As a preamble to a breeding programme for colour in roses, the relative quantities of carotenoids, eyanidin, pelargonidin, quercetin and kaempferol were determined in about 200 varieties and some species. Cyanidin was about normally distributed among red varieties, as were carotenoids and flavonols among white and yellow varieties. A positive relationship between pelargonidin and kaempferol was established, and a negative one between peiargonidin and quercetin. No other relations were found between the pigments.
Rapid quantitative determination of carbohydrates is possible with the aid of Dreywood's anthrone reagent, but the reproducibility of the method was found to be unsatisfactory. Better results were obtained by modifying the method and standardising it accurately. The modifications mainly bore on the composition and preparation of the reagent. The exclusion of dust during the determination was found to be very important.
Rapid simultaneous determination of glucose and fructose was possible by carrying out the reaction at 60° and 100°. An essential condition was that other carbohydrates and substances causing interference should be almost absent.
Application to the determination of sugars in tomato and apple is described.
A description is given of rapid methods for the determination of sugar and acid contents in apple to be used in breeding for fruit quality . Special attention is given to sampling. Besides the stage of maturity of the fruit, its position on the tree has an effect on the chemical composition of the sample . When only part of the fruit is used for analyzing, the difference in content of the exposed and shaded sides should be taken into account .With the pH determination in deep-frozen leaves the results depend largely on the duration of freezing and the time interval between thawing and pH measurement .
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