Preliminary Study Of Salt-tolerant Of Ricinus Communis

At present, the study on salt tolerance of plants were mostly measured about seed germination, or the growth and physiological indexes when the seedling growth under salt-tolerance respectively. But this trial will study all above under different treatments of NaCl with R. communis as experimental material. The study from seed germination to the plant growth and physiological indicators by the plant always under salt stress, The results are as follows:1. The germination, growth and fructification is normal when the ECe=0～30 dS m^-1, it can germinate but could not growth if the ECe=40 dS m^-1 , and the germination rate is zero when the ECe=50, 60 dS m^-1. This shows that germination of R. communis seed has a certain endurance of salt stress, but the maximum salinity of soil can not past ECe =30 dS m^-1.2. Salt stress significantly affect the growth of R. communis. With the increase of the salt stress, R. communis survival, seedling height and biomass all decreased, but the change of the water content is not obvious.3. With the increase of the salt stress, the content of Chlorophyll and the ratio of Chla/Chlb are reduces. This reveals that under high salt stress the photosynthetic capacity of R. communis reduces. But the carotenoids content of leaves are increasing, it shows that R. communis has a cercain endurance of salt stress.4. With the increase of the salt stress, Pn, Gs and Tr of the photosynthetic parameters has decreased significantly (P <0.05), while the Gs and Tr has declined. Because the pore structure of leaves are destructed under salt stress. thereby increasing the resistance of the gas transport. But with the increase of the salt stress Ci is increasing. which is contrast with Gs, so we can think that the main reason which causes Pn decline is non-stomatal limitation.5. The Fv and Fo of chlorophyll fluorescence parameters of R. communis leaves is not changed significant under salt stress (P >0.05); but Fv/Fm, NPQ, qP and Yield all decreased obviously(P <0.05).Salt damage is growing with prolonged of treatment time. This shows that the PSⅡhas little effect under short salt-treatment times. But long salt-treatment times lead low activity of PSⅡ, thereby the photosynthetic rate is reducing.6. Total concent of Na⁺ in one plant of R. communis and in different parts of a R. communis are gradually increased under salt stress(P <0.01). The distribution of content of Na⁺ in R. communis plants is leaf <stem <root. This indicates that in the root most Na⁺ are regionalization in vacuoles,which limit them to transport to the leaves, and reduce the damage on the leaves. Total concent of K⁺ in one plant of R. communis and in different parts of R. communis are gradually decreased under salt stress(P <0.01). The distribution of content of K⁺ in plants of R. communis is root < leaf < stem. In summary, R. communis has a cercain endurance of salt stress. Plants growth are inhibited significantly under high salinity, The maximum threshold of seed germination and seedling growth is ECe≤30 dS m-1.