ABSTRACT Polycross breeding is widely used in outcrossing forage and turf grasses to generate genetic diversity and develop improved cultivars; however, unknown paternal contributions limit accurate pedigree‐based genetic evaluation by obscuring additive genetic relationships among progenies. Here, we integrated expressed sequence tag‐simple sequence repeat (EST‐SSR)‐based paternal assignment with repeated‐record restricted maximum likelihood/best linear unbiased prediction (REML/BLUP) analysis to reconstruct full‐sib pedigrees, establish relationship matrices and estimate breeding values in tall fescue ( Festuca arundinacea Schreb.). Twenty‐one parental genotypes generated 960 open‐pollinated progenies, from which 120 full‐sib progenies were identified using EST‐SSR markers. All genotypes were evaluated under normal irrigation and salinity stress across eight cutting cycles during 2022–2023. Forage productivity, agro‐morphological, turf‐related, water‐status and salinity‐response traits were assessed, and marker‐derived pedigrees were incorporated into repeated‐record REML/BLUP models. Standardized breeding values were further integrated using principal component analysis and a PCA‐derived composite index (PCI) for multi‐trait selection. Salinity reduced overall trait performance, but response patterns differed between parental genotypes and progenies. Parental genotypes showed greater reductions in forage yield and relative water content, whereas progenies maintained forage production better. However, progenies exhibited larger declines in turf‐related traits, including ground coverage, turf quality and density. Salinity also reduced the heritability of fresh and dry forage yield from 0.49 and 0.51 to 0.24 and 0.23, respectively. In contrast, several turf‐related traits retained moderate‐to‐high additive genetic control. Genetic correlations indicated stronger forage–turf coordination under normal irrigation but reduced alignment under salinity. BLUP‐predicted breeding values also showed marked temporal and environmental variation; under salinity, FFY and DFY were positive in the initial cut but became negative in several subsequent cutting cycles. A marked summer decline followed by autumn recovery was consistent with a possible incomplete summer‐dormancy response. BLUP‐based PCA and PCI identified parental genotypes 14E, 6L and progeny 37 as broadly adapted candidates, whereas progenies 62 and 65 showed superior dual‐purpose performance for both forage productivity and turf‐related traits under saline conditions. Overall, the integrated marker‐resolved pedigree–REML/BLUP–PCA–PCI framework enabled evaluation of salinity responses, estimation of genetic parameters and breeding values, characterization of trait relationships and identification of promising genotypes. This framework provides an effective strategy for identifying superior forage–turf genotypes and highlights the importance of multi‐trait selection for improving salinity resilience in tall fescue. These candidates provide a basis for future crossing and independent validation under salinity.
Perennial ryegrass (Lolium perenne L.) underpins the pasture-based dairy industry in Australia, yet its shallow root system limits adaptation to drought conditions. Multispecies pastures, consisting of grasses, legumes and herbs, are increasingly adopted to improve ecosystem resilience, but their interactions with soil microorganisms, particularly in deeper soil layers, remain poorly understood. This study investigated bacterial and fungal communities in both topsoils and subsoils across monoculture (perennial ryegrass) and multispecies (ryegrass, chicory, clovers and other plants) pastures at eight dairy farms in Victoria, Australia, using quantitative PCR and amplicon sequencing. We found that microbial abundance and diversity declined with soil depth in both pastures, and were broadly comparable between monoculture and multispecies pasture systems. Microbial community compositions differed significantly between monoculture and multispecies pasture systems in both the topsoil and subsoil, across all sampling sites. Co-occurrence network analysis indicated that at three farm sites, the subsoil bacterial and fungal network of multispecies pastures exhibited a reduced number in nodes, edges and average degree, compared to monoculture ryegrass. This indicated multispecies pasture has a stronger interference to the subsoil microbiome than that of the monoculture ryegrass. Our results demonstrate distinct subsoil microbial communities between multispecies pastures and ryegrass monocultures, which indicate that pasture composition influences microbial community assembly at depth. This suggests that subsoil microbial interactions should be considered when evaluating the ecological impact of multispecies pasture selection.
