University of California Water Resources Center

Antitranspirants conserve water and maintain favorable plant water balances by reducing stomatal apertures, by forming a thin film over the leaves, or by reflecting excessive radiation. Under normal conditions, reductions in both transpiration and photosynthesis are to be expected, but reduction in growth does not always occur, and need not always be disadvantageous when it does. Antitranspirants do not raise leaf temperature excessively, and are not likely to interfere greatly with mineral nutrition. They are likely to be most effective in reducing transpiration when other factors (boundary layer and stomatal resistances) are not large. The effectiveness of an antitranspirant also depends on plant factors such as stomatal distribution and amount of new foliar growth, and on spray factors such as degree of coverage, concentration and amount of spray, and phytotoxicity.

Investigations on possible uses for antitranspirants included experiments on: 1) reducing irrigation frequency and growth of highway oleanders; 2) reducing water requirement turf grass; 3) growth, yield and water use of an annual field crop; 4) increasing survival of transplants; 5) increasing vase life of cut flowers and reducing water loss from bedding plants for shipment; 6) prolonging life of cut Christmas trees; 7) correcting plant disorders associated with water balance, e.g., lettuce tip burn, bean blossom drop, prune cracking, and cherry cracking; 8) increasing water potential and fruit growth of orchard trees, including olives, peaches and apricots.