Dormant Plants Research Articles

Internal cues for optimizing reproduction in a varying environment.

In varying environments, it is beneficial for organisms to utilize available cues to infer the conditions they may encounter and express potentially favourable traits. However, external cues can be unreliable or too costly to use. We consider an alternative strategy where organisms exploit internal sources of information. Even without sensing environmental cues, their internal states may become correlated with the environment as a result of selection, which then form a memory that helps predict future conditions. To demonstrate the adaptive value of such internal cues in varying environments, we revisit the classic example of seed dormancy in annual plants. Previous studies have considered the germination fraction of seeds and its dependence on environmental cues. In contrast, we consider a model of germination fraction that depends on the seed age, which is an internal state that can serve as a memory. We show that, if the environmental variation has temporal structure, then age-dependent germination fractions will allow the population to have an increased long-term growth rate. The more the organisms can remember through their internal states, the higher the growth rate a population can potentially achieve. Our results suggest experimental ways to infer internal memory and its benefit for adaptation in varying environments.

Molecular regulation of bud dormancy in perennial plants

Molecular regulation of bud dormancy in perennial plants

Elucidating Biological Functions of 9-cis-Epoxycarotenoid Dioxygenase Genes Involved in Seed Dormancy in Paeonia lactiflora

Abscisic acid (ABA) is a major phytohormone affecting seed dormancy and germination in plants. ABA is synthesized mainly through the C40 carotenoid pathway. In the ABA biosynthesis pathway, 9-cis-epoxycarotenoid dioxygenase (NCED) is a key rate-limiting enzyme that regulates the accumulation and content of ABA. However, the role of the NCED gene in perennial plants with complex seed dormancy remains largely unknown. Here, we cloned two differentially expressed paralogs of herbaceous peony NCED genes, named PlNCED1 and PlNCED2, and further identified their involvement in seed dormancy from perennial herbaceous peony experiencing complex double seed dormancy. The deduced PlNCED amino acid sequences had high sequence homology with NCED sequences from other plants and contained the typical conserved RPE65 domain of the NCED family. Phylogenetic analysis showed that PlNCED1 and PlNCED2 have a close relationship with PoNCED in Paeonia ostii and VvNCED6 in Vitis vinifera, respectively. A subcellular localization assay demonstrated that the PlNCED1 protein resided within the nucleus, while the PlNCED2 protein was located in the cytoplasm, indicating their different roles in the biosynthesis of ABA. Furthermore, the content of endogenous ABA in transgenic calluses showed that PlNCEDs were positively correlated with ABA content. Both PlNCED transgenic Arabidopsis lines and the functional complementation of Arabidopsis NCED mutants found that PlNCEDs promoted seed dormancy and delayed seed germination. These results reveal that PlNCEDs participate in the seed dormancy of herbaceous peony by regulating the accumulation of endogenous ABA.

Survival of Xanthomonas fragariae on Common Materials.

Xanthomonas fragariae causes strawberry angular leaf spot (ALS), an important disease for the strawberry nursery industry in North America. To identify potential inoculum sources, the survival of X. fragariae was examined on the surfaces of 11 common materials found in nurseries: corrugated cardboard, cotton balls, cotton cloth (t-shirt), strawberry leaf, sheet metal, plastic, rubber, Tyvek, wood (balsa), glass (microscope slide), and latex (latex glove). Prefabricated rectangular samples (7.62 by 2.54 cm) of each material were immersed in a bacterial suspension for 15 min, after which the samples were stored at approximately 20°C (room temperature) or -4°C (the cold storage temperature for dormant plants in strawberry nurseries) for 1, 3, 7, 14, 30, 60, 90, 180, 270, and 365 days after inoculation (DAI). After the storage period elapsed, bacteria were recovered from the surfaces of each of the samples with phosphate-buffered saline (PBS)-soaked cotton balls. Survival rate was determined with a viability real-time quantitative PCR procedure and in a plant bioassay that involved rub inoculation of strawberry leaflets with the PBS-soaked cotton balls used to recover bacteria from the samples. Results showed that X. fragariae could survive on all surfaces but that survival rate differed among materials and storage temperature. All materials were capable of harboring viable bacteria up to 7 DAI when stored at -4°C based on the formation of lesions on inoculated leaves in the plant bioassay. The longest survival observed was 270 DAI on cardboard stored at -4°C. At room temperature, cardboard, cotton balls, cotton t-shirt, and strawberry leaf tissue supported small bacterial populations up to 14 DAI. The information from this study can be used to improve sanitation practices for ALS management in strawberry nurseries.

