Ximen Island Research Articles

Comparison of physiological characteristics of Kandelia obovata at different ages in winter in the northernmost mangrove transplanted area of China

This study took place on Ximen Island within Ximen Island Marine Special Reserve, Yueqing County, Zhejiang Province, at the northernmost boundary of artificially planted mangrove plantations, to study changes in the physiological characteristics of different aged Kandelia obovata trees (aged 1, 2, 4, 8 and 53years). Leaves and stems of different aged K. obovata were sampled in November and December (mean air temperature was 15.8°C and 7.6°C, respectively) for measurements of physiological traits. Results showed that from November to December, content of both chlorophyll and carotenoids, the chlorophyll a/b ratio and activity of peroxidase (POD) in leaves, the content of total soluble sugars, free amino acids, and content of K+ in the leaves and stems first increased and then decreased with increasing age. Also, Na+ content in the leaves and stems, as well as malondialdehyde (MDA) content in leaves decreased. Importantly, the measured differences in these chemicals in trees of different ages were more significant in December. We conclude that older individuals of the mangrove K. obovata were able to survive by maintaining higher levels of photosynthetic pigments and activities of antioxidant enzymes, and were able to effectively regulate ion stabilization, which promoted carbon and nitrogen metabolism. Also, disorders related to the ion balance and carbon and nitrogen metabolism may not allow K. obovata seedlings to adapt to low temperature stress. Our findings indicate that attempts to provide safe overwintering of K. obovata seedling may face significant challenges.

强潮区较高纬度移植红树植物秋茄的生理生态特性

Ximen island of Yueqing bay,the northern boundary of artificially planted mangroves,was chosen as the study site.Changes of 1-and 4-year-old Kandelia candel at the tidal level of 1.96,1.66 and 1.35 m above the zero tidal level of Yellow Sea(Waterlogging time at this tidal level are 3.18,3.65 and 4.07 h per-tide-cycle respectively) on growth,photosynthetic pigments,activities of protective enzymes in leaves,contents of total soluble sugars and free amino acid and ion contents in leaves and stems were investigated.The results showed that the tidal level of 1.66 m above the zero tidal level of Yellow Sea was suitable for planting Kandelia candel,because the waterlogging time at this tidal level was less than 3.65 h per-tide-cycle.When the tidal level was 1.35 m above the zero tidal level of Yellow Sea,the waterlogging time at the tidal level was 4.07 h per-tide-cycle,which caused a series of effects.A decrease in the contents of chlorophyll,carotenoid,total soluble sugars and free amino acid,the activities of peroxidase(POD) in leaves,and the ratio of K+/Na+ in stems and leaves of 4-years-old Kandelia candel were detected.Moreover,a rapid increase in the contents of malondialdehyde(MDA) in leaves and Na+ concentration both in leaves and stems of 4-years-old Kandelia candel were found.Based on results listed above,a growth retard was detected when the waterlogging time was 4.07 h per-tide-cycle for 4-year-old Kandelia candel.However,this growth retard was not found in 1-year-old Kandelia candel under the same waterlogging time.Therefore,it is concluded that the older Kandelia candel could grow at 1.66 m above the zero tidal level of Yellow Sea,which is due to the maintaining of normal carbon and nitrogen metabolism under waterlogging time(less than 3.65 hours per-tide-cycle) at this tidal level.