| The growth patterns and the nutrient elements characteristics of plants are direct sense responses to the drought environment, and the stoichiometry of plants provide possible for exploring the environmental effects on the internal mechanism of plant organs functionc. Researching C,N,P content and their stoichiometry of plant roots, stem and leavesunder different soil moisture gradient will be of great importance in further clarifying matter accumulation and health status evaluation under drought stress.In this paper, Robinia pseudoacacia seedlings were selected as the research materials. By set the different soil moisture gradients of pot experiment, leaf photosynthetic and C,N,P content of root,stem and leaf were measured during the whole experiment period. Among its conclusions:(1)Under different drought stress,the growth characteristics of Robinia pseudoacacia seedings were significantly affected.Of the ground diameter,height,shoot dry weight and root dry weight of Robinia pseudoacacia seedings reduced gradually and were significantly affected by drought dress.(2)Under different drought stress, C content of Robinia pseudoacacia leaf, stem and root were significantly affected. C content of leaf,s tem and main root was in 381.2-440.2 g/kg-1,414.4-423.1 g/kg-1 and 360.0-401.1 g/kg-1. C content of leavesincreased gradually with the decreasing of soil water content. C content of stem did not show significant difference among drought stress treatments at 168 days and 250 days of the year N content range of Robinia pseudoacacia leaf, stem and main root were 17.0-27.3 g/kg, 8.75-15.18 g/kg and 7.91-14.19 g/kg separately. N content of Robinia pseudoacacia leaf will decrease obviously along with soil water content decreases when different day of the year reaches 168 days, 215 days and 250 days. In DOY 168 days, N content of Robinia pseudoacacia leaf decreased obviously when soil water content is 14%, compared to 6%, 8% and 10%. P content range of Robinia pseudoacacia leaf stem and main root were 0.83-1.37 g/kg、0.48-0.82 g/kg and 0.56-1.25g/kg. In DOY 168 days, P content of Robinia pseudoacacia leaf at soil water content of 6%was obviously higher than at soil water content of 8%, 10% and 14%(P<0.05).(3)Under different drought dress levels, C:N 、 C:P and N:P of Robinia pseudoacacia leaf, stem and main root were affected obviously. C:N range of Robinia pseudoacacia leaf, stem and main root were 15.1-24.9 、 27.6-48.4 and 27.4-48.3., C:P were 300.3-470.7、513.8-873.5, and N:P were 15.4-25.4、14.5-22.3' 9.56-18.2,respectively. C:N and N:P of Robinia pseudoacacia leaf increased gradually among drought stress treatment, but therewas not significant different in C:P. C:N, C:P and N:P of Robinia pseudoacacia stem decreased on different soil water content. C:N and N:P of Robinia pseudoacacia main root first increased and then decreased.(4)In DOY 168 days,photosynthetic rate of Robinia pseudoacacia leaf decreased with the decrease of soil water content, and when soil water content was 6%,photosynthetic rate was 0.46 μmol m-2 s-1 which was the lowest. In DOY 215 days,,photosynthetic rate of leaf at the soil water content of 14% treatment was significantly higher than at the soil water content of 8% and 6%(P<0.05).In DOY 250 days,photosynthetic rate of leaf at he soil water content of 14% and10% were significantly higher than at the soil water content of 8% and 6%(P<0.05).(5)When the soil water content is 6% and 8%,the C content of Robinia pseudoacacia leaf was significantly higher than that when the soil water content was 10% and 14%,but when the soil water content is 10% and 14%,the photosynthetic rate of Robinia pseudoacacia leaf was significantly higher than that when the soil water content is 6% and 8%. With the decrease of soil water content,the N content and photosynthetic rate of Robinia pseudoacacia decreased significantly.The C content of Robinia pseudoacacia leaf at the soil water content of 6% and 8% were significantly higher than at the soil water content were 10% and 14%,but the photosynthetic rate of Robinia pseudoacacia leaf at soil water content of 10% and 14% were significantly higher than at the soil water content of 6% and 8%.With the decreasing of soil water content,the N content and photosynthetic rate of Robinia pseudoacacia decreased significantly. |
PDF Full Text Request