Seaweed extracts have been used to improve resistance ability to drought and cold temperature because they contain a wide range of minerals and plant hormones such as abscisic acid, auxins, betaines, cytokinins, and gibberellins. Potassium (K) is well-known for one of the essential nutrients that also increase cold resistance of plants. Although increasing cold resistance by seaweed extracts and K have been reported, research results about interactions between seaweed extracts and K applications to Kentucky bluegrass for cold resistance are limited. The objective of this study was to evaluate seaweed extracts and K rates as late fall application for spring green-up of Kentucky bluegrass. The seaweed extracts at rates of 0, 1, 2, 4, and 8 mL m-2 are applied and potassium sulfate (0-0-50) as K sources was applied at the rate of 0, 10, 20, 40 g K2O m-2. There are significant differences among seaweed extracts and K rates for turfgrass color, quality, and turf coverage under the optimum air temperature range for cool-season grasses. Overall, the seaweed extracts of 4 mL m-2 had the greatest turf color and turf coverage and the K rate of 10 g m-2 had the greatest turf color, turf quality, and turf coverage. The higher rate of seaweed extracts than 4 mL m-2 and K rate than 10 g m-2 had no difference with control for turf quality and turf coverage.
Figures & Tables
Fig. 1. Mean turfgrass color of Kentucky bluegrass for potassium (K) rates in 2021. Each mean was calculated from 15 observations (three replications×five rates of seaweed extracts). Turfgrass color was rated visually every week from 2021 using a scale of 1 to 9 (1=straw brown, 6=acceptable, and 9=dark green). Vertical bars represent least significant difference (LSD) (=0.05) values for treatment comparison at a given day of treatment. The legend in the figure are K rates and unit is g m. NS means not significant.