Abstract:

The canopy structure characteristics, yield, and quality differences were comparatively investigated between the horizontal trellis system (HTS) and the delayed-open central leader system (DLS) of 'Hosui' pear tree with WinsCanopy2005a for Hemispherical Image Analysis. The results showed that mean leaf angle，canopy openness，direct PPFDs, indirect PPFDs and total PPFDs under tree were significantly or very significantly higher in HTS than that in DLS, but the leaf area indexes were significantly lower in HTS than in DLS. Single fruit weight, total contents of soluble solid and sugar, and sugar-acid ratio of HTS were higher by 23.59%, 9.7%, 11.25% and 29.08%, respectively. Whereas, fruit yield per tree, titratable acidity and stone cell contents were lower by 17.80%, 13.45%, and 30.43%, respectively, in comparison to DLS. Consistency of fruit quality in different positions of HDS was better than that of DLS, which was mainly ascribed to the relatively large canopy openness, higher PPFD and strong bearing branch, while its lower yield could be explained by its smaller shoot total volume and leaf area index. The significant correlations were found between the canopy characteristics parameters and yield as well as main quality indexes, for example, canopy openness were very significantly positively related to the total soluble sugars ( r = 0.9820**), but correlated negatively with titratable acidity ( r = - 0.9485**). It is suggested that the application of WinsCanopy2005a may be a new method for the research on tranining systems of pear tree.

Key words: pear, tree system, canopy, horizontal trellis system, delayed-open central leader system, yield, fruit quality