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The Responses of Jatropha Curcas L. Seedling in Different Soil Moisture

Author: LiuYu
Tutor: YeMeng；YinChunYing
School: Sichuan Agricultural University
Course: Forest cultivation
Keywords: Jatropha curcas L. soil moisture the growth physiology leaf ultrastructure
CLC: S792.99
Type: Master's thesis
Year: 2009
Downloads: 46
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Abstract

In this study,one year old Jatropha curcas L.seedlings were used as materials,three soil moisture treatments（80%FC（field capacity）,50%FC,30%FC） were applied in XiaoDeshi forest farm of Miyi County of Panzhihua City,Sichuan Province.The aim was to reveal the effects of different soil moisture on the growth and related physiological indexes of Jatropha curcas L.,to search for the most suitable soil moisture for it and provide some theoretical basis for its cultivation and management.The experiment results are as follows:（1） Soil moisture impacted the growth of Jatropha curcas L.obviously.The basal diameter was more sensitive than others,in the early（10th day） of experiment,the difference in same trait between different soil moisture has reached a significant level（P≤0.05）.The plant height,basal diameter and leaf number for the general trend was:80%FC＞50%FC＞30%FC.Under 80%FC,both the growth and biomass were the highest.Compare to 50%and 30%FC,the leaf biomass under 80%FC increased by 35%and 83%;stem biomass increased by 50%and 228%;root biomass increased by 75%and 178%;total biomass increased by 53%and 160%;the total leaves area increase by 47%and 90%.（2）Leaf stomatal conductance（gs）,intercellular carbon dioxide concentration（Ci）and transpiration rate（Tr）of 30%FC were all reduced than 50%and 80%FC,but the net photosynthetic rate（Pn） did not decline.The results showed that 30%FC was not caused drought stress to Jatropha curcas L.and it could reduce water consumption and improve water use efficiency by stomatal closure,reducing the intercellular carbon dioxide concentration and transpiration rate.（3）Under 80%FC the value of theδ¹³C was less than 50%and 30%FC as same as the result of WUE,the result showed that the water use efficiency of Jatropha curcas L.was reduced under 80%FC.（4）There were no significant differences in carbon content of Jatropha curcas L between different soil moisture.But the nitrogen contents of leaf,stem and root were decreased under 80%FC than 50%and 30%FC.It showed that 80%FC was not conducive to absorb nitrogen from the soil.Moreover,nitrogen is the main component of chlorophyll, the reduction of nitrogen content is not conducive to the formation of chlorophyll in the leaves.In the experiment,we also found that,under 80%FC treatment the chlorophyll a, chlorophyll b and carotenoids contents were all decreased than 50%and 30%FC.Therefore, we can determine that under 80%FC treatment,Jatropha curcas L.may be suffer from waterlogging stress. （5）The experiment showed that the chloroplast structure of 50%and 30%FC were both intact.There were appeared large transparent cavity and these large transparent cavities extruded the chloroplast even to out of shape and destroied the grana and strom under 80%FC.Under 80%FC,the number of mitochondria was increased while the structure of mitochondria was not destroyed.The increase in the number of mitochondria would protect itself when the Jatropha curcas L.suffer from stress.（6）In this experiment,under 80%FC,the malonaldehyde and peroxid contents were the highest,the membrane lipid peroxidation was enhanced.The content of soluble sugar and free proline are both the highest under 80%FC.And the result of the soluble protein content was:30%FC＞50%FC＞80%FC.The promotion of membrane lipid peroxidation and the change of osmolyte proved once again that under 80%FC the Jatropha curcas L. suffer from waterlogging stress.Comprehensive the experimental results,the Jatropha curcas L.in the higher soil moisture condition（＞= 80%FC） would result in waterlogging stress.Under 50%FC the growth and physiological indices were both relatively stable,and in the lower soil moisture condition（30%FC）,the growth,physiological indices and leaf ultrastructure were all not destroyed.Thus in the range from 30%to 50%of soil moisture condition the growth and physiological indicators are more suitable and more bcneficial to plant the Jatropha curcas L.

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