Seed Germination Of Several Indigenous Shrubs Respond To Water In The Karst Area In Guizhou

Robinia pseudoacacia, Sophora davidii, Lespedeza cuneata, Coriaria nepalensis,Pyracantha fortuneana play a significant role in the Karst area of Guizhou, the seeds of thesefive shrubs were used as experimental materials in this paper. In order to disclose thegermination strategies and adaptation mechanisms of these five shrubs in the Karstenvironment and to provide the theories for the vegetation restoration and ecologicalconstruction. We studied on the responses of seed germination to water utilizing efficiency,responses of seed germination to drought stress and soil burial depth, responses ofphysiological characteristics to drought stress during seed germination. The results indicatedthat:1. The responses of the seed germination of the five shrubs to water utilizing efficiencyshowed that the water utilizing efficiency of five kinds of shrubs in the order were L. cuneata,R. pseudoacacia, S. davidii, C. nepalensis, P. fortuneana. The lowest water content of seedgermination of five kinds of shrubs in the order were R. pseudoacacia, S. davidii, L.cuneata,P. fortuneana, C. nepalensis. The1000-grain weight of seeds was significant positivecorrelation with the quantity of imbibition (p＜0.01), the speed of water absorption wassignificant positive correlation with the quantity of imbibition (p＜0.05), the water utilizingefficiency was negative correlation with the1000-grain weight of seeds, the seeds of fiveshrubs had different responses to water, R. pseudoacacia and L. cuneata belong to relativelysensitive plants to water, S. davidii, C. nepalensis, P. fortuneana belong to relatively slowplants to water.2. The responses of the seed germination to drought stress showed that with degree ofdrought stress increased, the beginning of germination time and the mean time of germinationincreased; the seed germination percentage changed different, with degree of drought stressincreased, the seed germination percentage of R. pseudoacacia, C. nepalensis, P. fortuneanashowed decreasing trend, the seed germination percentage of S. davidii, L. cuneata washighest under moderate drought stress; The responses of the seed germination to droughtstress were different, seeds germinated in30%PEG of R. pseudoacacia, S. davidii, L. cuneata,the range of seeds germiantion of C. nepalensis was0-25%PEG, the range of seeds germination of P. fortuneana was0-20%PEG.3. The responses of the seed germination to soil burial depth showed that soil burialdepth had different influence on seedlings emergence, the suitable range of burial depth was1-7cm for R. pseudoacacia,1-5cm for S. davidii,0-3cm for L. cuneata,0-1cm for C.nepalensis and P. fortuneana. The most suitable burial depth was1cm for R. pseudoacacia, S.davidii, L. cuneata,0cm for C. nepalensis and P. fortuneana.4. The responses of physiological characteristics in seed germination to drought stressshowed that SOD, POD, CAT and GR activities raised during seed germination of S. davidii,C. nepalensis, P. fortuneana, the changes of enzyme activities had no obvious regularity;SOD、POD、CAT and GR activities declined firstly and then raised during seed germination ofR. pseudoacacia; The changes of SOD, POD, CAT and GR activities had no obviousregularity during seeds germination of L. cuneata.5. Comprehensive analysis showed that no matter in prosperity and adversity, the seedsgermination time of S. davidii, C. nepalensis and P. fortuneana were slowly and random, theseed germination pattern was delayed germination. But for R. pseudoacacia and L. cuneata,it was beneficial to seed germination in prosperity, whereas seed germination was delayed inadversity, the seed germination pattern performed two categories: quick germination anddelayed germination.