| Shortage of water resource has become a bottlenecks factor which seriously restricts agriculture of Xinjiang and the entire national economy sustainable development, in order to ensure sustainable development of industry, agriculture and economy, to construct water-saving society, water-saving agriculture must be developed, and so water-saving irrigation technique plays a decisive role in Xinjiang. The most important water-saving irrigation technique at present in Xinjiang is mulched drip irrigation, but it results in serious plastic film pollution problems. Compared with the mulched drip irrigation, subsurface drip irrigation (SDI) could isolate the dry air from the following moist soil, which does not need adopting film but could achieve the effect of inhibiting evaporation and water-saving. But the problems are for the clogging of emitters, eliability and uniformity of dropping, and seedling emergence and seedling irrigation, which constrain its development. Target at the above problems, this paper puts forward transplantation cotton without film technique under subsurface drip irrigation, combining subsurface drip irrigation technique with transplantation technique. This article took cotton as material, through tested holes and plot experiments, studied the influence of different cultivation patterns, transplantation time, gradual-seeding irrigation, irrigation quota and irrigation times on cotton growth and yield; because of adopting transplantation without film, its soil water movement, water requirement principle and so on are different from general subsurface drip irrigation and mulched drip irrigation, which has its own character. To study the influence of the above each factor on the cotton growth and yield transplantation without film under subsurface drip irrigation and its water requirement principle, and build water production function, to attain northern area irrigation system of transplantation cotton without film under subsurface drip irrigation.The main conclusions and findings are as follows:(1) Through two-year plot experiments, under the subsurface drip irrigation, whatever is cotton growth or yield, even water production efficiency, transplantation cotton without film has some advantages over directly sowing cotton with film. Therefore, to adopt transplantation cotton without film under subsurface drip irrigation has no adverse effect on cotton growth and yield, at the same time, which is favorable to solve plastic film pollution problems.(2) Through studying the influence of transplantation time on cotton, to determine the suitable temperature during the transplantation period which must be over 15℃, daily average temperature of underground 10cm should be stable over 17℃,suitable daily average temperature is 18.4～20℃, daily maximum temperature is 26.2～27.2℃, daily average temperature of underground 10cm is 20.92-22.22℃, daily maximum geothermal is 27.5-28.1℃; daily average geothermal of underground 15cm is 20.26-21.41℃, daily maximum geothermal is 24.6～25.1℃, daily lowest effective accumulated temperature after transplantation is 66.46-70.65℃, daily highest effective accumulated temperature is78.08-83.28℃, accumulated temperature of geothermal with 10cm is 104.72～106.71℃in transplantation period.Moreover,transplantation cotton without film should end early May, while cotton leaves should be 2-3,seeding age should be about 30 days during transplantation, but the specific transplantation time also should consider the local climate and seeding age conditions.(3) Irrigation with many times is generally to cotton growth and increase its yield transplantation without film under subsurface drip irrigation, especially for medium-scale irrigation treatment (390-450mm), taking yield and water utilization efficiency into account comprehensively, to adopt the method which combines irrigation quota(309-450 mm) with irrigation times(19 times) to irrigation, which is more conducive to high yield and high efficiency transplantation cotton without film under subsurface drip irrigation.(4) Water requirement in the whole growth stage transplantation cotton without film under subsurface drip irrigation show "slow-fast-slow" variation principle, water requirement is relatively small in early stage, both water requirement and water requirement intensity are at peak during the boll stage, and then they decrease to vary degree during the boll opening stage. Thee general variation trend of dry mass accumulation is consistent with water requirement, as "S"-type changes. As for as the dry mass accumulation change for each treatment with different organs are considered, dry mass accumulation of stems and leaves are into the critical period in the bud stage, but bud and bell are into critical stage in the flowering stage, which are at its peak in the belling stage. Both maximum values of both daily gains for dry mass and daily water requirement are in boll stage, daily gain for dry mass is between3.79 g and 4.99g, the daily average water requirement is between 4.88mm and 7.41mm.(5) To establish water production function of the whole growth period regarding actual irrigation quota, evapotranspiration as the independent variable, through analyzing the relationship between irrigation quota, evapotranspiration and corresponding seeding cotton yield, and taking the water production efficiency into account, to determine finally suitable irrigation quota which is 457mm in studied year, irrigation times is 19 times transplantation cotton without film under subsurface drip irrigation, establishing northern area cotton irrigation system with high water efficiency and yield(see as table 5-2)... |
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