Seed and fruit set are processes determining yield in many crops. However, many growth models for horticultural crops do not explicitly incorporate these processes. The aim of this study was to develop a quantitative model to predict seed set, fruit set, and fruit mass based on the effects of temperature and duration of a period with high or low temperature on pollen number and pollen quality (viability and germination fraction). To develop the model, we conducted an experiment where fruiting dwarf tomato plants were grown at 18°C and exposed to 14°C for 4, 6, or 8 days, 30°C and 34°C for 1, 3, or 4 days, and a control treatment at 18°C continuously. Temperatures of 30°C and 34°C reduced pollen viability and germination, resulting in lower seed set and fruit mass. While fruit set remained unaffected at 30°C, both 14°C and 34°C led to reduced fruit set. At lower temperatures (14°C), our model predicted decreased yields due to a lower number of fruits in the truss, resulting from reduced fruit set and smaller fruit size compared to the reference temperature (18°C). At higher temperatures (30°C), our model predicted reduced fruit yield due to smaller individual fruit size, resulting from low seed set. Our research introduces a modelling framework that accounts for the influence of periods with high or low temperature on seed set, a process that is almost never considered in growth models for horticultural crops. This framework is crucial for developing strategies to optimize crop yield in response to temperature fluctuations.

Background and AimsStomata are specialized epidermal structures typically restricted to aerial organs of vascular plants. Their absence on roots has long been regarded as a general anatomical rule. Although rare reports in certain dicotyledonous taxa have described root stomata, these occurrences have been considered transient or developmentally anomalous. Within Apiaceae, no confirmed occurrence has previously been documented. This study aimed to investigate the anatomical presence of stomata on the primary roots of Conium maculatum L. seedlings.MethodsSeedlings of C. maculatum derived from wild-collected populations and genebank accessions were examined using light microscopy. Transverse sections and epidermal surface preparations were prepared to confirm root identity and epidermal features. Taxonomic identity was verified using morphological traits and molecular data (ITS and rps16 sequences).Key ResultsMorphologically distinct stomata with characteristic guard cells were observed on the primary root. Their distribution was sparse and irregular. Root identity was supported by the overall anatomical organization of the examined sections, including a uniseriate epidermis and a broad parenchymatous cortex. Stomatal complexes were consistently detected across all examined accessions of the species.ConclusionsThis study provides the first anatomically verified and reproducible report of stomata on the primary root of C. maculatum within Apiaceae. These findings expand current knowledge of root epidermal anatomy in the family and indicate that further comparative surveys will be necessary to determine the taxonomic extent of this trait.

Extreme events (e.g. severe drought) can hinder the establishment of saplings in tropical forest plantations. To assess the resistance and recovery of three commercially important Amazonian tree species under drought conditions and to identify their key functional strategies for drought response, we conducted a controlled drought experiment exposing saplings of Bertholletia excelsa, Dipteryx odorata, and Tachigali vulgaris to water deficit followed by recovery. Tachigali vulgaris (fast-growing species) was more vulnerable to drought, as 80% of the drought-treated plants died. Nevertheless, the individuals who survived demonstrated a rapid recovery of physiological performance following rewatering. Bertholletia excelsa and D. odorata (slow-growing species) were more resistant to drought stress, as evidenced by lack of mortality in these species. Drought-stressed plants had the lowest growth rates, more biomass allocated to roots and less leaf biomass. The greater biomass allocation to roots in B. excelsa and D. odorata, together with their more conservative functional traits compared to T. vulgaris, appears to play an important role in their lower sensitivity to drought. These species exhibited strategies consistent with drought avoidance. Our results highlight the specific strategies of these species under water-deficit conditions and can help guide decisions on species selection and plantation management for reforestation under climate change scenarios.

