Comparative Study On Xerophytic Structure And Cold Resistance Of Leaves From Ten Poplar Clones

Poplar has a long history of planting in Chi na,with a wide range of distribution,and is suitable for fiber industry,paper box board,agricultural tools,etc.Poplar faction poplar is generally drought-resistant,wind-resistant,cold-resistant,light-loving,warm and cool climate,fast-growing,long-lived,as one of the Northwest Plains sand barren afforestation species.Its wood texture is straight,fine structure,mechanical strength bureau poplar wood forefront,for construction,matchsticks and other uses.In this study,ten poplar asexual lines,namely 07-17-18,07-23-23,07-30-11,Qinbai Poplar 1,Qinbai Poplar 3,Qinbai Poplar 5,Maobai Poplar 30,Xinjiang Poplar,I-101 and 84 K Poplar,were used as test materials to study the drought and cold resistance of each poplar asexual line by paraffin sectioning and determination of seedling physiological and biochemical indexes,and the results were obtained as follows:(1)The leaves of all 10 poplar asexual lines had obvious drought structures,from outer to inner cuticle,upper epidermis,fenestra tissue,spongy tissue and lower epidermis in order;The main vein thickness,spongy tissue thickness,palisade tissue thickness/spongy tissue thickness among all clones were the most representative after the principal component analysis was used to process the measured index data.(2)The affiliation function was used to synthesize the drought resistance of the poplar a sexual lines under test.The drought resistance of the ten poplar asexual lines was ranked as f ollows: Qinbai Poplar 5>07-23-23>07-30-11>Mao Bai Poplar 30>84k>I-101>Qinbai Poplar1>Xinjiang Poplar>Qinbai Poplar 3>07-17-18.(3)Ten poplars were treated with six different temperature gradients of CK,-15°C,-20°C,-25°C,-30°C and-35°C.The relative conductivity of the dormant annual branches of the asexual lines was obtained using the conductivity method and the semi-lethal temperature of the test seedlings was derived;the activities of antioxidant enzymes(SODase,CATase and PODase)and the contents of malondialdehyde and soluble protein were measured for each asexual line at different temperature gradients.(4)The ten poplar asexual lines were ranked as follows: Qinbai Poplar 5>07-23-23>07-30-11>84K>Xinjiang Poplar>Qinbai Poplar 1>Maobai Poplar 30>I-101>Qinbai Poplar 3>07-17-18.(5)The ten poplar asexual lines were classified into five categories according to their str ongest to weakest cold resistance using the systematic clustering method of cluster analysis:the first category was Qinbai poplar 5.The second category was 07-23-23,07-30-11,84 K,X injiang poplar,Qinbai poplar 1.The third category was Maobai poplar 30,I-101.the fourth c ategory was Qinbai poplar 3.the fifth category was 07-17-18.