Application of Fall Nitrogen Increased Spring Tall Fescue Yield

Late season nitrogen fertilization is a practice that has long been implemented in turfgrass production. This practice involves applying nitrogen from September through December and results in an extended green period in the fall without stimulating excessive shoot growth. The longer green period results in higher levels of carbohydrate reserves and enhanced root growth compared with a spring-summer fertilization program. In addition to these benefits, sods fertilized in late fall have been shown to green up two to six weeks earlier in the spring. Limited research has considered the impact of late fall nitrogen applications on grass growth in hayfields and pastures. The objective of this study was to evaluate the impact of late fall nitrogen fertilization on dry matter production of an established tall fescue stand. In 2020 and 2021, the study was conducted at the UK Research and Extension Center located in Princeton, KY. The experimental design was a random complete block with four replications. In early December 2020 and 2021, 0, 34, 67, and 101 kg ha-1 was applied as ammonium nitrate, ammonium sulfate, and Anuvia SYMTRX 20S. An additional 90 kg ha-1 was applied as urea to all plots the following spring. Plots were harvested on 13-May-2021 and 24-May-2022 using a self-propelled sickle bar type forage harvester equipped with load cells. Averaged across sources, first harvest yields ranged from 3428 to 5675 and 3929 to 5831 kg ha-1 in 2021 and 2022, respectively. Fall applied nitrogen resulted in a linear increase in dry matter yield of 25.0 and 21.2 kg ha-1 in 2021 and 2022, respectively. Nitrogen sources had no impact on dry matter yield (P \u3e 0.05). Plots receiving fall applied nitrogen also initiated growth earlier in the spring

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Cytological and Agronomic Evaluation of Interspecific Hybrids Between \u3cem\u3eTrifolium repens\u3c/em\u3e L and \u3cem\u3eT. Occidentale\u3cem\u3e coombe

Trifolium occidentale is a diploid wild relative of T. repens with adaptation to dry, saline coastal habitats. Transfer of drought and salt-tolerant adaptive traits from this potential source of germplasm to T. repens could be valuable if interspecific hybridization can be achieved efficiently. To achieve hybridisation, 4x plants of T. occidentale were generated through colchicine chromosome doubling. Interspecific 4x F1 plants were achieved without embryo rescue. F2 populations and backcross (BC) hybrids to white clover were also efficiently achieved. Although male and female fertility in primary F1 and F2 hybrids were lower than in white clover, they were adequate to produce large amounts of seed from small numbers of inflorescences. Thus, early generation pre-breeding interspecific hybrid populations can be readily developed, opening the way for transfer of traits from T. occidentale to white clover. For effective introgression (backcross) breeding, it is also essential that interspecific chromosome pairing and recombination occur. In this study, it was apparent that chromosome pairing was occurring not only between T. occidentale and T. repens subgenomes, but also between the ancestral subgenomes of T. repens. Thus, interspecific hybridization has the potential for major genome recombination and opens the way for introgression of traits from T. occidentale into white clover. Eighty hybrid families, comprising backcross one (BC1), backcross two (BC2) and their inter-crosses, were evaluated in the field and compared with eight commercial T. repens cultivars and nine T. repens x T. uniflorum backcrosses under three natural summer droughts. Some hybrid families performed as well as, or better than, elite cultivars and had superior recovery after drought periods. Selected plants were inter-crossed to further reshuffle the inter-specific chromosomes for introgression

Future Scenario Projections of Livestock Carrying Status of Grassland Ecosystem in Kazakhstan

As a country dominated by animal husbandry, the livestock carrying status in Kazakhstan has a prolonged impact on grassland degradation and restoration, and thus on the supply of grassland ecosystem services. Here we predict future conditions of livestock carrying status by modeling change in potential forage supply and consumption from 2020 to 2030, using three alternative scenarios following Representative Concentration Pathways, specifically SSP2 (RCP4.5, MESSAGE), SSP1 (RCP2.6, IMAGE) and SSP3 (RCP7.0, AIM), namely BAU, TSS and SSS respectively. Our future scenarios suggested that from 2020 to 2030, the forage consumption in central and southern regions of Kazakhstan is predicted to increase rapidly, while forage supply will decrease in these regions, especially the northern parts. The livestock carrying status in the southern regions tends to be overloaded to different degrees especially under the SSS and BAU scenarios, whereas the other areas hold surplus status. Our study could serve as a scientific basis for enhancing grassland management and achieving the target of the Sustainable Development Goals 2030

Canopy Characteristics and Growth Rate of Bahiagrass Monoculture and Mixtures with Rhizoma Peanut

