不同温度对巨柏幼苗光合及生根的影响

Effects of different temperatures on photosynthesis and rooting of Cupressus gigantea seedlings

通过人工气候箱控制不同温度(7.5、12.5、17.5、22.5、27.5℃)条件,研究巨柏幼苗在各设定温度下的生长发育及光合作用变化,以期为巨柏优质壮苗培育奠定基础。结果表明:1)不同温度显著影响巨柏幼苗的生长。在17.5℃时幼苗株高、地上干物质量、地下干物质量、新生根干物质量及新生根数均达到最大值,在12.5和22.5℃时幼苗的各项生长指标较17.5℃时略有降低。而在27.5和7.5℃时巨柏幼苗生长欠佳,各指标显著低于在其他温度条件下。2)巨柏幼苗光合作用在不同温度下存在差异。在17.5℃时净光合速率、气孔导度及蒸腾速率均达到最大,胞间CO_2浓度最小,在7.5℃时巨柏幼苗的净光合速率、气孔导度及蒸腾速率最小,胞间CO_2浓度最大。3)巨柏幼苗新生根在17.5℃时生物量最大(P<0.05),在7.5℃时最少,仅约为17.5℃时的1/5。在17.5和22.5℃时新生根长度、表面积及体积较大,而在27.5、12.5和7.5℃时表现欠佳;新生根比根长在7.5℃和27.5℃时均较大,而在12.5、17.5、22.5℃时较小,且三者之间差异不显著。以上结果表明,在不同温度下巨柏幼苗生长发育和光合作用表现不同,17.5℃是其较为适宜的生长温度,而相对高温和低温均不利于其进行光合作用及新生根的生长。

The Cupressus gigantea seedlings were cultivated under different temperatures(7.5,12.5,17.5,22.5,27.5℃)through artificial weather boxes,and the effects of different temperatures on growth,development and photosynthesis of seedlings were investigated.The results showed that:1)Different temperatures significantly affected the growth of C.gigantea seedlings.The seedling height,aboveground dry mass,underground dry mass,new root dry mass and new root number reached the maximum at the temperature of 17.5℃,followed at 12.5 and 22.5℃,and they were poor at 27.5 and 7.5℃(P<0.05).2)The photosynthesis of the C.gigantea seedlings was different under the different temperatures.The net photosynthetic rate,stomatal conductance and transpiration rate reached the maximum,and the intercellular CO2 concentration was the smallest at 17.5℃,but on the contrary at 7.5℃.3)The biomass of the new root was the highest at 17.5℃(P<0.05),which was significantly higher than the other temperatures.While,the new root biomass was very small at 7.5℃,only accounted for about 1/5of biomass at 17.5℃.The new root length,surface area and volume were relatively large at 17.5 and 22.5℃compared with the other temperatures.The new root specific length was larger at 7.5 and 27.5℃than at 12.5,17.5 and 22.5℃,and the difference between the three temperatures was not significant.The above results show that the growth,development and photosynthesis of C.gigantea are different under the different temperatures,and the relative suitable growth temperature is 17.5℃,while the relative high temperature and relative low temperature are not conducive to its photosynthesis and the growth of new rooting.