| The Loess Plateau is a typical ecological fragile area in China because of its harsh natural environment.As one of the main contents of the ecological agriculture,the fruit crop intercropping system which is widely used by local farmers can improve the land use efficiency,reduce soil erosion and increase the economic income.With the increase of intercropping years,the contradiction between fruit trees and crops is becoming more and more serious.The sharing of resources between fruit trees and crops in the intercropping system will inevitably lead to competition.With the increase of intercropping years,the competition for water,fertilizer and light between fruit trees and crops will become more and more prominent.In order to coordinate the competition relationship between fruit trees and crops,this paper took apple peanut intercropping system with different intercropping years(3 years,5 years and 7 years)on the Loess Plateau of west Shanxi Province as research object.Soil moisture content which is between two rows of apple trees(spacing of 5m)and at different distances from the apple trees was monitored by oven drying method and analyzed the spatial distribution of soil moisture,the main competition areas of soil moisture,the growth characteristics,biomass and yield of fruit trees and peanut to improve the productivity and soil water use efficiency of fruit crop intercropping system in this region and finally provide theoretical support for the efficient and sustainable management of fruit crop intercropping system.The results showed that:(1)Compared with peanut monoculture system and apple monoculture system,the soil moisture of apple peanut intercropping system in 3 kinds of intercropping years showed negative effect.Under certain conditions,with the increase of intercropping years,the soil moisture content of apple peanut intercropping system decreased gradually,and the difference was significant(P<0.05).With the increase of intercropping years,the soil moisture content of apple peanut intercropping system decreased gradually,and the difference was significant(P<0.05).Compared with peanut monoculture system and apple trees monoculture system,the soil moisture of 3 kinds of apple peanut intercropping system with different intercropping years all showed negative effect.When the intercropping years was 3,the average soil moisture content was 19.54%,16.09%,13.57%and 14.27%at the seedling stage,flowering stage,podding stage and mature stage of peanut.Compared with peanut monoculture system,the average of soil moisture content in intercropping system decreased by 18.36%,15.86%,19.92%and 18.51%;the average of soil moisture content in intercropping system decreased by 8.62%?5.97%?12.87%and 10.14%compared with apple trees monoculture system.When the intercropping years was 5,the soil moisture content of apple peanut intercropping system were not more than 20%in different phenophases(including seeding stage,flowering stage,bearing pod stage and mature stage)of peanut.The average of soil moisture content in intercropping system decreased by 41.97%,42.42%,49.25%,42.72%and 23.43%,31.76%,36.52%,29.04%compared with peanut monoculture system and apple trees monoculture system.When the intercropping years was 7,the average soil moisture content showed seeding stage(13.89%)>flowering stage(11.01%)>mature period(10.24%)>pod stage(8.60%)and had a certain degree of reduction compared with the corresponding monoculture system.The soil moisture content of the intercropping system with different intercropping years has the same distribution regularity.In the vertical direction,the soil moisture content increased with the increase of soil depth.In the horizontal direction,taking 2.5m from apple trees as the dividing line,soil moisture content increased at first and then decreased with the increase of the distance from trees,and showed just like a parabolic upward opening.(2)When the intercropping period is 3,the main competition area of soil moisture and the competition width in apple peanut intercropping system can not be determined quantitatively.When the intercropping years is 5 years and 7 years,the main competition area of soil moisture and the competition width n apple peanut intercropping system can be effectively determined.Taking into account the four phenological periods of peanut,the main competition area when the intercropping years is 5 was 0.7m-1.9m away from the south side of apple trees and 0.5m-1.7m away from the north side of apple trees,where the competitive width is 1.2m.The main competition area when the intercropping years is 7 was 0.5m-1.9m away from the south side of apple trees and 0.7m-1.9m for the north side and the competing widths are 1.4m and 1.2m,respectively.(3)When the intercropping years was 3,5,7,the fruit tree heigh of apple peanut intercropping system were 2.14m,2.67m and 3.04m,decreasing by 4.04%,4.30%and 4.10%compared the monoculture system.The greater the peanut intercropping years,the average plant height of peanut is lower,the peanut monocropping system(20.62cm)>intercropping years was 3(19.09cm)>intercropping years was 5(12.55cm)>intercropping years was 7(9.43cm).There was no significant difference in chlorophyll content of apple trees between different intercropping years.The average value of chlorophyll content in peanut leaves decreased gradually with the increase of intercropping years,and the lowest value appeared at 17.92 mg·m2 in peanut seedling.With the increase of intercropping years,the root dry weight,stem quality,leaf dry mass and total biomass of peanut intercropping system were decreased to some extent,and the degree was more obvious when the intercropping years is greater.When the intercropping years is 3 and 5,the apple peanut intercropping system and the apple trees monoculture system have yet to be fruitful.When the intercropping years is 7,the yield(12973kg/hm2)of the apple trees monoculture system is larger than that of intercropping system(11875 kg/hm2).(4)It is suggested that the pruning,pull and other measures,or increasing the intercropping distance and even being interrupted should be taken to the fruit trees without affecting the growth and development of the fruit trees.It is also suggested during the seedling stage and flowering period of peanut,the main competition area of soil moisture in the intercropping system was covered with film or plant straw mulching to reduce the soil moisture evaporation.At the same time,the rainwater accumulation project was constructed according to the terrain,so that the rainfall can be enriched and lead to the main competitive areas of soil moisture thereby enhancing the rainfall productivity and increasing economic benefits of the apple peanut intercropping system. |
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