Studies On Drought And Cold Resistance Of Exotic Dwarf Bamboo

Evergreen and colour-leaf tree species are short in the cities of northern part of china. In order to enrich the plant resources and enhance diversity for the northern cities, five dwarf bamboo species or fom Shibataea chinensis, Arundinaria argenteostriata, Sasaella masamuneana f.aureostriata, Arundinaria fortunei, Sasa auricomaas, were introduced into Taian city . the study includes phenology character, growth rhythm,ecological adaptation and biological characteristics in the new planting site. Comprehensive researchs were conducted to study the drought and cold resistance of those five bamboo species in order to proride scientific and theoretical basis for future bamboo introduction.The main results are as the followings:1 The height growth of those five dwarf bamboos appears a slow-fast-slow trend and the grow curl appeared a"S"form. each kind has a different time of high growth. the five dwarf bamboos ' overall height come to their final design in the first part of June, but there is still shooting phenomenon, but the growth ability of the shoot height is not enough, the growth cycle is also very short.2 The results show that all of those five dwarf bamboo species can be safely overwintered without using any pretection treatments. The landscape scenic beauty index of shibataea chinensis in the winter still kept very high. The result also shows that all of those dwarf bamboos can be safely overwintered. The summer landscape scenic beauty index of Sasa auricoma still kept very high, and other four species belong to the scend class. Shibataea chinensis, Arundinaria argenteostriata and Sasaella masamuneana f.aureostriata have stronger pest resistance, houever the Sasa auricoma and Arundinaria fortunei were attacted by red mite in the early June. 3 The diurnal variation of photosynthesis for the five dwarf bamboos are all double-peak curve and all obviously show the phenomenon of midday depression of photosynthesis. During the depression, RH became lower and Ta became higher, the concentration of CO₂ became lower, too. The increase of the difference of saturated humidity would speed up transpiration, lower the leaf water potential; and both the raise of temperature and the drop of concentration of CO₂ would influence the open and close of stomata and the net photosynthetic rate. Through analysis, it is known that the main limiting factor of the depression for dwarf bamboo is the reduction of stomatal conductance, which is limited by stomatal factors. 4 By adopting the fuzzy mathematics membership functions , the drought resistance physiological indexes such as proline,soluble sugar,soluble protein,SOD,POD,chlorophyll a,chlorophyll b,malondialdehyde were analysized and evaluated comprehensively . the results showed that the size order of drought resistance is Shibataea chinensis,Sasaella masamuneana f.aureostriata,Arundinaria argenteostriata,Arundinaria fortunei,Sasa auricoma. 5 Via the analysis of the photosynthetic light-response curve for the five dwarf bamboos, it is knwon that the at the point of light saturation, using binomial regress can get relatively ideal results; if using the non-rectangular hyperbola, the compensation point can be easily found. The size order of the the five dwarf bamboos tolerant to shade is Shibataea chinensis,Sasa auricoma,Sasaella masamuneana f.aureostriata,Arundinaria argenteostriata,Arundinaria fortunei. 6 Semilethal temperature of the trees can be estimated via finding knee point of Logistic equation fitting, semilethal temperature of Shibataea chinensis is about -34℃, the semilethal temperature of Sasaella masamuneana f.aureostriata and Arundinaria fortunei is about -17℃, and the semilethal temperature of Sasa auricoma and Arundinaria argenteostriata is -15℃. Introducing region is in the middle of Shandong Province where the anual average temperature is 12.8℃, the minimum temperature is -27.5℃, and the minimum temperature in general years is not lower than -14℃. Taking synthetical evaluation for the five dwarf bamboos in artifical low temperature, it the result show that the size order of the cold-resistant capability is Shibataea chinensis,Sasaella masamuneana f.aureostriata,Sasa auricoma,Arundinaria fortunei,Arundinaria argenteostriata.7 With the overwintering process of the five dwarf bamboos, the water content of leaf tissue show a decreased trend, but the water saturation deficit increased gradually, at first the SOD activity increase with the decrease of natural temperature, later the activity decrease when the temperature recovers. The trends of the POD activity change of the five dwarf bamboos are different, however, in general, they take on the common trend of increase-decrease type. Soluble protein and natural temperature show incomplete negative correlation, these indexes begin to recover after the temperature recovers. Taking comprehensive evaluation for the cold resistance ability of the five dwarf bamboos, it shows the cold resistance ability of the five dwarf bamboos is in the following: Shibataea chinensis,Sasaella masamuneana f.aureostriata,Arundinaria argenteostriata,Arundinaria fortunei,Sasa auricoma.