Effects of wheat straws under high dosage on growth and yield formation of cotton

【Objective】The effects of high dosage of wheat straws on weed control and cotton yield formation in Yangtze River Basin were studied, these works provided theoretical basis for integrated technique model of chemical fertilizers and chemical herbicides reductions in cotton field.【Method】Taking insect-resistant cotton variety GK19 as material, the experiment was conducted involving three wheat straw mulching rates15000 kg/ha(M1), 20000 kg/ha(M2) and 30000 kg/ha (M3), and no straw mulch was the control (M0, CK). The effects of high dosages straw mulching on weed control, soil moisture content, chlorophyll content, plant height, numbers of bud and bolls during the seedling stage, flowering and boll stage and boll-opening stage were measured.【Result】The results showed that high dosages of wheat straw mulching could inhibit the germination of weeds during the whole growth periods. Compared with the non-straw returning treatment, high dosage wheat straw mulching significantly increased the soil moisture(P<0.05), and increased with the increase of wheat straw mulching. The soil water content of M0 field maintained at 20.79%-21.70% during the whole growth period of cotton, while that of wheat straw mulching treatments reached 26.25%-35.65%. Wheat straw mulching could also significantly promote the rapid growth of cotton and improve the chlorophyll synthesis of leaves, but with the increase of straw mulching, there was no significant effect on them(P>0.05). In addition, high dosage wheat straw mulching significantly increased the numbers of branches, buds and bolls. The number of branches and bolls of the M0 treatments were only 8.0 and 10.7 at the boll opening stage, while the treatments of wheat straw could reach 12.2-13.2 and 25.9-29.9.【Conclusion】Wheat straw mulching contributes to weed control and regulating the growth and development of cotton and yield formation by one-time application for 15000 kg/ha after seedling thinning in Yangtze River Basin, which can reduce the input of chemical herbicide and chemical fertilizer.