent with the local irrigation quota. The experiment was carried out from April to October in 2023 and 2024. The cotton sowing dates in both years were April 17th, and the harvest date was in late October. The tested cotton variety was 'Xinluzhong 54', adopting the planting mode of "one film, three pipes, and six rows". The width of the plastic film was 205 cm, and the drip irrigation belts were laid in the narrow rows. The distances between the narrow rows, wide rows, and between the films were 13 cm, 73 cm, and 30 cm respectively. The specific layout is as Figure 1 shown. The groundwater in the study area was used as the saline water irrigation source, and the variation range of the groundwater salinity during the whole growth period was 5.21 - 5.92 g / L. The cotton growth period was irrigated 10 times in total. The start time was in mid-June, that is, after the cotton entered the budding stage, and the irrigation interval was 7 days. The specific irrigation scheme and irrigation amount are shown in Table 1. The application amount of experimental fertilizers referred to the local level, with 350 kg / hm of nitrogen fertilizer (N), 120 kg / hm of phosphate fertilizer (P2O5), and 90 kg / hm of potassium fertilizer (K2O). 2 , 120 kg / hm of phosphate fertilizer (P2O5), 2 , 90 kg / hm of potassium fertilizer (K2O)2 In addition, 45 kg / hm of Bacillus subtilis was applied 2 and applied once at the first irrigation and applied with the drip water; saline water irrigation was started at the budding stage according to different saline water supplementary irrigation schemes.

[0039] To prevent headless cotton caused by thrips damage, when the cotton emergence rate reached 80%, 55.0 g·hm of 70% imidacloprid wettable powder was sprayed -2 When the cotyledons were flattened, 30.0 g·hm of mepiquat chloride was sprayed -2 When there were 2 true leaves, timely intertillage and soil covering were carried out to increase the soil temperature and prevent weed growth. When there were 4 true leaves, 15 g·hm of mepiquat chloride was sprayed -2 to prevent the emergence of tall and slender cotton.

[0040] At the early flowering stage, chemical regulation was carried out appropriately again. The drone was used to spray 15 g·hm -2 of mepiquat chloride to shape the fruiting branches and prevent the closure of rows. From the full flowering stage to the boll stage, that is, around July 5, 120 g·hm-2 of mepiquat chloride was sprayed for one heavy control, and the distance between fruiting branches was controlled at 7-8 cm, and the fruiting branches were shaped again. Seven days later, a chemical topping agent was used for topping.

[0041] The irrigation ratio and irrigation amount at each growth stage are shown in Table 1.

[0042] Table 1 Number of saline water supplementary irrigation times and irrigation amount at different growth stages of each treatment

[0043]

[0044]

[0045] 1.3 Measurement indexes and methods

[0046] (1) Measurement of cotton plant height and stem diameter

[0047] Six plants were randomly selected from each plot of each treatment, 3 plants in the inner row and 3 plants in the outer row, and plants with uniform growth and good growth were observed and marked. The plant height was measured with a steel tape measure and the stem diameter was measured with an electronic digital vernier caliper. The measured results were averaged to obtain the average plant height and stem diameter of the treatment. The measurement period was once every 10 d.

[0048] (2) Measurement of cotton dry matter

[0049] At the seedling stage, budding stage, flowering stage, boll stage and boll opening stage of cotton, 3 representative plants were selected from each treatment plot to measure their fresh weight and dry weight. The dry weight was measured by the drying method. Before measuring the dry weight, the roots, stems, leaves, buds, bolls and flowers of the plants were separated, put into the oven for blanching treatment (105 °C for 30 min), and then dried at 75 °C for 48 h, and the dry weight was weighed.

[0050] (3) Determination of cotton yield

[0051] During the boll-opening stage, select three cotton fields with consistent boll-opening and an area of 6.67 m 2 in each treatment. Count the number of plants and bolls within this area, then pick 50 cotton bolls, dry them and weigh them. Calculate the seed cotton yield for each treatment, take the average of three replicates as the seed cotton yield of this treatment, and convert it to the cotton yield per mu.

[0052] 1.4 Data processing and analysis

[0053] Use Excel 2020 software for data sorting, Origin2019b software for drawing, and SPSS23.0 for statistical analysis. Use Adobe Illustrator CC for graphic optimization.

