Stomatal responses to rapidly imposed water stress and light/dark transition in norflurazon-treated wheat leaves

Hoglund, H. O. and Klockare, R. 1987. Stomatal responses to rapidly imposed water stress and light/dark transition in norflurazon-treated wheat leaves.
Stomatal responses to rapidly imposed water stress and to light/dark transition were studied in leaves of wheat ( Triticum aestivum L. cv. Starke II) treated with nor-flurazon (NF) which is known to inhibit abscisic acid (ABA) accumulation. The stomatal response was studied in an open air flow system. It was shown that these plants have the ability to respond to externally added ABA. When the water potential in the nutrient solution was rapidly reduced, stomata in green plants responded with a transient opening followed by a strongly decreased aperture. NF-treated plants responded with a similar rapid opening of stomata, but the following closure was strongly reduced. Transfer from light to darkness induced a rapid closure of stomata in green plants but the closing response was strongly delayed in NF-treated plants. These results indicate that NF affects one or more regulators involved in the closure of stomata under rapidly imposed water stress and in the light/dark transition. The possibility that this regulator is ABA is discussed.