リンゴ園における葉面積の推定法

Abstract

The relationship between leaf area and branch diameter was examined to establish a method for estimating orchard leaf area. Measurements were obtained from 15-25-year-old “Fuji” apple trees on a domestic clonal rootstock (Malus prunifolia) trained to an open-center or modified center-leader shape in 22 commercial orchards of various soil conditions located in Aomori prefecture.The relationship between leaf area (Y) and branch diameter (X) was represented by a single regression equation:log Y=-0.710+2.145log X The correlation was fairly high (r=0.931), considering that the sample branches were taken under a wide range of orchard conditions. This was considered to be attributable to the facts that samples were selected from branches of at most 5cm in diameter measured at the point just below the lowest leafy branchlets.The following method was proposed for estimating the total leaf area of an apple tree. The leaf area on all individual branches of less than 5cm in diameter is estimated from their diameter, using the regression equation presented above. The values of the leaf area of individual branches are then summed up for the whole tree.The leaf area of scaffold branches which was estimated using this method gave a close approximation to the actual leaf area (r=0.920).It is concluded that the above estimation method provides a rapid and reasonably accurate measurement of the total orchard leaf area and can be used for a satisfactorily wide range of orchards.