The Effect Of Exogenous NAA On Photoassimilate Reallocation Of Poplar

The paper studied on the effect of exogenous NAA on photoassimilate reallocation of Populus×euramericana'Nanlin 895'. The results were as follows:1. The sugar transport and distribution in Populus×euramericana'Nanlin895'aseptic seedling followed the principle of subjective need. AI activity in stems was significantly higher than that in roots of Populus×euramericana'Nanlin 895', the NI activity in stems was similar with that in roots. It was shown that sink strength of stems was stronger than the roots. Also, the high SPS, SS activities in roots and stems were more beneficial to transport from leaves to roots and stems.2. The activities of sucrose-metabolizing enzymes and contents of chlorophyll were improved by appropriate concentration NAA (especially 10mg/L) treatments, and it would reach the most influential effect when the leaves were incubated about 16h.3. The results showed that they could lead to the most significant effect on soluble sugar content, sugar-metabolizing enzymes activities and endogenous hormones content in stems and leaves of Populus×euramericana'Nanlin895'aseptic seedling by foliage spray of 100mg/L NAA 4 days. They enhanced the sink strength of stems and source strength of leaves, increased activities of endogenous IAA, GA and ZR, decreased ABA activity. And they promoted the photoassimilates transport from source to sink. But higher concentration (200～400mg/L) or longer treatment time (7～10d) of NAA could decrease promoting strength or inhibit plant growth.4. Under different concentrations NAA treatments, the AI, NI and SPS regulated the soluble sugar content in leaves, and the total soluble sugar and sucrose content were mainly related to AI, SPS and SS activities in stems. Under different times NAA treatments, the sucrose content was mainly related to the AI and SS activities in leaves, and the total soluble sugar and sucrose content in stems were mainly regulated by AI and SS. In roots, the soluble sugar content was regulated synthetically by sugar-metabolizing enzymes.5. The variation range of the effective concentration and time of NAA were closely related to vegetation growth state under different experimental system.The results showed that they could increase the soluble sugar and biomass accumulation in leaves and stems of Populus×euramericana'Nanlin895'cutting seedlings by foliage spray of 10mg/L NAA 6 days.