Physiological Responses Of Two Woody Ornamental Plants To Drought Stress

In recent years,with the increasing of global temperature,drought stress has become increasingly severe,and plant growth has been affected.Catalpa ovata and Acer negundo are important woody ornamental plants in northern China.It is of great significance to study the growth and physiological responses of these two plants to drought stress.In this paper,1-year-old C.ovata and A.negundo seedlings were used as experimental materials,and drought stress was carried out by natural drought method.Samples were taken at 0?5?10?15?20 and 27days after the beginning of stress.The changes of growth indexes,physiological and biochemical characteristics of two plants in different drought stages and after rehydration were measured.In order to reveal the response law of C.ovata and A.negundo to drought stress.The main results are as follows:(1)Drought stress inhibited the plant height growth rate of C.ovata and A.negundo seedlings.The leaf relative water content of C.ovata and A.negundo was negatively correlated with drought stress time,the root-shoot ratio increased with the drought stress time.Leaf area of A.negundo was significantly inhibited on the 20 th day of drought.(2)The Chla,Chlb and Chlt C.ovata leaves decreased significantly with the extension of drought stress time,Car content showed a trend of first increase and then decrease.The contents of Chla,Chlb and Chlt and Car in A.negundo leaves increased first and then decreased.(3)With the increase of drought stress time,the net photosynthetic rate and stomatal conductance of C.ovata and A.negundo seedlings showed a downward trend,reaching the lowest value on the 20 th day of drought.The intercellular CO₂ concentration of both showed an upward trend in varying degrees with the extension of drought stress time.(4)In terms of physiology and biochemistry,C.ovata and A.negundo seedlings could resist drought stress by increasing antioxidant enzyme activity and osmotic regulation ability.(5)After rehydration treatment of C.ovata and A.negundo seedlings,most growth and physiological indexes recovered in varying degrees.(6)Through fuzzy membership function analysis,the results showed that the drought resistance of A.negundo seedlings was greater than that of C.ovata.