外源硅添加对楠木幼苗生长及光合特性的影响

Effects of Exogenous Silicon on Growth and Photosynthetic Characteristics of Phoebe bournei Seedlings

摘要:

为探究外源硅添加对光照胁迫下楠木(Phoebe bournei)幼苗生长的影响，以楠木1 a生幼苗为研究对象，分析不同光照强度和硅添加对楠木幼苗生长、生物量、叶形态和光合参数的变化。结果表明，遮荫与硅添加对楠木幼苗生长和光合性状产生了显著影响，适度的遮荫和硅添加有利于楠木幼苗苗高、地径、各器官生物量和叶形态(叶长、叶宽和叶面积)的生长。光照强度的降低有利于楠木幼苗叶片叶绿素的积累，在15%~60%光照强度下硅添加进一步促进了叶绿素的积累，使楠木幼苗更适应光照胁迫；在15%~40%的中低光照强度下1000~2000 mg/kg的硅添加有利于提高楠木幼苗叶片的叶绿素荧光参数,促进楠木幼苗的光合作用；而40%光照强度下1000~2000 mg/kg的硅添加更有利于提高楠木幼苗叶片净光合速率、气孔导度和蒸腾速率，降低胞间CO₂浓度，促进楠木幼苗光合能力的提高，提高楠木幼苗光照胁迫适应能力。因此，楠木幼苗适宜在一定的遮荫条件下更新造林，而硅添加有利于缓解光照胁迫，改善楠木幼苗在不同光照强度下的叶形态和光合作用效率，提高其对光照胁迫的生长适应性，进而促进苗木的生长，有利于造林更新成效的提高。

Abstract:

In order to investigate the effects of exogenous silicon addition on the growth of Phoebe bourneiseedlings under light stress, the changes of different light intensity and silicon addition in the growth, biomass, leaf morphology and photosynthetic parameters of P. bourneiseedlings were analyzed. The results showed that shading and silicon addition had significant effects on the growth and photosynthetic traits of seedlings. Moderate shading and silicon addition were beneficial to the growth of seedling height, ground diameter, biomass of organs and leaf morphology (length, width and area) of seedlings. The decrease of light intensity was conducive to the accumulation of chlorophyll in leaves, and the addition of silicon further promoted the accumulation of chlorophyll in the 15%-60% light intensity, which made seedlings better adapt to light stress. The addition of 1 000 to 2 000 mg/kg silicon under 15% to 40% light intensity could improve the chlorophyll fluorescence parameters in leaves and promote photosynthesis. The addition of 1 000~2 000 mg/kg silicon under 40% light intensity was more conducive to improving the net photosynthetic rate, stomatal conductance and transpiration rate of leaves, reducing the intercellular CO₂ concentration, promoting the improvement of photosynthetic capacity of seedlings, and improving the adaptability of seedlings to light stress. Therefore, the regeneration of P. bournei seedlings was suitable under certain shade conditions, and the addition of silicon was conducive to alleviating light stress, improving the leaf morphology and photosynthetic efficiency of seedlings under different light intensity, improving their growth adaptability to light stress, and then promoting the growth of seedlings, which is conducive to the improvement of afforestation and regeneration effect.