Effects of Light Intensity and Different Tending Measures on Chlorophyll and Photosynthetic Characteristics of Tilia amurensis Artificially Regenerated under Forest Canopy
The artificially renewed 2 years Tilia amurensis seedlings under the canopy of the secondary forest are taken as the research object,and two kinds of light intensity(High light(HL,gap),Low light(Low light,LL,canopy))and 4 kinds of tending measures excluding underground competition(fertilization(F),root cutting(T),root cutting and fertilizer(T+F),control(CK)).The chlorophyll and photosynthetic parameters of Tilia amurensis seedlings were determined,and the effects of light intensity and tending measures to eliminate underground competition on photosynthetic physiology of artificial renewal of Tilia amurensis seedlings under the canopy were investigated.The results showed that HL increased the net photosynthetic rate,transpiration rate and stomatal conductivity of Tilia amurensis seedlings compared with LL,and the net photosynthetic rate under HL was significantly higher than LL(P＜0.05),while the intercellular CO2 concentration showed the opposite trend,and HL significantly decreased the intercellular CO 2 concentration of Tilia amurensis seedlings compared with LL(P＜0.05).Light intensity and the interaction of root cutting,fertilization and light intensity had significant effects on chlorophyll content of Tilia amurensis seedlings.Compared with HL,chlorophyll a,chlorophyll b and total chlorophyll contents in leaves of Tilia amurensis seedlings under LL were significantly increased by 36.1％,37.3％and 36.3％,respectively(P＜0.05).Among the 8 treatment combinations,the chlorophyll content of Tilia amurensis seedling leaves under F,T,T+F and CK treatments under LL was significantly higher than that under HL(P＜0.05),and the chlorophyll content of Tilia amurensis seedling leaves under T and T+F treatments under LL was significantly higher than that under CK treatment(P＜0.05).In conclusion,Tilia amurensis seedlings have strong photosynthesis in the strong light environment such as the gap in the forest,and can adapt to the weak light environment by increasing chlorophyll content in the weak light environment such as the forest canopy.Meanwhile,the chlorophyll content of Tilia amurensis seedlings can be further improved by root cutting and root cutting combined with fertilization in the weak light,and the adaptability of seedlings to the weak light can be improved more quickly.
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