Efficiency of Biostimulants for Alleviating Shade Effects on Forage Grass

Abstract

Shade is considered an abiotic stress factor which reduce the primary metabolism and restricts normal growth in forage grass in integrated systems. Biostimulants are beneficial in promoting growth and protecting plants against environmental stresses. This is the first study that links biostimulants and the primary metabolism of plants grown under contrasting light intensities. We investigated how the use of biostimulants modifies the primary metabolism, reducing the deleterious effects of shading in the development of tropical forage grass Brachiaria brizantha cv. BRS Piatã. The association of Pseudomonas fluorescens and Burkholderia pyrrocinia, inoculated by soil drench, were used as biostimulants. We measured leaf anatomy, plant growth, and biochemical parameters. The use of biostimulants increased the shade tolerance on B. brizantha by modifying leaf structure, increasing the chlorophyll content, and inducing the production of osmoregulants, such as carbohydrates and proteins. In turn, increasing the accumulation of primary metabolites, promoted root development, plant height, and leaf area, resulting in more vigorous plants with greater biomass production. These results suggested that forage grass can be protected from inhibitory effects of the shade stress by the biostimulants, and this would improve its survival and growth in integrated crop-livestock-forestry systems.

Biostimulants in the Production of Forage Grasses and Turfgrasses

“…Effective microorganisms Brachiaria brizantha improved shade tolerance, increased chlorophyll, osmoregulating compounds, root development, plant height, leaf area and biomass yields [69] Chitosan perennial ryegrass decreased heavy metal concentrations in soil, promoted early germination and elongation of leaves, did not increase resistance to pink snow mould [70][71][72] Silicon various grass species increased crude protein content, improved nutritional value and reduced fibre levels in mixed grass stands (especially in periods of drought), improved yield of grass and clover swards, higher crude protein content and better organic matter digestibility in organic farming, higher total protein content, improved nutritional value of protein and increased energy in silage compared to non-fertilised swards [48,73,74] Synthetic biostimulants annual ryegrass and Festulolium increased protein content, higher chlorophyll content, increased plant dry matter yield, increased soluble sugars content [35] Synthetic biostimulants timothy-grass increased leaf greenness index (SPAD values) [75,76] Synthetic biostimulants orchard grass increased number of shoots, leaf blades, dry weight of leaf blades, enhanced photosynthetic capacity, higher chlorophyll content, increased photosynthetic activity, increased SPAD leaf greenness index [50] 3.1. Natural Biostimulants…”

“…In the work of Lopes et al [69], EM (Burkholderia pyrrocinia rhizobacteria and Pseudomonas fluorescens) improved shade tolerance in Brachiaria brizantha by increasing chlorophyll content and stimulating the production of osmoregulating compounds such as carbohydrates and proteins. Biostimulants promoted root development, increased plant height, leaf area and biomass yields.…”

Desenvolvimento inicial de arroz de terras altas inoculado e coinoculado com rizobactérias multifuncionais

“…Rhizobacteria have different mechanisms of action, allowing them to act in various ways, such as through the production of phytohormones, the availability of nutrients, or the control of pathogens or other stresses. For this reason, they are classified as bio-stimulators, biofertilizers, or biocontrol agents (Santos Lopes et al, 2021a;Santos Lopes et al, 2021b;A. P. da Silva & Dourado, 2022a).…”