Drought and biostimulant impacts on mineral nutrients, ambient and reflected light-based chlorophyll index, and performance of perennial ryegrass

Abstract

ABSTRACTWater shortage is a critical issue worldwide, and it may adversely impact non-food landscape plants. Thus, the impact of two levels of evapotranspiration-based (ETc) water stresses and two biostimulants consisting of s-abscisic acid (s-ABA) and glycine betaine (GB), and their combined applications on perennial ryegrass (Lolium perenne) under climatic and soil conditions of the Intermountain West, USA, were studied. Clippings with 50% ETc had higher percentage dry weight (DW) but lower fresh weight (FW) and chlorophyll index (CI) than those with 75% ETc. The performance rating of plots with 75% ETc was significantly higher (better) than those receiving the 50% ETc treatment. Clippings with the 75% ETc treatment had higher concentrations of nitrogen (N), nitrate, phosphorous (P), sulfur (S), potassium (K), sodium (Na), and copper (Cu) than those with the 50% ETc treatment. Considering all mineral nutrient values, CIs, and performance ratings, we conclude that the application of 75% ETc is sufficient for maintaining a healthy turfgrass with a satisfactory appearance, while we can save 25% water as compared to the application of water at 100%. The application of biostimulants had no effect on clipping or root FWs, DWs, or percentage DWs. Clippings from GB-treated turfgrass had significantly higher N than those from all other biostimulants or non-treated control. Additionally, clippings from the plots with the GB treatment had significantly higher S, K, and Cl but lower Zn. Clippings from the s-ABA-treated turfgrass also had significantly higher K than those in non-treated control. Average performance ratings in s-ABA and GB, and s-ABA and GB were significantly higher than those in non-treated control, underscoring the values of these biostimulants in the reduction of drought stress.