論文の公開元へ園地当たりの葉量が等しい条件下における樹幅と樹高の違いが果樹園の光環境に及ぼす影響 : 樹冠設計システム（CDS）を用いたモデル実験
概要
In order to investigate the effects of tree width or tree height on orchard light environment where the foliage biomass per orchard land area was equal, the following model experiments were done. Using four kinds of tree widths, three kinds of tree heights and various alternatives in the training- pruning procedures, the next ten crown model groups (CMGs) were designed by the CDS method (Yamamoto, 2020), viz., thick type and medium height(CMG1), thick type and short height(CMG2), slender type and medium height(CMG3), slender type and short height(CMG4), ultraslender type and medium height(CMG5), ultraslender type and short height(CMG6), thin hedgerow type and medium height(CMG7), thin hedgerow type and short height(CMG8), ultrathick type and medium height(CMG9)and ultrathick type and long height(CMG10). A sort of green road with an applicable width was given to each CMG. Sum total 46,080 crown models were designed. The total number of crown models was 9,591, which satisfied the five restrictions, i.e. the tree height, the east-west tree width, the north-south tree width, the upper limit of leafy blocks number per tree and the lower limit. Orchard light environment, photosynthesis and characteristics of canopy shape were analyzed on these crown models using the same methods as described in the previous reports (Yamamoto, 2015, 2016). As the result, great differences in the light environment were found between the crown model groups. For example in the experiment plot of four primary scaffold branches (PSBs), by comparing CDMPPFD (the daily mean of leaf PPFD on a clear day) between the ten CMGs, the next relationship of the mean CDMPPFD were found as follow; CMG3≥ CMG4≥ CMG6> CMG8> CMG7≥ CMG5> CMG1≥ CMG9≥ CMG2> CMG10. There was the close correspondence between the order of the mean CDMPPFD and that of the characteristics of canopy shape. The causes were considered that the proportion of the leaf layers at crown surface more increases and the shades inside the crown more decreases as the crown becomes thinner. The mean CDMPPFD of five crown models were compared, whose CDMPPFD was the highest to the fifth in each crown model. When the mean CDMPPFD of CMG1 was 100, the relative value of CMG6 was over about 140, that of CMG3 and CMG4 were over about 138, and that of CMG7 and CMG8 were over about 134. On the contrary, the relative values in CMG2, CMG9 and CMG10 were under about 100. However, the large effect of the tree height on the CDMPPFD could not be recognized in many crown model groups except of cases between MG5 and CMG6.
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