| Myrica Rubra is the one of the famous specialty fruits in China, which is widely distributed in south China. Because of its fast growth, earlier listed, high economic benefit, facility Myrica Rubra has been popularizing in Zhejiang province. CO2is the main raw material of photosynthesis. Previous studies showed that CO2enrichment can promote crop and fruit growth, improve fruit quality. However, few researches have been done to study the effect of CO2addition on growth and development of fruits and its quality, mechanism also hasn’t been known. The study was carried out in Wenzhou, Zhejiang province in2011.Based on the control test, during the young fruit period and mature period of Myrica Rubra, the concentration of CO2was controlled at about1000μL·L-1in facility, compared with the Myrica Rubra in greenhouse without carbon addition and in field, studying the effect of the carbon addition on photosynthetic characteristic, fruit growth and development, fruit quality of Myrica Rubra. Under carbon addition condition, the effect of different leaf numbers retained in single branch and different canopy position of fruit growth was also studied at the same time. Accroding to the test, fruit growth simulation model was established. The results provide support for Myrica Rubra environment optimization management and revealing the influence mechanism of carbon addition for Myrica Rubra growth and development, which showed important academic value to enriching the theory and practice of carbon addition for facilities fruit trees. The main conclusions are as follows:(1) The study showed that CO2addition in facility has significant influence in photosynthetic characteristics of Myrica Rubra. The chlorophyll content in leaves of Myrica Rubra with carbon addition reached41.7%, the Myrica Rubra without carbon addition was42.9%, the field Myrica Rubra is42.1%, The chlorophyll content had no significant differences between the groups. The maximum photosynthetic rate of Myrica Rubra at different growth period showed the law that Myrica Rubra with carbon addition in greenhouse> Myrica Rubra without carbon addition in greenhouse> Myrica Rubra in field, solar energy use efficiency of Myrica Rubra with CO2addition was1.23times of the Myrica Rubra without carbon addition,1.5times of the Myrica Rubra in field. The carboxylation efficiency of Myrica Rubra with carbon addition was0.044, the Myrica Rubra without carbon addition was0.033, theMyrica Rubra in field was0.031. The Myrica Rubra without carbon addition in greenhouse can low light compensation point, increase light saturation point. The tendency of diurnal variation of photosynthesis of Myrica Rubra under different treatments was consistent, double peak type in sunny day, single peak type in cloudy day. The relationship between net photosynthetic rate and leaf temperature was nearly sigmoid curve for Myrica Rubra under different treatments. The relationship between net photosynthetic rate and air relative humidity is quadric curve.(2) Carbon addition can promote fruit growth and development. The study showed mature date of Myrica Rubra with carbon addition treatment was7days earlier than Myrica Rubra without carbon addition treatment,19days earlier than Myrica Rubra in field respectively from young fruit to mature period. Enriching carbon can accelerated fruit growth rate, promote fruit maturing in advance to reach harvest standard. The fruit diameter of Myrica Rubra with carbon addition was increased by13%than Myrica Rubra without carbon addition treatment and30% than Myrica Rubra in field respectively when harvested. Under carbon addition condition, keeping5,10,15,20leaves and one fruit in a single branch, determination showed that Myrica Rubra growth rate was positively correlated with the increase of leaf number. When keeping25leaves, fruit growth rate was decreased than20leaves retained, because of more leaves has more respiration consumption, decreased assimilation substance from source to fruit, so the single branch with20leaves retained was the optimum. Based on the experiment data, Myrica Rubra fruit growth model was established as the scale of light temperature effect, with the independent data to validate, results showed that the regression estimate of the standard error and the determination coefficient of fruit diameter based on1:1line between simulated values and measured values were0.03cm and0.99respectively. Under carbon addition condition, fruit in south canopy had the largest fruit diameter, fruit across diameter and fruit vertical diameter reached3.62cm and3.48cm respectively, while fruit in west canopy were the smallest, fruit across diameter and fruit vertical diameter were3.04cm and3.02cm respectively, fruit diameter in different tree canopy from big to small order were:south, east, north, west.(3) Carbon addition had a significant influence in Myrica Rubra fruit, study showed that vitamin C content in fruit during mature period under carbon addition treatment were27.8%higher than Myrica Rubra in field, per fruit weight increased by24.0%, total acid decreased by20.0%, content of soluble solid substance decreased by0.19%, sugar content increased by1.13%, the ratio of sugar and acid increased obviously. Fruit with carbon addition treatment and without carbon addition treatment had similar quality, sugar content increased and acid content decreased significantly. Economic benefit analysis showed the economic benefit of Myrica Rubra tree under carbon addition treatment was1.48times higher than the tree without carbon addition treatment,4.36times higher than the tree in field.All in all, carbon addition could increase photosynthetic rate significantly, promote fruit growth, improve Myrica Rubra quality effectively, increase yields, improve economic benefit. The study results provide scientific basis for Myrica Rubra in greenhouse with carbon addition decision and environmental regulation. |
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