Genetic Parameters and Selection in Full-Sib Families of Tall Fescue Using Best Linear Unbiased Prediction (BLUP) Analysis of Animal Breeding and Genetic

Background: Better understanding of genetic structure of economic traits is crucial for identification and selection of superior genotypes in specific breeding programs. Best linear unbiased prediction (BLUP) is the most efficient method in this regards, which is poorly used in forage plant breeding. The present study aimed to assess genetic variation, estimate genetic parameters, and predict breeding values of five essential traits in full sib families (recognized by EST-SSR markers) of tall fescue using REML/BLUP procedure. Method: Forty-two full-sib families of tall fescue (included of 120 individual genotypes), recognized by EST-SSR markers’ along with twenty-one their corresponding parental genotypes were assessed for biomass production and agro-morphological traits at three harvests (spring, summer, and autumn) in the field during 4 years (2017-2020). Results: Considerable genotypic variability was observed for all traits. Low narrow-sense heritability (h2n) for dry forage yield (DFY) at three harvest indicates that non-additive gene actions may play an important role in the inheritance of this trait. Higher h2n of yield related traits and flowering time and also significant genetic correlation of these traits with forage yield, suggests that selection based on these traits via developing an index may lead to indirect genetic improvement of DFY. Conclusion: Our results showed the adequacy of REML/BLUP procedure for identification and selection of preferable parental genotypes and progenies with higher breeding values for future breeding programs such as variety development in tall fescue. Parental genotypes 21M, 1M, and 20L were identified as superior and stable genotypes and could also produce the best hybrid combinations when they were mostly used as maternal parent.

Endophyte Infected Tall Fescue: Plant Symbiosis to Animal Toxicosis

Endophyte-infected fescue is a major cool season forage used for livestock production in the United States and through other areas of the world. A unique aspect of this forage resource is the symbiotic relationship with an endophytic fungus (Epichloë coenophiala) that has detrimental impact on herbivores due to toxic ergot alkaloids. Research over the past 50 years has unveiled details regarding this symbiotic relationship. This review focuses on the origin of tall fescue in the United States and the consequences of its wide-spread utilization as a livestock forage, along with the discovery and toxicodynamics of ergot alkaloids produced by E. coenophiala. The majority of past ergot alkaloid research has focused on observing phenotypic changes that occur in livestock affected by ergot alkaloids, but recent investigation of the metabolome, transcriptome, and proteome have shown that fescue toxicity-related illnesses are much more complex than previous research suggests.

Robotic Mowing of Tall Fescue at 90 mm Cutting Height: Random Trajectories vs. Systematic Trajectories

Tall fescue (Schedonorus arundinaceus (Schreb.) Dumort.) is often managed with a cutting height ranging from 70 to 100 mm in ornamental lawns. Some autonomous mowers have been specifically designed to maintain mowing height in the same range. Generally, autonomous mowers operate by following random trajectories, and substantial overlapping is needed to obtain full coverage of the working area. In the case of tall grass, this may cause lodging of grass plants, which in turn may reduce turf quality. The introduction of a navigation system based on systematic trajectories has the potential to improve the performances of autonomous mowers with respect to machine efficiency and turf quality. With the aim of determining the effects of reduced mowing frequency and systematic navigation systems on turf quality and mower performances in terms of working time, energy consumption and overlapping, the performances of two autonomous mowers working with random and systematic trajectories were tested on a mature tall fescue lawn at 90 mm cutting height. The working efficiency was approximately 80% for the systematic trajectories and approximately 35% for the random trajectories; this was mainly due to the lower overlapping associated with systematic trajectories. Turf quality was slightly higher for the mower working systematically (a score of 8 using a 1–9 score with 1 = poor, 6 = acceptable and 9 = best) compared to the one working randomly (quality of 7 and 6 on a 1–9 scale with 1 = poor and 9 = best). No appreciable lodging was observed in either case. For tall, managed lawns, systematic trajectories may improve autonomous mowers’ overall performances.

Aerenchyma Formation in Adventitious Roots of Tall Fescue and Cocksfoot under Waterlogged Conditions

The formation of aerenchyma in adventitious roots is one of the most crucial adaptive traits for waterlogging tolerance in plants. Pasture grasses, like other crops, can be affected by waterlogging, and there is scope to improve tolerance through breeding. In this study, two summer-active cocksfoot (Dactylis glomerata L.) cultivars, Lazuly and Porto, and two summer-active tall fescue (Lolium arundinaceum Schreb., syn. Festuca arundinacea Schreb.) cultivars, Hummer and Quantum II MaxP, were selected to investigate the effects of waterlogging on root growth and morphological change. Cultivars were subjected to four periods of waterlogging treatments (7, 14, 21 and 28 days), while comparable plants were kept under free drained control conditions. The experiment was arranged as a split–split plot design, with waterlogging treatments (waterlogged, control) considered as main plots, time periods (days of waterlogging) as subplots and cultivars as sub-subplots. Plants began to show signs of waterlogging stress 14–21 days after the onset of waterlogging treatments. There were no significant differences in shoot biomass between the waterlogged and control plants of any cultivar. However, waterlogging significantly reduced root dry matter in all cultivars, with greater reduction in cocksfoot (56%) than in tall fescue (38%). Waterlogging also led to increased adventitious root and aerenchyma formation in both species. Cocksfoot cultivars showed a greater increase in adventitious roots, while tall fescue cultivars had a greater proportion of aerenchyma. Both cultivars within each species showed similar responses to waterlogging treatments. However, an extended screening program is needed to identify whether there are varietal differences within species, which could be used to discover genes related to aerenchyma or adventitious root formation (waterlogging tolerance) for use in breeding programs.

Persistence of perennial ryegrass, tall fescue and cocksfoot following annual sowings: influence of grass species, ryegrass cultivar and pasture age on yield, composition and density

Persistence is an important component of perennial pasture-grass productivity. Defining traits that affect persistence is essential for improving pasture longevity through plant breeding and for identifying persistence traits that should be included in cultivar ranking indices. Compared with conventional longitudinal studies, where a single sowing is monitored over time, repeated annual sowings allow the effects on persistence of sowing year and the ensuing interactions between environment and age of pasture to be identified. An experiment was commenced in 2015 under sheep grazing in Canterbury and in 2016 under cattle grazing in Waikato, where eight cultivars of perennial ryegrass representing different ploidy, flowering date, and cultivar age (release date), and one cultivar each of tall fescue and cocksfoot were sown in four randomised complete blocks in autumn each year. This paper reports interim data on spring and autumn pasture yield, composition, and density of 3-year-old, 2-year-old and 1-year-old pastures exposed to the same environmental conditions within the same, single year. There were significant effects on yield, botanical composition, basal cover and tiller density due to cultivar, pasture age, and their interaction. When the confounding effect of year-to-year variation was removed by comparing each age cohort in the same year, the underlying differences among grass species and cultivars, and ages of pasture, is starting to reveal the nature of this influence on pasture persistence.