Seed functional traits in cultivars of tall fescue (Schedonorus arundinaceus) are affected by the non-toxic fungal endophyte AR584

Abstract

Context: Tall fescue (Schedonorus arundinaceus) is one of the most important cultivated forage grasses in temperate regions but its association with some Epichloë fungal endophytes usually makes it unsuitable for livestock feeding due to toxic alkaloids. However, re-inoculation of plants with non-toxic endophytes can result in positive effects for livestock feeding. Aims: Assess the effects of the non-toxic AR584 endophyte on seed viability and germination in two tall fescue cultivars. Methods: The effects of AR584 endophyte (presence/absence) and tall fescue cultivar (INIA Aurora/Taita) were evaluated on seed viability and germination responses across a range of temperature and water availability regimes. Response to constant temperature and water availability was characterised by the thermal-time and hydro-time models, respectively. Key results: Under accelerated aging conditions, endophyte presence reduced seed viability in cultivar Taita. For both cultivars, endophyte-infected seeds showed a lower germination rate than endophyte-free seeds, except for INIA Aurora under low incubation temperatures. Also, endophyte-infected seeds in both cultivars displayed lower germination rates and final germination as the water potential was lowered. Conclusions: A strong cultivar-by-endophyte interaction for seed germination indicates the need to understand how specific cultivar-endophyte combinations best fit a given environmental condition, as defined by temperature and water availability. Implications: The information we present can be valuable not only for farmers who have to decide what to cultivate but also for seed companies that have to preserve seed quality.