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| The Growth and Photosynthetic Performance in Sea Weed Gracilaria chouae in a Pond in Summer |
| LI Xin-shu,ZHONG Zhi-hai,XU Jun-tian,FU Guang-hui,CHEN Bai-yao |
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Abstract The effects of water depth (20 cm ,50 cm and 80 cm) on growth rate ,photosynthesis and photosynthetic pigments contents were studied in sea weed Gracilaria chouae cultured in shrimp and crab polyculture ponds during summer ,and the effects of light intensity and temperature on grow th of the sea weed were also studied in a laboratory .The results showed that daily relative growth rate (RGR) of the sea weed was found to be decreased gradually with increase in water depth ,with daily RGR of 11 .7% at water depth of 20 cm ,9 .7% at 50 cm and 7 .1% at 80 cm .The maximum net photosynthetic rate was also reduced with increase in water depth .The indoor experiment results showed that the light and temperature had significant effects on RGR of the sea weed ,light playing more significant role than temperature .The daily RGR of 22 .9% was observed in the sea weed under light intensity of 14 000 lx ,while only daily RGR of 4 .9% was found under light intensity of 2200 lx .Light intensity also affected photosynthetic pigment contents significantly ,increase in chlorophyll a with increasing water depth ,and decrease in phycoerythrin with increase in water depth ,indicating that the pigmentation rearrangement is physiological adaptation of G .chouae to light intensity .
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Received: 25 April 2014
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