Effects of within-species genetic diversity on yield in sown grass-legume mixtures remain poorly understood. We analysed yield data from a common experiment implemented across 10 field sites and 3 years, in which both sown species diversity and legume genetic diversity were manipulated. At each site, the experimental design included four monocultures (two grasses and two legumes), and four-species mixtures with varying sown proportions (ranging from dominant by one species to equal proportions of all four). In communities containing legumes, each legume species was established with two levels of a genetic diversity treatment: a single locally adapted cultivar selected for agronomic performance (low genetic diversity) and multiple cultivars (high genetic diversity). We investigated the effects of species diversity and legume genetic diversity on annual yield. Increased species diversity resulted in higher annual yields. Across all sites and years, the mean monoculture yield was 8 t ha(-1) and the equi-proportional four-species mixture yielded 10.7 t ha(-1) (+34%, p < 0.05). Legume genetic diversity did not affect annual yield (p > 0.05), either in legume monocultures or in grass-legume mixtures. Overall, with the greater generality of interpretation from the multi-site and multi-year design, these results show that species diversity in agricultural grasslands was the primary driver of effects of diversity on yield, and legume genetic diversity had no effect. Future work could investigate whether genetic diversity plays a stronger role under field conditions of environmental stress.
This study evaluated the efficacy of tea polyphenol extract (TP, 4 g/kg DM), oak tannin extract (OT, 15 g/kg DM), and sucrose (S, 10 g/kg DM) on alfalfa ensiling dynamics and the subsequent performance and milk fatty acid composition in mid-lactation dairy cows. Seven multiparous Simmental cows were assigned to the treatments in a switch-back design, with each period lasting 21 days. Within the evaluated silos, TP and OT silages appeared to exhibit enhanced proteolysis inhibition, evidenced by higher crude protein (CP) content and reduced protein loss compared to C and S silages (p < 0.05). The additive treated silages were characterized by improved fermentation quality, showing elevated lactic acid and decreased butyric acid concentrations (p < 0.05). TP supplementation was associated with a mitigation of lipolysis, facilitating the preservation of polyunsaturated fatty acids (PUFAs) (p < 0.05). Overall, milk fat and lactose concentrations remained largely unaffected by polyphenol supplementation; however, a concurrent decline in milk protein content was observed (p < 0.05), which was significantly influenced by the treatment & times; period interaction (p = 0.0161). Statistically significant differences were detected among treatment groups regarding Sigma SFA, Sigma PUFA, and the PUFA/SFA ratio (p < 0.05). Consequently, under the current experimental conditions, TP extract showed potential in mitigating lipolysis in silage and reducing PUFA loss, while OT extract appeared more conducive to preserving endogenous PPO activity. Overall, the supplementation suggested a capacity to enhance the nutritional quality of milk fat by selectively reducing Sigma SFA and omega-6 fatty acid concentrations without compromising production performance, although the observed decline in milk protein remains a critical factor for application.
Plant growth regulators are widely used in turfgrass management to control shoot growth. However, their effects on the mechanical properties of plant tissues remain poorly understood. This study evaluated the influence of seven plant growth regulators (trinexapac-ethyl, paclobutrazol, flurprimidol, mefluidide, ethephon, indole-3-acetic acid (IAA) and gibberellic acid) and their application rates on the tensile properties of Kentucky bluegrass (Poa pratensis L.) leaves under controlled conditions. Three cultivars ('Baronial', 'Niweta' and 'Limousine') were tested in the experiment. Mechanical parameters, including stress-at-break, strain-at-break, modulus of elasticity and work-to-break, were determined using a tensile test. Plant growth regulator type and cultivar significantly affected all analyzed mechanical traits, whereas application rate influenced mainly stress-at-break and modulus of elasticity. Most PGRs reduced stress-at-break and modulus of elasticity, indicating decreased tissue strength and stiffness, while their effects on strain-at-break and work-to-break were less consistent. The highest stress-at-break and modulus of elasticity values were observed for gibberellic acid, whereas the lowest values were observed for mefluidide and flurprimidol. Responses to application rate were generally weak and inconsistent, and only paclobutrazol showed significant but weak rate-related relationships for strain-at-break and work-to-break. In contrast, cultivar-related differences were pronounced, with 'Baronial' showing higher mechanical strength and stiffness, and 'Limousine' exhibiting greater extensibility. The results indicate that mechanical resistance in Kentucky bluegrass is primarily determined by structural and genetic factors, and only secondarily influenced by plant growth regulator application. This study provides new insight into the biomechanical effects of growth regulators in turfgrass and highlights potential trade-offs between growth control and mechanical durability.
