温度和时间对海带(Saccharina japonica)孢子囊孢子放散及后期生长发育的影响

Performance of Spore Release, Gametogenesis and Growth of Sporophytes Resulted from Sorus Cultured under Different Temperature and Culture Periods

中文关键词: 海带  孢子囊  游孢子萌发  养殖

英文关键词: Saccharina japonica  Sorus  Zoospore germination  Cultivation

中文摘要:

      为了能够节约制冷成本，合理延长种海带在海上的预留时间，系统研究了不同温度(20、21、22、23、24℃)和培养时间(4、8、12、16 d)对两个海带品系(“205”和“C033”)孢子放散能力及胚孢子萌发率、受精率、雌配子体发育和幼孢子体生长的影响。结果显示,当海水温度达到24℃时，孢子囊几乎丧失了放散能力，20–23℃的游孢子放散量差别不显著。在相同温度下，孢子囊培养时间为12、16 d的胚孢子萌发率大于4、8 d；同时，孢子囊培养16 d的雌配子体和幼孢子体具有最小值。在相同培养时间下，23℃(或24℃)的雌配子体和幼孢子体远远小于20–22℃的。相关性分析表明，海带雌配子体大小与幼孢子体大小具有显著正相关性(P<0.01)。结果显示，当温度达到23℃或培养时间达到16 d时，海带孢子囊受到了胁迫，不利于雌配子体的发育和幼孢子体的生长。温度对孢子囊的作用更迅速，而时间对孢子囊的作用较为缓慢，可能是一种累积效应。

英文摘要:

      In North China Sea, parental sporophytes of the farmed seaweed Saccharina japonica are often selected for the release of the spores. A circulated cold water system is usually applied for the production of the seedlings of S. japonica (artificially cooled from 24℃ to 7℃). Generally a shorter culture period would reduce the production cost. The parental plants usually grow on the longlines in the seawater, hence would undergo the temperature rise in summer (from 20 to 25℃). There have been very few studies about the effect of higher temperature on spore release, gametogenesis, as well as the growth of the sporophytes of S. japonica. In the present study, we tested the growth of two strains, “205” and “C033”, under five temperature settings and four culture time settings. The results were described below: (1) the release of the spores remained unchanged at the temperature 20 to 23℃ but failed at 24℃; (2) under the same temperature, the germination rate of spores from the sorus cultured for 12 and 16 days were higher than that cultured for 4 and 8 days; (3) for the same culture period, the female gametophytes and their sporophytes from the sorus cultured at 23℃ were smaller in size than those cultured at 20-22℃; (4) under the identical conditions, both female gametophytes and their sporophytes exhibited the smallest size on the 16th day in all culture trials; (5) the size of gametophytes was positively correlated with the size of sporophytes. Our results suggested that either high temperature (>23℃) or prolonged culture period (>16 days) at the normal temperature (20-23℃) would impair the sorus of the parental plants.