Reaction Of Six Shrubs Growing To Water Stress And Their Osmotic Adjustments

The six shrubs,Caragana korshinskii,Atraphaxis bracteata,Hedysarum mongolicum, Hedysarum scoparium,Buddleja alternifolia,Atriplex canescens,have a higher value for the sand.We researched their drought adaptability under long period water control test(suitable for water,moderate drought,severe drought)by potted cultivate 1-year seedlings,though respectively testing their biomass,leaf water status,cell membrane permeability,organic and inorganic osmotica(proline,betaine,soluble sugar,soluble protein,K⁺,Na⁺,C^1-),the results showed that:1.The total fresh weight(FW) and dry matter accumulation(DMA) of Atriplex canescens and Buddleja alternifolia' are significantly higher than that of other 4 species under the appropriate water conditions.They both have higher total FW and DMA under the moderate drought condition,and Atriplex canescens is better than the other even under the severe drought condition.But they all decreased of 6 species under the moderate drought and severe drought conditions compared with the suitable for water condition.and the 6 species have the same physiological response with FW and DMA.At pre-dawn,the leaf water potential and leaf water content declined,membrane permeability ascended,and which were more affected under the severe drought condition than under the moderate drought condition.The 6 species were different in extent of decline of total FW and DMA,ascending of membrane permeability and decline of the pre-dawn leaf water potential and leaf water content.They all can resist drought,relatively adapt to moderate drought condition,and Caragana korshinskii, Atraphaxis bracteata and Atriplex canescens were stronger than Hedysarum mongolicum, Hedysarum scoparium and Buddleja alternifolia.Buddleja alternifolia is the last specie among 6 species adapted to plant in the severe drought area.2.Except Atriplex canescens,the root FW of other 5 species increased in drought stress. It's sameness in the stem FW and leaf FW.For extent,drought stress was less affected underground root than ground root,leaf was the most sensitive to drought stress.With the falling of FW ratio of ground part,however,the FW ratio and root/shoot ratio of 6shrubs were increasing in drought stress,and it's the same performance under the severe drought condition. The characteristics of plant root reflect its drought adaptability.It's different drought defence to drought resistance which was reflected by the extent of root FW ratio and root/shoot ratio, which showed that drought resistance was decided by combine of drought defence and drought tolerance.3.In drought stress,6 shrubs represented osmoregulation process of drought tolerance, but their performance were different in joined material,accumulate extent,process period, drought stress strength.Except organic material,inorganic ion also play a role.Betaine joined the whole osmoregulation process,other osmotic adjust materials are exceptions.