Abstract:To investigate the effects of installation depths of water-conduct device on root distribution and root growth in dwarf close planting jujube under indirect subsurface drip irrigation (ISDI), three installation depths of water-conduct device were considered in the experiment. The installation depths of water-conduct device were 20cm (T1), 27cm (T2) and 35cm (T3), respectively, with surface drip irrigation (DI) as comparison. Different depths, horizontal distances of jujube roots system distribution were obtained by annular ditch layered methods, the results showed that there were significant differences in jujube roots system distribution under DI and ISDI. On root morphology, root distributions were shallow and horizontal extension under DI. The distribution of root in different soil layers was uniform, and growth direction of root was basically downward under ISDI. ISDI significantly increased the root length density of fine roots (d＜5mm), which increased by 1~2 times than that of DI. Root length density of d>5mm and root system distribution distance in horizontal direction were reduced, and the proportion of fine root length in 20~40cm soil layer was increased. With the increase of depth of water-conduct device, the root length density of fine roots (d＜2mm) was decreased in 0~20cm soil layer and increased gradually in 20~60cm in vertical direction under ISDI. In horizontal direction, the fine root length density of each treatment was comparatively concentrated distribution in 0~20cm soil layer，70% of root was distributed in horizontal range of 0 ~ 20cm, the fine root distribution distance of each treatment was increased. With the increase of depth of water-conduct device, the horizontal distribution distances of roots of different diameter in 0~20cm soil layer tended to be reduced, but that in 20~40cm soil layer tended to be increased. Generally, with the increase of depth of water-conduct device, fine root distribution showed developing trend from shallow and wide to narrow and deep.