[0054] 2 Results and analysis

[0055] 2.1 Effects of different saline water supplementary irrigation on the changes in cotton plant height and stem diameter

[0056] The changes in cotton plant height and stem diameter under different treatments in 2023 and 2024 are as follows Figure 2 (2023) and Figure 3(As shown in (2024)). In 2023 and 2024, the growth trends of cotton plant height under different treatments were basically the same. It showed rapid growth from 40 to 80 days after sowing, and the growth rate tended to level off after topping. Compared with the CK treatment, the maximum plant heights of cotton in the G1 treatment increased significantly by 12% and 9% respectively in the two years. In addition, the G2 treatment also significantly increased the maximum plant height of cotton in 2024, by 9%, but there was no significant difference from the CK treatment in 2023. In contrast, the maximum plant heights of cotton in the G3, G4, and G5 treatments were significantly lower than those in the CK treatment in both years, decreasing by 8%, 7%, and 17% respectively in 2023 and by 5%, 16%, and 23% respectively in 2024. Compared with the G1 and G2 treatments, the maximum plant heights of cotton in the G3, G4, and G5 treatments were also significantly lower in the two years. The stem diameter of cotton showed a trend of rapid growth first and then stability in 2023 and 2024, and reached the maximum value at the boll-opening stage. In 2024, compared with the maximum stem diameter of cotton in the CK treatment, the G1 treatment and the G2 treatment increased significantly by 16% and 11% respectively. However, there was no significant difference between the G3, G4, and G5 treatments and the CK treatment. In 2023, compared with the CK treatment, the maximum stem diameters of cotton in the G2, G3, G4, and G5 treatments decreased significantly by 7%, 14%, 23%, and 25% respectively, while there was no significant difference between the G1 treatment and the CK treatment. Similarly, compared with the G1 and G2 treatments, the maximum stem diameters of cotton in the G3, G4, and G5 treatments were significantly lower in the two years. In summary, the G1 treatment significantly increased the maximum plant height and stem diameter of cotton, and the G2 treatment also significantly increased the maximum plant height of cotton in 2024. On the contrary, the maximum plant height and stem diameter of cotton in the G3, G4, and G5 treatments were significantly lower than those in the CK treatment and the G1 and G2 treatments.

[0057] 2.2 Effects of Different Brackish Water Supplementary Irrigations on Dry Matter of Cotton

[0058] The biomass of each organ during the boll opening stage of cotton under different treatments in 2023 and 2024 is shown in Table 2. There were significant differences in boll biomass and total biomass between the G1 treatment and the CK treatment in both years (p<0.05). In 2023, compared with the CK treatment, the boll biomass and total biomass of the G1 treatment increased by 7.6% and 5.1% respectively. In 2024, compared with the CK treatment, the G1 treatment increased by 16.1% and 11.1% respectively. However, there were no significant differences in boll biomass and total biomass between the G2 treatment and the CK treatment in both years. In contrast, the boll biomass of other treatments (G3, G4, G5) was lower than that of the CK treatment, decreasing by 19.3%, 18.0% and 20.4% in 2023, and by 11.3%, 44.1% and 46.1% in 2024. Similarly, in terms of total biomass, the G3, G4, and G5 treatments were still lower than the CK treatment, decreasing by 15.0%, 17.5%, 16.6% in 2023 and by 9.1%, 33.2%, 29.9% in 2024. The root biomass and stem biomass of the G1 treatment increased compared with the CK treatment in both years. In 2023, they increased by 4.6% and 21.1% respectively, and in 2024, they increased by 5.1% and 6.9% respectively. In 2023, the root biomass and stem biomass of the G2 treatment were lower than those of the CK treatment, decreasing by 8.7% and 0.7% respectively, while in 2024, the root biomass was the same as that of the CK treatment, and the stem biomass decreased by 6.8%. The root biomass and stem biomass of the G3, G4, and G5 treatments decreased compared with the CK treatment in both years. The root biomass decreased by 9.2%, 6.7%, 5.0% and 4.4%, 30.4%, 25.4% in the two years respectively, and the stem biomass decreased by 20.4%, 23.4%, 15.9% and 10.2%, 19.9%, 7.3% in the two years respectively. It is worth noting that the leaf biomass of the G1 treatment decreased by 13.9% compared with the CK treatment in 2023, but instead increased by 3.4% in 2024. The leaf biomass of G2, G3, G4, and G5 decreased compared with the CK treatment in both years, decreasing by 7.9%, 18.0%, 30.2%, 27.8% in 2023 and by 3.5%, 4.5%, 16.1%, 6.8% in 2024. In summary, compared with the CK treatment, the G1 treatment showed a significant increase in boll biomass and total biomass in both years. There was no significant difference between the G2 treatment and the CK treatment, and the biomass indexes of the G3, G4, and G5 treatments were lower than those of the CK treatment.

