Studies On Stress Resistance Of Myrica Rubra And Ilex Rotunda

Myrica rubra, an evergreen fruits tree widely distributed in south China, and also a good Ornamental tree, belongs to the family Myricaceae; Ilex rotunda, an evergreen tree with high medicinal value, which is graceful and the fruits of which look good, belongs to Aquifoliaceae. The exploitation and utilization of plant resources is of great significance for enriching garden plant species and improving the quality of landscape and providing more suitable tree species for greening afforestation.Research on the environmental adaptability features of plants such as the stress resistance is an important basis of developing plant resources. The shade tolerance, drought tolerance and waterlogging resistance of M. rubra and I. rotunda were studied in this reaserch, which provide the theoretical foundation for popularization and application in urban landscape and greening afforestation. The main results were as follows:?1? Compared with the control group, P_nmax, LCP, AQY and RD of M. rubra all showed a fluctuating significantly decreased trend, but LSP fluctuatedly increased; the P_nmax and LSP of I.rotunda fluctuatedly decreased significantly, but the LCP?RD?AQY fluctuatedly increase significantly.?2? Compared with the control group, F₀ and F_m of M. rubra all declined with the increase of the shading intensity; F_v/F_m, Y??? and ETR increased first, then decreased, and achieved the maximum in 50% light intensity, the NPQ of M. rubra fluctuating increased slightly. The F₀ and F_m of I.rotunda declined with the increase of the shading intensity, the F_v/F_m?Y???and ETR increased first and then decreased and increased last, the NPQ declined significantly.?3? With the increase of the shading intensity, the LSW of M. rubra increased first and then decreased and increased last, but the LSW of I. rotunda decreased first and then increased. Both of which achieve the minimum in 50% light intensity and maximum in 25% light intensity. The Soluble protein content of M. rubra and I. rotunda decreased first and then increased, but M. rubra declined significantly as a whole and I. rotunda increased significantly as a whole. The Chlorophyll content and Chlorophyll a/b of M. rubra remain the same as a whole, the Chlorophyll content of I. rotunda declined significantly, and the Chlorophyll a/b increased fluctuatedly. Principal component analysis of characteristic indexes showed that the shade tolerance ability decreased in the order of M. rubra>I. rotunda.?4? with the increasing of water stress, The SOD activity of M. rubra declined inconsistently, the MDA, chlorophyll content and soluble sugar content increased in varying degrees, but the soluble protein content is not sensitive to stress changes. The SOD activity, soluble protein content and soluble sugar content of I. rotunda decreased first and then increased and reached the maximum under severe drought, the MDA and chlorophyll content increased. The Proline content and the relative conductivity of M. rubra and I. rotunda changed basically the same, the former decreased first and then increased, while the latter increased first and then decreased and increased last. Principal component analysis of characteristic indexes showed that the drought tolerance ability decreased in the order of I. rotunda>M. rubra.?5? With the increase of flooding time, the SOD activity and proline content of M. rubra decreased first and then increased, the MDA and chlorophyll content increased first and then decreased, the soluble protein and soluble sugar content increased. The SOD activity, MDA and soluble sugar content of I. rotunda decreased, the soluble protein content increased as a whole, and the proline content decreased first and then increased, while the chlorophyll content increased first and then decreased and increased last. The change of relative conductivity of M. rubra and I. rotunda were consistent basically, which increased first and then decreased and increased and decreased last. Principal component analysis of characteristic indexes showed that the waterlogging resistance ability decreased in the order of I. rotunda>M. rubra.