Effects of cutting height, fungal symbiont and soil properties on meadow fescue’s growth

Abstract

Grasses have a beneficial effect on the soil organic matter content, and hence carbon sequestration of agricultural soils throughout the world. Because grasslands cover one-third of the land on Earth and meadows and pastures approximately 70% of the world’s agricultural area, grasses serve as a powerful carbon sink. Meadow fescue is an important perennial pasture and forage grass in Scandinavia. It has deep roots, rapid growth in spring, high after growth ability, low straw formation and excellent winter hardiness. It has excellent forage quality and amount of yield and superior fiber digestibility. Meadow fescue cultivars are often symbiotic with seed transmitted systemic fungal endophytes (Epichloë uncinata) offering various benefits for their hosts, for example increased growth and reproduction, and resistance to herbivores, pathogens and abiotic environmental stresses, and systemic fungal endophytes thereby enhance the competitive abilities of endophyte-infected plants. In my master’s thesis I studied the effects of cutting height, residues of glyphosate based herbicides (GHBs) in soil, sterilized soil and fungal endophyte Epichloë uncinata to aboveground biomass production, root biomass and chlorophyll content in a greenhouse experiment. To test the importance of cutting height to grass performance, I assigned grasses to three different cutting treatments: uncut, cut to the height of 5 cm and cut to the height of 15 cm. Half of the plants were symbiotic to the fungal endophyte, the other half were endophyte-free. Plants were assigned to three different soil groups: control, GBH treated and sterilized soil. Cutting height significantly affected the total aboveground plant biomass, root biomass and chlorophyll content. Uncut meadow fescues produced the largest total aboveground biomass and root biomass which were significantly higher compared to total aboveground biomass and root biomass from grasses cut to 15 cm or 5 cm. The grasses cut to the height of 5 cm had the smallest total aboveground biomass and root biomass, which were further significantly smaller compared to grasses cut to 15 cm. Endophyte did not affect the total aboveground biomass, root biomass or the chlorophyll content of the plants. Meadow fescues produced higher amount of total aboveground biomass when growing in a sterilized soil compared to control or GBH treated soil. Root biomass was not significantly affected. Glyphosate residues in the soil decreased the amounts of total aboveground and root biomass of grasses. Chlorophyll content was highest in plants growing in sterilized soil. I conclude that to improve the total aboveground plant biomass and root biomass, the use of GBHs should be avoided and rotational grazing, in which animals are moved between pastures before they have been eating the grass too low, should be preferred. This will enable farmers to collect more harvest and sequester more carbon at the same time.