Effects Of Rainfall Exclusion On Non-structural Carbohydrate And Ecological Stoichiometry Of Pinus Massoniana In Serious Red Soil Erosion Area

In order to reveal the effect of drought stress on non-structural carbonhydrate transfer and conversion, carbon, nitrogen and phosphorus ecological stoichiometry, stablecarbon isotope composition(δ13C), malonaldehyde(MDA) of adult Pinus massonian in different isolated rainfall period (115th days,160 days,190 days,224 days,262 days,336 days, 378 days,420 days,439 days,469 days). We set the field fixed isolated rainfall experiment to simulate drought in the serious soil erosion of Changting County of Fujian Province.The result indicated that:(1) During the process of isolated rainfall, the NSC content of leaves from treatment group were higher than the control group, this result were caused by the soluble sugar content of treat group increased in the early time, but by the starch increased in late. The above results showed that the accumulation of soluble sugar increased from leaves under drought stress is light, but with the increasing of the degree of drought stress, more and more into starch storage.The total soluble sugar content of the branches from the treat group was higher than the control group, the content of starch in genera lower than that of the control group. That under drought stress, the branches began to starch into soluble sugar, in order to provide the energy required to maintain respiration.(2) During the process of isolated rainfall, the change of leaves and branches C content were stable, branches C content is more affected by the water shortage; isolated rainfall treatment makes the Pinus massoniana leaves and branches of N content were higher than control group, but nitrogen use efficiency were generally significantly higher than control group.(3) During the process of isolated rainfall, the value of δ13C from leaves of treat group was significantly higher than control group(P<0.01). It also shows that Pinus.massoniana have more efficient water utilization strategies under drought stress, and this was why it still has high NSC content in drought stress. There was no significant correlation between leaf nitrogen and water utilization efficiency, but the treatment group have a very significan negative correlation(P<0.01), water shortage has strengthened the restrict relationship between them.(4) Except in isolated rainfall 224-262 days (dormant) had no significantly difference, other times isolated rainfall treatments made the treatment group Pinus massoniana leaf MDA content significantly higher than control group(P<0.01).