| Water storage pit irrigation is a micro-irrigation system that applies rainwater,irrigation water or fertilizer to the root zone of the crop through the wall of the storage pit.The method has the characteristics of water retention,fertilizer and water and fertilizer integration.Under the condition of water storage pit irrigation,the water distribute in the deep layer of the soil,and the root is induced deeply to promote the growth and development of the deep root system.The root is the main organ of fruit trees to absorb water and nutrients,soil conditions affect the spatial distribution of apple root system,and the growth of root system also affects the formation of fruit tree yield and quality.This paper is based on the dwarf red Fuji 4a apple trees,set up three kinds of deep pit(20cm,40 cm and 60 cm deep pit depth)and three kinds of irrigation on upper and lower limit(the field capacityof 50% to80%,60% to 90% and 70% to100%),meanwhile,surface irrigation(CK)was used as the control.T1 treatment pit is 20 cm deep,and upper and the lower limit of irrigation water is 50% to 80% of the field capacity.T2 treatment pit is 20 cm deep,and upper and the lower limit of irrigation water is 60% to 90% of the field capacity.T3 treatment pit is 20 cm deep,and upper and the lower limit of irrigation water is 70% to 100% of the field capacity.T4 treatment pit is 40 cm deep,and upper and the lower limit of irrigation water is 50% to 80% of the field capacity.T5 treatment pit is 40 cm deep,and upper and the lower limit of irrigation water is 60% to 90% of the field capacity.T6 treatment pit is 40 cm deep,and upper and the lower limit of irrigation water is 70% to 100% of the field capacity.T7 treatment pit is 60 cm deep,and upper and the lower limit of irrigation water is 50% to 80% of the field capacity.T8 treatment pit is 60 cm deep,and upper and the lower limit of irrigation water is 50% to 80% of the field capacity.T9 treatment pit is 60 cm deep,and upper and the lower limit of irrigation water is 70% to 100% of the field capacity.Using field location monitoring,investigation sampling and indoor analysis method,study on spatial and temporal variations of orchard soil moisture,the changes of time and space of the root distribution and fine root dynamics characteristics under water storage pit irrigation.The following main research results are obtained: 1.Dynamic characteristics of soil moisture in orchard under water storage pit irrigation.The soil moisture content is the largest in the near of soil surface and decreases with the increase of soil depth surface irrigation.The changes of vertical soil moisture content of water storage pit irrigation were shown as the increase of soil depth,soil water content was first increased and then decreased.When the upper and lower limits of the irrigation water are the same,the maximum soil moisture content increases with the depth of the pit,and the soil moisture is more obvious to the deep migration,and the position of the maximum soil moisture content increases gradually.When the depth of the pit are the same,the soil moisture content increases gradually with the increase of the upper and lower limit of the irrigation water,and the maximum soil moisture content appears in the same position.The depth of the pit mainly affects the soil water distribution,and the upper and lower limit of irrigation water mainly affect the soil moisture content.Under the influence of both,the distribution condition of soil moisture is changed.During the whole period,the average moisture content of the ground irrigation was lower than that of water storage pit irrigation.The average soil moisture content in the whole growth period increase with the pit depth deepening and,with the increase of upper and the lower limit of irrigation water,namely the pit depth is 60 cm,and upper and the lower limit of irrigation water is 70% to 100% of the field capacity when moist soil moisture content is the highest.2.Characteristics of root growth under water storage pit irrigation.(1)in terms of the root length density of apple tree,the root length density increased first and then decreased with time,and decreased with the deepening of soil depth during the whole bearing period.The distribution of root length density in each growth period showed that the root of surface irrigation was mainly concentrated in the 0-40 cm soil layer,and the root of water storage pit irrigation was mainly concentrated in the 20-80 cm soil layer.The soil depth in the high area of root length is 30-70 cm in the treatment of 40 cm depth,which was more consistent with the root distribution region,which was better than treatment of 20 cm and 60 cm pit depth.Compared with treatment of different upper and lower limit irrigation water,the range of the high-value region of the root length increased gradually.The deep of water storage pit affects the soil layer depth of the high area of root length density,and the upper and lower limit of irrigation water can influence the peak of root length density.The water pit irrigation method can significantly increase the root in the deep soil and induce the root of fruit trees to grow deep.