| Loess hilly and gully region in North Shaanxi is suitable for the production of high-quality apples due to its superior soil resources and unique climatic conditions and hillside apple industry has gradually become the largest local characteristic industry. But the area rainfall is small and uneven distribution, coupled with the strong sunshine and dry air, soil water evaporation loss quickly, hilly apple orchard seasonal drought and water shortage serious. Efficient irrigation using limited rain water resources is an effective way to improve the soil water environment of the hilly apple orchard. Aiming at the key problem of water resources waste caused by low utilization ratio of irrigation water in apple production, so combine the rainwater infiltration promotion pipe and traditional trickle-irrigation to be assembled and integrated into a new water-saving irrigation technology: the root-area trickle-irrigation. In order to discuss the application effect of the root-area trick-irrigation in hilly orchard, explore the differences of apple trees’ growth and fruit when soil water condition in hilly orchard reaches standards of the eugenic area and provide scientific basis for development of water saving irrigation technique. The six-year Fuji apple trees in hilly areas of Mizhi County was adopted as the research object, the precipitation and soil water storage capacity of optimal apple eugenic area Luochuan County was used as the trickle-irrigation basis, compared with hole-irrigation method and traditional trickle-irrigation method. The influence of different irrigation methods on soil water distribution, water use efficiency, budding, fruit setting, branches and leaves growth, fruit development was analyzed, as well as the differences between apple trees growing in hilly orchard and eugenic area. Main research results are as follows:(1) The root-area trickle-irrigation technique can increase infiltration depth of irrigation water, reduce evaporation loss, effectively improve soil water content of 40~60cm soil layer, improve soil moisture environment of hilly apple orchard, achieve a longer time to apple trees’ water supply, and remit the water stress condition of apple trees in dry season. During the dry season(April 1- July 16), compared with traditional trickle-irrigation and hole-irrigation. The average soil water storage capacity increased by 5.92~6.29% and 10.45~11.87%.(2) The root-area trickle-irrigation technique can promote apple trees to sprout and bear fruits to significantly improve the germination rate and fruit setting rate of apple trees, make apple trees to grow branches and leaves as soon as possible and increase the fruiting quantities. Compared with traditional trickle-irrigation and hole-irrigation. The germination rate increased by 2.77~3.46% and 4.05~5.24%. The fruit setting rate increased by 1.42~2.53% and 1.42~2.53%.(3) The root-area trickle-irrigation technique can promote the growth of new treetop of apple trees and significantly improve the new treetop length, new treetop thickness and proportion of medium and long branches of apple trees, which is in favor of the development of medium and long branches of apple trees and makes apple trees form bearing branch groups in advance. Compared with traditional trickle-irrigation and hole-irrigation. The proportion of middle long branches increased by 1.3~2.4% and 3.7~3.8%.(4) The root-area trickle-irrigation technique can promote the growth of leaves of apple trees and significantly improve the relative water content, fresh weight per 100 leaves, leaves area and thickness of apple trees for the better photosynthesis. Compared with traditional trickle-irrigation and hole-irrigation. The leaf relative water content increased by 1.64~5.14% and 4.62~8.87%. The fresh weight per 100 leaves increased by 1.02~3.80% and 2.46~4.99%.(5) The root-area trickle-irrigation technique can promote the fruit development of apple trees and significantly improve the transverse and longitudinal diameter of fruit, fruit shape index, excellent fruit rate, single fruit weight and apple yield of apple trees, so increase economic benefit of the orchard. Compared with traditional trickle-irrigation and hole-irrigation. The excellent fruit rate increased by 9.3~16.4% and 20.2~34.1%. The single fruit weight increased by 0.97~1.52% and 2.20~3.18%. The apple yield increased by 7.51~8.01% and 13.59~13.88%.(6) The root-area trickle-irrigation technique can save irrigation water resources and significantly improve the water utilization efficiency of apple trees and make the water-saving and yield-increasing effect the best. Compared with traditional trickle-irrigation and hole-irrigation. The amount of irrigation water was saved by 16.88% and 29.19%. The water utilization efficiency increased by 10.17~15.28% and 16.93~31.45%.In summary, the root-area trickle-irrigation technique shows broad application prospect for hilly apple orchard in loess hilly region of North Shaanxi. However, if only relying on artificial limited watering, hillside apple production can not reach production level of the eugenic area. |
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