Iron Fertilization Effects on Shoot/Root Growth, Water Use, and Drought Stress of Creeping Bentgrass

Abstract

Abstract Creeping bentgrass ( Agrostis palustris Huds.) golf greens in the U.S. Southeast are subjected to summer drought and heat stresses. This study was initiated to determine the effects of foliar Fe on FC‐sufficient bentgrass shoot responses, root growth, and respones to drought stress. Ferrous sulfate (FS), Lawn‐Plex (LP), and Sequestrene 330 (Seq. 330) (FeSO 4 ‐7H 2 O; Fe phosphate‐citrate; and sodium ferric diethlenetriamine‐pentaacetate, respectively) were applied to a golf green at 1.12 kg Fe ha −1 per month for a 17‐mo period. All Fe sources improved color and visual quality throughout the year; summer color improved 5.9% compared to 8.6 to 9.5% for all other seasons. Total extractable tissue Fe was not well correlated with color ( r < 0.54). Iron carriers had different effects on growth, especially between late summer and winter. Lawn‐Plex increased cool‐season clipping yields while Seq. 330 reduced verdure in the summer by 18% compared to the control. Root growth (weight and length) was equal to, or less than the control for all Fe treatments. In August, FS‐treated plants exhibited a 31% decrease in root length density (RLD) in the 0 to 10 cm zone. In October, 10‐ to 20‐cm depth RLDs were reduced relative to the control by 31% for FS and 28% LP for treatments. While LP tended to reduce rooting, it was the only Fe carrier to exhibit consistently better (15– 40%) soil moisture extraction than the control. Iron had no apparent effect on canopy temperature as a stress indicator. Since shoot growth, root growth, and water extraction responses often varied with Fe carrier, many reported Fe effects are probably due to the carrier rather than Fe. Exceptions would be the color and visual quality improvements observed for all Fe carriers.