Study On Drought Resistance Of Ten Quality Poplar Clones

Drought has always been one of the most important issues in global environmental governance,large range of wide area of arid and semi-arid areas of China,but still need to further strengthen the construction,within the planning and construction period,a complete and stable northwest ecological barrier will be built.Poplar as one of the main tree species of fast-growing and high-yield timber forest,the asexual propagation ensures that its fine characters will not change and the three significant benefits guarantee its production position in forest cultivation.Through the selection and introduction of drought-resistant varieties,and then through regional cultivation experiments.The clones adapted to the environment of Northwest China and with good resistance to adversity were selected to be popularized,which could further meet the raw material demand of poplar production and processing in China.On the other hand,it can also provide a lot of germplasm resources for the construction of the three north shelterbelt.In this paper,the method of controlling water by artificial potting is adopted.Using five populus nigra clones which come from Italy——La,Pa,Ta,Ti,Qg,ZL-46 and 107 yang as the comparison.Using five poplar clones which come from Italy——A23,A39,A46,A50,A54,84 K and I-101 as the comparison.Three gradients were set: normal water supply(100% of field capacity),light stress(60% of field capacity),and severe stress(30%of field capacity).Each selected clone seedlings were measured under different gradient its growth indexes and physiological and biochemical index.Analysis of the influence of different stress gradient on the selected clones,the drought-resistance comprehensive evaluation system was constructed,the drought resistance ability of all the tested clones was ranked.It can be used to reasonably select the parent combination of cross breeding in the later stage,it also provides some theoretical basis for the introduction and cultivation of different site conditions.The results showed that under the influence of stress,the single leaf area,root dry weight of all the tested Ti clones were the smallest under the two stress gradients,and the root development was most obviously inhibited.107 yang had the lowest leaf area under severe stress,its photosynthetic rate,stomatal conductance and water use efficiency were the lowest under the same stress gradient.This suggests that the inhibition of photosynthesis was the most obvious.The leaf relative conductivity of ZL-46 was the highest,this shows that the cell membrane permeability of ZL-46 was suffered most severely harm under the two gradients.Ta clones have the lowest ground diameter under the same gradient.Under the two gradients,the relative water content of Pa clones was the lowest,this shows that its water retention was the worst.Under the influence of stress,compared with other tested clones in the same stress,the plant height,ground diameter,leaf area,aboveground biomass,and root dry weight of 84 K were the lowest,that mains its aboveground biomass accumulation and root development were significantly inhibited.Under mild stress,water use efficiency and leaf relative water content of 84 K were the lowest compared with other clones.The relative conductivity of A23 was the highest under two kinds stress gradients,it indicated that the permeability of A23 cell membrane was damaged obviously.Under severe stress,stomatal conductance and water use efficiency of A23 were the lowest compared with other clones.The results of drought resistance coefficient method showed that the drought resistance ability of the 14 tested clones was in the order of I-101 > 107 yang > Qg > A54 >A23 > A39 > Pa > 84 K > A46 > A50 > Ti> ZL-46 > Ta > La.