Understanding relationships among canopy light interception (LI), canopy height and structure, and leaf area index (LAI) informs management decisions and can improve efficiency of forage-livestock systems. In a long-term experiment in Florida, USA, we assessed the LI, LAI and sward height relationships of rhizoma peanut (Arachis glabrata Benth., RP)-bahiagrass (Paspalum notatum Flügge) mixed swards compared with bahiagrass monoculture to determine whether changes in canopy structure affect herbage accumulation (HA) rate due to changes in radiation use. Treatments were arranged in a semi-factorial, split-plot design (r=4). Bahiagrass monoculture and bahiagrass-RP mixtures were whole-plot treatments. Sub-plot treatments were an undefoliated control, forage clipped to 5 cm when LAI \u3e 3, and forage clipped to 5 cm when LAI \u3e 3 and fertilized immediately after with 20 kg N ha-1. During 2021, LI, LAI and canopy height were measured weekly using a LiCOR LAI-2200 and a rising plate meter (platemeters g1000), respectively. The proportion of bahiagrass and RP in total herbage mass was determined for each treatment in July 2021. Herbage accumulation rate was calculated as HA during the regrowth period divided by days between clipping events. The relationship of LI and LAI was assessed with a negative exponential model. Relationships of cumulative LAI and sward height and days after clipping were determined using regression analysis. Incorporating RP into bahiagrass increased LI at shorter sward height compared with bahiagrass monoculture due to a greater LAI mm-1 of sward height (190-220 vs. 150-160 mm). Fertilized mixtures achieved LAI95 faster than bahiagrass monoculture, however, changes in mixture canopy structure did not result in greater radiation-use efficiency compared with fertilized bahiagrass monoculture. Herbage accumulation rate decreased for mixtures containing more than 30% RP. Application of this information can improve the efficiency of grazing systems and maximize HA of bahiagrass-RP mixtures, either under rotational or continuous stocking

PROFILES OF SATISFACTION AND FRUSTRATION OF UNDERGRADUATE GENERAL CHEMISTRY STUDENTS’ BASIC PSYCHOLOGICAL NEEDS AT THE BEGINNING AND END OF THE SEMESTER

The early college years represent an adjustment period characterized by motivational destabilization and academic and career-related uncertainty for many STEM majors (Robinson et al., 2019). Although students who begin college less academically prepared than their peers are at greater risk of struggling in introductory STEM courses, many still struggle in these courses despite adequate academic preparation (Perez et al., 2014). Self-determination theory proposes that motivation, optimal functioning, and psychological well-being occur through the satisfaction, as opposed to the frustration, of three basic psychological needs for autonomy, competence, and relatedness (Ryan & Deci, 2020). Although many studies in educational settings demonstrate the positive outcomes associated with need satisfaction, little is known about need frustration and how it may be experienced simultaneously with need satisfaction within the same learning context. Therefore, this study aims to examine individual differences in basic psychological need satisfaction and frustration as possible mechanisms underlying variation in STEM student motivation, psychological adjustment, and intentions to persist. Specifically, in these two studies, profiles are defined at both the beginning and end of the semester based on satisfaction and frustration of students’ needs for autonomy, competence, and relatedness while simultaneously examining their associations with students’ perceptions of the learning environment, motivation, psychological adjustment, and intentions to persist in STEM. Three distinct profiles of students’ satisfaction and frustration of basic psychological needs were identified at each time point in the academic semester. Profile characteristics were similar at each time point yet varied in size. One profile was characterized by need frustration prevailing over need satisfaction. A second characterized by need satisfaction prevailing over need frustration. The third profile was characterized by moderate levels of both satisfaction and frustration. The moderately satisfied and frustrated profiles were the largest groups at both time points. Furthermore, perceptions of the learning environment predicted profile membership and need profile membership was associated with distinct motivational, psychological adjustment, and academic outcomes at each time point. Implications of these profiles in understanding variation in motivation, persistence, and student well-being for STEM students are discussed

Root and Aboveground Traits Expressed by Landraces and Interspecific Hybrid of Alfalfa (\u3cem\u3eMedicago sativa\u3c/em\u3e. Hybr. (Alborea)) with Putative Drought Tolerance in Mediterranean Environments

Alfalfa’s drought tolerance has not been a major breeding target until recently, and the extent of genetic variation for this trait and its contributing mechanisms have not been thoroughly elucidated. Eight populations, including four landraces (Alta Sierra, Aragon, APG6567, APG44669), two Australian cultivars (Venus and Genesis), and two interspecific hybrids (AF3448 and AF3347) of alfalfa were selected based on their outstanding breeding values for dry matter production and plant persistence in Mediterranean drought-prone environments. The objective of this work was to evaluate the below and above ground phenotypic expression of these drought-tolerant alfalfa accessions, in order to identify morpho- physiological mechanisms conferring to alfalfa greater agronomical performance in drought-prone environments. Individual plants of each population were established on mesocosms of PVC tubes 11 cm in diameter and 100 cm in depth. Plants were grown at two water regimes: with water deficit (WD) and well- watered (WW). Both trials were organized in a complete block design with four replicates. Plant height, stem elongation rate, shoot dry matter, chlorophyll content, stomatal conductance, canopy temperature, leaf area, specific leaf area, crown diameter, relative length density, and root dry matter at 0-30, 30-60 y 60-100 cm were determined. The water regime affected significantly the phenotypic expression of all above and belowground morpho-physiological traits evaluated (P \u3c 0.05), which resulted in a 40% reduction in shoot dry matter and plant height in WD relative to WW. Alfalfa populations with putative drought tolerance in Mediterranean environments did not exhibit a unique phenotypic strategy for facing severe water stress. Populations APG44669 and Alta Sierra showed divergent phenotypic expression in terms of stomatal conductance, leaf traits, root architecture, and root biomass partitioning profile

