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A perennial topic of research on giftedness has been individuals' perceptions of and attitudes towards giftedness, the gifted, and gifted education. Although giftedness is a culturally constructed concept, most examination of the term's meanings and implications has used reactive measures (i.e., surveys) to tap respondents' giftedness-related perceptions and attitudes within the context of formal education. To provide a better understanding of the cultural meanings associated with giftedness—the term's cultural framing—we investigated the depiction of giftedness within a professional cultural product removed from education, namely, a large corpus of US fictional texts. We examined patterns of word usage in the vicinity of the term gift*, when used in the dictionary senses related to giftedness, in a large corpus of US fictional texts of recent decades, consisting of 485,179 text samples and 1,002,889,754 word tokens. Via inductive methods of quantitative text analysis, we explored themes occurring in the vicinity of gift*; and with an existing lookup dictionary, we assessed deductively the overall emotional valance of the writing near gift*. Our investigation revealed ways in which the literary exploration of giftedness coheres with and distinguishes itself from the outlooks on giftedness noted for survey-based research in education settings. In fictional texts, giftedness evinces special associations with humanities domains and beauty and, on balance, correlates positively with emotionally positive words. [ABSTRACT FROM AUTHOR]

Affected by climatic factors and human activities, the conditions of the sediment deposition of the Three Gorges Reservoir (TGR) in the upper Yangtze River have undergone significant changes, the understandings of the sedimentation in TGR and its factors remain unclear. In this paper, the regime for sediment deposition in TGR from 2003 to 2017 is analyzed based on field data, its influence factors are discussed, and the empirical formulas governing the relationships are presented. The results show that the sedimentation pattern of the TGR is discontinuous and that the perennial inundated area is the key sedimentation area, while the reaches of Xiangxizhen, Wushan, Fengjie, Wanxian, Huanghuacheng, Lanzhuba, and Tunaozi are the main deposition reaches in the reservoir, with the same characteristics of wider cross-sections. Sediment deposition in the TGR is affected by the incoming water and sediment, the operation rule of the reservoir, and by the characteristics of different reaches. Compared with the factors influencing the total sediment trapping ratio of the reservoir, local reach conditions are also the main factors influencing the sediment trapping ratio of the reaches due to the difference of sediment carrying capacity between wider reach and narrow reach. The sediment trapping ratios for reservoir scale and reach scale can be good indicators that reflect sedimentation in the TGR; the calculated sediment trapping ratios agree well with field observations. With the continuous construction and operation of the main and tributary reservoirs in the upper Yangtze River, the existing sedimentation regime of the TGR will persist for many years. [ABSTRACT FROM AUTHOR]

Detecting changes in the phenological responses of herbaceous species as a function of predicted climate change is important for forecasting future scenarios for the functioning of dry tropical forests, especially when predicting an increase in the frequency and intensity of extreme droughts. Because of the sensitivity of plants to water availability, our study hypothesizes that if years become drier or wetter, herbaceous plants will synchronously change the onset, duration, and intensity of their vegetative phenophases.We used a historical series of 60 years of precipitation observations for the Caatinga vegetation to define daily average of precipitation for rainy (Twet), median (Tcontrol), and dry (Tdry) years. We simulated past average daily rainfall (Twet, Tcontrol, and Tdry) while growing two herbaceous perennials and two herbaceous annuals. We monitored plant growth and measured the activity (absence or presence) and intensity of vegetative phenophases. We used circular statistical analysis to assess differences between treatments.Our results revealed that leaf production was seasonal but relatively uniform for perennial species and highly seasonal (wet season) for annual species. Simulated dry years induced lower leaf emergence concentrated over a few months in annual species, but this effect was more strongly significant in one of the two perennial species. Both annual and perennial species can experience delayed and less intense leaf abscission during the rainy season in years with below‐average precipitation. In contrast, large voluminous rains in years with above‐average precipitation can accelerate and intensify the process of leaf renewal.If future precipitation reductions occur, the changes in phenological response indicate that the cover of annual and perennial herbaceous species in this study will likely decrease, altering the landscape and functioning of dry tropical forests. However, the potential trade‐offs observed may help populations of these species to persist during years of severe drought in the Caatinga. [ABSTRACT FROM AUTHOR]

At Plato's insistence to become as godlike as one can, the Neoplatonists seek their salvation in union with the first principle they call the One, identifying this union as the highest end of philosophy. As with all aspirations, the transition from theoretical ideal to practical implementation remains a perennial problem: how is it possible for a person, as a mere mortal, to leave the person's confined ontological station to unite with the divine, transcendent first principle? This paper is an attempt to reconstruct Proclus' highly distinctive answer to this question of enormous importance through a close examination of his development of the late Neoplatonic notion of the One in the soul (τὸ ἐν ἡμῖν ἓν). [ABSTRACT FROM AUTHOR]

Agricultural practices shape arthropod communities in arable fields, consequently influencing their interactions and the resulting ecosystem services, in particular pest regulation. Predatory arthropods play a pivotal role by preying on herbivores, soil fauna, and on other predators. However, the intricate mechanisms through which agricultural practices shape the dietary preferences of predators, and regulate herbivore populations remain complex and inadequately understood.We assessed how fertilisation with organic fertiliser and extending crop rotations with perennial ley affected predation pressure across prey taxa. We mapped predator and prey trophic linkages with molecular analysis of carabid predator gut contents, and measured densities and taxonomic richness of predators, herbivores, and soil fauna in 19 cereal fields during three samplings across the growing season.We derived two food web structure metrics: prey vulnerability that is the average number of predators feeding on a selected prey, and predator trophic redundancy, that is dietary overlap. Prey vulnerability was compared among soil fauna, herbivores, and other predator species (that is interspecific intraguild predation) over the growing season, and across treatments. The mechanistic underpinnings of observed shifts in vulnerability of herbivorous prey at different crop stages were identified using information criteria to select among candidate variables related to the richness, density and interaction structure of the different guilds during both the current, and the previous crop stages.Agricultural diversification via organic fertilisation combined with perennial ley in the crop rotation decreased the vulnerability of both intraguild prey and soil fauna prey, and stabilised herbivore vulnerability. Mechanistically, the vulnerability of herbivorous prey at crop ripening emerges from the combination of predator richness and trophic redundancy during this sampling round, rather than from carryover effects from previous crop stages.Synthesis and applications: Our results suggest that locally provided resource continuity through diversified cropping practices bolster biological pest regulation, thus underline the importance of lesser disturbance in arable ecosystems for the provision of ecosystem services. Enhanced predator species richness together with availability of alternative prey through the season underpins this enhanced pest regulation. [ABSTRACT FROM AUTHOR]