[0059] Table 2 Biomass of each organ of cotton during the boll opening stage under different treatments (kg / ha)

[0060]

[0061] Note: Different letters indicate significant differences at the 5% level.

[0062] To further analyze the distribution of dry matter in cotton, a diagram showing the proportion of dry matter in each organ during the cotton boll-opening stage was drawn ( Figure 4 ). The proportion of dry matter distributed in each organ under different treatments was boll > leaf > stem > root in sequence. In 2023 ( Figure 4 the left figure), the proportion of dry matter in the bolls under the CK treatment was 50%, lower than that under the G1 (53%) treatment. The proportion of dry matter in the bolls under the G2 treatment was 49%, similar to that of CK; in contrast, the proportions under the G3, G4, and G5 treatments were 41%, 38%, and 34% respectively, all lower than CK. However, in 2024 ( Figure 4 the right figure), the distribution of dry matter in the bolls under different treatments showed a different trend from that in 2023. The proportion of dry matter in the bolls under the CK treatment was 55%. Compared with CK, the proportions of dry matter in the bolls under the G1 (57%) and G2 (58%) treatments both increased, while the proportions under the G3 (51%), G4 (44%), and G5 (42%) treatments were still lower than CK. In terms of the proportion of dry matter distributed in leaves, the proportion under the CK treatment in 2023 was 22%, higher than that under the G1 (19%) and G2 (19%) treatments. However, the proportions of dry matter in leaves under the G3, G4, and G5 treatments were all higher than that under the CK treatment, reaching 25%, 27%, and 29% respectively. In 2024, the proportion of dry matter in leaves under the CK treatment was 21%, still higher than that under the G1 (19%) and G2 (19%) treatments, but lower than that under the G3 (21%), G4 (26%), and G5 (27%) treatments. This change may be somewhat related to the decrease in boll biomass. In terms of the distribution of dry matter in stems, the proportion under the CK treatment in 2023 was 18%, the same as that under the G1 treatment, but lower than that under the G2 (21%) treatment. The proportions of dry matter in stems under the G3, G4, and G5 treatments were all 24%, higher than that under the CK treatment. In 2024, the proportion of dry matter in stems under the CK treatment was 17%, slightly higher than that under the G1 (16%) and G2 (15%) treatments. However, the proportions of dry matter in stems under the G3 (19%), G4 (21%), and G5 (22%) treatments were still higher than that under the CK treatment. The differences in the proportion of dry matter in roots among different treatments were small in 2023. The proportions under the CK treatment, G1, and G2 treatments were all 10%, while those under the G3, G4, and G5 treatments were slightly higher, all 11%. By 2024, the proportion of dry matter in roots under the CK treatment was only 8%, the same as that under the G1 and G2 treatments, while those under the G3, G4, and G5 treatments were 8%, 9%, and 9% respectively. To sum up, different supplementary irrigation schemes have an impact on the distribution of dry matter in each organ of cotton, especially showing different changing trends in the distribution proportions of bolls, leaves, stems, and roots. Under different supplementary irrigation schemes, the proportion of dry matter distributed in bolls under the G1 and G2 treatments is relatively high, while those under the G3, G4, and G5 treatments are relatively low.

