Foliar and Root Nitrogen Fertilization of Five Warm Season Turfgrasses Under Salinity Stress.

Salinity stress is a widespread turfgrass management problem in coastal areas and environments where water use restrictions are common.  However, little is known about salinity stress and it’s affect on foliar and root fertilization of urea nitrogen on turfgrasses.  The goal of this project was to evaluate performance of three ultradwarf bermudagrasses ( Cynodon transvaalensis Burtt-Davy)  ‘Champion’, ‘Mini-Verde’, ‘Tif-Eagle’, ‘Seadwarf’ Seashore paspalum (Paspalum vaginatum Swartz.), and ‘Diamond’ Zoysiagrass (Zoysia matrella (L.) Merr) under salinity stress and two nitrogen fertility regimes.  Foliar and root applications of urea nitrogen at 9.76 kg ha^-1 were applied weekly for a total of 12 weeks under greenhouse conditions.  A control (0 ppm NaCl) and saline (8,000 ppm NaCl) solutions were applied every 48 hours to bring the root-zone to field capacity.  At the conclusion of the first year, differences of nitrogen content in leaf tissue were observed at the cultivar level.   However, salinity irrigation and fertility regimes did not significantly alter nitrogen content in leaf tissue.   Stress levels as indicated by electrolyte leakage (EL) and proline accumulation indicated differences in cultivars of ultradwarf bermudagrass.  ‘Champion’ performed most poorly.  Compared to root targeted fertilization, foliar applications of urea resulted in higher levels of phosphorus and potassium in leaf tissue.  These preliminary results suggest that foliar and root applications of nitrogen are not affected by saline irrigation but there are significant nutrient benefits of foliar fertility over root absorption.  Additional results and observations will be compiled after year two of the study.