A quantitative histochemical procedure for measurement of starch in apple fruits

Measurements of starch (e.g. amyloplasts in stomatal guard cells, sieve ele ments, root tips or the starch sheath) is often very difficult using most a nalytical methods. An evaluation was made of interactive computer image ana lysis of starch measurements in apple fruits. The results obtained indicate that quantitative histochemistry can be an appropriate method to quantify starch. Correlations for starch values between the image analysis system an d a colorimetric system were quantified. The thickness of plastic-embedded slices had no influence on the accuracy of the area occupied by image-quant ified starch (starch/slice) or on its variance. The magnification of the ob jective also had no effect on measured starch-occupied areas (starch/slice) , but there were big differences in variance. The number of replications re quired to establish statistically significant differences were calculated.