| Turpan and Kumul, famous for their grapes in the world, serve as renowned grape production base and at the same time they are also located in the region where water resource is severely short. At present backward grape irrigation mode is still practised there and the majority of this region still keeps the traditional ground irrigation method, so that irrigation quotas can reach as much as1800m3per mu. Though grape micro-irrigation technique was introduced and practised in this area since the1980s, successful mode of irrigation hasn’t been obtained so far. Therefore, this research and study is aimed at the problems existing in the application of microirrigation technique in grown-up grapes and a series of investigations were carried out to find out the rules of water requirement, features of water consumption, screening and optimization of microirrigation technique, field experiment study on comprehensive regulation and control techniques of agricultural water saving. The following are experimental results of research and study in three years:(1) Analysis was made on near45years’interannual change features of every climatic change factors, the results of which showed that the temperature and rainfall in Turpan and Kumul were on the rise while wind speed was in the trend of notable decrease. There were dramatic changes in temperature and wind speed in the middle of1980s.The reference evaporation in Turpan and Kumul was in the trend of fluctuating decrease and dramatic changes occurred in1986. Correlation degree analysis showed that there was biggest correlation between wind speed and reference evaporation in both seasonal climate variables and yearly climate variables.(2) Based on climate environment in Turpan and Kumul, analysis and evaluation was made on the transpiration calculation model that is frequently used at present, the results of which showed that model of Blany-Criddle was characterized with the least parameters, convenience in data collection and classification and high computational accuracy, which showed notable correlationship with the computational results through model FAO56-PM. Therefore, Blany-Criddle model can be adopted to calculate evapotranspiration quantity of reference crop in Turpan region.(3) Based on formula Penman-Monteith and climatic features in Turpan region, formula Penman-Monteith had been simplified, leaving out parameter saturation deficiency. The relations between potential evapotranspiration of reference crop ETO(PM) through formula Penman-Monteith and potential evapotranspiration of reference crop ETO through simplified formula showed that there was favorable linear relationship. Simplified formula Penman-Monteith not only required less monitoring items to make computation easier, but also much less expenses and human resources were required because of decrease in monitoring items.(4) In cloudless and fine days, daily change of every component of water and heat balance in the vineyard was in typical unimodal curve. Latent heat, sensible heat and soil heat flux increased and decreased corresponding to the increase and decrease of net radiation, but the peak value appeared in different times. Latent heat flux took up the majority of the expenditure of net radiation, whose changing rules showed the best consistency with the daily changing rules of net radiation. Mild changes showed in soil heat flux and its trend was almost the same with that of net radiation, but behind the trend of net radiation2-3h.(5)In cloudless and fine days, the change of daytime evapotranspiration rate of grapes was in unimodal pattern. Evapotranspiration appeared after8:00in the morning with rapid increase afterwards and reached peak value at13:00-14:00at noon with rapid decrease corresponding to evapotranspiration rate. Water consumption by grapes in the whole growing period was in unimodal curve which was on the rise first and on the fall then. The total water consumption by grapes was about1200mm and its daily average water consumption intensity was about5.0mm/d, which could reach as much as8.78mm/d in fruit swelling period. Sensitive period of grape’s water consumption is fruit swelling period, followed by budding leaves, burgeoning period and fruit maturity period and maturity period of branches and tendrils.(6) In the whole growing period, the irrigation quotas in gobi gravel area was higher than that of loam area. In gobi gravel area, the irrigation quotas in the condition of dependable crop is765m3per mu a year and irrigation quotas was35m3per mu at one time. The irrigation period is determined by water need critical and uncritical period, the latter of which lasts7to9days while the former of which lasts3to5days. In loam area, the irrigation quotas are670m3per mu a year and irrigation quotas is30m3at one time. In this area, critical irrigation period lasts9to13days while uncritical irrigation period lasts5to7days.(7) In loam area in Turpan and Kumul basin with extreme arid weather, where traditional farming practice has been adopted, the distribution range of grown-up grape’s root system is comparatively smaller, so it would be better to adopt arrangement mode of one-ditch with two pipes; while in gravel land which is under improvement, the distribution range of grown-up grape’s root system is comparatively larger, so it would be better to adopt arrangement mode of one-ditch with three pipes.(8) In accordance of the arid and severe environmental conditions in Turpan and Kumul region, mist microenvironmental monitoring technology in vineyard crown were developed, through which grapes were strengthened to struggle against severe environment and through which the purpose of production increase and quality improvement could be realized. Compared with conventional microirrigation technology, grapes were sprayed7～8m3at each time for4to5times and the daytime highest temperature under grape arbor could be notably lowered by3to8℃, which could stop high temperature from scorching grapes, enabling grapes’ yield to increase by17%and its commodity rate to increase by20%.(9) Application of antitranspirant in the vineyard showed that spray of antitranspirant could effectively prevent transpiration in the vineyard and lower transpiration rate on grapes leaves, that the application could notably improve photosynthesis in grape leaves and water use efficiency, that more importantly grape yield could be raised by as much as20%, that the period of validity of using antitranspirant could last about9days, and that there were slight differences in period of validity among different antitranspirants.(10) Research and study also involved the measure of soil moisture conservation through the use of plastic film and straw curtain. The results showed that because of the measures to preserve soil moisture, contact surface between soil surface and air had been decreased so that soil moisture was obviously stopped from being evaporated, that the measure could sharply enable soil to retain water and preserve soil moisture and that the measure of soil moisture conservation was advantageous in growth of new shoots, average weight of fruit grain, yield and other aspects over the contrast group where no such measure was adopted.(11) The research also involved soil conditions in Turpan and Kumul where the soil is rich in gravels in some area, and the soil is poor in retaining water and where deep percolation has been serious. Research was conducted in using water-retaining agents in the soil rich in gravels. The result showed that the use of water-retaining agents could effectively retain water from irrigation, that water use efficiency was raised sharply, and that grape plants were strengthened so that quality of grapes and its yield were improved at the same time.(12) This research and study have been conducted on comprehensive monitoring water consumption to further improve water use efficiency in farmland. The research and study involved a series of measures and techniques, such as the technique of crown layer’s environmental regulation and control to decrease large quantity of transpiration, application of antitranspirants and the measure to cover the surface soil to decrease useless evaporation and to preserve soil moisture, and the technique that combined water-retaining and soil moisture conservation to prevent water in root system from leakage loss with fine-tuning dripping irrigation technique, thus forming a comprehensive mode to monitor and control the use of water and fertilizer, in which water-saving agricultural technology was made use of in the interface between grown-up grape’s crown layer and air, the interface between soil and air, and the interface between root system and soil. |
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