Co-Authors:
Lachover, D., Division of Agricultural Chemistry, The Volcani Institue of Agricultural Research, Bet Dagan, Israel
Abstract:
A pot experiment was carried out on the effect of potassium fertilization of four soil types selected as being most characteristic of Israel, and which had not received any potassium dressing for several years. The response of the 'Roma' variety of processing tomato to potassium sulfate was tested. A good correlation was found between various criteria in evaluating the nutritional status of the crop, including visual symptoms, potassium uptake in specific organs of the tomato plant, and certain biological fruit qualities. Accordingly, data were gathered which aid in determining 'deficient' and 'normal' levels of K in the tomato variety tested. In spite of the characteristic difference in exchangeable K reserves in the various soils tested, the application of the potassic fertilizer brought about a large and significant increase in the yield of fruit. This was expressed not only in the total weight of the yield but, in what is more important commercially, in the higher grade of the fruit. The biological quality of the fruit rose as a result of potassium dressing in all types of soil. This was expressed as a significant increment in the dry matter and reducing sugar contents. Contrary to expectations K-dressing did not bring about changes of any importance in the vitamin C or citric acid contents. The findings for N and P concentration in the leaf and fruit samplings seem to point to a certain decrease in their levels due to application of K fertilizer. It is quite possible that, since potassium was the limiting factor in growth in the control plants and gave a relative poor growth of the crop and a low yield of fruits, the amount of nitrogen and phosphorus added was for them in an excess, leading to an increase in both of the elements in the non-fertilized plants. © 1972 Dr. W. Junk N.V.