Variance of Growth and Physiological Difference in Cold Resistance of Kandelia obovate Seedlings from Different Provenances
Low temperature is the predominating factor for Kandelia obovata northward distribution,screening cold-resistant germplasm is of great significance for mangrove northward migration,introduction cultivation.This study provides the important reference for the northward introduction cultivation of mangrove plant K.obovata and the ecological conservation.The hypocotyls of three provenances from Zhangjiang Estuary,Fuding in Fujian Province and Longgang in Zhejiang Province were used as objects,the growth characteristics of K.obovata seedlings were investigated through indoor cultivation experiments.The cold damage of seedlings was observed after each temperature was treated for 24 hours with the artificial climate incubators used to set temperatures of 18℃,4℃,and 0℃,analyzing changes in physiological and biochemical indexes of the leaves from different provenances.The results showed that the plant height,ground diameter growth,biomass of the seedlings in Zhangjiang Estuary were significantly high-er than those from other provenances.Under the stress of low temperature,the seedlings in Zhangjiang Estuary of Fujian Province suffered the most severe cold damage compared with the other two provenances.At 0℃,the content of osmoregulatory species in Fuding provenance was significantly higher than those in Zhangjiang Estuary and Longgang provenance,with 147.4%and 84.0%,respectively.With the descent of temperature,the SOD activity in the leaves of Zhangjiang Estuary seedlings in Fujian Province increased first and then reduced,the SOD activity in Fuding seedlings de-creased first and then increased,and the SOD activity in Longgang seedlings increased with the highest at 0℃.The MDA content of the seedlings from Zhangjiang Estuary in Fujian Province was significantly higher than those from Fu jian Province and Zhejiang Province,which was 117.1%and 70.0%higher at 0℃,respectively.Therefore,under the same conditions the seedling growth of Longgang provenance in Zhejiang Province was rela-tively low;however,with the increase of low-temperature stress,the seedlings showed strong PRO and SOD activities and increase of soluble sugar content,displaying the strongest cold resistance,accordingly,K.obovata seedlings of Longgang provenance should be prioritized in the mangrove con-struction.
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