Argentina is the country with the highest proportion of arid and semi-arid ecosystems in Latin America. In the rangelands of Southwestern Buenos Aires (Patagones Department), there is a clear advancement of the agricultural frontier to the detriment of the native forest in this region. Due to rainfall variation and seed acquisition, Thinopyrum ponticum is cultivated as a forage perennial crop in this region. Our objective was to evaluate the performance of T. ponticum as a facilitating crop for the medium-term rehabilitation of natural grasslands in semi-arid areas. The working hypotheses were that: 1) native perennial grass cover increases over the years and 2) diversity and specific richness of the vegetation are enhanced by the duration of Tall Wheatgrass implantation. Data were collected from commercial plots where T. ponticum was shown: recent implantation (5–8 years, RI); medium implantation (13–15 years, MI); and old implantation (20–22 years, OI). Thirty-four species were identified and classified into seven functional groups: Annual grasses, annual herbs, perennial herbs, exotic perennial herbs, perennial forage grasses, exotic perennial forage grasses, perennial forage exotic grasses, and non-forage perennial grasses. Thinopyrum ponticum 's total cover was between RI and OI. Total cover, species richness, and Shannon-Weaver diversity index showed no differences among treatments. Perennial forage grasses exhibited higher cover values in sites with greater implantation age and annual grasses showed the opposite response. Our results indicated that T. ponticum does not invade the sampled plots and enhances the colonization of the planted plots by perennial forage native species. However, even though the herbaceous cover had been recovered, the woody layer which could provide environmental services and specific values for conservation was not. [ABSTRACT FROM AUTHOR]

Perennials are usually pre-cultivated on vegetation mats consisting of coconut fiber (coir), which require weather-dependent irrigation and regular fertilization with fast-acting fertilizer to achieve a saleable condition as quickly as possible. In the pre-cultivation of sheep's wool–coir–vegetation mats, nitrogen (N) is already sufficiently contained in the vegetation mats due to the natural nitrogen content of the sheep's wool fibers, so that additional liquid fertilization during pre-cultivation can be dispensed with if necessary. In this study, sheep's wool–coir–vegetation mats of 4.5 kg/m2 were pre-cultivated with 16 perennial plants (8 species) in 2018. Variant 1 (V1) received regular fertilization with mineral liquid fertilizer (total 8.7 g N/m2) during pre-cultivation. Variant 2 (V2) was not fertilized during pre-cultivation. In spring 2019, all pre-cultivated vegetation mats were lifted and laid on an area prepared with topsoil. No additional fertilization was applied after laying. The overall impression, plant height, number of flowering perennials, and plant coverage were examined in the 2018 and 2019 growing seasons, with only minor differences observed between V1 and V2. The number of flowers, biomass, and nitrogen content were determined for the two aster species used. There were differences between V1 and V2 in 2018, but not in 2019. The coverage of perennials of 50%, which is the prerequisite for the saleability of the vegetation mats, was already achieved on both V1 and V2 after 4 months of pre-cultivation. The overall impression of the perennials on both V1 and V2 also did not differ during pre-cultivation nor in the following year. Therefore, liquid fertilization is not necessary during the pre-cultivation of perennials on sheep's wool–coir–vegetation mats. [ABSTRACT FROM AUTHOR]

Incorporating forage legumes into grasslands is a recommended climate change mitigation strategy, but accruing desired benefits from legumes is contingent upon their resilience when exposed to climate change factors (CCF). Our objective was to synthesize literature describing responses to CCF of a broad array of forage legume species, including annuals and perennials from both temperate and tropical/subtropical regions. Most‐represented species in the related literature include alfalfa (Medicago sativa L.), various Trifolium and Lotus species, rhizoma peanut (Arachis glabrata Benth.), and capitata stylo (Stylosanthes capitata Vogel). The data indicate that while CCF effects on forage legumes can be generalized, interactions among CCF, species, and site‐specific soil/climate conditions may cause variation from expected responses. In most instances, exposing forage legumes to CO2 enrichment (eCO2) increased forage accumulation (FA), but elevated temperature (eT) often reduced the magnitude of the positive response to eCO2. Photosynthetic acclimation to eCO2 occurs in non‐N‐fixing plants, but legume nodules are large C sinks and drive sustained increases in legume FA to eCO2. Legume N2 fixation and the proportion of legume N derived from N2 fixation increase with eCO2, but the magnitude of the increases lessens with eT. Legume nutritive value (NV) responses to eCO2 are less pronounced than FA responses, but decreased herbage N and greater nonstructural carbohydrate concentrations are common. Exposure to eT negatively affects NV unless intervals between defoliation events are shortened. Limited data on reproductive performance show CCF affect flower number, pollen grain morphology and viability, and behavior of pollinators, potentially influencing legume reproductive success. [ABSTRACT FROM AUTHOR]

Within the family Fabaceae, the genus Glycine is composed of two subgenera annuals (2n=40) and perennials. This life strategy transition may have differentially affected the evolution of various gene families. Its cultivated species G. max has high level of susceptibility to major pathogens including viruses, bacteria and fungi. Understanding nucleotide-binding domain leucine-rich repeat (NLR) genes evolution in soybean is of paramount importance due to their central role in plant immunity and their potential in improving disease resistance in soybean cultivars. In this study, we investigated the significance of this annual-perennial transition on the macroevolution of NLR genes in the genus Glycine. Our results reveal a remarkable distinction between annual species such as Glycine max and Glycine soja, which exhibit an expanded NLRome compared to perennial species (G. cyrtoloba, G. stenophita, G. dolichocarpa, G. falcata, G. syndetika, G. latifolia and G. tomentella). Our evolutionary timescale analysis pinpoints recent accelerated gene duplication events for this expansion, which occurred between 0.1 and 0.5 million years ago, driven predominantly by lineage-specific and terminal duplications. In contrast, perennials initially experienced significant contraction during the diploidisation phase following the Glycine-specific whole-genome duplication event (-10 million years ago). Despite the reduction in the NLRome, perennial lineages exhibit a unique and highly diversified repertoire of NLR genes with limited interspecies synteny. The investigation of gene gain and loss ratios revealed that this diversification resulted from the birth of novel genes following individual speciation events. Among perennials, G. latifolia, a well-known resistance resource, has the highest ratio of these novel genes in the tertiary gene pool. Our study suggests evolutionary mechanisms, including recombination and transposition, as potential drivers for the emergence of these novel genes. This study also provides evidence for the unbalanced expansion of the NLRome in the Dt subgenome compared with the At subgenome in the young allopolyploid G. dolichocarpa. To the best of our knowledge, this is the first study to investigate the effect of annuality and perenniality life transition on the evolution of NLR genes in the genus Glycine to identify its genomics resources for improving the resistance of soybean crop with global importance on the economy and food security. [ABSTRACT FROM AUTHOR]

