Drought and Biostimulant Impacts on Important Attributes of Perennial Ryegrass for Orchard and Vineyard Floor in the Intermountain West Region of the United States

Abstract

Water shortage is a critical issue worldwide, mandating the use of efficient irrigation systems (i.e. drip and micro-jet) in modern orchards and vineyards to irrigate only the target trees and vines. Therefore, this issue may adversely impact orchard floor vegetation, which is needed to prevent tractor traffic compaction. Thus, the impact of two levels of evapotranspiration-based (ETc) water stresses and biostimulants consisting of abscisic acid (s-ABA), Glycine betaine (GB), digoxin, nano silica and some of their combined applications on perennial ryegrass ( Lolium perenne, L.) under climatic and soil conditions of the Intermountain West, USA were studied. Comparing two levels of irrigation, grass clippings with 50% ETc had higher electrolyte leakage and proline but lower visual performance, chlorophyll index (CI) and chlorophyll b than those with 75% ETc. With the exception to the digoxin at 0.5 mg·T ^-1, clippings from all biostimulant-treated plots had significantly better visual performance and higher CI, proline, chlorophyll a and b and potassium (K) concentration than those from the un-treated control. These results underscore the value of these biostimulants for improving the orchard and vineyard floor grass covers under drought stress conditions that prevail in the western United States.