Plant species contribution to bioretention performance under a temperate climate

Bioretention systems are green infrastructures increasingly used to manage urban stormwater runoff. Plants are an essential component of bioretention, improving water quality and reducing runoff volume and peak flows. However, there is little evidence on how this contribution varies between species, especially in temperate climates with seasonal variations and plant dormancy. The aim of our study was to compare the performance of four plant species for bioretention effectiveness during the growing and dormant periods in a mesocosm study. The species selected (Cornus sericea, Juncus effusus, Iris versicolor, Sesleria autumnalis) are commonly used in bioretention and cover a wide range of biological forms and functional traits.All bioretention mesocosms were effective in reducing water volume, flow and pollutant levels in both of the studied periods. Plants decreased runoff volume and increased contaminant retention by reducing water flow (up to 2.7 times compared to unplanted systems) and increasing water loss through evapotranspiration during the growing period (up to 2.5 times). Plants improved removal of macronutrients, with an average mass removal of 55 % for TN, 81 % for TP and 61 % for K compared to −6 % (release), 61 % and 22 % respectively for the unplanted systems. Except for Sesleria, mass removal of trace elements in planted mesocosms was generally higher than in unplanted ones (up to 8.7 %), regardless of season. Between-species differences in exfiltration rate and improved water quality followed the same order as their evapotranspiration rate and overall size, measured in terms of plant volume, leaf biomass, total leaf area and maximum average root density (Cornus > Juncus > Iris > Sesleria). By increasing evapotranspiration, plants decreased runoff volume and increased contaminant retention. Nutrient removal was partly explained by plant assimilation. Our study confirms the importance of plant species selection for improving water quality and reducing runoff volume during bioretention under a temperate climate.

Effect of the photoperiod on bud dormancy in Liriodendron chinense

Bud dormancy and its release are complex physiological phenomena in plants. The molecular mechanisms of bud dormancy in Liriodendron chinense are mainly unknown. Here, we studied bud dormancy and the related physiological and molecular phenomena in Liriodendron under long-day (LD) and short-day (SD). Bud burst was released faster under LD than under SD. Abscisic acid (ABA), superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GR) activities were increased significantly under LD in Liriodendron buds. In contrast, the contents of gibberellic acid (GA3), ascorbic acid (AsA), glutathione (GSH), malondialdehyde (MDA), and ascorbate peroxidase (APX) activity decreased under LD but increased under SD. Differentially expressed genes (DEGs) were up-regulated under LD and down-regulated under SD and these changes correspondingly promoted (LD) or repressed (SD) cell division and the number and/or size of cells in the bud. Transcriptomic analysis of Liriodendron buds under different photoperiods identified 187 DEGs enriched in several pathways such as flavonoid biosynthesis and phenylpropanoid biosynthesis, plant hormone and signal transduction, etc. that are associated with antioxidant enzymes, non-enzymatic antioxidants, and subsequently promote the growth of the buds. Our findings provide novel insights into regulating bud dormancy via flavonoid and phenylpropanoid biosynthesis, plant hormone and signal transduction pathways, and ABA content. These physiological and biochemical traits would help detect bud dormancy in plants.

Later Growth Cessation and Increased Freezing Tolerance Potentially Result in Later Dormancy in Evergreen Iris Compared with Deciduous Iris.