Introduction: Habitat loss and degradation pose significant threats to global fish and wildlife populations, prompting substantial investments in habitat creation and restoration efforts. Not all habitats provide equal benefits, leading to challenges in prioritizing restoration actions. For example, juvenile anadromous salmonids require high quality rearing aquatic habitats to achieve the physiological requirements needed to successfully migrate to the ocean. However, there are profound disagreements among anadromous salmon restoration managers whether it is best to focus efforts on restoring in-channel habitats that are available for the entire rearing period or floodplain habitats that, while facilitating greater growth and survival than in-channel habitats, are only available for a few weeks at a time and are typically only activated every two-to-three years. Methods: We used an existing fall-run Chinook salmon decision-support model to evaluate under what conditions floodplain restoration would provide greater benefits than in-channel habitat restoration. The simulations included a wide range of floodplain inundation frequencies and durations and floodplain benefits in the form of increased survival and growth relative to in-channel habitats. Results: The simulations results indicated that in-channel habitat restoration was always the best habitat restoration action when there was no existing in-channel habitat despite simulating a wide range of flood frequency, duration, and growth and survival benefits. Floodplain restoration was generally best when there was sufficient in-channel habitat available to successfully rear most of the juveniles produced by the returning adult salmon. Discussion: We hypothesize that in-channel and floodplain habitats have different roles in salmon population maintenance with in-channel habitats regulating the overall population size and floodplains acting as recurrent resource pulses. Our study provides a quantitative framework to evaluate the benefit of these two habitat types and provides generalizable rulesets that can be used by managers when implementing habitat restoration strategies for species that inhabit both in-channel and floodplain habitats. [ABSTRACT FROM AUTHOR]

Juvenile survival is critical to population persistence and evolutionary change. However, the survival of juvenile plants from emergence to reproductive maturity is rarely quantified. This is especially true for long‐lived perennials with extended pre‐reproductive periods. Furthermore, studies rarely have the replication necessary to account for variation among populations and cohorts. We estimated juvenile survival and its relationship to population size, density of conspecifics, distance to the maternal plant, age, year, and cohort for Echinacea angustifolia, a long‐lived herbaceous perennial. In 14 remnant prairie populations over seven sampling years, 2007–2013, we identified 886 seedlings. We then monitored these individuals annually until 2021 (8–15 years). Overall, juvenile mortality was very high; for almost all cohorts fewer than 10% of seedlings survived to age 8 or to year 2021. Only two of the seedlings reached reproductive maturity within the study period. Juvenile survival increased with distance from the maternal plant and varied more among the study years than it did by age or cohort. Juvenile survival did not vary with population size or local density of conspecific neighbors. Our results suggest that low juvenile survival could contribute to projected population declines. [ABSTRACT FROM AUTHOR]

This essay reinvigorates the Huxley/Osmond theory that psychedelic drugs can occasion a cross-cultural mystical experience characterized by a sense of "unity with ultimate reality." It offers a long-overdue rejoinder to the position of Constructivist authors such as Steven T. Katz, Hans Penner, and Stephen Prothero that Aldous Huxley's Perennial Philosophy is a defunct position. Specifically, the essay answers three erroneous charges: (1) that Huxley posited his viewpoint as the "core" or "essence" of religion, (2) that Huxley believed he was describing a set of universally shared religious beliefs, and (3) that Huxley's position depends on a belief in—and the possibility of—a state of "pure consciousness." In all cases, these charges will be shown to be erroneous. Moreover, it will also be argued that these claims are inaccurate for most forms of the Perennial Philosophy, and that the Perennial Philosophy is not a homogenous viewpoint, but rather a family of theories as are Existentialism, Postmodernism, and Idealism. The essay ends with a look at new directions for testing the Huxley/Osmond position, including with psychedelic drugs. [ABSTRACT FROM AUTHOR]

Background: Sublingual immunotherapy (SLIT) for perennial allergic rhinitis (AR) has not been extensively studied in preschoolers. We investigated the efficacy and safety of house dust mite (HDM) SLIT‐tablet for children aged 1–4 years. Methods: Children aged 1–4 years with AR were divided into SLIT (n = 22) and control (n = 12) groups based on their guardians' preferences. The SLIT group received a daily dose of 10,000 JAU of HDM SLIT‐tablet for 12 months, whereas the control group received symptomatic treatment only. Results: The baseline median age was 41 and 34 months in the SLIT and control groups, respectively, and the median AR symptom score was 4 for both groups. Compared with baseline, the AR symptom score had decreased significantly in the SLIT group after 12 months (score: 3, p =.002), whereas it tended to increase in the control group (score: 6, p =.08). Adverse reactions to SLIT were mild and occurred in eight patients (36%). In the SLIT group, Dermatophagoides (D.) farinae‐specific IgE (sIgE) levels increased during the first 6 months and decreased to baseline levels at 12 months. In the control group, D. farinae‐sIgE levels had increased significantly at 12 months compared to baseline (p =.01). D. farinae‐specific IgG4 and HDM IgE‐blocking factor levels were significantly increased at 12 months compared to baseline in the SLIT group only (p <.001). A lower wheezing frequency was seen in the SLIT group (0.3%) compared to the control group (0.7%). Conclusion: This pilot study demonstrated the efficacy, safety, and immunomodulatory effects of HDM SLIT‐tablet in preschoolers with AR. [ABSTRACT FROM AUTHOR]

This study aimed to clarify the diagnostic and predictive factors for perennial allergic rhinitis (PAR) onset in children by analyzing the results of the Chiba High-risk Birth Cohort for Allergy study, which examined newborns with a family history of allergies. Overall, 306 pregnant women were recruited. Their newborns were examined by otolaryngologists and pediatric allergists at 1, 2, and 5 years of age. Participants with clinical and laboratory data available at all consultation points were considered eligible. Among 187 eligible participants, the prevalence rates of PAR were 2.1%, 4.3%, and 24.1% at 1, 2, and 5 years of age, respectively. AR-specific nasal local findings and eosinophils in nasal smear were observed in a substantial number of patients with PAR at 1 and 2 years of age. Factors present up to 2 years of age that were associated with PAR onset at 5 years of age, in descending order, were as follows: sensitization to house dust mites (HDM), nasal eosinophilia, and sensitization to cat dander. In 44 cases with HDM sensitization, nasal eosinophilia up to 2 years of age achieved a sensitivity of 76.0% and a specificity of 73.7% for predicting PAR onset at 5 years. Rhinitis findings and nasal eosinophilia are useful auxiliary diagnostic items for pediatric PAR. Sensitization to HDM and nasal eosinophilia were the most influential factors associated with future PAR onset. A combination of these factors may facilitate the prediction of PAR onset. [ABSTRACT FROM AUTHOR]

Context: Data are lacking on the effects of selected endophytes of perennial ryegrass (Lolium perenne L.) on ryegrass persistence. Aim: We aimed to determine the impact of Epichloë endophyte on the persistence of mid- and late-heading perennial ryegrass cultivars. Method: Two mid-heading (Samson, Bronsyn) and two late-heading (One50, Rohan) cultivars, infected with selected endophytes (AR37, nea2/6) or with standard toxic endophyte, were established in a replicated plot study grazed by cattle in a subtropical environment of the upper North Island of New Zealand. Persistence characteristics were quantified at least five times per annum, over 4 years. Key results: Endophyte strain had an effect on persistence; infection with standard endophyte resulted in higher ryegrass ground cover percentage, ryegrass content in pasture dry matter and autumn yield than infection with nea2/6 on many occasions, and with AR37 on some occasions. There were negligible impacts on ryegrass tiller density or nutritive value. Trends were dominated by the main effect of endophyte; interactions with heading date were inconsistent. Conclusions: Cultivars were more persistent when infected with standard endophyte than with selected endophytes, although persistence declined over 4 years for all cultivars and irrespective of heading date. Implications: Reliance on selected endophyte is unlikely to prevent persistence decline of perennial ryegrass in a subtropical environment. Other strategies will be required to maintain the persistence of high-quality pastures based on perennial ryegrass. We determined the impact of endophyte strain (standard toxic endophyte, selected strains nea2/6 and AR37), on the persistence of four perennial ryegrass cultivars. Standard endophyte resulted in greater persistence than the selected endophytes, with higher ryegrass ground cover percentage and content in pasture dry matter by the end of the study, and higher herbage yields in autumn. Persistence declined over 4 years for all cultivars, regardless of endophyte. [ABSTRACT FROM AUTHOR]