New Insights for Benefit of Legume Inclusion in Grazing Systems

The benefits and challenges of legume inclusion in grazing systems have been well documented over time and across different regions. Recent investigations have provided novel insights into the benefits of legume inclusion in grazing systems. Our objective is not to provide a wide overview of the benefits of legume inclusion but to explore novel insights of recent advancements made from studies evaluating legume inclusion in grazing systems. Efficiency of resource use through legume inclusion in grazing systems can reduce the water footprint associated with beef production through improvements in forage nutritive value and animal performance. These efficiencies also translate into improvements in nutrient cycling and nutrient transfer, which are critical for sustaining productivity of grazing systems. Moreover, evidence exists highlighting the importance of root contact between grasses and legumes for sharing N. Provisioning of floral resources from legumes has also been shown to be important for providing habitat for pollinator species. Lastly, soil microbial abundance of microorganisms associated with N2 fixation can be altered according to species present within a pasture, especially when legumes are present. Insights derived from such recent studies continue to provide evidence for the need to continue to develop legume-based grazing agroecosystems

Looking at Cell Wall Components with Our Customers in Mind

Fiber digestibility of alfalfa for animal nutrition is a complex system encapsulating animal, plant, and microbe biological traits. Understanding all components within the system is key to predicting forage quality. We investigated the relationship between alfalfa cell wall components and invitro neutral detergent fiber digestibility (IVNDFD) speed (16-hr) and potential (96-hr) of by cattle ruminant microbes. A composite alfalfa (Medicago sativa L.) population from seven commercial cultivars underwent two cycles of bidirectional selection for plants with low or high stem 16-hr IVNDFD and low or high stem 96-hr IVNDFD. The resulting selected populations were then evaluated by near inferred spectrometry for structural cell wall components and thier relationship with IVNDFD. Hemi-cellulose and cellulose components were found to have a greater negative correlation (-0.85 & -0.86) on the speed of digestion (16-hr IVNDFD) than lignin (-0.70). Whereas, for the overall potential of stem digestibility, lignin (-0.89) had the greatest negative correlation. The relationship between cellulose and lignin with IVNDFD was futher supported with the use of a path model. Lignin and 96-hr IVNDFD had the strongest broad sense heritability across the populations (0.74 & 0.70 respectively). Pectin components correlated positively with speed of digestion (0.41) but had limited correlation on the overall digestibility potential. As IVNDFD increased with each breeding cycle, it remained stable across environments along with concentrations of total cell wall components, lignin, hemi-cellulose, and pectin. However, the cellulose concentrations were not stable across environments. Cell wall components such as hemi-cellulose and lignin could be used as selection traits for increased IVNDFD breeding and may be a way to link invitro digestibility to plant trait genes for genomic selection

Perennial Ryegrass ‘Virazón’, a New Cultivar for Warm Temperate Areas in Uruguay and South America.

‘Virazón’ perennial ryegrass (Lolium perenne L.), a grazing-type tetraploid cultivar, was developed by the National Institute of Agricultural Research (INIA) in Uruguay as a part of the Joint Venture with PGG Wrightson Seeds and Grasslands Innovation Limited and commercially available since 2021. ‘Virazón’ was developed after 6 cycles of selection from crosses with cultivar Horizon from New Zealand based on climate adaptation, dry matter production, vigor, rust resistance, seed yield, and persistence under Uruguayan conditions. The aim was to obtain a perennial ryegrass with 3 years of consistent production. ‘Virazón’ was evaluated in forage yield trials in comparison with commercial varieties at different locations and additionally, it was tested at the Dairy Unit of INIA La Estanzuela under grazing conditions and is being validated on farms in different regions and production systems of Uruguay. Forage yields of ‘Virazón’ have been 20% greater than cultivar Horizon across 3-year evaluations with 70% persistence at the end of the third year and were consistently at least 35% superior to the rest of the evaluated cultivars. ‘Virazón’ has shown broad adaptation to Uruguayan environmental conditions, with improved persistence compared with the introduced cultivars, and remarkable forage yield. On farm trials showed great performance with excellent complementarity with legumes, adaptation to different soil types and limitating conditions like flooding or high summer temperatures