Effects Of Threetree Shape On The Sugar Accumulation Process And Activities Of Sorbitol-invertase During The Development Of Pyrus Pyrifolia Sunhwang

Pyrus pyrifolia ’Sunhwang’ was used as test materials. The sugar content and activities of the sorbitol-invertase were determined during the fruit development stage. It compared the sugar content and activities of the sorbitol-invertase in fruit that on different parts of the tree (the tree shape included Sparse canopy shaped,level-shaped and V-shaped). And it studied the effects of tree shaped on the sugar accumulation process and activities of sorbitol-invertase in fruit.The results were as follows:the accumulation of starch and sorbitol were the main sugar accumulation in early development stage and the accumulation of fructose was the main sugar accumulation in the late development stage. In the whole development stage of the fruit,the contents of sorbitol and starch first increased and then decreased. All of the soluble sugar content increased gradually while the fruit growing.But the increment of each soluble sugar are not the same. the increment of fructose was most obvious.sucrose was fllowed.glucose was the least.The activities of SDH and SOX increased from early to middle development stage and decreased in the late stage. And they were higher in the late stage than that in prophase. Both of them controlled sorbitol-invertase in the fruit.The increase of SDH-activities catalytic sorbitol transformed to fructose.So the content of fructose increased.The increase of SOX-activities catalytic sorbitol transformed to glucose.That made sorbitol decreasing and glucose increasing.The change of sugar content and activities of the sorbitol-invertase were the same in the fruit that on the different parts of each tree shape.It showed that the upper and external fruit were the highest, and fruit in middle canopy were better than in lower and inner.The Sunshine hours of Sichuan Basin is less. Sunshine is very improtant for leaves growing, fruit internal quality, appearance of fruit and tree body forming.some parts of the tree had better sunshine.So they had higher photo synthetic active radiation energy,higher leaf net photo synthetic rate, more photosynthate,more accumulation of carbohydrates and better enzyme-microenvironment.All of them could make the fruit have good development,appearance and quality.The results showed that canopy openness and photosynthetic photon flux density (PPFD) were significantly higher in Horizontal trellis system than that in the other two. The light transmittance and photosynthetic capacity in Horizontal trellis system was the best among the three tree form. In the fruit, the contents of the soluble sugar,starch,glucose,fructose,sucrose,sorbitol and the activities of sorbitol-invertase were the highest in the level-shaped system,following by V-shaped system, the Sparse canopy shaped the lowest.And that showed significant differences.Summarization above showed that the level-shaped system was the most suitable tree shape for planting pear in Sichuan.It could be extended to other place in Sichuan.