Context: Data are lacking on the effects of heading date of perennial ryegrass (Lolium perenne L.) on ryegrass persistence. Aim: We aimed to determine the impact of heading date on perennial ryegrass persistence. Method: Two mid-heading (Samson, Bronsyn) and two late-heading (One50, Rohan) cultivars, infected with Epichloë endophytes (AR37, nea2/6 or standard toxic), were established in a replicated plot study grazed by cattle in a subtropical environment of the upper North Island of New Zealand. Persistence characteristics were quantified at least five times per annum, over 4 years. Key results: Late-heading cultivars had higher yield, nutritive value, perennial ryegrass content in pasture dry matter, ground cover and tiller density than mid-heading cultivars. There were large seasonal impacts on all ryegrass characteristics, with a major decline over summer and recovery during late autumn into early spring, with less recovery in the final year. Overall, there was a strong linear decline in ryegrass content measured during spring (2018–21). Conclusions: The two late-heading cultivars were more persistent than the two mid-heading cultivars, although persistence declined over 4 years for all cultivars. Implications: Results support industry recommendations of choosing late-heading cultivars for improved pasture quality and persistence. We determined the impact of heading date on persistence of perennial ryegrass cultivars infected with a range of endophytes, in a plot study grazed by cattle. The two late-heading cultivars were more persistent than the two mid-heading cultivars, with higher yield, nutritive value, perennial ryegrass content in pasture dry matter, ground cover and tiller density, although persistence declined over 4 years for all cultivars. [ABSTRACT FROM AUTHOR]

This article evaluates select Mangave cultivars, which are a new addition to the horticultural scene. Mangaves are low-maintenance, versatile plants that can withstand various temperatures and are suitable for landscapes and containers. The article provides information on the breeding of Mangaves and the trial details of the evaluated cultivars. It also includes evaluations of the cultivars based on their appearance, growth habits, and flowering characteristics, categorizing them into excellent, fair, and poor ratings. The document emphasizes the importance of considering a mangave's flowering age and response to environmental conditions when selecting a cultivar. [Extracted from the article]

Geoclimatic events driving South American aridization have generated biota differentiation due to barriers and new environment formation. New environments allow species climatic niche evolution, or the geographical expansion of an existing one. Understanding the role these processes play may clarify the evolution of South American biota. Gomphrena L. ranges across almost all the continent's arid environments. We tested whether South American drylands are biogeographically connected through the Gran Chaco but, due to different aridity levels, lineage diversification could have also been associated with the evolution of climatic niches and morphological or physiological traits. With available data, we generated a dated phylogeny, estimated ancestral ranges, performed diversification analyses, reconstructed ancestral states of two characters, and examined if niches have changed between lineages. Results showed that Gomphrena diversified throughout the easternmost South American drylands ~15.4 Ma, and subsequently three independent clades colonized the western arid regions during the last Andean pulse, and after the marine transgressions (~4.8–0.4 Ma) via the Gran Chaco. The colonization implied an increase in the diversification rate of annuals over perennials and the progressive east–west differentiation of the occupied climatic niche. This diversification was influenced by C4 photosynthesis, which could have acted as a niche opener to conquer new environments after the Paranaean Sea withdrew. Spatiotemporal patterns found in Gomphrena suggest that geographical expansion and evolution of climatic niches played a common but decoupled role in promoting diversification. These results show that the Gran Chaco may have acted as a historical connection linking South American drylands. [ABSTRACT FROM AUTHOR]

Robert Trueman (2022) sets out and defends an 'immodest' identity theory of truth: that is, an identity theory in which the facts with which true propositions are identical are things whose totality is the world: i.e. obtaining states of affairs. This brief reply argues that Truman's theory falls foul of a perennial objection to such immodest identity theories: namely, that it cannot explain how a candidate proposition's putative elements can be unified into a proposition proper without this proposition being true. [ABSTRACT FROM AUTHOR]

In artificially controlled pot experiments, perennial ryegrass was mixed with other leguminous plants (white clover and alfalfa) and treated with lead, zinc and cadmium (337 mg·kg, 648 mg·kg, and 9 mg·kg, respectively) to simulate compound pollution conditions. The results showed that the concentrations of heavy metals, transport factors, and bioconcentration factors in mixed planting of ryegrass decreased compared with those in monoculture. Regardless of whether heavy metal pollution was introduced, mixed planting increased the aboveground and underground biomasses of ryegrass. The different mixed planting treatments had no significant impact on the chlorophyll concentration of ryegrass. The mowing time, mixed planting treatment, and heavy metal treatment had impacts on antioxidant and osmotic adjustment substances, and there were some interactions. The mixed planting treatment did not significantly affect glutathione concentration, cysteine concentration, or nonprotein thiol. Mixed planting generally increased the nitrogen and phosphorus concentrations of ryegrass while reducing the stoichiometric ratio of carbon, nitrogen, and phosphorus. These results suggest that the mixed planting of ryegrass with legumes promotes the growth of ryegrass in the presence of high concentrations of heavy metal pollution. However, it does not enhance the ability of ryegrass to remediate heavy metal pollution in the soil. [ABSTRACT FROM AUTHOR]

We assessed the effect of grazing and plant patchiness on the perennial grass seed bank in litter patches in relation to co-occurring shrub, annual grass, and forb seed banks in disturbed rangelands of the Patagonian Monte. We hypothesized that litter patches in disturbed rangelands have a perennial grass seed bank but co-occurring seed banks of annual lifeforms reduce the opportunities for perennial grass reestablishment at these patches. We evaluated the effect of microsite (bare soil vs. vegetated) and grazing (grazed vs, non-grazed) on the (1) size (seeds m−2) of the four seed banks, (2) frequency of microsites with the respective seeds, and (3) frequency of co-occurrence of the perennial grass with shrub, annual grass and forb seed banks in litter patches at 5 dates (2009–2011). We found the smallest perennial grass and annual grass seed banks in litter patches under grazing and in bare soil microsites. The shrub and forb seed banks in litter patches were smaller at vegetated than at bare soil microsites under grazing and the reverse occurred in non-grazed conditions. The sizes of all seed banks were positively related to the frequency of litter patches with the respective seeds. In these litter patches, the size of perennial grass and shrub seed banks did not vary with grazing, and/or microsite while the size of annual grass and forb seed banks decreased with grazing and increased in vegetated microsites. The perennial grass seed bank in litter patches co-occurred mostly with forb and annual grass seed banks (several times larger). This is probably a constraint for the reestablishment of perennial grasses. However, although scarce, litter patches with exclusive perennial grass seed bank or co-occurring perennial grass and shrub seed banks could be an opportunity for perennial grass reestablishment. [ABSTRACT FROM AUTHOR]

