Drought Induced Cuticular Changes to Creeping Bentgrass As It Affects Foliar Absorption of 15N.

Foliar fertilization is a common practice to deliver nitrogen to golf course putting greens.  Unfortunately, very little is known about the mechanisms involved with nutrient uptake by foliar application.  The goals of this study were to understand cuticle changes under drought affecting nutrient absorption.  ‘A1-A4’ creeping bentgrass (Agrostis stolonifera L.) under drought treatments was studied to determine morphological and compositional changes to the cuticle and how it affects foliar absorption.  Water deficiency treatments included: control, level I and level II at 100% ET, 50% ET and 25% ET returned, respectively.  Morphology and composition of the cuticle were analyzed using scanning electron microscopy and gas chromatography.  Foliar absorption was studied by a foliar application of ¹⁵N-labeled urea applied at 0.732g N m^-2.  Nutrient absorption was determined by measuring %¹⁵N recovery within plant tissue using mass spectrometry.  A surfactant added to the nutrient solution was studied to determine any potential benefit to increasing foliar absorption.  Preliminary results indicate total cuticle wax increased with drought treatments, while %¹⁵N recovery decreased.  Further analyses will be made to determine the correlation between cuticle changes and %¹⁵N recovery.