Effects of Foliar Application of Calcium Solutions on the Incidence of Blossom-end Rot of Tomato Fruit

Abstract

The reduction on the incidence of blossom-end rot (BER) of tomato fruits by foliar applications of a) plant extract (PE) containing an organic chelating agent; b) PE chemically combined with Ca (PE-Ca); c) PE-Ca mixed with sugar ester (PE-Ca+SE); d) PE-Ca+Fe; e) PE-Ca+Zn; f) PE-Ca+xylose; g) calcium chloride, and h) calcium nitrate was studied. The tomato plants were grown in a rockwool system.
1. The foliar application of PE-Ca+SE and PE-Ca+Zn significantly reduced the incidence of BER as compared with the control. These treatments increased the marketable yield significantly and did not decrease the fruit quality. Thus, the foliar application of Ca solution containing SE or Zn was recommended to reduce the BER incidence of tomato fruits.
2. Ca concentration of young fruits decreased quickly as the fruit grew, attaining the minimum value when the fresh weight became about 20 g, at which time the symptoms of BER began to appear. Compared with the normal fruits, BER fruits had considerably lower Ca concentration. A clear relationship between the BER incidence and the K/Ca ratio of young fruits or foliar Ca concentration was not botained.