The release of cultivars of two perennial grains is a milestone in perennial grain and oilseed development. Agronomic studies can progress by having stable genetics upon which to conduct research. Agriculture has generally committed to enhancing soil health, with perennial grains and oilseeds offering potentially non-animal-related alternatives to our current choices. Utilizing perennial grains and oilseeds offers potential to small-grain producers to improve, or at least maintain, their soil quality as perennial grains generally have little soil disturbance post-seeding. Understanding perennial grain and oilseed development and how they interact with their growth environment will provide us with baselines upon which to gauge agronomic interventions as we attempt to increase productivity without negative environmental impacts. [ABSTRACT FROM AUTHOR]

This article presents the results of a three-year experiment (2018–2020) conducted at the Agricultural Experiment Station in Bałcyny (north-eastern Poland) with the aim of determining Jerusalem artichoke (JA) yields and the energy balance of biomass production in (i) a perennial cropping system (only aerial biomass was harvested each year) and (ii) an annual cropping system (both aerial biomass and tubers were harvested each year). When JA was grown as a perennial crop, the demand for energy reached 25.2 GJ ha−1 in the year of plantation establishment and 12.3–13.4 GJ ha−1 in the second and third year of production. The energy inputs associated with the annual cropping system were determined in the range of 31.4–37.1 GJ ha−1. Biomass yields were twice as high in the annual than in the perennial cropping system (20.98 vs. 10.30 Mg DM ha−1). Tuber yield accounted for 46% of the total yield. The energy output of JA biomass was 1.8 times higher in the annual than in the perennial cropping system (275.4 vs. 157.3 GJ ha−1). The average energy gain in JA cultivation ranged from 140 (perennial crop) to 241 GJ ha−1 (annual crop). The energy efficiency ratio of JA biomass production reached 7.7–13.3 in the perennial cropping system, and it was 20% lower in the annual cropping system. These results imply that when JA was grown as an annual crop, an increase in energy inputs associated with plantation establishment (tillage and planting) and the harvest and transport of tubers was not fully compensated by the energy output of tubers. [ABSTRACT FROM AUTHOR]

Plants especially need to adapt to all different light environments (shade, high light, etc.) due to the essential role of light in plant life. Either shade or high-light microenvironmental conditions are common for cool-season turfgrasses, such as perennial ryegrass (Lolium perenne L.). In order to study how a plant highly conserves microRNA, miR164-affected perennial ryegrass were studied under different light intensities. OsmiR164a-overexpression (OE164), target mimicry OsmiR164a (MIM164), and CRES-T (chimeric repressor gene-silencing technology) OsNAC60 (NAC60) transgenic plants and wild-type (WT) plants were evaluated in both field (shade and full sun) and growth chamber conditions (low, medium, and high PAR at 100, 400, and 1200 µmol s−1 m−2). Morphological and physiological analysis showed miR164 could fine-tune perennial ryegrass adaptation to changing light intensity, possibly via the regulation of target genes, such as NAC60. Overall, OE164 and NAC60 plants were similar to each other and more sensitive to high light, particularly under the field condition, demonstrated by smaller size and much poorer grass quality; MIM164 performed more like WT plants than either the OE164 or NAC60 plants. This study indicates the potential of genetic manipulation of miR164 and/or its targeted genes for turfgrass adaptation to changing light environments, and future research to further investigate the molecular mechanism beneath would be warranted. [ABSTRACT FROM AUTHOR]

Perennial tall grasses show promise as bioenergy crops due to high productivity and efficient nutrient use. Ongoing research on bioenergy grasses seeks to reduce their reliance on synthetic nitrogen (N) fertilizer, the manufacture of which relies on fossil fuel combustion. Excessive use of fertilizers also causes adverse environmental consequences and leads to the evolutionary loss of plant traits beneficial to sustainable N cycle. Notably, perennial tall grasses have exhibited the potential to maintain high biomass yield without the need for N fertilizer or causing soil N depletion. Perennial grasses can be adept at interacting with their microbial partners to facilitate N acquisition and retention via mechanisms such as biological N fixation and nitrification inhibition. These inherent N management traits should be preserved and optimized at the this early stage of bioenergy grass breeding programs. This review examines the impact of external N on bioenergy grass production and explores the potential of leveraging advantageous N‐cycling attributes of perennial tall grasses, laying groundwork for future management and research efforts. With minimized dependency on external N input, the cultivation of perennial energy grasses will pave the way toward more resilient agricultural systems and play a significant role in addressing key global energy and environmental challenges. [ABSTRACT FROM AUTHOR]

Marshallia legrandii (Oak Barrens Barbara's-buttons) is a critically imperiled perennial herb in North Carolina and Virginia's Piedmont region. We completed a flowering census of this species at 2 of its 3 known populations in 2021, and again at the largest of those measured populations in 2022. We compared flowering density with canopy openness at both sites. At the largest population, we also measured competing vegetation, soil properties, and Oak Barrens Barbara's-buttons density to describe its habitat. Here, we also implemented an experimental augmentation of Oak Barrens Barbara's-buttons to monitor planting survival and growth under different light environments. We found that Oak Barrens Barbara's-buttons can flower under a broader range of canopy openness than previously believed. In addition to light, we found that competing vegetation, soil temperature, and soil moisture are important predictors of flowering success. Survival of augmented Oak Barrens Barbara's-buttons was nearly 90%, and 28–42% of plants bloomed 2 years after planting. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria (LAB) are commonly used as silage inoculants. Manganese sulphate (MnSO4) has been proposed to protect certain LAB during oxygen exposure and improve silage aerobic stability (ASTA). The aim of the present study was to assess the efficacy of inoculants in preservation of different forages. A short‐term screening trial investigated the effect of 24 additive treatments, compared to a negative control, on ensiling perennial grass in mini‐silos (2.75 L) for 7 d. The additive treatments comprised different ratios of Lactiplantibacillus plantarum [IMI 507026, IMI 507027, and IMI 507028] and Pediococcus pentacaceus [IMI 507024 and IMI 507025], with or without MnSO4. Target parameters, such as low levels of fresh matter loss, pH, acetic acid, ammonia‐nitrogen fraction (NH3–N/Total N), and high levels of lactic acid and ASTA, were considered for treatment selection. Eight treatments were selected based on a principal component analysis and hierarchical clustering of the target parameters. These selected treatments subsequently underwent a 100 d long‐term trial using lucerne, perennial grass, and perennial grass‐white clover forages. All silages treated with the eight additives exhibited an improved homolactic fermentation and a lower (p <.001) pH, acetic acid, and ethanol content than the control. Although DM losses and ASTA markedly improved in the treatments containing MnSO4 in the short‐term trial, these effects were not observed in the long‐term trial. These outcomes suggest that the selected additives can improve silage fermentation quality across a broad range of forages, but further studies are required to assess the impact of MnSO4 on ASTA. [ABSTRACT FROM AUTHOR]

