LED光质及光周期对香子含笑幼苗生长和光合特性的影响

香子含笑(Michelia gioii)为我国珍贵阔叶树种,在用材、香料、景观等方面具有重要价值。为了进一步培育优良苗木和开发利用其非木质资源,该研究将香子含笑幼苗放置在由2个光周期(12、16 h·d^-1)和4种光质(R:B=8:1、R:B=6:1、R:B:P:G =8:1:1:1、R:B:P:G=6:1:1:1,其中R、B、P、G分别代表红光、蓝光、紫光、绿光)两两组合成、光照强度一致的8个光照条件下生长。结果表明:(1)香子含笑幼苗的苗高和地径增长量、叶长宽比、最大净光合速率、暗呼吸速率及光补偿点在12 h·d^-1光周期R:B=6:1光质下最高,叶面积和叶绿素含量在16 h·d^-1光周期R:B:P:G=6:1:1:1光质下最高。(2)16 h·d^-1光周期处理下的苗高增长量、叶面积、质量指数、叶绿素a+b含量、叶绿素a/b比值、类胡萝卜素含量和光饱和点均高于12 h·d^-1光周期。(3)在红蓝组合光质基础上添加紫、绿光提高了幼苗的质量指数,并影响光合色素的合成和积累;(4)光质R:B=6:1与R:B=8:1相比,更具有促进香子含笑幼苗苗高、地径、叶片生长及提高光合作用的潜力。综上结果认为,对于促进香子含笑幼苗生长和进行光合作用,光周期为 16 h·d^-1光质为R:B:P:G=6:1:1:1光照条件的潜力较大,其次是光周期为12 h·d^-1光质为R:B=6:1的光照条件。

Effects of LED light qualities and photoperiods on growth and photosynthetic characteristics of Michelia gioii

Michelia gioii is a precious broad-leaved tree species in China, which is of great value in terms of wood, fragrance and landscape. In order to further cultivate excellent seedlings and develop and utilize the non-woody resources, the seedlings of M. gioii were placed under eight light conditions with the same light intensity, which were composed by two photoperiods(12, 16 h·d^-1)and four light qualities(R:B=8:1, R:B=6:1, R:B:P:G=8:1:1:1, R:B:P:G=6:1:1:1, R, B, P and G respectively represent red light, blue light, purple light and green light). The results were as follows:(1)The growth of seedling height and ground diameter, leaf aspect ratio, maximum net photosynthetic rate, dark respiration rate and light compensation point reached the maximum values under the light quality R:B=6:1 with a photoperiod of 12 h·d^-1, while the leaf area and chlorophyll content were the highest under the light quality R:B:P:G=6:1:1:1 with a photoperiod of 16 h·d^-1.(2)Compared to the treatment of photoperiod 12 h·d^-1, the indicators in growth of seedling height, leaf area, quality index, chlorophyll a+b content, chlorophyll a/b ratio, carotenoid content and light saturation point showed higher under photoperiod 16 h·d^-1.(3)The addition of purple and green light into the red-blue light combination increased the quality index of seedlings and positively affected the synthesis and accumulation of photosynthetic pigments.(4)Compared with the light quality R:B=8:1, R:B=6:1 had more potential to promote the growth of seedling height, ground diameter and leaf, and to improve the photosynthesis of M. gioii seedlings. In conclusion, the light quality R:B:P:G=6:1:1:1 with a photoperiod of 16 h·d^-1 demonstrates the higher possibility to promote the growth and photosynthesis of M. gioii seedlings, followed by the light quality R:B=6:1 with a photoperiod of 12 h·d^-1.