Studies on productivity of standard-sized apple trees, 4: The relations of canopy form and orchard density to leaf-area index and yield
1990
Asada, T. (Hirosaki Univ., Aomori (Japan). Faculty of Agriculture)
This study was carried out to clarify the relation of the form and spread of tree canopies and orchard density, defined as the percentage of land area covered by canopies, to leaf area index (LAI) and yield per ha. Data were collected in 1986 and 1987 in 27 commercial orchards of various soil and topographical conditions located in Aomori prefecture. The trees were "Fuji" apple trees grafted on domestic clonal rootstock (Malus prunifolia) or seedlings (M. sieboldii) trained to an open-center or modified leader shape; the age of the trees ranged from 15 to over 50 years. The percentage of land area covered by tree canopies ranged from 67.0% to 96.8%, with an average of 87.9%. This high coverage was due mostly to the characteristic canopy form, which was very flat, with a large within-tree variation of vertical depth of canopy, and which allowed orchard traffic under the tree canopy. The LAI on a ha basis was linearly correlated not only with the percentage of land area covered by tree canopies (r = 0.700), but with the volume of canopy per covered land area (r = 0.587). The multiple linear regression of LAI on those two variable accounted for 69.4% of the variance, where the contribution to LAI of the former variable was about 1.5 times larger than the latter one. The highest yield per ha for given percentage of land area covered by trees increased with the increase of the coverage, without differences in yield per unit leaf area
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