摘要
The authors studied the effects using three different levels of irrigation on the growth and biomass allocation in H. ammodendron and T. ramosissima seedlings in the shelterbelt along the Tarim Desert Highway. The three irrigation amounts were 35 (CK), 24.5 (treatment 1), and 14 (treatment 2) kg·ind. plant-1·once-1, respectively. The results show that (1) the vertical depth of the two seedlings’ root increased with lower levels of irrigation showing that the two species adapted to decreased irrigation by root elongation in the hinterland of the Taklimakan Desert, and the vertical root depth of H. ammodendron under treatment 2 was notably higher than CK. (2) Compared with CK, the belowground biomass of treatment 1 and 2 both showed a significant increase as follows: H. ammodendron seedlings in- creased by 14.51% and 37.03% under treatment 1 and 2, respectively, while T. ramosissima seedlings increased by 68.19% and 25.78% under treatment 1 and 2, respectively. This means that H. ammoden- dron seedlings were more adapted to the conditions in treatment 2 while T. ramosissima seedlings were better adapted to treatment 1 conditions. (3) When compared with CK, the fine root bomass of these two species all exhibited some increase under both treatments, and ANOVA analysis showed that the biomass of deep layer root of the two species under treatment 2 was notably higher than CK and treatment 1. This should help seedlings to more effectively absorb soil water from deep layers during dry conditions. (4) The root-shoot ratio was different for these two species. For H. ammodendron seed- lings, the root-shoot ratio was less than 1, while for T. ramosissim seedlings it was larger than 1. The root-shoot ratio of H. ammodendron seedlings increased with decreasing levels of irrigation, and that of T. ramosissim seedlings also increased under treatment 2. (5) With decreasing levels of irrigation, due to the difference of species, the growth variation of aboveground indexes was also different, while compared with CK, it was not significant.
The authors studied the effects using three different levels of irrigation on the growth and biomass allocation in H. ammodendron and T. ramosissima seedlings in the shelterbelt along the Tarim Desert Highway. The three irrigation amounts were 35 (CK), 24.5 (treatment 1), and 14 (treatment 2) kg·ind. plant?1·once?1, respectively. The results show that (1) the vertical depth of the two seedlings’ root increased with lower levels of irrigation showing that the two species adapted to decreased irrigation by root elongation in the hinterland of the Taklimakan Desert, and the vertical root depth of H. ammodendron under treatment 2 was notably higher than CK. (2) Compared with CK, the belowground biomass of treatment 1 and 2 both showed a significant increase as follows: H. ammodendron seedlings increased by 14.51% and 37.03% under treatment 1 and 2, respectively, while T. ramosissima seedlings increased by 68.19% and 25.78% under treatment 1 and 2, respectively. This means that H. ammodendron seedlings were more adapted to the conditions in treatment 2 while T. ramosissima seedlings were better adapted to treatment 1 conditions. (3) When compared with CK, the fine root bomass of these two species all exhibited some increase under both treatments, and ANOVA analysis showed that the biomass of deep layer root of the two species under treatment 2 was notably higher than CK and treatment 1. This should help seedlings to more effectively absorb soil water from deep layers during dry conditions. (4) The root-shoot ratio was different for these two species. For H. ammodendron seedlings, the root-shoot ratio was less than 1, while for T. ramosissim seedlings it was larger than 1. The root-shoot ratio of H. ammodendron seedlings increased with decreasing levels of irrigation, and that of T. ramosissim seedlings also increased under treatment 2. (5) With decreasing levels of irrigation, due to the difference of species, the growth variation of aboveground indexes was also different, while compared with CK, it was not significant.
基金
Supported by Major Orientation Foundation of the CAS Innovation Program (Grant No. KZCX3-SW-342)
Research Developing Planning Program of National High and New Technology of China (Grant No. 2004BA901A21-1)