Coastal wetland plants are adapted to fluctuating and often harsh environmental conditions. In urban wetlands, plant functional groups display a range of physiological and morphological strategies in response to abiotic stress. However, differences amongst functional groups and the coordination between leaf traits, nutrient status, and environmental variation remain poorly understood in these systems. This study evaluates trait-environment relationships in three dominant species-Acrostichum danaeifolium (fern), Dalbergia ecastaphyllum (nitrogen-fixer shrub), and Laguncularia racemosa (halophytic tree)-across contrasting wetland soils and seasonal periods in a tropical urban reserve. We measured leaf gas exchange, specific leaf area (SLA), nutrient content, and photosynthetic nitrogen use efficiency (PNUE) across wet and dry periods on two soils in the Ciénaga Las Cucharillas Natural Reserve, Puerto Rico. Soil bulk density, salinity, and bioavailable nutrients were also quantified. Multivariate analyses (principal component analysis) were used to assess trait covariation. Species differed significantly in morphological and physiological traits. L. racemosa exhibited the highest assimilation rates, PNUE, and succulence, consistent with an acquisitive resource-use strategy. In contrast, A. danaeifolium showed high SLA and water content but conservative stomatal behaviour and lower PNUE, indicative of a shade-tolerant strategy. Dalbergia ecastaphyllum maintained high water-use efficiency during the dry period and exhibited adaptive responses to slightly and moderate saline soils, indicative of a nutrient acquisitive strategy. Soil type influenced elemental availability but had limited effects on photosynthetic rates. Trait differentiation amongst coexisting wetland species reflects contrasting resource-use strategies shaped by both seasonality and soil environment. These findings underscore the functional diversity and adaptive capacity of tropical wetland vegetation under urban and hydrological pressures.

Cytoplasmic male sterility (CMS) is a common biological phenomenon in chilli pepper hybrid production. Although several restorer-of-fertility (Rf) genes have been identified in pepper CMS lines, a regulatory network has yet to be constructed. Morphological characteristics of the sterile, maintainer, and restorer flower buds were studied at three different developmental stages. We conducted transcriptome analysis of the CMS/Rf system in pepper plants. Pentose and glucuronate interconversion pathways were particularly enriched in most comparison groups. In addition, differentially expressed genes among the different lines at flower bud stages 2 and 3 were generally enriched in amino sugar and nucleotide sugar metabolism pathways. In our study, the small auxin upregulated RNA (SAUR), A-ARR and GH3 genes in the plant hormone signal transduction pathway, Capana12g000348, CKX7 and cis-zeatin O-glucosyltransferase (CISZOG) genes in the zeatin biosynthesis pathway, and receptor-like protein kinase 2 (RLK2) in the germplasm development signal pathway showed gradual upregulation across developmental stages in the restorer line. However, expression of these genes was stable in the sterile and maintainer lines. qRT-PCR analysis showed that SAUR, A-ARR, GH3, Capana12g000348, CKX7, CISZOG, CRE1, AHP and TIR1 participate in CMS fertility regulation in chilli pepper. We constructed a regulatory network based on critical genes. Overall, our research provides a solid theoretical foundation for the development of CMS fertility studies on chilli pepper.

Plant invaders can promote invasion success through interactions with soil-biota (i.e. soil-conditioning), forming feedback, which can change in strength and direction over time. Thus, native plant responses to invader soil-conditioning dynamics may be dependent on the degree of invasion and could additionally be mediated by plant functional traits. To investigate the temporal dynamics of invader-soil-conditioning and the role of traits in mediating plant responses, we conducted a greenhouse experiment focusing on Oncosiphon pilulifer, an invasive annual forb spreading across the Southwestern United States and Western Australia. We grew Oncosiphon and six native plants in live whole soil vs sterilized whole soil inocula from an existing Oncosiphon invasion gradient, with four levels of invasion ranging from uninvaded, small patches, large monocultures, and the origin point of invasion resulting in a space-for-time substitution. We measured plant biomass, mycorrhizal root colonization, and leaf and root traits. We found native plant growth was reduced with soil from patchily invaded soils, while mycorrhizal root colonization rates were reduced with Oncosiphon monoculture soil. Oncosiphon itself experienced reduced growth over the course of invasion, with consistently low root colonization. Our trait analysis suggests that an interaction between root and leaf traits can mediate plant vulnerability to invader impacts on soil-biota.

[This corrects the article DOI: 10.1093/aobpla/plaf066.].