Winter dormancy is a protective survival strategy for plants to resist harsh natural environments. In the context of global warming, the progression of dormancy has been significantly affected in perennials, which requires further research. Here, a systematic study was performed to compare the induction of dormancy in two closely related iris species with an ecodormancy-only process, the evergreen Iris japonica Thunb. and the deciduous Iris tectorum Maxim. under artificial conditions. Firstly, morphological and physiological observations were evaluated to ensure the developmental status of the two iris species. Furthermore, the expression patterns of the genes involved in key pathways related to plant winter dormancy were determined, and correlation analyses with dormancy marker genes were conducted. We found that deciduous iris entered dormancy earlier than evergreen iris under artificial dormancy induction conditions. Phytohormones and carbohydrates play roles in coordinating growth and stress responses during dormancy induction in both iris species. Moreover, dormancy-related MADS-box genes and SnRKs (Snf1-related protein kinase) might represent a bridge between carbohydrate and phytohormone interaction during iris dormancy. These findings provide a hypothetical model explaining the later dormancy in evergreen iris compared with deciduous iris under artificial dormancy induction conditions and reveal some candidate genes. The findings of this study could provide new insights into the research of dormancy in perennial plants with an ecodormancy-only process and contribute to effectively managing iris production, postharvest storage, and shipping.

Rhizosphere Soil Microbial Survival States and N-Related Process during Riparian Plant Dormancy: Influences of Plant Locations and Plant Species

The plant dormancy period in the riparian zone affects the activity of microorganisms and their related nitrogen (N) process, which necessitates an investigation of the influence of the dormancy period on the microbial community. This study sampled two groups of soils (ashore and offshore soils) of two typical plants (Acorus calamus, Canna indica) in rhizosphere soils and bulk soils during the dormancy period to study the microbial communities. The results suggested that in ashore soils, especially in Canna indica soils, there was a lower abundance of N-related genes (4.79 × 106 copies/g) due to relatively competitive ecological niche competition because of possible sufficient substrate. Therefore, microbial communities still play a major role in the removal of N-related nutrients during plants’ dormancy period. In addition, the results also showed that during the plant dormancy period, the cell necrosis processes accounted for relatively lower proportions (15.75%, 7.54%, 21.46%, and 5.23% in ashore and offshore Canna indica and ashore and offshore Acorus calamus, respectively), suggesting an unexpected fairly strong microbial survival ability in the dormancy period compared to the commonly expected weak microbial state. This high microbial vitality provides us insight into the restoration of riparian soils during the plant dormancy period.

CRISPR-Cas9-mediated mutagenesis of kiwifruit BFT genes results in an evergrowing but not early flowering phenotype.

Phosphatidylethanolamine-binding protein (PEBP) genes regulate flowering and architecture in many plant species. Here, we study kiwifruit (Actinidia chinensis, Ac) PEBP genes with homology to BROTHER OF FT AND TFL1 (BFT). CRISPR-Cas9 was used to target AcBFT genes in wild-type and fast-flowering kiwifruit backgrounds. The editing construct was designed to preferentially target AcBFT2, whose expression is elevated in dormant buds. Acbft lines displayed an evergrowing phenotype and increased branching, while control plants established winter dormancy. The evergrowing phenotype, encompassing delayed budset and advanced budbreak after defoliation, was identified in multiple independent lines with edits in both alleles of AcBFT2. RNA-seq analyses conducted using buds from gene-edited and control lines indicated that Acbft evergrowing plants had a transcriptome similar to that of actively growing wild-type plants, rather than dormant controls. Mutations in both alleles of AcBFT2 did not promote flowering in wild-type or affect flowering time, morphology and fertility in fast-flowering transgenic kiwifruit. In summary, editing of AcBFT2 has the potential to reduce plant dormancy with no adverse effect on flowering, giving rise to cultivars better suited for a changing climate.

Genome-Wide Identification of MAPKK and MAPKKK Gene Family Members and Transcriptional Profiling Analysis during Bud Dormancy in Pear (Pyrus x bretschneideri).

