江蓠的光合作用研究——不同光照强度对光合作用的影响

STUDY ON PHOTOSYNTHESIS OF CRACILARIA——Ⅰ. EFFECT OF VARIOUS LIGHT INTENSITY ON PHOTOSYNTHESIS

本文介绍了用氧电极法测定广东沿海大量生产的细基江蓠、海南岛水池产江蓠、江蓠和海丰产江蓠生态种的光合活性同光强关系的结果。试验结果表明:初夏时,四种江蓠的光补偿点为1000米烛光,光饱和点为400—7000米烛光;12月和翌年2月,江蓠和细基江蓠的光饱和点为 12,000和 14,000米烛光。12月和翌年2月两次测定的结果相同,但和初夏时比较相差悬殊。初夏时江蓠的净光合速率较低,12月和翌年2月时较高。1983 年初夏时,发现海南岛水池产江蓠分枝的净光合速率大于主枝,这现象在1984年2月对江蓠和细基江蓠的测定中亦得到证实。细基江蓠孢子体顶端部净光合速率大于中部和基部,而中部和基部的净光合速率无明显差异。这些研究结果,为江蓠人工栽培,和江蓠“切割增产”提供了科学依据。

The relation between light intensity and photosynthesis activity of four mainspecies of Gracilaria (i. e. G. tenusitipitata, G. sp.-Hainan. G. verrucosa,and G.sp.--Haifeng), in Guangdong province, were measured in May and December of 1983and in February of 1984. The results of the experiment as in the following:1. In the early summer, the common light compensation point of the four speciesof Gracilaria is 1,000 Lux. From December to February of the second year. while thelight saturation point of G.verrucosa and G. tenunistipitata is 12,000 Lux and 14,000Lux respectively. The difference between two seasons is so wide. That is because fromApril, to June it is the time for spores scattering and germinating while in winter itis the best time for growing. So that need for ligh intensity was different in differentgrowing season.2. The net photosynthetic rate of Gracilaria was comparatively low in the earlysummer,but was very high in December and February of second year.3. The net photosynthetic rate of the sub--branches were higher than that of themain branches. This characteristic was found in G. sp-Hainan in early summer 1983,and in G. tenuistioitata and G. verrucosa in February 1984.4. The net photosynthotic rate on the apical part of the sporophyte of G. tenuisti-pitata was higher than that on the middle and lower parts of which show the samerate. The results will provide a scientific basis for 'cutting for increasing production'technique of Gracilaria.From the experiment, the results could be concluded: In expecting to get a goodharvest, the culturing-raft should be set in the upper layer of seawater during theirfast growing period so that the algae can receive strong light to strengthen photosyn-thesis. while the algae grow to late stage the raft should be set in the lower layer inorder to avoid the strong light and to minimize the adherence of miscellaneous algae.