[0063] 2.3 Effects of Different Brackish Water Supplementary Irrigations on Cotton Yield and Irrigation Water Productivity

[0064] In 2023 and 2024, the yields of the G1 treatment were significantly higher than those of the CK treatment (p<0.05). Compared with the CK treatment, the yields of the G1 treatment increased by 8.03% and 8.66% respectively in the two years. The G2 treatment showed stability in the two years. There was no significant difference in the yield of the G2 treatment compared with the CK treatment in 2023, and the yield of G2 in 2024 increased by 7.57% compared with the CK treatment. This indicates that the G1 and G2 treatments can maintain a relatively high yield level within two years. In contrast, the yields of the G3, G4, and G5 treatments were significantly lower than those of the CK treatment in the two years (p<0.05). In 2023, compared with the CK treatment, the yields of the G3, G4, and G5 treatments decreased by 10.53%, 13.46%, and 17.92% respectively, and in 2024, they decreased by 2.29%, 4.23%, and 7.91% respectively compared with the CK treatment; a similar pattern was observed for the irrigation water productivity in the two years. In 2023 and 2024, the irrigation water productivity of the G1 treatment was significantly higher than that of the CK treatment (p<0.05). Compared with the CK treatment, the irrigation water productivity of the G1 treatment increased by 7.97% and 8.21% respectively in the two years of irrigation. The performance of the G2 treatment was inferior to that of the G1 treatment in the two years, but there was still a slight increase compared with the CK treatment. The increases in 2023 and 2024 were 0.72% and 7.46% respectively. In contrast, the irrigation water productivities of the G3, G4, and G5 treatments were lower than those of the CK treatment and gradually decreased with the increase in the amount of saline water supplementary irrigation. In 2023, compared with the CK treatment, the decreases in the irrigation water productivities of the G3, G4, and G5 treatments were 10.14%, 13.04%, and 18.12% respectively, and in 2024, the decreases were 2.24%, 4.48%, and 8.21% respectively; with the gradual increase in the amount of saline water irrigation for the G1 to G5 treatments, the demand for fresh water decreased, and the irrigation cost also decreased accordingly. Among different supplementary irrigation schemes, the G1 treatment had the best effect in improving yield and irrigation water productivity, could effectively reduce the irrigation cost, and the G2 treatment could also maintain a relatively high yield level. On the contrary, the yields and irrigation water productivities of the G3, G4, and G5 treatments were significantly lower than those of the CK treatment, and the effect became worse with the increase in the number of saline water irrigation times.

[0065] Table 3 Cotton yield and irrigation water production efficiency

[0066]

[0067] Note: Different letters indicate significant differences at the 5% level.

[0068] 2.3 Effects of different saline water supplementary irrigation on cotton quality

[0069] To evaluate the effects of different saline water supplementary irrigation conditions on cotton quality, the present invention mainly detects seven key indicators of cotton quality: upper half mean length, uniformity index, breaking tenacity, micronaire value, elongation, reflectance, and yellowness (see Table 4). It can be found from the data in the table that the value of the upper half mean length (mm) of the CK treatment is the highest, while the mean length of other treatments (G1 - G5) gradually decreases with the increase in the number of saline water irrigation times. In 2023 and 2024, compared with the CK treatment, there was no significant difference in the G1 treatment, while significant differences were presented in the G2, G3, G4, and G5 treatments (p < 0.05). In 2023, compared with the CK treatment, the mean length of the G1 treatment increased by 1%, and the G5 treatment decreased the most, by 3%. In 2024, compared with the CK treatment, the mean length of the G1 treatment increased by 4%, and the G3 treatment decreased the most, by 10%. During the two years, the change in the uniformity index was relatively small, and the uniformity of all treatment groups was above 83%, indicating that the fiber length distribution was relatively uniform. For the breaking tenacity in 2023, the highest value of the CK treatment was 31.47 cN / tex, and the lowest value of the G5 treatment was 28.7 cN / tex. Among different saline water treatments, it decreased with the increase in the number of saline water supplementary irrigation times, while there was no significant difference among the treatments in 2024 (p < 0.05). The micronaire value under different saline water treatments decreased with the increase in the number of saline water supplementary irrigation times in 2023, while it was the opposite in 2024, reflecting the change in fiber maturity or fineness. The numerical changes in reflectance and yellowness showed the change in fiber color characteristics. There was no significant difference in reflectance among the treatments during the two years (p < 0.05). The overall yellowness value of each treatment was lower in 2024, indicating that the cotton was whiter, while the overall yellowness value of each treatment was higher in 2023, especially in the G3 and G4 treatments. Based on the above, it can be concluded that the G1 treatment has the least impact on the quality of cotton under different saline water supplementary irrigation treatments, and it can even play a role in improving some qualities of cotton.

[0070] Table 4 Cotton Quality under Different Treatments in 2023 and 2024

[0071]

[0072] Note: Different letters indicate significant differences at the 5% level.

