Thuja orientalis seeds was treated by different molecular weight, different concentra tion and different lasting time in the Seedling Laboratory of Northeast Forestry University. The results are as follows:(1) it...Thuja orientalis seeds was treated by different molecular weight, different concentra tion and different lasting time in the Seedling Laboratory of Northeast Forestry University. The results are as follows:(1) it shows sighificant promoting effects on the germination viability of seeds bydifferent molecular weight of PEG(-6000, -10000 and -20000), and PEG-10000 is the best.(2)Different on germination viability , germination rate and simple vigor index are made bydifferent concentration of the same weigh moleculart(PEG-10000), the promoting effects are shownwhen the concentration is below 30%, and from 20% to 30% is the best range, but inhibitions will beshown if the concentration is more than 35%. (3)The most suitable lasting tiem of osmose treatmentof PEG10000 ~ 20% concentration is from 2 to 4 days, not more than 6 days, but it will showsignificant inhibition if the treated time is more than 8 days. (4)The treatments of PEG10000 andPEG20000 with higher molecular weigh can increase the germination rate and seed vigor , and decrease the electric conductivity of the seed soaking liquid after the natural air-dry treatment. Thesuitable time of natural air-dry is aboul 6 to 8 hours. It is also concluded that the PEG osmose treatmat is an effective method to increase the germination rate by the field shoulation in the laboratroy.展开更多
Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries...Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.展开更多
文摘Thuja orientalis seeds was treated by different molecular weight, different concentra tion and different lasting time in the Seedling Laboratory of Northeast Forestry University. The results are as follows:(1) it shows sighificant promoting effects on the germination viability of seeds bydifferent molecular weight of PEG(-6000, -10000 and -20000), and PEG-10000 is the best.(2)Different on germination viability , germination rate and simple vigor index are made bydifferent concentration of the same weigh moleculart(PEG-10000), the promoting effects are shownwhen the concentration is below 30%, and from 20% to 30% is the best range, but inhibitions will beshown if the concentration is more than 35%. (3)The most suitable lasting tiem of osmose treatmentof PEG10000 ~ 20% concentration is from 2 to 4 days, not more than 6 days, but it will showsignificant inhibition if the treated time is more than 8 days. (4)The treatments of PEG10000 andPEG20000 with higher molecular weigh can increase the germination rate and seed vigor , and decrease the electric conductivity of the seed soaking liquid after the natural air-dry treatment. Thesuitable time of natural air-dry is aboul 6 to 8 hours. It is also concluded that the PEG osmose treatmat is an effective method to increase the germination rate by the field shoulation in the laboratroy.
基金The Fundamental Research Funds for the Central Universities under contract Nos 201512002 and 201612002
文摘Seasonal fishing closures are often used in fisheries management to conserve overfished stocks.As one of the unintended consequences,fishermen often contend for maximizing catches immediately after reopening fisheries.The resultant large catch landings in a short time period(i.e.,pulse fishing)may undermine the benefit of closure.We implemented an end-to-end model OSMOSE-JZB(Object-oriented Simulator of Marine ec OSystem Exploitation OSMOSE)modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community,population,and individual.Our study demonstrated that the three-month closure was successful in conserving fish stocks.There were small variations on ecological indicators(i.e.,total biomass of the community,mean trophic level of the community,mean trophic level of the catch,and Shannon-Wiener biodiversity index)when pulse fishing occurred.Pulse fishing seemed not to result in a great shift in community structure.Compared to other species,the biomass of two large predatory fishes were more susceptible to pulse fishing.Pulse fishing could change the pressure of predators to fish stocks via food webs,especially for young individuals.Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing.Although the results derived in this study may be specific to the target ecosystem,the general approach is applicable to other ecosystems when evaluating fishing impacts.
