Use of Minolta SPAD-502 chlorophyll meter to quantify the effectiveness of mid-summer trunk injection of iron on chlorotic pear trees

摘要: Abstract The severity of leaf chlorosis in iron (Fe)‐deficient fruit trees is often characterized using a semi‐quantitative visual rating index that subject to evaluator bias. Analytical instruments are now available provide quantitative measure green color could substitute for ratings. We injected limbs mature chlorotic pear (Pyrus communis L. cv. Bartlett) with distilled water or solution 0.1% Fe (w/v) as FeSO4‐7H2O on 17 July 1995. Treatments were replicated eight‐fold. On 18 August 1995, Minolta SPAD‐502 chlorophyll meter was used the 30 randomly sampled leaves located above point injection each limb. Average higher Fe‐injected tree than water‐injected experimental block. Leaf (mean±SD) averaged 34.7±3.8 SPAD units and 27.3±3.8 trees. absolute increase mean 7.4 w...