湛江 5 种红树林树种光合作用特性及光合固碳能力研究.

The photosynthetic characteristics of five mangrove tree species in Techeng Island of Zhanjiang City were measured by Li-6400 photosynthetic measurement system to explore the factors on diurnal course of photosynthesis and evaluate their photosynthetic carbon fixation capacity. The results showed that daily variation of net photosynthetic rate in leaves of Kandelia candel and Rhizophora stylosa presented a single-peak curve, however, Avicennia marina, Bruguiera gymnorhiza and Aegiceras corniculatum presented a double-peak curve and an obvious “midday depression” phenomenon occurred, with the peak values at 10:00 am and 14:00 pm. Among them, midday-depression of photosynthesis in Avicennia marina and Bruguiera gymnorhiza was affected by stomatal limitation, however, Aegiceras corniculatum was affected by non-stomatal limitation. By path analysis, photosynthetic active radiation(PAR)was the decision factors and vapor pressure deficit(VPD)was the main limiting factors which affecting the characteristic of net photosynthetic rate(Pn)of Avicennia marina and Aegiceras corniculatum. In contrast to the situation of Avicennia marina and Aegiceras corniculatum, leaf temperature(Tl)was the main limiting factor and stomatal conductance(Gs)was the decision factor which affected Pn of Rhizophora stylosa and Kandelia candel. Gs was also the decision factors which affected Pn of Bruguiera gymnorhiza. The daily net carbon fixation amount was significant different among the five mangrove trees based on the leaf net photosynthesis rate, of which Kandelia candel was the highest(13.83 g·m-2·d-1), followed by Avicennia marina and Aegiceras corniculatum (9.48 and 8.24 g·m-2·d-1, respectively), the lowest was Bruguiera gymnorhiza and Rhizophora stylosa(6.72 and 6.30 g·m-2·d-1, respectively). The light compensation point(LCP)values of five mangrove trees ranged from 28.3 to 37.0 μmol·m-2·s-1 which showed the typical properties of sun plants. The light saturation point(LSP)values range between 169.3 and 1 189.3 μmol·m-2·s-1 of which Aegiceras corniculatum was the largest but Rhizophora stylosa is minimal. There were significant differences among the five mangrove tree plants of apparent quantum yield(AQY)(P<0.01), of which Avicennia marina was up to 0.064 mol·mol-1 while Bruguiera gymnorhiza was the lowest 0.005 mol·mol-1. The magnitude on grey correlation degree between light response parameters and daily net photosynthetic carbon fixation in leaves of mangrove tree species was the maximum net photosynthetic rate(Pmax), LSP-LCP, AQY, LSP and LCP. [ABSTRACT FROM AUTHOR]