The mitogen-activated protein kinase (MAPK) cascade consisting of three types of reversibly major signal transduction module (MAPKKK, MAPKK, and MAPK) is distributed in eukaryotes. MAPK cascades participate in various aspects of plant development, including hormone responses, cell division and plant dormancy. Pear is one of the most economically important species worldwide, and its yield is directly affected by dormancy. In this study, genome-wide identification of MAPKK and MAPKKK gene family members in Pyrus x bretschneideri and transcriptional expression analysis of MAPK cascades during pear dormancy were performed. We identified 8 MAPKKs (PbrMKKs) and 100 MAPKKKs (PbrMAPKKKs) in Pyrus using recent genomic information. PbrMAPKKs were classified into four subgroups based on phylogenetic analysis, whereas PbrMAPKKKs were grouped into 3 subfamilies (MEKK, Raf, and ZIK). Most PbrMAPKKKs and PbrMAPKKs in the same subfamily had similar gene structures and conserved motifs. The genes were found on all 17 chromosomes. The comprehensive transcriptome analysis and quantitative real-time polymerase chain reaction (qRT–PCR) results showed that numerous MAPK cascade genes participated in pear bud dormancy. The interaction network and co-expression analyses indicated the crucial roles of the MAPK member-mediated network in pear bud dormancy. Overall, this study advances our understanding of the intricate transcriptional control of MAPKKK-MAPKK-MAPK genes and provides useful information on the functions of dormancy in perennial fruit trees.

Analyze breaking palm oil dormancy through chemical processes using multivariate analysis of variance

Palm oil is a dormant plant. The main cause of oil palm seed dormancy is the hard and thick seed coat or shell, inhibiting the effective absorption of water and gases. The presence of a seed coat barrier causes the germination process of oil palm seeds to be hampered. This study aims to determine the effect of chemical treatment on breaking palm oil dormancy by immersion in a solution of strong acids, namely H2SO4, KNO3, and HCl. This study used a completely random design (CRD) with three treatments, four observations, and five replications. The results of the following study were analyzed using MANOVA with the parameters observed were germination rate, germination rate, seedling height, and most extended root length. Based on the analysis results, it was found that immersion with a solution of a strong acid, namely H2SO4, KNO3, and HCl, had different effects on breaking palm oil dormancy. The highest average germination rate was through immersion with HCl, which produced an average of 65.24. The highest average germination was through immersion in H2SO4 with an average of 8.52. In contrast, the average seedling height and most extended root length were soaked in HCl with an average of 35.28, and 15, respectively. Based on the results obtained, the best chemical treatment for breaking palm oil dormancy is through soaking with HCl.

Long-Term Monitoring and Management of American Chaffseed (Schwalbea americana) in the New Jersey Pine Barrens: Population Ecology of an Endangered Hemiparasite

We studied the long-term demographic structure of the endangered hemiparasitic plant, Schwalbea americana (American chaffseed), in the New Jersey Pine Barrens from 1991 to 2020 in order to address important questions about its population biology, life history, and responses to management. These included the relative contributions of dormancy, recruitment, and other life stages to annual population changes, as well as its ecological responses to fire, mowing, and other factors over time. Following baseline surveys in 1991, we conducted annual censuses from 1993 to 2020 and individualistic plant monitoring from 1999 to 2020. The Schwalbea population initially exhibited positive growth, with major increases observed in the early 2000s, followed by steady, long-term declines. We used generalized linear models and mixed effects models to analyze the relationships between demographic and environmental variables at the population and individual levels, respectively. Dormant season prescribed burning and mowing yielded significant increases in flowering, stems, and survival, with apparent residual benefits in subsequent years following repeated treatments. Germination declined to 0% after 4 y in seed viability experiments, and recruitment was more strongly correlated with estimated seed bank sizes than with flowering alone. Dormant plants represented an average of 21% of the total population, with 20% of above-ground plants entering dormancy annually. Most dormancy events (92%) were 1–3 y in duration, indicating that mortality cannot be distinguished from dormancy for a minimum of 3 y after disappearance. Annual survivorship was high (mean = 88%), with 9% of individuals surviving 18 y on average, but differed significantly by cohort and increased with management. Significant differences were observed in size and flowering by age/stage class. However, size alone was insufficient to identify Schwalbea recruits from older plants, due to overlap of their lower size ranges. Long-term declines in survival and recruitment persisted despite suppression of woody succession by hand clipping and intermittent mowing and burning. Increased frequency of mowing or burning may be needed to sustain this population in the future. The relationships of growth and vital rates to other factors are provided, and the benefits of individualistic data for informing Schwalbea monitoring and management are discussed.

WRKY Gene Family Drives Dormancy Release in Onion Bulbs.

