| Wheat cotton intercropping mode can make full use of soil fertility and growing season,early maturing cotton intercropping can effectively shorten the wheat cotton symbiosis period,which is conducive to stable yield and income of cotton.Due to the wide distribution of suitable areas for Early Maturing Cotton and the wide range of sowing date,it can meet different maturity systems.Reasonable sowing date is conducive to the formation of cotton yield and the realization of higher annual benefit,which is one of the important control measures for the construction of high-efficiency wheat cotton intercropping mode.In this study,two Early Maturing Cotton Varieties(Lumian 2387 and Jinke 707)were used as materials to study the differences of cotton growth,yield,quality and utilization efficiency of temperature and light resources under different sowing dates,including May 10(SD1),May 20(SD2),May 30(SD3)and June 10(SD4),mainly have the following conclusions:1 Study on the growth and development of cotton in wheat cotton intercropping with variety and sowing date(1)With the delay of sowing date,the results of two years were as follows:the bud period of intercropping cotton was shortened,the boll opening period and growth period were shortened first and then extended,and the boll opening period was extended.(2)Sowing date and variety have great influence on the agronomic characters of Early Maturing Cotton.Every 10 days delay of sowing date can reduce the plant height by about 20 cm and the number of fruit branches by about 1.5.The root load capacity of Lumian 2387 in SD2 and Jinke 707 in SD1 is higher than other treatments,which indicates that appropriate early sowing is conducive to creating a favorable nutrient growth foundation for short season cotton.(3)The maximum biomass accumulation of Lumian 2387 was the largest at sd1 sowing date,and Jinke 707 was the largest at SD2 sowing date.However,considering the dry matter accumulation and distribution coefficient,the dry matter transfer from vegetative organs to reproductive organs of Jinke 707 was larger at SD1 sowing date and Lumian 2387 at SD2 sowing date,which was conducive to the increase of reproductive distribution coefficient.2 Effects of varieties and sowing date on cotton yield and fiber quality in wheat cotton intercropping(1)There was significant interaction effect between varieties and sowing date on seed cotton yield.The seed cotton yield of Lumian 2387 was the highest in SD2 sowing date,4300 kg/hm~2 in2019,3986 kg/hm~2in 2020,and Jinke 707 was the highest in sd1 sowing date,5110 kg/hm~2 in2019,3608 kg/hm~2in 2020.(2)Under SD2 sowing date,the single boll weight of lower part,middle part and upper part of Lumian 2387 was higher than other sowing dates.Under SD2 sowing date,the single boll weight of upper part and middle part of Jinke 707 was the largest.In 2019,the lower boll weight was the largest under SD3 treatment,and in 2020,the lower boll weight was the largest under SD4 treatment.It showed that early sowing could improve the single boll weight of middle and upper fruit branch,late sowing could improve the single boll weight of lower fruit branch.(3)Varieties and sowing date had significant effects on cotton fiber quality,and the response of fiber quality in different parts of cotton to sowing date was also different.The overall fiber quality of Jinke 707 was higher than that of Lumian 2387.Late sowing was beneficial to improve the fiber quality of the lower branches,but it would reduce the fiber quality of the upper and middle branches;early sowing was not conducive to improve the fiber quality of the middle and lower branches,although the bolls were evenly distributed.3 Effects of varieties and sowing date on PARI and resource utilization efficiency of wheat cotton intercropping(1)With the increase of cotton canopy depth,the photosynthetic effective radiation increased from slow to fast in the position near the cotton row,but it increased slowly in the middle of the cotton row.The vertical and horizontal vertical distribution profile of the whole cotton canopy was in a"V"shape.With the development of cotton population,the par of canopy increased at first and then decreased.There was a positive correlation between PAR and Lai in different sowing dates.(2)Early sowing can significantly improve cotton canopy structure,improve the utilization of temperature and light resources,and the appropriate sowing date(lm2387 is SD2,jinke707 is SD1)has higher canopy photosynthetically active radiation than late sowing,The photosynthetic effective radiation and resource utilization efficiency of cotton were different,and the overall performance of lm2387 was higher than that of Jinke 707. |
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