Study On The Drought Resistance Of Four Dwarf Ornamental Bamboos

Bamboo, as a grass Bambusoideae perennial evergreen plant, mainly grows in warm and humid regions of tropic and subtropic.In China it generally distributes in the south of Yangtze River areas. Being an important type of garden landscape plant, it plays a great role in city ecological environment construction and landscaping view. Compared with the situation of bamboo growth in the south of China, bamboo is applied less in the northern areas, due to the drought and cold. The mainly limited factor baffled the growth of bamboo is the lack of the water-supply.In order to searching the possibility of bamboo surviving in north China and supplying a theoretical basis for ornamental bamboo in landscaping applications, we selected four dwarf ornamental bamboos as experimental materials including Pleioblastus kongosanensis f. aureostratus Muroi et Y. Tanaka (e), Sasa fortunei (Van Houtte) Nakai), Sasa auricoma EG Camus and Sasa argenteostriatus Camus, through water-controlled method with bamboo planted in potted, we studed the morphology and the aspects of physiological and biochemical of the four types of dwarf ornamental bamboo, at the same time, we analyzed drought resistance mechanisms, and also evaluated comprehensively drought resistance by using principal component analysis and membership function.The results are as follows:(1)The morphological response of four dwarf ornamental bamboo under drought stressUnder the continuing drought stress, the four dwarf ornamental bamboos changed differently through the leaves yellow and curling in various degrees. The bamboo leaves rolled occasionally in test three days. In test six days, the leaf roll became seriously. S. argenteostriatus occurred a phenomenon that the leaves withered at tips. The leaves of P. kongosanensis f. aureostratus tests curled but remain green, the leaves of S. auricoma curled and withered, S. fortunei appeared a little withered or browning leaves, the branches and leaves of S. argenteostriatus became yellow.Almost no leaves were able to be collected in test 12 days. In conclusion, estimating from the morphology of four dwarf ornamental Bamboo, the drought resistance are in the order of P. kongosanensis f. aureostratus>S. fortunei>S. auricoma>S. argenteostriatus.(2)The physiological response of four dwarf ornamental bamboo undering drought stressDuring drought stress, the curves of the various physical signs diverse from each other along with stress time. The line of the chlorophyll content with the lasting drought stress decreased. The graphes of the relative membrane permeability, MDA and proline with the drought stress extend showed increasing trend.The curves of soluble sugar, soluble protein, as well as POD, SOD, CAT activity at the first section increased and subsequently decreased.Compared with the control, sustained drought 12 days P. kongosanensis f. aureostratus, S. fortunei, S. auricoma, S.argenteostriatus when the yellow stripe bamboo, their leaf water content decreased by 3.95%,5.37%,9.86%,67.90%; the relative membrane permeability increased to 50.31%,69.09%,86.53%,573.79%; the MDA content increased by 1.66,2.35,2.85,5.03 times; the chlorophyll content decreased by 22.39%,20.87%,9.22%,30.43%; the soluble sugar, the soluble protein and SOD, POD activity of the first 6 days of drought stress reached the peak, while the CAT activity in drought stress when the first 3 days reached the peak, after CAT activity continued to decline in drought stress.Through the analysis of variance on the four bamboos in various physiological changes, it indicates that bamboo species and stress intensity on the physiological indexes were highly significant.(3)The main component analysis of four dwarf ornamental bamboo physiological and biochemical indexesThe ten physiological parameters of four dwarf ornamental bamboo were analyzed. The indexes had definited correlation between leaf water content and chlorophyll, soluble sugar, soluble protein, CAT, POD, and SOD as well were positively. And it was negatively related to MDA, proline the correlation and relative membrane permeability. Related to the correlation between each index was significantly related to some factors. Some of the tens were highly significant correlation. Some correlation was not strong. All the physiological indicators indicate a certain degree of information overlapped effects. It is a better choice to choose the principal component analysis to evaluate the drought resistance.Principal component analysis showed, the order of drought index to react four ornamental bamboo drought was CAT, SOD, proline, POD, soluble protein, leaf water content, relative electrical conductivity, soluble sugar, MDA,chlorophyll content.(4) Comprehensive assessment of drought resistance in four bamboo speciesHense, the drought resistance of plant is a complex and integrative character, it is difficult to fully reflect the dirct evaluation criteria of the true drought resistance condition by taking a single index as the drough resistance. Therefore, it is suitable to use the membership function to carry out a comprehensive evaluation of the drought resistance in four dwarf ornamental bamboo. By the subordinate function of four dwarf ornamental bamboo drought resistance, the result is that it was in the order of P. kongosanensis f. aureostratus>S. fortunei>S. auricoma>S. argenteostriatus, which is matched with four dwarf ornamental bamboo morphology under drought stress consistent performance.