Education is one of the defining features of human civilization. The United Nations' Sustainable Development Goal 4 evangelizes inclusive and equitable access to quality education and promotes lifelong learning opportunities without recourse to gender. Nigeria has made giant strides in bridging the gender gap associated with access to education. However, gender disparity in access to education remains a perennial problem, given that females encounter barriers ranging from cultural stereotypes, harmful religious sentiments, systemic impediments, a lack of political will and other complex socio-economic challenges. This paper sketches the education system, illuminates the socio-economic and infrastructural challenges to education on a broader level and analyzes the perennial and contemporary challenges to female education in Nigeria. It outlines potential trajectories and opportunities for a robust multistakeholder partnership framework anchored on shared interest to bridge the gender divide in educational access and advance female education in Nigeria. [ABSTRACT FROM AUTHOR]

Biomass allocation in plants is the foundation for understanding dynamics in ecosystem carbon balance, species competition, and plant–environment interactions. However, existing work on plant allometry has mainly focused on trees, with fewer studies having developed allometric equations for grasses. Grasses with different life histories can vary in their carbon investment by prioritizing the growth of specific organs to survive, outcompete co‐occurring plants, and ensure population persistence. Further, because grasses are important fuels for wildfire, the lack of grass allocation data adds uncertainty to process‐based models that relate plant physiology to wildfire dynamics. To fill this gap, we conducted a greenhouse experiment with 11 common California grasses varying in photosynthetic pathway and growth form. We measured plant sizes and harvested above‐ and belowground biomass throughout the life cycle of annual species, while for the establishment stage of perennial grasses to quantify allometric relationships for leaf, stem, and root biomass, as well as plant height and canopy area. We used basal diameter as a reference measure of plant size. Overall, basal diameter is the best predictor for leaf and stem biomass, height, and canopy area. Including height as another predictor can improve model accuracy in predicting leaf and stem biomass and canopy area. Fine root biomass is a function of leaf biomass alone. Species vary in their allometric relationships, with most variation occurring for plant height, canopy area, and stem biomass. We further explored potential trade‐offs in biomass allocation across species between leaf and fine root, leaf and stem, and allocation to reproduction. Consistent with our expectation, we found that fast‐growing plants allocated a greater fraction to reproduction. Additionally, plant height and specific leaf area negatively influenced the leaf‐to‐stem ratio. However, contrary to our hypothesis, there were no differences in root‐to‐leaf ratio between perennial and annual or C4 and C3 plants. Our study provides species‐specific and functional‐type‐specific allometry equations for both above‐ and belowground organs of 11 common California grass species, enabling nondestructive biomass assessment in California grasslands. These allometric relationships and trade‐offs in carbon allocation across species can improve ecosystem model predictions of grassland species interactions and environmental responses through differences in morphology. [ABSTRACT FROM AUTHOR]

Exotic annual grass invasion is a widespread threat to the integrity of sagebrush ecosystems in Western North America. Although many predictors of annual grass prevalence and native perennial vegetation have been identified, there remains substantial uncertainty about how regional‐scale and local‐scale predictors interact to determine vegetation heterogeneity, and how associations between vegetation and cattle grazing vary with environmental context. Here, we conducted a regionally extensive, one‐season field survey across burned and unburned, grazed, public lands in Oregon and Idaho, with plots stratified by aspect and distance to water within pastures to capture variation in environmental context and grazing intensity. We analyzed regional‐scale and local‐scale patterns of annual grass, perennial grass, and shrub cover, and examined to what extent plot‐level variation was contingent on pasture‐level predictions of site favorability. Annual grasses were widespread at burned and unburned sites alike, contrary to assumptions of annual grasses depending on fire, and more common at lower elevations and higher temperatures regionally, as well as on warmer slopes locally. Pasture‐level grazing pressure interacted with temperature such that annual grass cover was associated positively with grazing pressure at higher temperatures but associated negatively with grazing pressure at lower temperatures. This suggests that pasture‐level temperature and grazing relationships with annual grass abundance are complex and context dependent, although the causality of this relationship deserves further examination. At the plot‐level within pastures, annual grass cover did not vary with grazing metrics, but perennial cover did; perennial grasses, for example, had lower cover closer to water sources, but higher cover at higher dung counts within a pasture, suggesting contrasting interpretations of these two grazing proxies. Importantly for predictions of ecosystem response to temperature change, we found that pasture‐level and plot‐level favorability interacted: perennial grasses had a higher plot‐level cover on cooler slopes, and this difference across topography was starkest in pastures that were less favorable for perennial grasses regionally. Understanding the mechanisms behind cross‐scale interactions and contingent responses of vegetation to grazing in these increasingly invaded ecosystems will be critical to land management in a changing world. [ABSTRACT FROM AUTHOR]

In Canada, new forage varieties need not undergo grazing trials before registration and sale. To evaluate the effect of grazing, six cool-season species including meadow bromegrass (Bromus riparius Rehmann), orchardgrass (Dactylis glomerata L.), sainfoin (Onobrychis viciifoila Scop.), and three alfalfa varieties (Medicago sativa L.) were established in monocultures and grass–legume binary mixtures in Saskatchewan, Canada. Forage treatments were randomly established within each of three 3.5 ha paddock replicates. In Year 1, 69 Bos taurus crossbred steers, and in Year 2, 149 steers were homogenously allocated to the three paddocks for the grazing trials. Alfalfa monocultures had the greatest (p < 0.05) pre-graze forage yields and crude protein content. Leaf area index was greater in alfalfa monocultures than in all other treatments (p < 0.01). Etiolated growth differed (p < 0.05) among binary mixtures but not monocultures. Alfalfa monoculture stands were preferred over grass monocultures and most grass–legume mixtures, and sainfoin was avoided relative to alfalfa. Killarney orchardgrass was the least productive and least preferred among forages evaluated. In summary, alfalfa monocultures had greater (p < 0.05) forage yields and quality than sainfoin monocultures, grass–legume binary mixtures, or grass monocultures. [ABSTRACT FROM AUTHOR]

Grain from improved varieties of the perennial grass Thinopyrum intermedium (Host) Barkworth & D.R. Dewey is marketed under the trade name Kernza (common name intermediate wheatgrass, IWG). While a growing body of evidence is available on the nutritional quality of Kernza, gaps exist for components such vitamins and minerals and protein quality. Therefore, we performed two studies on early-generation breeding program material, characterizing nutritional quality by quantifying macronutrients, sugars, dietary fiber, amino acid profiles, fat composition, vitamins, minerals, carotenoids, antioxidants, and antioxidant activity. The IWG studied frequently had concentrations significantly different from the reference values for whole wheat flour. For example, IWG had 50% higher protein, 129% higher dietary fiber, and 65% higher ash content than reference whole wheat flour. Calcium and selenium were 267% and 492% higher, respectively, in IWG than whole wheat flour. Riboflavin and folate were 43% and 447% higher, respectively, and niacin 74% lower in IWG versus whole wheat flour. We identified lysine as the limiting amino acid, although its concentration was 33% greater in IWG than in whole wheat flour. These results support potential benefits of Kernza for human nutrition. This work supports ongoing studies to further characterize and evaluate nutritional quality during the domestication and breeding process. [ABSTRACT FROM AUTHOR]

