| Field experiments were conducted to investigate the effects of different irrigation amounts,emitter discharges and capillary arrangements on cotton at the 31st Regiment in Korla of Xinjiang from April to October during 2018(86°56?58?E,40°53?03?N).Three drip irrigation levels,designated as full irrigation(W3:100%ET_c,ET_c is the crop evapotranspiration),moderate irrigation(W2:80%ET_c)and low irrigation(W1:60%ET_c),two emitter discharges(1.8 L/h and 2.4 L/h)and two capillary arrangements(the narrow row arrangement(N)in the middle of the two narrow rows and the wide row arrangement(M)of the local common machine sowing)were applied in the experiments,with a total of 12treatments.Understanding of the effects of different irrigation amounts,emitter discharges and capillary arrangements on cotton growth,yield,water use efficiency,nutrient absorption and utilization,the law of soil water and salt change and transport law of nitrate nitrogen in soil under drip irrigation under mulch.The main conclusions are as follows:(1)The results of the experiment showed that different irrigation amounts,emitter discharges and capillary arrangements have significant influence on cotton growth.Under the same emitter discharge and capillary arrangements,the plant height,stem diameter,LAI,dry mass accumulation increased with the increase of irrigation amount;.Under the same irrigation amounts and capillary arrangements,the plant height,stem diameter,LAI,dry mass accumulation of D2.4 were significantly higher than those of D1.8;Under the same irrigation amounts and emitter discharges,the plant height,stem diameter,LAI,dry mass accumulation of M were significantly higher than those of N.The interaction between the three factors had significant effects on cotton growth and dry matter accumulation,the W3D2.4M had the best growth and the highest dry matter accumulation of 29065.82 kg/hm~2?(2)The results of the experiment showed that different irrigation amounts,emitter discharges and capillary arrangements have significant influence on cotton seed cotton yield and its components,nitrogen accumulation,WUE and IWUE were significant.Under the same emitter discharge and capillary arrangements,the seed cotton yield,effective boll number and nitrogen accumulation increased with the increase of irrigation amount,showed that W3>W2>W1,the nitrogen accumulation of different organs showed that cotton boll>leaf>stem;but the WUE and IWUE decreased with the increase of irrigation amount.Under the same irrigation amounts and capillary arrangements,the seed cotton yield,100boll weight,effective bolls per plant and IWUE of D2.4 treatment were significantly higher than those of D1.8 treatment;Under the same irrigation amounts and emitter discharges,the wide row arrangement(M)is more suitable for cotton to grow,the WUE and IWUE of M were significantly higher than those of N,the wide row arrangement(M)was more suitable for cotton growth.W3D2.4M has the highest seed cotton yield of 7346.48 kg/hm~2.(3)The effects of irrigation amounts,emitter discharges and capillary arrangements on soil moisture and inorganic nitrogen transport in cotton field were studied.Soil moisture content increases with the increase of irrigation amount;Under the same irrigation amounts and capillary arrangements,the uniformity of D2.4 is better on the main root area(0-40 cm,and the soil moisture content under the emitter flow is higher.Under the same irrigation amounts and emitter discharges,the soil moisture content in the membrane with wide row arrangement(M)is higher.The results of the experiment showed that different irrigation amounts have significant influence on soil nitrate nitrogen content,showed W1>W2>W3.In the vertical direction,with the deepening of the soil layer,it shows a trend of increasing first and then decreasing.Under the same irrigation amounts and capillary arrangements,the content of soil nitrate nitrogen decreases with the increase of emitter flow.(4)The effects of the experiment showed that different irrigation amounts,emitter discharges and capillary arrangements have significant influence on salt distribution were analyzed,with the development of soil growth,the average salt content of the whole soil layer changed little,but the salt distribution in the main root zone(0-40 cm)of cotton showed an upward trend,and the salt content under the emitter flow was generally low.In the horizontal direction,the salt distribution in the soil moved from the inside of the wet body to the edge,and the salt accumulation in the bare land was obvious.In the vertical direction,the salt content in the surface layer was relatively low.Salt accumulates around50 cm,the salt content of 50-80 cm soil layer was relatively lower.Under the same emitter discharges and capillary arrangements,soil salt content decreased with the increase of irrigation.Under the same irrigation amount and capillary arrangements,the uniformity of soil water distribution in the main root zone(0-40 cm)of D2.4 treatment was better,and the salt content was lower.The water salt distribution of W3D2.4M treatment was the most suitable for cotton growth.(5)Considering cotton growth,yield and soil water,fertilizer and salt transport law comprehensively,irrigation amount of 100%ET_c,emitter discharge of 2.4 L/h and capillary arrangement of wide row(M)is the most appropriate combination of irrigation parameters. |
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