Photosynthetic Physiology Characterististics In Seedlings Of Cyclobalanopsis Multinervis And Michelia Foveolata

Light is the most important environmental factor that affect growth and development of plants. Photosynthetic adaptability is the important ecological factor that limits distribution and survival of plants during gardending and planting. Mastering the especial requirement of every plant to light, we can succeed in afforeststion and introdution. Everygreen broad-leaved ornamental plants become the main force of afforestation in city because they can grow all the year round. So far new variety is deficient and difficult to popularize because it is hard to know the eclolgical adaptability of plants, so we can't adjust measures to local conditions. In this paper, we systematically studied photosynthetic characteristics, light response characteristics, photosynthetic diurnal variation, growth, biomass, seasonal variation of physiological characteristics and leaf anatomy of Cydobalanopsis multinervis and Michelia foveolta under different shadings (full light, one layer shading, two layers shading) by ecophysiological methods. This paper will provide scientific foundations for establishments of measures of planting and management by estimating ecophysiological characteristics of seedlings of Cydobalanopsis multinervis and Michelia foveolta. The main results were as follows:1.Photosynthetic characteristics and light response characteristics of Cydobalanopsis multinervis and Michelia foveolta under different shadings.Pn of Cydobalanopsis multinervis was decreased in level of extreme significance by shading. There were no significant difference of Pn of Michelia foveolta under three light treatments, but Pn of Michelia foveolta was relatively higher under one layer shading. Comparing with full light treatment (control), Tr, Gs, WUE and light saturation point were significantly decreased, Ci was increased by shading. So far as curve of light response, seedlings of 2 tree species represented higher photosynthetic capability under shading treatments in the ranges of low light. In the ranges of high light, Pn of Cydobalanopsis multinervis was higher under full light treatment and Pn of Michelia foveolta was higher under one layer shading.2.Photosynthetic diurnal variation of Cydobalanopsis multinervis and Michelia foveolta under different shadings.The curves of photosynthetic diurnal variation were changed by shading in Cyclobalanopsis multinervis and Michelia foveolta, Pn of Cyclobalanopsis multinervis was decreased obviously during daytime. With the increasing of shading, Pn of Michelia foveolta was decreased before noon, Pn was the highest at 11:00am under one layer shading. Moreover there were no significant difference of Pn under full light and two layers shading treatments after noon. Tr and Gs were decreased obviously by shading during daytime, but photosynthetic diurnal variation of Ci were contrary to Pn. Pn of Cyclobalanopsis multinervis and Michelia foveolta were decreased obviously at 13:00pm, which appeared "Midday depression of Pn".3. Growth and seasonal variation of physiological characteristics of Cyclobalanopsis multinervis and Michelia foveolta under different shadings.Plant height and perimeter of Cyclobalanopsis multinervis were decreased in level of extreme significance, which resulted in decreacing branches and leaves dry weights, roots dry weights, the whole dry weighys of plant under shading. But Michelia foveolta had obvious growth dominance under one layer shading, the increasing of plant height is relatively high, there were no significant difference in increased perimeter, branches and leaves dry weight, roots dry weights, the whole dry weights of plant in Michelia foveolta between full light and shading treatments. Branches and leaves dry weights/Roots dry weights is higher in Cyclobalanopsis multinervis and Michelia foveolta under shading, which revealed that growth of roots were restrained by shading. From June to October, special leaf weights,. Chla/Chlb and soluble sugar contents were decreased in Cyclobalanopsis multinervis and Michelia foveolta under shading, but leaf w...