Effect of diurnal temperature difference on lipid accumulation and development in Calanus sinicus(Copepoda:Calanoida)

Calanus sinicus,the dominant copepod in the Yellow Sea,develops a large oil sac in late spring to prepare for over-summering in the Yellow Sea Cold Water Mass(YSCWM).The lipid accumulation mechanism for the initiation of over-summering is unknown.Here,we cultured C3 copepodites at four constant temperatures(10,13,16,and 19℃) and at three temperature regimes that mimicked the temperature variations experienced during diurnal vertical migration(10-13℃,10-16℃,and 10-19℃) for 18 days to explore the effects of temperature differences on copepod development and lipid accumulation.C.sinicus stored more lipid at low than at high temperatures.A diurnal temperature difference(10-16℃ and 10-19℃)promoted greater lipid accumulation(1.9-2.1 times) than a constant temperature of either 16℃ or 19℃,by reducing the energy cost at colder temperatures and lengthening copepodite development.Thereafter,the lipid reserve supported gonad development after final molting.Only one male developed in these experiments.This highly female-skewed sex ratio may have been the result of the monotonous microalgae diet fed to the copepodites.This study provides the first evidence that diurnal temperature differences may promote lipid accumulation in C.sinicus,and provides a foundation for future investigations into the mechanisms involved in over-summering in the YSCWM.

Improved root zone temperature buffer capacity enhancing sweet pepper yield via soil-ridged substrate-embedded cultivation in solar greenhouse

A novel soilless cultivation method,called as soil-ridged substrate-embedded cultivation(SSC)was invented,and an experiment was designed to investigate root zone temperature and production efficiency of sweet pepper cultivated by two SSC patterns,i.e.,SSC-P(polyethylene groove inserted)and SSC-W(wire-mesh groove inserted),and also other two cultivation methods,i.e.,soil ridge(SR)and naked polyethylene groove(PG).Results showed that PG,SSC-P and SSC-W increased the average minimal root zone temperature by 1.01℃,0.75℃,and 1.16℃ compared to SR(16.33℃)during March 16-20,2015.During June 1-5,SSC-P and SSC-W decreased the average maximal root zone temperature by 1.28℃ and 1.29℃ compared to SR(34.99℃),while PG increased it by 1.44℃.PG,SSC-P,and SSC-W decreased the differences of average daytime and night time temperatures by 1.34℃,2.13℃,and 2.88℃ compared to SR(4.56℃)during early stage.However,SSC-P and SSC-W decreased temperature differences of average daytime and night time by 0.9℃ and 1.07℃ compared to SR(0.95℃)during later stage,but PG improved by 2.85℃.Temperature difference of daytime and night time of SSC-W was minimal,and the temperature difference between the diurnal highest and the lowest temperature of SSC-W was also minimal.The buffer capacity of SSC-W was slightly better than that of SSC-P.SSC-W significantly improved the growth of sweet pepper compared to SR.Similarly,fruit yield per square meter of sweet pepper cultivated on SSC-P and SSC-W improved by 21.24%and 50.33%,respectively compared to SR(3.06 kg/m^(2)),while PG lowered the yield by 13.72%.SSC-W was a better SSC pattern compared with SSC-P in terms of production efficiency.