| Apple industry is an important pillar industry of agricultural economic development in Shaanxi Province. However, these apple producing areas are generally short of water resources with backward irrigation method and extensive irrigation management, resulting of lower water use efficiency and water demand over supply in apple orchard, and seriously restrict the development of high yield and efficiency apple industry in Shaanxi. Thus, in order to ensure high yield and quality, it is of great importance to make use of limited water resources rationally and efficiently. Therefore, we carried out the supplementary irrigation in apple testing base of Tuojiahe reservoir management division in Luochuan country, Shanxi province, over the growing seasons of 2014-2015, soil water dynamics, water consumption rules and the effects of different supplementary irrigation treatments on growth characteristics,yield, quality of apple tree. Monthly meteorological data of 27 weather stations in Shaanxi during 1961-2013 and Penman-Monteith equation were used to estimate ET0 at month time scale, crop coefficient and ETc(evapotranspiration) was determined by FAO based on measured apple tree Kc(crop coefficient). Making use of software ArcGIS10.2’s inverse distance weighted spatial interpolation analysis function, the spatial distribution of average annual meteorologic factors, ETc and NIR(net irrigation requirements) of apple in the growth period in Shaanxi can be obtained. Mann-Kendall method was used to analyze the change trends of ETc. Four represent planting sites in each of four superior climate zone of apple were selected to get information on long series of climate data, crop coefficient and soil conditions.ETc(evapotranspiration) was determined by FAO based on measured apple tree Kc(crop coefficient), To calculate the accurate irrigation water quota during the growth period in different hydrological years, water balance method was applied to calculate water balance processes by using ten days period as time unit. The main achievements were as follows:(1) Seasonal dynamics of soil moisture is characterized as: In spring(March to May), as the day warms up, the apple tree complete the bud flowering and fruit set with less precipitation, resulting of soil water consumping of the last year; In summer(June to August),temperature and precipitation gradually reached the highest level of the year, the middle maturity apple varieties form crown canopy and finished fruit expansion, both surface(0~1m)and deep(1~2m) soil moisture are constantly consumed, the consumption value has come to the maximum and it is also the main period of supplementary irrigation; in fall(Sep. to Orc.),the consumption value decreasing gradually and both surface and deep soil moisture has come to the recovery phase, however, the soil moisture restoration of deep soil depends on the precipitation and irrigation.(2) The water consumption value of apple tree is influenced by rainfall and supplementary irrigation in the current year. The differences of consumption value are small in wet year. The water consumption of all irrigated treatments are higher than rainfed treatment, and the differences of consumption value between high irrigation amount and low treatment is bigger, the value is 42.0 and 33.0mm for drip and pipe irrigation respectively. In local, the apple tree July is the maximum water demand stage, April to May is the water-sensitive stage, Early May to late June is the critical water stage, and these water demand stages are not synchronize.(3) Both shoot length and fruit volume are gradually increasing with irrigation volume increases, the fruit growth curve approximating “S”. High water supplementary irrigation(DI3and PI3) promote the shoot growth and fruit expansion of Gala, however, redundant shoots may cause canopy closure, thus restricting fruit growth, and under medium and low supplementary irrigation level, the vegetative growth is suppressed, while under medium supplementary irrigation level, the apple tree’s vegetative growth is suppressed with less impact on fruit volume.(4) Supplementary irrigation can improve the production of apple, and a moderate reduction of water consumption is beneficial to the improvement of the water use efficiency.The effect of high supplementary irrigation on improving fruit quality is indistinct. In terms of production and fruit quality only, DI2 and PI2 can improve water use efficiency and fruit quality with a slight decline in production.(5) The evapotranspiration of apple during apple growth period(Apri to Orc.) in study area was 400~700mm, in general, from the north to the south, from the east to the west,cET decreased gradually. Mann-Kendall trend analysis showed that the trend ofcET is not significant in the inter annual variation. The net irrigation requirement at different frequency years were generally declining consistent withcET, on an average for many years, Thehighest values of NIR are located in Yulin and Weinan region(230~320mm), the lowest values are located in Baoji(15~100mm), and the medium values are located in Yan’an,Tongchuan and Xianyang(100~200mm). At 25% frequency year, the net irrigation requirement for the highest,and lowest values zone is 100~250mm and 0mm, which, at 50%frequency year, is 200~315mm and 15~100mm, at 75% frequency year, is 350~480mm and100~250mm, and at 90% frequency year is 400~530mm and 180~300mm. From its change trends of 27 stations, only Luochuan, Tongchuan, Changwu, Fufeng, Liquan, Yaoxian and Linyou show a downward trend, Suide increased significantly(P<0.05) and Baojixian very significant increased(P<0.01), while other stations are not significant. Generally, the irrigation water requirement of apple in research area showed an increasing trend.(6) Generally, the study area is moderately depending on irrigation, the irrigation requirement index varied from 0.03 to 0.51. The lowest values are located in the southwest region, and there is little need for irrigation in some areas, the highest values are located in the northeast and southeast.(7) Compared with full irrigation, non-sufficient irrigation postponed irrigation time with reduced irrigation quota and irrigation times, moreover, the water saving effect is more remarkable as drought conditions worsen. The overall trend of irrigation water quota is as follows: the eastern tableland area of Weibei plateau> hilly and gully area of northern Shaaxi > Weibei Plateau Gully Area> the western tableland area of Weibei plateau; the apple of Shaanxi need irrigation in different hydrological years except that Qianyang(the western tableland area of Weibei plateau) don’t need irrigate in rainy years, the irrigation water quota increased gradually with worsening drought conditions, under drip irrigation, irrigation quota in different hydrological years(the frequency of net irrigation water requirement was 25% for rainy years, 50% for normal years, 75% for dry years and 90% for extreme drought years) for Hilly and gully region of northern Shaanxi under sufficient irrigation scheduling was 45, 60,80, 110 mm, respectively, under non-sufficient irrigation scheduling was 30, 50, 75, 100 mm,respectively; for Weibei Plateau Gully Area under sufficient irrigation scheduling was 15, 30,60, 85 mm, respectively, under non-sufficient irrigation scheduling was 10, 25, 55, 80 mm,respectively; for the western tableland area of Weibei plateau, under sufficient irrigation scheduling, irrigation was not need in rainy years, for normal years, dry years and extreme drought years were, respectively, 10, 30, 75 mm, under non-sufficient irrigation scheduling,only drought and extreme drought years should irrigate, the irrigation quota were, respectively,20 and 70 mm; for the eastern tableland area of Weibei plateau under sufficient irrigation scheduling was 60, 75, 105, 120 mm, respectively, under non-sufficient irrigation scheduling was 30, 60, 80, 105 mm, respectively. |
PDF Full Text Request