Onion (Allium cepa L.) is an important bulb crop grown worldwide. Dormancy in bulbous plants is an important physiological state mainly regulated by a complex gene network that determines a stop of vegetative growth during unfavorable seasons. Limited knowledge on the molecular mechanisms that regulate dormancy in onion were available until now. Here, a comparison between uninfected and onion yellow dwarf virus (OYDV)-infected onion bulbs highlighted an altered dormancy in the virus-infected plants, causing several symptoms, such as leaf striping, growth reduction, early bulb sprouting and rooting, as well as a lower abscisic acid (ABA) level at the start of dormancy. Furthermore, by comparing three dormancy stages, almost five thousand four hundred (5390) differentially expressed genes (DEGs) were found in uninfected bulbs, while the number of DEGs was significantly reduced (1322) in OYDV-infected bulbs. Genes involved in cell wall modification, proteolysis, and hormone signaling, such as ABA, gibberellins (GAs), indole-3-acetic acid (IAA), and brassinosteroids (BRs), that have already been reported as key dormancy-related pathways, were the most enriched ones in the healthy plants. Interestingly, several transcription factors (TFs) were up-regulated in the uninfected bulbs, among them three genes belonging to the WRKY family, for the first time characterized in onion, were identified during dormancy release. The involvement of specific WRKY genes in breaking dormancy in onion was confirmed by GO enrichment and network analysis, highlighting a correlation between AcWRKY32 and genes driving plant development, cell wall modification, and division via gibberellin and auxin homeostasis, two key processes in dormancy release. Overall, we present, for the first time, a detailed molecular analysis of the dormancy process, a description of the WRKY-TF family in onion, providing a better understanding of the role played by AcWRKY32 in the bulb dormancy release. The TF co-expressed genes may represent targets for controlling the early sprouting in onion, laying the foundations for novel breeding programs to improve shelf life and reduce postharvest.

Advances in the Understanding of Reactive Oxygen Species-Dependent Regulation on Seed Dormancy, Germination, and Deterioration in Crops.

Reactive oxygen species (ROS) play an essential role in the regulation of seed dormancy, germination, and deterioration in plants. The low level of ROS as signaling particles promotes dormancy release and triggers seed germination. Excessive ROS accumulation causes seed deterioration during seed storage. Maintaining ROS homeostasis plays a central role in the regulation of seed dormancy, germination, and deterioration in crops. This study highlights the current advances in the regulation of ROS homeostasis in dry and hydrated seeds of crops. The research progress in the crosstalk between ROS and hormones involved in the regulation of seed dormancy and germination in crops is mainly summarized. The current understandings of ROS-induced seed deterioration are reviewed. These understandings of ROS-dependent regulation on seed dormancy, germination, and deterioration contribute to the improvement of seed quality of crops in the future.

Biofertilizer microorganisms accompanying pathogenic attributes: a potential threat.

Application of biofertilizers containing living or dormant plant growth promoting bacterial cells is considered to be an ecofriendly alternative of chemical fertilizers for improved crop production. Biofertilizers opened myriad doors towards sustainable agriculture as they effectively reduce heavy use of chemical fertilizers and pesticides by keeping soils profuse in micro and macronutrients, regulating plant hormones and restraining infections caused by the pests present in soil without inflicting environmental damage. Generally, pathogenicity and biosafety testing of potential plant growth promoting bacteria (PGPB) are not performed, and the bacteria are reported to be beneficial solely on testing plant growth promoting characteristics. Unfortunately, some rhizosphere and endophytic PGPB are reported to be involved in various diseases. Such PGPB can also spread virulence and multidrug resistance genes carried by them through horizontal gene transfer to other bacteria in the environment. Therefore, deployment of such microbial populations in open fields could lead to disastrous side effects on human health and environment. Careless declaration of bacteria as PGPB is more pronounced in research publications. Here, we present a comprehensive report of declared PGPB which are reported to be pathogenic in other studies. This review also suggests the employment of some additional safety assessment protocols before reporting a bacteria as beneficial and product development.

