Effects of foliar antitranspirant or calcium nitrate applications on yield and blossom‐end rot occurrence in greenhouse‐grown peppers

Abstract

In order to reduce blossom‐end rot occurrence in greenhouse‐grown peppers, experiments were conducted to determine whether foliar applications of antitranspirants would decrease transpiration of pepper (Capsicum annuum L. cv. Hungarian Wax or Midal) leaves and subsequently redirect the flow of calcium (Ca) from plant foliage to developing fruit. Foliar calcium nitrate [Ca(NO₃)₂] applications were also carried out as a possible means to increase fruit Ca concentration and reduce blossom‐end rot. Initial studies indicated that two antitranspirant applications of 2.5% ‘Vapor Gard’ (di‐1‐p‐menthene) early in the fruiting phase of ‘Hungarian Wax’ peppers significantly increased early yield and tended to increase total Ca in the fruit. In subsequent experiments, weekly applications of either antitranspirant ‐ 1% ‘Vapor Gard’ or 1% ‘Folicote’ (a wax emulsion concentrate) ‐ throughout the fruiting phase significantly increased fruit Ca of ‘Midal’ peppers during at least part of the reproductive stage, and significantly reduced blossom‐end rot‐affected yield. Weekly Ca(NO₃)₂ applications significantly elevated leaf Ca as well as fruit Ca concentrations, and was the most effective treatment in alleviating blossom‐end rot. However, all weekly Ca(NO₃)₂ and antitranspirant treatments caused significant declines in marketable yield, so that these treatments, although effective in reducing blossom‐end rot, cannot be recommended for commercial use.