Effects Of Water Stress On Seed Germination And Physiological Characteristics Of Sycamore

This study includes two parts:The fist part was that in order to study the water tolerance of Sycamore in seed germination stage,the effects of different concentrations(0%?5%?10%?15%?20%?25%?30%)of PEG stress on seed germination,growth,Relative conductivity and the organic osmoregulation substances were measured with seeds of Platanus×acerifolia(Including four excellent Tree)and using Petridish and filter paper germination method.The correlation analyses were done between seed germination,Relative conductivity and PEG stress.Under the continuing drought conditions,the one year P.occidentalis L.(Including four Pedigrees),Platanus×acerifolia and Platanus orientalis L.'physiological parameters such as leaf relative water content(RWC),proline contents(Pro)and so on were measured by potting experimen.The membership function and grey correlative degree analysis were done between the protective enzyme activities,the contents of MDA and Drought resistance of Sycamore for comprehensive evaluation.The main conclusions are as follows:(1)The study about Seeds germination experiment of Sycamore Respectively under different temperatures(15,20,25,30?)and different illumination(0 hour,12 hour,24hour)showed that the preference temperature was 25?and the preference illumination was 12 hour.(2)Under the optimum temperature and the optimum illumination conditions,PEG inhibited seeds germination of Sycamore;when PEG concentration is greater than 20%,the seeds of the four tree species were not germinating.With the increase of PEG concentration,Germination rates,Germination vigor and Germination index of Sycamore seeds all decreased,Height and fresh weight in Sycamore sprouts all increased and root length increased,relative conductivity in Sycamore sprout increased and soluble protein contents increased in the beginning and decreased at last.(3)Through principal component analysis,it was showed that the related sequence between indexes and Sycamores seed germination under drought stress was,Germination rate>Seedling height>Root length>Germination index>Fresh weight>Soluble protein content>Relative conductivity>Germination Vigor.The order about the drought resistance of the sycamores seeds was:EQ-2>EQ-1>EQ-3>EQ-4.(4)With the increase of drought stress,the protective enzyme activities of Sycamore seedlings all increased in the beginning and decreased at last,RWC all decreased,the contents of Pro and MDA all increased.The changing of physiological indexes in different species showed different range.(5)The results of grey correlative degree analysis indicated that the correlation order between physiological indexes and drought resistance was :POD>CAT>SOD>Pro>RWC>MDA.The membership function was used to rank their drought tolerance,and the order was :Platanus occidentalis>Platanus acerifolia > Platanus orientalis.