Winter resistance and frost resistance of representatives of the genus Cotinus Mill. in the conditions of the Right Bank Forest Steppe of Ukraine

Aim. The goal is to assess the winter and frost resistance of plants of representatives of the genus Cotinus Mill. from the collection of the National Dendrological Park "Sofiyivka" of the National Academy of Sciences of Ukraine and the Botanical Garden named after Academician Alexander Fomin of the Taras Shevchenko National University of Kyiv. Methods. The frost resistance of plants was investigated in the laboratory of plant physiology of the Institute of Horticulture of the National Academy of Sciences of Ukraine, by the method of direct freezing of shoots during the period of forced dormancy of plants. The intensity of damage (browning) of tissues on transverse sections of shoots was assessed using a six-point scale by M. A. Solov'eva (1982). The objects of study were plants C. obovatus Raf., C. coggygria Scop., C. coggygria 'Royal Purple', C. coggygria 'Purpurea'. Winter hardiness was assessed visually on an eight-point scale by S. Ia. Sokolov, (1957). Results. According to estimates of the general freezing of plants in the winter period of 2014–2020, minor injuries were found in all representatives of the genus Cotinus, which were estimated at 1–2 points. The results of experimental studies of plant frost resistance showed that in most variants of the experiment, the tissues of the upper internode and buds froze more. The tissues of the medial part of the shoot turned out to be the most resistant to freezing. According to the results of artificial freeze testing of cut shoots of C. coggygria and C. coggygria 'Royal Purple", sampled in the period of forced dormancy of plants, insignificant tissue damage was revealed at freezing temperature of –25 °С and –30 °С (0.63–1.70), only at temperature of –35 °C, the score of bark damage was 2.3–2.5 points. Conclusions. The low temperatures of the winter period of the study area cannot be considered as limiting abiotic factors that limit the widespread use of the studied representatives of the genus Cotinus in landscape construction. The high potential of frost and winter hardiness of the studied taxa gives grounds to test them in the more northern regions of the Right Bank Forest-Steppe of Ukraine to create garden and park compositions, because due to high decorative flowering and specific crown shape they have an attractive appearance in both group and solitary plantations.

Effect of Photoperiod, Propagative Material, and Production Period on Greenhouse-grown Ginger and Turmeric Plants

The objectives were to 1) compare growth and yield of different ginger (Zingiber officinale) and turmeric (Curcuma longa) propagules grown under two photoperiods (Expt. 1); and 2) evaluate whether their growing season could be extended with night interruption lighting (NI) during the winter (Expt. 2). In Expt. 1, propagules included 1) micropropagated tissue culture (TC) transplants, 2) second-generation rhizomes harvested from TC transplants (2GR), and 3) seed rhizomes (R). Plants received natural short days (SDs) or NI providing a total photon flux density (TPFD) of 1.3 µmol·m−2·s−1. Providing NI increased number of new tillers or leaves per plant, rhizome yield (i.e., rhizome fresh weight), and dry mass partitioning to rhizomes in both species. There was no clear trend on SPAD index in response to photoperiod or propagative material. Although TC-derived plants produced more tillers or leaves per plant, 2GR ginger and R turmeric produced a higher rhizome yield. In Expt. 2, seed rhizomes of ginger and turmeric were grown under five treatments with different photoperiods and/or production periods: 1) 20 weeks with NI (20NI), 2) 24 weeks with NI (24NI), 3) 28 weeks with NI (28NI), 4) 14 weeks with NI + 10 weeks under natural SDs (24NISD), and 5) 14 weeks with NI + 14 weeks under natural SDs (28NISD). NI provided a TPFD of 4.5 µmol·m−2·s−1. Lengthening the production period and providing NI increased rhizome yield and crude fiber content in both species. SPAD index decreased when plants were exposed to natural SDs at the end of the production period (NISD treatments). Results demonstrate the potential to overcome winter dormancy of ginger and turmeric plants with NI, enabling higher rhizome yield under natural SDs.