Background: Perennial malaria chemoprevention (PMC) aims to protect children at risk from severe malaria by the administration of anti-malarial drugs to children of defined ages throughout the year. Sulfadoxine-pyrimethamine (SP) has been widely used for chemoprevention in Africa and a child-friendly dispersible tablet formulation has recently become available. Methods: This qualitative non-interventional observational study was conducted in Benin, Côte d'Ivoire, and Mozambique between February and June 2022. Prototype blister packs, dispensing boxes and job aids designed to support dispersible SP deployment for PMC were evaluated using focus group discussions (FGD) and semi-structured in-depth individual interviews (IDI) with health authorities, health personnel, community health workers (CHWs) and caregivers. The aim was to evaluate knowledge and perceptions of malaria and chemoprevention, test understanding of the tools and identify gaps in understanding, satisfaction, user-friendliness and acceptability, and assess the potential role of CHWs in PMC implementation. Interviews were transcribed and imported to ATLAS.ti for encoding and categorization. Thematic content analysis used deductive and inductive coding with cross-referencing of findings between countries and participants to enrich data interpretation. Continuous comparison across the IDI and FGD permitted iterative, collaborative development of materials. Results: Overall, 106 participants completed IDIs and 70 contributed to FGDs. Malaria was widely recognised as the most common disease affecting children, and PMC was viewed as a positive intervention to support child health. The role of CHWs was perceived differently by the target groups, with caregivers appreciating their trusted status in the community, whereas health authorities preferred clinic-based deployment of PMC by health professionals. Empirical testing of the prototype blister packs, dispensing boxes and job aids highlighted the context-specific expectations of respondents, such as familiar situations and equipment, and identified areas of confusion or low acceptance. A key finding was the need for a clear product identity reflecting malaria. Conclusion: Simple modifications profoundly affected the perception of PMC and influenced acceptability. Iterative quantitative investigation resulted in PMC-specific materials suited to the local context and socio-cultural norms of the target population with the aim of increasing access to chemoprevention in children most at risk of severe malaria. [ABSTRACT FROM AUTHOR]

Background and aims: The escalating issue of soil saline-alkalization poses a growing global challenge. Leymus chinensis is a perennial grass species commonly used in the establishment and renewal of artificial grasslands that is relatively tolerant of saline, alkaline, and drought conditions. Nonetheless, reduced seed setting rates limit its propagation, especially on alkali-degraded grassland. Inter-annual variations have an important effect on seed yield and germination under abiotic stress, and we therefore examined the effect of planting year on seed yield components of L. chinensis. Methods: We grew transplanted L. chinensis seedlings in pots for two (Y2), three (Y3), or four (Y4) years and collected spikes for measurement of seed yield components, including spike length, seed setting rate, grain number per spike, and thousand seed weight. We then collected seeds produced by plants from different planting years and subjected them to alkaline stress (25 mM Na2CO3) for measurement of germination percentage and seedling growth. Results: The seed setting rate of L. chinensis decreased with an increasing number of years in pot cultivation, but seed weight increased. Y2 plants had a higher seed setting rate and more grains per spike, whereas Y4 plants had a higher thousand seed weight. The effects of alkaline stress (25 mM Na2CO3) on seed germination were less pronounced for the heavier seeds produced by Y4 plants. Na2CO3 caused a 9.2% reduction in shoot length for seedlings derived from Y4 seeds but a 22.3% increase in shoot length for seedlings derived from Y3 seeds. Conclusions: Our findings demonstrate significant differences in seed yield components among three planting years of L. chinensis under pot cultivation in a finite space. Inter-annual variation in seed set may provide advantages to plants. Increased alkalinity tolerance of seed germination was observed for seeds produced in successive planting years. [ABSTRACT FROM AUTHOR]

Perennial ryegrass is the most widely grown temperate grass species globally as a source of forage (grazing, hay, silage) or for amenity use. It is a part of landscape, protects soil from water and wind erosion, enriches it with organic substances and improves its fertility. During the period 2015-2020 in the Institute of Forage crops (IFC) - Pleven a collection nursery was studied in field non-irrigated conditions on leached black soil, in block duplicate method, in 2 replications with a total of 19 accessions of perennial ryegrass, with 50 individual plants each (25 plants for forage and 25 plants - for seeds), including 14 varieties and 5 ecotypes, 10 tetraploid and 9 diploid, from Bulgaria (BG), Belgium (BE), and Romania (RO). The aim is to determine the vitality per year and longevity (after many years, more than 3-4) of perennial ryegrass collection accessions and to make a selection of the most vital and long - lasting genotypes. Scale of survival according to the International Classifier for the family Poaceae (Bukhteeva et al., 1985) was used - limiting factors of the environment are cold - winter, drought and high temperatures - summer. An autumn inventory of the individual plants no./% was carried out annually, as 25 plants per sample = 100%., and vitality classification as follows: Very Low - less than 1 to 20% of plants are left alive; Low - more than 21 to 50%; Medium - more than 51% to 70%; High - more than 71 to 90%; Very High - more than 90% of the plants are still alive. Computer statistical processing of the data (via Excel, at P = 0.05) included variance analyses. Data on vitality and longevity are characterized by: marginal values (min and max), arithmetic mean (x), standard deviation (SD) and coefficient of variation (CV,%). Variation was considered weak, moderate, or strong at CV values, respectively: up to 10%; > 10-20%, and > 20% (Dimova and Marinkov, 1999). When grown for fodder, the local ecotypes Sokolare, Topolovgrad and Bekovi skali are the most viable by years and the longest surviving up to 5 years, with the percentage of plants alive in the fifth year being the highest for the Sokolare ecotype. Ecotype Sokolare is strongly influenced by the method of use, which is the longest-lasting and most viable when grown for fodder - 5 years and the shortest - when grown for seeds - 3 years. All diploid varieties live up to 4 years, and only the Harmoniya variety up to 5 years, with the Bulgarian varieties Harmoniya and Strandzha being the most viable and long-lasting when grown for fodder. Harvesting once a year for seeds extends the life cycle of diploid varieties up to 5 years and for the Harmoniya variety - up to 6. The Bulgarian tetraploid varieties Tetrany, Tetramis and the Belgian varieties Floris, Melpetra and Melverde are the most durable and long-lasting. One-time harvesting per year for seeds extends the life cycle of the tetraploid varieties up to 5 years, and for the Bulgarian varieties Tetrany, Tetramis and the Belgian varieties Floris, Melpetra and Melverde - up to 6. [ABSTRACT FROM AUTHOR]