Pediocactus bradyi, a semi-globose cactus endemic to northern Arizona, displays a root-contraction mechanism to survive extreme drought: its roots contract, pulling the stem below ground during dry periods, re-emerging once rains return. To quantify how root contraction shapes population dynamics, we developed an integral projection model based on 31 years of demographic data from a P. bradyi population on the Navajo Nation Off-Reservation Trust Land. We explored two scenarios: one including root contraction and one excluding it. We found that, being ∼10% of the individuals and mostly confined to smaller individuals, root contraction did not have an effect on the long-term population growth [λ = 1.041 (1.039, 1.303) with contraction vs. λ = 1.044 (1.035, 1.289) without]. Also, we show that larger individuals have higher survival and reproductive rates, while growth declines beyond 35 mm in diameter. An elasticity analysis confirmed that survival and growth are the main vital rates affecting population growth, followed by root elongation after contraction. Thus, while root contraction may improve individual survival, elongation is in fact more important at the population level. Therefore, as with most cacti species, conservation efforts should focus on ensuring the survival of large individuals irrespective of their root contraction status.

Plants use chemicals to respond to their environments. Despite the impact of competition on plant productivity, few studies consider how plant–plant competition affects phytochemistry; most phytochemistry studies focus on plant–consumer interactions. It therefore remains unclear how plants chemically respond to changes in both competition and consumer pressure. We used 1H-NMR spectroscopy to characterize the phytochemistry (both primary and secondary metabolites) of a C4 grass (Andropogon gerardi) and a legume (Lespedeza capitata) in a field experiment. Both species were grown with intraspecific or interspecific neighbours (monoculture or 16-species polyculture) with or without a combined fungicide + insecticide treatment (consumers reduced vs. consumers present) in a factorial design. We measured species aboveground biomass, healthy plant cover (NDVI) and phytochemistry in the four treatments to determine whether plants alter their biomass, phytochemistry, or both in response to neighbours and herbivory. Phytochemistry of A. gerardi did not vary with neighbour identity or consumers, in contrast to A. gerardi biomass, which was higher under interspecific competition and when consumers were reduced. Phytochemistry of L. capitata was also unrelated to consumer reduction, though L. capitata had higher NDVI under reduced consumers. However, L. capitata had lower biomass and exhibited phytochemical signs of metabolic stress (lower sugars and higher amino acid production) when grown with interspecific neighbours. Theory and empirical work have focused on coevolution with consumers as driving phytochemical variation, but our results suggest that—at community scales—the competitive environment may be more important than consumer pressure in determining short-term phytochemical responses of some species.

Hybridization, polyploidization, and apomixis are evolutionary forces that obscure genetic differentiation and boost morphological variability. These processes have shaped the family Rosaceae, particularly the genus Crataegus, which includes both diploid and polyploid species reproducing sexually or via apomixis. In Central Europe, C. monogyna and C. laevigata are predominantly diploid sexuals, while C. rhipidophylla is mainly a polyploid apomict. These species hybridize to form C. × media, C. × macrocarpa, and C. × subsphaerica. Our aim was to assess how hybridization, apomixis, and polyploidy shape Crataegus diversity by integrating genetic, morphological, and cytological data. Leaves and fruits were collected from ten natural populations where all three species coexist and hybridize. Species identification was performed with novel nuclear microsatellites, marking the first genetic-based Crataegus taxonomy in Central Europe. Ploidy levels were estimated by flow cytometry (FCM), including seed screening to infer reproductive modes. A combined morphological analysis of leaves and fruits was used to distinguish parental species and evaluate hybrid variability. Genotyping identified distinct genetic clusters for parental species and their hybrids, with geographic structuring within C. laevigata and C. rhipidophylla. Morphological data clearly separated genetically defined parental species, although hybrids can be difficult to distinguish from parents due to a big overlap in morphology. FCM indicated that C. × media is predominantly a diploid sexual hybrid like its diploid parents, while other tri- or tetraploid hybrids with polyploid C. rhipidophylla as a parent are apomictic. Ploidy rather than hybridization dictates the mode of reproduction.