Bud burst induction in BRS-Carmem vine minicuttings under controlled environment

A search for new products and alternative techniques to artificially overcome the dormancy of temperate climate plants has increased. Thus, the present work aimed to evaluate the efficiency of the application of vegetable oil, mineral oil, garlic extract and hydrogenated cyanamide on budburst of ‘BRS Carmem’ vine under controlled environment (B.O.D). The randomized design arranged in a 2 × 6 factorial scheme was used as a statistical model, with four repetitions with nine minicuttings per plot. The first factor consisted of the exposure or not of the minicuttings to 400 hrs of cold (<7.2 oC), and the second factor was composed by the alternative tests: control; mineral oil (MO), vegetable oil (VO); MO + VO, hydrogenated cyanamide; and garlic extract. The bud swell and sprouting formation at 20 days after the application were evaluated, and the average time and speed index of bud swell, and the average time and speed index of sprouting were calculated. For minicuttings not exposed to the cold, the best results in terms of bud swell and sprouting was observed with the application of MO, followed by the application of hydrogenated cyanamide. For minicuttings exposed to 400 hrs, the best results regarding bud swell and sprouting was observed with the application of the oils association. It can be concluded that the best results for sprouting were obtained when minicuttings were not exposed to cold with an application of the association of MO and VO.

Integrating evolutionary potential and ecological function into agricultural seed production to meet demands for the decade of restoration

The UN Decade on Ecosystem Restoration will result in an unprecedented need for seeds. Agricultural production, or the growing of plants under controlled conditions to produce desired resources, can be a helpful tool for providing the quantities of seeds needed for large‐scale restoration. In some ecosystems, agricultural production of native plant seeds is part of the restoration process. This is particularly true for native plants that are similar to major food crops, such as native grasses. However, conventional crops have contrasting characteristics (e.g. fast growing, high yield for a focused use) from those desired in restored vegetation (plants capable of surviving and providing ecosystem services in variable environments). This contrast leads to significant, often opposing differences in desirable characteristics in crop versus natural systems. Examples include rapid germination in domesticated crops versus seed dormancy in wild plants, uniform germination, growth and flowering versus bet‐hedging strategies, or high seed retention versus seed dispersal. While it may be useful to maximize productivity of native plants in agricultural environments with similar trait modifications, for restoration, the demands of the natural environment should be primary, and agricultural production should aim to maximize the diversity, function, and evolutionary potential of native species. Any perceived benefits that come from the production of large quantities of inexpensive seeds that cannot meet the needs of wild communities are short‐sighted. We suggest research directions that will be needed to meld agricultural production needs with those of restoration practitioners, as a challenge for those invested in the procurement and use of wild seeds.

Environmental regulation of dormancy, flowering and runnering in two genetically distant everbearing strawberry cultivars

The environmental control of dormancy and its relation to flowering and runner formation is poorly understood in everbearing (EB) strawberry cultivars. We studied the topic by growing plants of the seed-propagated F1-hybrid ‘Delizzimo’ and the runner-propagated ‘Favori’ cultivar in daylight phytotron compartments under short day (SD) and long day (LD) conditions at temperatures of 6, 16 or 26 °C for 5 and 10 weeks. This was followed by forcing at 20 °C and 20-h photoperiod for 10 weeks with and without preceding chilling at 2 °C for 6 weeks. The results showed that dormancy in EB strawberry is regulated by a complex interaction of temperature, photoperiod and chilling in much the same way as known for seasonal flowering (SF) cultivars. Surprisingly, the EB cultivars exhibited the same SD dormancy induction response as SF cultivars, despite their opposite photoperiodic flowering requirements. However, at 26 °C the EB cultivars developed partial dormancy also under LD conditions. As known for SF cultivars, none of the EB cultivars became dormant at 6 °C regardless of daylength conditions, whereas they were increasingly sensitive to SD dormancy induction at intermediate and high temperatures. Similar to SF cultivars, the EB cultivars needed exposure to SD and relatively high temperatures for at least 10 weeks for attainment of the semi-dormant state that is typical for strawberry in general. As reported for SF cultivars, there was a close interrelation between the control of flowering, runner formation and dormancy also in the EB cultivars. ‘Favori’ had an obligatory LD requirement for flowering at 26 °C and was almost day neutral at 16 °C, while ‘Delizzimo’ behaved as a quantitative LD plant at both temperatures, and both cultivars were completely day neutral at 6 °C. Except for the stricter LD control of flowering in ‘Favori’, the overall environmental responses were quite similar in the two genetically distant cultivars. Chilling for six weeks at 2 °C was adequate for complete reversal of the constrained elongation of leaf petioles and flower trusses in dormant plants, but had little or no effect on the degree of flowering and runner formation.