(2)in terms of the root surface area density of apple tree,root surface area density distribution are similar to those of root length density,also show the root surface area density is decreased with the increasing of time,and then decreases with the deepening of soil depth.Apple tree’s root surface area density are mainly distributed in 0-80 cm soil layer,root surface area density focused on 0-60 cm soil layer in surface irrigation treatment,the roots of the water storage pit irrigation treatment focused on 20-80 cm soil layer,shows that a large number of root distribution in the surface soil under surface irrigation,is not conducive to the root absorb the deep soil moisture and nutrients,tree is hard to adapt to arid environment,greatly weakened the stability of fruit trees.Under the condition of water storage pit irrigation,the soil water is transported to a deep level,while the water retention is also relatively good,so as to induce the deep roots growth.The depth of the soil layer in the high value area of the root surface area was 30-50 cm in treatment of 20 cm pit depth,treatment of 40 cm pit depth is 30-60 cm,and treatment of 60 cm pit depth is 40-80 cm.It shows that the surface area of the root surface is moved down with the increase of pit depth.Compared with different irrigation treatments,the peak value of root surface area density in T5 was 1.02 and 1.52 times higher than that of T6 and T4 respectively.3.Dynamic characteristics of fine roots.(1)in terms of the growth dynamics of fine roots,the growth peak of water storage pit irrigation is greater than that of ground irrigation,and the soil depth in the high-value area is different.The high-value area of the ground irrigation treatment is in the range of 20-40 cm soil layer,while the high-value area of the water storage pit irrigation is within the range of 30-60 cm soil layer.It is indicated that the water content in deep soil is high,which can induce deep roots growth.Compared with the growth dynamics of the water storage pit irrigation,the growth of the tree root and save irrigation water were comprehensively considered,T5 was suitable for the growth of the root of the apple tree.(2)in terms of the death dynamics of fine roots,the death dynamics distribution of water storage pit irrigation and ground irrigation is different.Compared with CK and T5,the peak value of death in CK is greater than that of T5,and the depth of soil in the high-value area of death is different.The high value area of death is within the range of 20-90 cm soil layer in CK,while the T5 is within the range of 30-50 cm soil layer.It is suggested that water pit irrigation has a good inhibitory effect on the death of deep root,which is more beneficial to the growth of the apple trees than the surface irrigation.Among them,the T5 has a good inhibitory effect on the death of fine roots.4.The change characteristics turnover of fine roots.(1)in terms of the turnover of total root length,For the turnover rate of 1,the surface irrigation is greater than T2,T6 and T8.For the turnover rate of 2,the treatment of water storage irrigation is lower than that of surface irrigation.It shows that there is a large amount of extant quantity in water storage pit irrigation,and the annual death rate is small.Compared with water storage pit irrigation,T5 was suitable for the growth of fine roots,and the annual growth of fine roots was greater than the annual mortality.(2)in terms of the turnover of fine roots in different soil layers,the surface irrigation treatment each soil layer is the turnover rate of 2 is greater than the turnover rate of 1.Compare the treatment of diffent pit depth,the pit depth of 40 cm is more suitable for the root,the annual growth of fine roots was greater than the annual mortality,as the depth of the soil layer deepens,the gap between the turnover rate of 2 and the turnover rate of 1 is gradually increasing.Compare the treatment of diffent irrigation,of the fine root.At the pit depth of 40 cm,with the increase of irrigation water,the the depth of the soil layer for turnover rate of 1 was deeper than that of the turnover rate of 2.Description of water storage pit irrigation is a kind of deep irrigation,irrigation,The more irrigation,the more water into the deep soil infiltration,which makes the deep soil water content higher,the fine root growth is greater than the fine root death,The turnover rate of 1 is greater than the turnover rate of 2,while the surface soil moisture content is relatively small,and the death rate of fine root is greater than that of fine root growth,and the turnover rate of 2 is greater than that of turnover 1. |
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