| The analysis is based on the experiment in the Guangxi Plant Research Institute where the Eucalyptus urophylla xE.grandis have been cultivated as research materials for6months by controlling the water condition. The experiment has been designed to six different water level of soil moisture, namely,90%-100%of underground water (90%for short),70%-80%of underground water (70%for short),50%-60%of the ground water (50%for short),30%-40%of underground water (30%for short),70%-80%of the underground anhydrous (70%anhydrous for short),30%-40%underground anhydrous (30%anhydrous for short). The purpose of this experiment is to observe Eucalyptus urophylla×E.grandis’photosynthetic system under the water stree and and to simulate the variation process of its effects to underground water, so as to provide some experimental data and theory to the eucalyptus cultivation in Guangxi. The research results are as follows:The diurnal fluctuation of Eucalyptus urophylla×E.grandis’water potential:From the summer diurnal variation characteristics of Eucalyptus urophylla Leaf, it indicates that there is little influence to the Eucalyptus urophylla×E.grandis’root system which is cultivated in the soil under underground water condition. And the comparison result is(P>0.1). Also, under the decline of moisture content in soil, the eucalyptus urophylla×E.grandis’s roots would differentiate the distribution of water, thus regulating its own root absorption to meet the needs of the water deficit and adjust his capability of water absorption to meet the water deficit. When the differences is significant (P<0.01) in the condition of serious deficiency of the water in soil without not groundwater sometimes (soil moisture30%anhydrous), the Eucalyptus must be irrigated for that their general growth should not be affected. Net photosynthetic rate (Pn) evaluation of plants to adapt to the growth of the importance of environmental indicators is closely related to plant growth state and its environment. In the summer, most of the diurnal variation of photosynthesis of Eucalyptus urophylla different level of treatment showing the type of" two-humped ",2. The temperature influence to the growth: From the summer and winter Photosynthetic response curve, it shows that it is not suitable to cultivate Eucalyptus urophylla xE.grandis in the low temperature region, or the net productivity of Eucalyptus urophylla xE.grandis can not be fully utilized under low temperature conditions. What’s more, if the low temperature problem would not be solved properly, the Eucalyptus urophylla extension would be restricted..3. The allelopathic effects of Eucalyptus urophylla xE.grandis:By comparison, this experiment shows that the Eucalyptus root system reflects the some similar element with the groundwater, which has restrain radish seed’s sprouting, root system’s and seedling’s growing development, and on the contras, has promote the growth of cabbage. This finding indicates that to a Eucalyptus urophylla grow in normal condition, the secretion of its root system reflects allelopathic effects and the allelopathic effect differ from different crops. Thus, this simulate experiment indicate that to cultivate an eucalyptu urophyllaxE.grandis need planty of water and it could not be plant in a low rainfall region.4. The overview of the experiment:Comprehensively, in this experiment, Eucalyptus urophylla could adapt to low temperatures, but its productivity in low temperature is much lower than in high temperature and the impact of Eucalyptus urophylla in dry conditions is of distinctness (P<0.01), therefore it is not to suitable to plant it in arid environments. The secretion of Eucalyptu root system reflects allelopathic effects, which is not totally unfavorable to ecological effects by the three results in this experiment. |
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