Physiological And Ecological Characteristics Of Kolkwitzia Amabilis Graebn Under Drought Stress And Comparative Analysis Of Seedling Growth

Kolkwitzia amabilis Graebn belongs to Caprifoliaceae Kolkwitzia,is a unique single species of rare and endangered plants,is also a famous flower and fruit plants.The study of the effects of stress on the growth and physiological and biochemical characteristics of Kolkwitzia amabilis can provide a theoretical basis for the breeding and cultivation of its provenance.In this study,phenological characteristics were measured and recorded in detail.At the same time,the growth,physiological and biochemical indicators of Kolkwitzia amabilis plants under drought stress were tested and analyzed,and the growth characteristics of different origins of it were compared at sowing and seedling stage.The main results are as follows:(1)The period of Kolkwitzia amabilis is synchronous with the northern climate.The leaf spreading period is from mid-march to mid-late April,the beginning flowering period is from late April to early may,the flowering period is from late April to early may,the end flowering period is from mid-may,the fruit ripening period is from mid-june,the fruiting period is from mid-october,the deciduous period is from mid-november to early December,and the deciduous period is from mid-december to early December.Kolkwitzia amabilis exists for a long time,and does not fall off until the next year,so it has a long viewing time and high viewing value,making it a good landscaping tree.(2)Kolkwitzia amabilis has certain drought tolerance.In 13 days of continuous drought,the seedling wilting,with the increase of drought stress time,the growth of plant height,average diameter of roots,relative content of leaves,fresh weight of roots,fresh weight of stems,water content of roots,water content of stems and photosynthetic capacity of leaves decreased,leaf malondialdehyde(MDA)content and so on is on the rise,POD activity showed a trend of rise before they are lower,this suggests that continued drought will slow down Kolkwitzia amabilis growth and cause damage.Principal component analysis showedthat root morphological parameters,biomass,leaf water physiology,photosynthetic system parameters,membrane permeability,CAT index load factor were large,so the above indexes could be used as the main indexes to evaluate the drought resistance of Kolkwitzia amabilis.(3)There are some differences in seedling growth characteristics among different origins of Kolkwitzia amabilis.The seedling growth index of three origins was determined and analyzed,and there were significant differences among seedling emergence rate,root length,branch number,leaf length,leaf width,leaf length/leaf width,stomatal density,chlorophyll fluorescence parameters(Fo,Fv/Fm,Fv/Fo,qP,ETR).The origins of Shanxi province is the best,followed by Shandong and Hebei.