[0073] Through the experiments in 2023 and 2024, the present invention found that different saline water supplementary irrigation treatments significantly affected the growth dynamics of cotton plant height and stem diameter (p < 0.05). Among them, the G1 and G2 treatments showed significant improvements in plant height and stem diameter (p < 0.05), indicating that appropriate saline water supplementary irrigation, especially during the budding and flowering stages, can effectively promote the growth of cotton.

[0074] In terms of cotton biomass accumulation, the present invention finds that appropriate saline water irrigation can promote the growth of cotton during the critical growth periods (bud stage, flowering and boll stage). The G1 treatment showed significant advantages compared to CK in terms of boll biomass and total biomass, with increases of 7.6% and 5.1% in 2023, and 16.1% and 11.1% in 2024 (p<0.05).

[0075] The results of the present invention show that the application of appropriate saline water irrigation during the appropriate growth period has potential feasibility and economy in cotton production. In particular, the G1 treatment with one-time supplementary irrigation of saline water at the bud stage increased the yield by 8.03% and 8.66% in 2023 and 2024 respectively, significantly improving the cotton yield and irrigation water productivity (p<0.05). It also had the least impact on the quality of cotton and even played a role in improving some qualities of cotton.

[0076] The results of the present invention show that the saline water supplementary irrigation scheme under the G1 treatment (one-time supplementary irrigation of saline water at the bud stage, 8.9% of the irrigation quota) significantly increased the maximum plant height and stem diameter of cotton, effectively improved the biomass and the distribution ratio of dry matter, thus significantly increasing the seed cotton yield and water production efficiency. In addition, there was no significant difference in the maximum plant height, stem diameter and dry matter weight of cotton under the G2 treatment (one-time supplementary irrigation of saline water at the bud stage and the flowering stage respectively, 20% of the irrigation quota) compared with the conventional fresh water irrigation treatment, while the yield also increased significantly in 2024. Irrigating appropriate saline water during the appropriate growth period can optimize the growth status of cotton and increase the seed cotton yield, and some qualities of cotton can also be improved. However, excessive saline water irrigation will inhibit crop growth and reduce yield (G3, G4, G5 treatments). Therefore, in the case of scarce fresh water resources, it is recommended to use saline water with a concentration of 5.21 - 5.92 g / L for one-time supplementary irrigation at the bud stage or one-time supplementary irrigation at the bud stage and the flowering stage respectively.

[0077] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for increasing cotton growth and yield by using salt water irrigation, characterized in that: Salt water irrigation is only used once during the bud stage, and the amount of salt water irrigation accounts for 8.9% of the total irrigation amount. Fresh water irrigation is used during the remaining growth period.

2. A method for increasing cotton growth and yield by using salt water irrigation, characterized in that: Salt water irrigation is used once during the bud stage and once during the flowering stage. The amount of salt water irrigation during the bud stage and flowering stage is 8.9% and 11.1% of the total irrigation amount respectively. Fresh water irrigation is used during the remaining growth period.

3. The method according to claim 1 or 2, characterized in that: During the cotton growing period, irrigation was carried out 10 times, starting from the bud stage, with an irrigation interval of 7 days.

4. The method according to claim 1 or 2, characterized in that: Total irrigation capacity is 4500m 3 / hm 2 .

5. The method according to claim 1 or 2, characterized in that: The saline water mineralization ranges from 5.21 to 5.92 g / L.

6. The method according to claim 2, characterized in that: The saline water irrigation once during the flowering period is the fifth irrigation after the first irrigation.

7. The method according to claim 1 or 2, characterized in that: During the first irrigation, Bacillus subtilis was applied with water drops at a rate of 40-50 kg / hm2. 2 ; The irrigation method is drip irrigation under the film.

8. The method according to claim 1 or 2, characterized in that: The planting adopts the "one film, three tubes and six rows" planting mode; the "one film, three tubes and six rows" planting mode includes a film covering width of 205cm, and drip irrigation tapes are laid in narrow rows; the distances between narrow rows, wide rows and films are 13cm, 73cm and 30cm respectively.

9. The method according to claim 1 or 2, characterized in that: The cotton is planted in the southern Xinjiang region, and the cotton variety is 'Xinluzhong No. 54'.

10. The method according to claim 1 or 2, characterized in that: The cotton is sown in mid-April and harvested in late October.

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