Study Of The Ecological Factors On The Growth Of Caulerpa Lentillifera

This work investigated the influence of light intensity,photoperiod,temperature,salinity,different nitrogen sources and different phytohormones on the growth of Caulerpa lentillifera,so as to provided the scientific basis for artificial breeding ofCaulerpa Llentillifera.The results are as follows:1.The results of light intensity test on Caulerpa lentilifera showed that:40001x light intensity made Caulerpa lentilifera the highest relative weight gain rate,specific growth rate and branching rate,they were 31.86 ±6.2%?2.76 ±0.47%·d-1 and 1.30±0.26 ind· d-1 respectively,the experimental group of 10001x made the relative weight gain rate and specific growth rate minimum,with no difference from 70001x group.The light intensity of 40001x made the biggest branching rate of 1.30±0.26 ind"d-1.Different light intensities had no significant difference on the polysaccharide content(P>0.05),but had significant effect on chlorophyll-a content and protein content(P<0.05).The phytoplankton species and content of aquaculture water changed obviously along with the increase of light intensity.2.Influence of photoperiod on Caulerpa lentillifera's growth.The results showed that:experimental group of 16L:8D produced the largest relative weight gain rate of 32.20±0.48%and the largest specific growth rate of 2.80±0.35%·d-1,an insignificant difference from 12L:12D group and 16L:8D group(P>0.05).The relative weight gain rate and specific growth rate were minimum and the daily adding weight were up before they were falling with the extension of incubation time in experimental group of 20L:4D.Different photoperiod had no significant difference on the branching rate and protein content(P>0.05),but the chlorophyll-a content was influenced significantly.3.U5(52)uniform design was then carried out to set up 5 combinations of temperature and salinity to study the joint effect of temperature and salinity upon Caulerpa lentillifera growth,the results showed that the relative weight gain rate and branching rate was 35.28-40.64%· d-1 and 1.52-1.78 ind-d-1 respectively under 25.6-25.8? and a salinity of 31.6-32.5.This was the optimal value for the most desirable growth performance.4.The results of optimum nitrogen source test of Caulerpa lentillifera showed that the most suitable nitrogen for the growth of Caulerpa lentillifera was nitrate,then ammonium and the last was urea,the optimum concentration of three nitrogen sources for Caulerpa lentillifera's growth were 8.8×10-4,mol/L?1.8×10-5 mol/L?1.8×10-5 mol/L respectively.There was a significant correlation between daily adding weight and pH value of nutrient solution with different nitrogen sources.The biochemical component content changed when the types and concentrations of nitrogen source was changing.5.The effects of phytophormones that GA,6-BA and IAA on the growth of Caulerpa lentillifera had been studied with single factor analysis method.Research findings were shown as follows:0.8 mg/L or 1.4 mg/L of 6-BA and 11 mg/L of IAA could make the relative weight gain rate and the specific growth rate of Caulerpa lentillifera maximum respectively,IAA had no obvious effects on the relative weight gain and the specific growth rate of Caulerpa lentillifera.The optimal concentration for branching of GA.6-BA and IAA were 14 mg/L?0.4 mg/L?5 mg/L respectively,the biochemical composition changed when adding different phytohormones.