Question: Do shrubs negatively affect the germination of perennial grass species in regeneration microsites? We experimentally analyzed the effect of soils from plant patches dominated by two shrub species (Larrea divaricata and Schinus johnstonii) and their propagules on the germination of three co‐dominant herbivore‐preferred perennial grass species (Poa ligularis, Nassella tenuis and Pappostipa speciosa). Location: Patagonian Monte, Chubut Province, Argentina (42°07′ S, 64°59′ W; 43°06′ S, 65°43′ W; 42°29′ S, 66°34′ W). Methods: We conducted two simultaneous microcosm experiments. In the first experiment, we sowed perennial grass propagules of the three species alone and combined with non‐scarified shrub propagules in Petri dishes with three substrate types (filter paper, inert soil and soil from shrub patches). In the second experiment, we sowed perennial grass propagules of each species combined with scarified and non‐scarified propagules of both shrub species in Petri dishes with soil taken from plant patches dominated by L. divaricata and by S. johnstonii. Both experiments lasted 3 months. We calculated the germination proportion and mean germination time (MGT) of propagules for each perennial grass species in each treatment. Results: Propagules from neighboring shrubs had a clearer negative effect on grass germination compared with shrub soils. Shrub propagules negatively affected the germination proportion of P. ligularis and N. tenuis, and induced longer MGT in the three perennial grass species. The combination of S. johnstonii soil and propagules negatively affected P. ligularis and P. speciosa germination. The combination of L. divaricata soil and scarified propagules completely inhibited P. speciosa germination. Conclusions: Our results highlighted the complexity of interactions between shrubs with high phenolic contents (soils and propagules) and the germination of perennial grass species in arid environments. Schinus johnstonii soil and propagules had stronger effects on perennial grass germination than L. divaricata soil and propagules. The negative effects of shrubs on microsite quality and germination processes depended on the specific shrub/grass interaction. [ABSTRACT FROM AUTHOR]

Among plants, there is considerable variation in lifespan: annuals live less than one year, whereas perennials live for several years, with the longest-living perennial having survived 43,600 years. As proposed by the Disposable Soma Theory, this lifespan variation among plants likely reflects differential investment of limited energy and nutrient resources, with perennials investing more energy and nutrients into biomolecular maintenance compared to annuals in order to ensure persistence over multiple seasons. Such differential investment may be particularly important during periods of exogenous stress, which are known to accelerate biomolecular damage. The present study evaluated this hypothesis using annual and perennial flax (Linum L.) subjected to two exogenous stressors—increased oxidative stress (i.e., foliar H2O2 spraying) and complete prolonged darkness. As chlorophyll has been shown to exhibit degradation in response to changes in environmental conditions, we utilized changes in chlorophyll levels during and after periods of exogenous stress to evaluate our hypotheses. We predicted that i) perennials would exhibit a slower rate of chlorophyll degradation during exposure to exogenous stressors compared to annuals, and ii) perennials would exhibit a faster rate of chlorophyll resynthesis following such exposure compared to annuals. Chlorophyll levels before, during, and after exposure to both exogenous stressors were measured in two separate trails, once using image colour analysis and once using spectrophotometry. While chlorophyll degradation rates in response to oxidative stress did not differ between annuals and perennials, contrary to our predictions, chlorophyll resynthesis rates following such exposure were significantly higher in perennials, as predicted. When plants were subjected to complete prolonged darkness, chlorophyll degradation rates were significantly lower in perennials than annuals, as predicted; however, when plants were subsequently reintroduced to natural photoperiod, chlorophyll resynthesis rates did not consistently differ between annuals and perennials, though they tended to be higher in the latter, as predicted. Overall, our study illuminates that evolutionary transitions between life history strategies in plants have been accompanied by physiological modifications to chlorophyll dynamics that permit perennial species to better maintain chlorophyll levels—and thus photosynthetic energy acquisition—in the face of exogenous stressors, which likely underlies their capacity to survive for multiple growing seasons. Future studies should explore whether other key biomolecules (e.g., proteins, DNA) are also better maintained in perennial plants, especially in the face of exogenous stress. [ABSTRACT FROM AUTHOR]

Quantifying the relative strength of isolating barriers is a major focus of research on plant speciation. Contrasting life histories and mating systems have the potential to limit gene exchange between closely related populations growing in sympatry. However, few studies have quantified reproductive isolating barriers between conspecific annual and perennial populations and their contributions to total reproductive isolation (RI). Incarvillea sinensis Lam. (Bignoniaceae) is an insect‐pollinated herb with largely allopatric annual and perennial populations that differ in mating systems. The perennial populations are primarily outcrossing whereas annual populations are predominantly selfing. At a rare sympatric site in northern China we estimated prezygotic and postzygotic barriers to gene exchange between annual and perennial plants and found complete RI between the two life histories. Annuals exhibited significantly higher ecogeographic isolation than perennials whereas perennials experienced more isolation through pollen–pistil interactions than annuals. Crosses between annuals and perennials demonstrated that postzygotic barriers influencing fruit and seed formation, F1 germination and survival were negligible for annuals but played a small role for perennials. However, F1 hybrids of crosses between annuals and perennials produced no pollen and their ovules were largely sterile. Our study provides insight into the relative importance of prezygotic and postzygotic isolating barriers between closely related annual and perennial populations of I. sinensis and some of these barriers could have been involved with speciation. Annuals and perennials of I. sinensis represent two biological species and thus deserve to be recognized as distinct taxonomic species. [ABSTRACT FROM AUTHOR]

Recognizing genetic variation and classifying genetic resources are very important in the management and conservation of plant genetic resources. Thymus species (Lamiaceae), a number of which are found in Iran's flora, comprise herbaceous annual and perennial plants with significance in ethnomedicine. Here, the genetic diversities of twenty T. daenensis and T. eriocalyx ecotypes collected from different regions at the West Azerbaijan province (Iran) were investigated using ISSR molecular markers. Seven out of fifteen ISSR markers, with clear bands, were used. The cluster analysis using NTSYS-PC2 software and genetic structure by STRUCTURE Var 2.3.4 software were performed, and Nei distance was used for UPGMA method. A total number of five hundred and fifty-six polymorphic bands were obtained with an average of 79.42 bands per primer. The average percentage of polymorphic bands was calculated as 95.79% per primer. Eighty polymorphic loci with an average of 11.42 bands per primer were obtained, and P3 and P7 primers showed the highest (0.92) and the lowest (0.64) PIC values, respectively. Also, P2 and P5 primers showed the highest (15.89) and the lowest (5.2) MI values, respectively. Similarities varied from 0.2 (in ecotype TdS vs. ecotype TdPo and TdU1) to 0.67 (in ecotype TdPi vs. ecotype TdMo). The highest distinction between the groups was obtained at the cut point with four groups at a similarity level of 34%. According to the molecular variance analyses, most of the variations were seen within the groups. Finally, P2 and P3 primers are being recommended as efficient markers for genetic diversity analyses in Thymus species. [ABSTRACT FROM AUTHOR]