| Suitable tree system of pear is the important conditions which make a mature tree fast, have early, high harvest, high quality, efficiency and make tree strong long life. Tree system must meet breed character and planting density, three factor coordinated make varieties characters and tree system well, also density rationally. The same place, the same variety and planting density, the possible reasons for the different quality is tree system, because light distribution with tree system appeared difference, photosynthesis product photosynthesis produced is different, eventually lead to total soluble solids in the fruits accumulation are different. But in many indicators of pear quality, sugar is also the most important, because it is the important component of the total soluble solids, also is the main factor of influencing flavor indexes. So it is necessary studied micro reason that different lighting distribution caused sugar different accumulation.This experiment had be done since 2008 to 2010. Horizontal trellis system, V-shaped system, Y-shaped system, Delayed-open central leader system was the four researched tree system, sugar accumulation process and its relationship with the activity of sucrose metabolizing enzyme in the cultivar 'Nakai' pear were studied. The results were as follows:(1)sucrose, glucose, fructose content increasing gradually with 'Nakai' pear fruit growing, but growing trend showed different. Sucrose changed sharply trend; Fructose was slow growth early and followed by sharply increased, the trend was s-type; And glucose was fluctuation trend, but the general trend was still straight increased. Sugar content was fructose highest when cultivar 'Nakai' pear matured, sucrose and glucose content did not differ.(2) Inr was gradually reduced with fruit growed, AI fell rapidly with fruit growing but increased slightly in mid-term; NI remains at low status during fruit development, later still reduced, but the change was not obvious. SS (breakdown direction) presented slow increase trend throughout the development process in the cultivar 'Nakai' pear; SS (synthetic direction) was slightly lower in early, late gradually increasing trend. In the whole development fruit, SPS was a'increase -reduce-increased'trend, increased slightly in early fruit growing, followed with slow reduced, then SPS activity increased rapidly with fruit mature later.(3) Within sucrose metabolism in the cultivar 'Nakai' pear, SS and the SPS was the key enzymes that influencing the metabolic. The SS (synthetic direction) and the SPS influenced the sucrose accumulation in fruit development of mid-term and mature, was the the key enzyme that effected sucrose sucrose synthesis; And SS (breakdown direction) was a significantly negative correlation with the accumulation of sucrose in the whole process of fruit development, was influenced the key enzyme of sucrose decomposition. In fruit development process, Inr activity had been low level, and had little correlation with sucrose content, so Inr played regulating role in sucrose metabolism, was not the key enzymes.(4) Under different tree system, fructose, sucrose and glucose content were highest with Horizontal trellis system, followed by V-shaped system and Y-shaped system, Delayed-open central leader system were lowest. The net enzyme activity were highest with Horizontal trellis system, followed by V-shaped system.Comprehensive showed, Horizontal trellis system was a suitable pluning way for cultivar 'Nakai' pear, and Horizontal trellis system had acommodious operating space in the tree that can make its advantages planting grasses, raise pigs and poultry free, developing circular agriculture, increasing production efficiency. |
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