The Stress Resistance Of The Seedling Of Handroanthus Chrysotrichus

Handroanthus chrysotrichus is a kind of flower tree that is native to South America,and it has a unique ornamental effect and good application value in landscape architecture.And this species has been introduced successfully in Guangzhou area,and shows good adaptability.But at the moment,there are few resistances about the tolerance to extreme environment factors.In order to better clear the best scope in our country,avoid blind introduction,to carry out the stress resistance of Handroanthus chrysotrichus is necessary.This study's experimental material is the seedling of Handroanthus chrysotrichus.The main task of this study is determining the change of physiological and biochemical indices,photosynthesis indices,chlorophyll fluorescence indices and biomass indices at different drought stress stages,different flood stress stages,different gradient of low temperature stress and different concentration of salt stress.Analyze its response to various stresses by analyzing the data with multiple comparisons and principal component analysis,in order to further proved the response mechanism of plants to adversity and provide basic theory basis for the promotion of Handroanthus chrysotrichus.The main results are as follows:(1)The seedling of Handroanthus chrysotrichus had poor drought tolerance.And on the 4th day of drought stress test,the plant was moderately damaged.The 8th day was the critical value of drought death.(2)At the early stage of the water stress(0 ~ 12 d),the damage of Handroanthus chrysotrichus was not obvious.In the late water stress(18~30d),plants suffered worse,and this indicates that this tree can only withstand about half a month of water flooding,beyond which the plant growth will be seriously affected.(3)The cold resistance of the seedling of Handroanthus chrysotrichus is poorer.Plant in 6 ? treatment issued by heavy damage,plant in near-death state when 2 ?.So 2 ? is the critical value of seedling death at low temperature.(4)When the salt concentration was below 0.4%,the damage of Handroanthus chrysotrichus was not obvious,and the dry weight of ground part,dry weight of underground part and total dry weight are slightly downward.When the concentration of salinity is greater than 0.6%,the damage to the Handroanthus chrysotrichusi began to increase,and the dry weight of ground part dropped sharply,and the underground part and total dry weight began to rise.(5)In physiological and biochemical aspects,in the drought stress,water stress and temperature stress,the activity of SOD total variation is not obvious,and MDA content were started to rise sharply when plants suffer intensifies,and proline and soluble sugar content were also when plants suffer increased up to the maximum.Aspects,chlorophyll fluorescence parameters in drought stress,water stress and temperature stress,Fv/Fm,Y(?),qP and NPQ in plants suffer began to increase sharply.In terms of photosynthetic indicators,when the water-flooded stress became dominated by non-stomatal factors,Pn,Gs and Tr began to decrease significantly,Ci changed from decrease to increase,and Ls changed from increase to decrease.