| Dalbergia hupeana Hance is not only a unique precious timber tree species in China,but also a very important medicinal and nectar plant and an excellent host tree species of Laccifer lacca,which has a high economic value and a good development prospect in landscape application.In order to speed up the development and utilization of D.hupeana,pot experiment was tanken to carry out NaCl and drought stress on D.hupeana by using its container seedling as experimental material.We analyzed the response mechanism of D.hupeana to NaCl and drought stress according to the dynamic changes of growth and physiological indicators of D.hupeana in each treatment group.The main results are as follows:(1)The response of D.hupeana to NaCl stressUnder the treatments of 0.2% and 0.4% NaCl,the morphology of D.hupeana showed no symptoms of salt injury,it could also promoted the growth of plant height,leaf thickness and length,decreased the stem diameter,leaf area,leaf width and LRWC compared with the control group but with no significant difference.In the process of stress,the photosynthetic pigments,SOD,POD,soluble sugar and soluble protein contents were higher than 0 d and the control group at the same time;Although LRWC and soluble protein content were lower than the control group until stressed 28 days,the difference is not significant.It means that D.hupeana can adapt to low NaCl concentration stress through its own osmotic adjustment and increase antioxidant enzyme activity.The 0.6%,0.8% and 1.0% NaCl treatment groups showed some degree of salt injury symptoms with the prolongation of stress time,especially the 1.0% NaCl treatment group was more serious,which significantly inhibited the growth of plant height,stem diameter and leaf area,but had no significant difference on leaf thickness and shape index;the LRWC,photosynthetic pigment contents gradually decreased with the increase of stress concentration and time,SOD and POD activity,soluble sugar and soluble protein content first increased and then decreased with the prolongation of stress time,which was significantly lower than the control group.This indicates that when the NaCl concentration is greater than 0.6%,D.hupeana can be adjusted by through self-regulation to avoid injury when it was stressed for 7 days,but when the stress time was extended to 28 days,the symptoms of salt injury were more obvious and significantly inhibited the growth of D.hupeana.The results show that D.hupeana can adapt to salt stress within 0.6% concentration and can be cultivated in a slightly saline soil environment,although 0.8% and 1.0% NaCl stress is not lethal for 28 days,serious salt injury occurs;There is a strong correlation between various indicators,especially among the physiological indicators;Leaf area,stem diameter,leaf thickness,LRWC,chl a,chl b,POD,SOD,soluble protein and other indicators contribute to the principal component analysis which could be used to evaluate the response of D.hupeana to NaCl stress.(2)The response of D.hupeana to drought stressCompared with the control group,the morphology,leaf size and other physiological indicators of D.hupeana in the mild drought stress group were not significantly different in each stress period;In the moderate drought stress group,D.hupeana temporarily wilted after 14 days and LRWC decreased,but it can improve the water retention of cells by increasing the activity of SOD and POD,and accumulating Osmoregulation Substances,Although it had some inhibition on the growth of leaf size,plant height and stem diameter,there had no significant difference compared with the control group.Under severe and extreme drought stress,the LRWC of D.hupeana decreased significantly,and the leaves experienced wilting and defoliation phenomena,which significantly inhibited the growth of plant height,stem diameter and leaf size;The SOD activity,soluble sugar and soluble protein content increased significantly compared with the control group,while POD decreased significantly when it was stressed for 7 days;After 14 days of stress,photosynthetic pigments,antioxidant enzyme activities and osmoregulation substances all showed a downward trend,and the extreme drought stress treatment group decreased more than severe drought stress;At 28 days of stress,the D.hupeana leaves in the severe drought stress treatment group withered and drooped,and the base leaves were slightly yellowed and dropped,while the extreme drought stress treatment group was completely withered.In summary: D.hupeana has strong drought resistance and can adapt to mild and short-term moderate drought stress.The phenomenon of wilting and withering of leaves easily occurred after 14 days of severe and extreme drought stress.Comprehensive analysis results show that plant height,stem diameter,leaf area,LRWC,photosynthetic pigments,SOD,soluble sugar and other indicators can be used to evaluate the drought resistance of D.hupeana. |
PDF Full Text Request