AN AGENT FOR CHEMICAL THINNING OF APPLE FRUITS BASED ON NAPHTHENIC ACIDS

摘要

The invention solves the problem of chemical fruit thinning in order to regulate the productivity and fruit size without decline in fruit quality. In the available literature it has not been reported so far that naphthenic acids may cause abscission of young apple fruit, nor can enhance the growth of the remaining fruit on the trees, but it is known to exhibit the physiological activity analogue to plant hormones of auxin type. The core of invention consists in fact that naphthenic acids applied at the rate of 2.6 ppm thins young apple fruits similarly to thinning effect of NAA at the rate of 16.5 ppm. It thins fruits more selectively than NAA which means that more central fruits persist on a tree. The application of naphthenic acids increases the average fruit weight and diameter, while fruit firmness is unaffected. The number of small fruits after treatment is at the level of untreated control. To test the effectiveness of naphthenic acids as a thinning chemical, a concentrated solution containing 1.42 g of naphthenic acid in 100 ml was used, which have to be diluted prior application to the appropriate final concentration in the range of 0.5 to 5 mg/1 of naphthenic acid, depending on the intensity of of fruit set.