Second-year Plants Research Articles

Rice hull-based substrates and the influence of the type of transplant and the age of the plant on the strawberry culture

The soilless growing of strawberries using local materials as a substrate is an alternative to reduce costs and reuse waste. The objective of this work was to evaluate the growth and yield of strawberry plants cultivar Aromas, originated from bare root and plug plants, as well as second-year plants in comparison to first-year plants, in substrates formulated with raw rice husk (RRH) and two types of conditioners [carbonized rice husk (CRH) and commercial substrate (S10)]. The experimental factors consisted of four substrates [RRH (100%), RRH + CRH (80 %: 20 %), RRH + S10 (80 %: 20 %), and RRH + CRH + S10 (80 %:10 %:10 %)], two types of transplants (plug plants and bare-root), and the maintenance of second-year plants in comparison to first-year plants. For the first year of growing, regardless of the substrate, plug plants showed greater growth and yield, providing an increase of 62.1 % in the commercial yield of plug plants in relation to the growing of bare-root transplants. As for the growing of bare-root transplants, the addition of CRH and its simultaneous use with commercial substrate S10 as RRH conditioners increased plant growth. However, fruit yield gains were less expressive and clear positive responses for this variable were obtained only with the simultaneous use of CRH and the commercial substrate S10. The results obtained in the second experiment indicate that second-year plants, on mean, showed greater vegetative growth, number and yield of fruits, however, with lower mean weight of fruits than the plants of the first year. First year plants showed superior commercial yield in the RRH + S10 substrate.

PECULIARITIES OF MORPHO-ANATOMICAL STRUCTURE OF GYPSYWORT (LYCOPUS EUROPAEUS L.) IN RESPONSE TO TREATMENT WITH SILICON-BASED MICROFERTILIZER

Background. For the comprehension the mechanisms of adaptation and increasing the bioproductivity of the Gypsywort, at the level of variability of micromorphological and anatomical features of the epidermis of the leaf plate and stem, it is proposed to study the reactions of plants to the use of micronutrients with adaptagenic properties.
 Scientific originality. For the first time in the conditions of crop rotation, the adaptogenic effect of the micro-fertilizer Siliplant on the plants of the Gypsywort at the degree of the epidermal structures of the leaf and stem was shown and confirmed.
 This work aim is to identify the morpho-anatomical features of Gypsywort, emerged as the result of exogenous treatment of plants with microfertilizer Siliplant.
 Materials and methods. The Gypsywort’s plants, growing in the conditions of field crop rotation at the experimental field, were treated in the budding by micro-fertilizer Siliplant (0.055 gallons per acre). The control variant was treated with water. The consumption of the solution was 32,07 gallons per acre. The research material was collected under the second-year plants during the mass flowering phase. Leaf plates of the middle part of the shoots (10 pcs.) were taken from plants (5 pcs. of each variant). The anatomical method of analysis included microscopy and microphotography. A 9x Ernst Zeits Wetzlar light microscope and a 14.0 Mp USB 2.0 C-Mount camera were used for the study. The sample consisted of 10 measurements, statistical processing of the results was performed in Microsoft Excel. For each studied trait, its average value (M), the error of the mean (m) and the coefficient of variation (Cv%) were determined.
 Results. The number and size of stomata were determined, the classification of trichomes was refined, their distribution, the density of pubescence and the number of essential oil glands were studied explored depending on the treatments of plants with Si-based microfertilizer. It has been found out that in plants growing in the field practically do not have hydathodes and pubescence increases.
 Conclusion. Treatment of plants with silicon Si-based microfertilizer contributes to their adaptation to xeromorphic conditions: pubescence decreases, the number of essential oil glands increases, the growth of the bark and xylem elements intensifies. The increased number of stomates and their sizes in the variant with silicon-containing microfertilizer, compared to the control samples indicates its anti-stress effect on the gypsywort plants. The established features of the anatomical structure of plants can also be important in determining the authenticity of medicinal raw materials of Lycopus europaeus L. plants during microscopic analysis.

Plant density and manure application affected yield and essential oil composition of Bakhtiari savory (Satureja bachtiarica Bunge.)

The use of soil amendments and cultivated techniques are effective strategies in improving plant yield. Bakhtiari savory (Satureja bachtiarica Bunge.) is an endemic medicinal plant of Iran with various medicinal purposes. To observe the effect of cattle manure (30 t ha−1) and plant density (high plant density, HPD: 80,000; medium plant density, MPD: 40,000, and low plant density, LPD: 26,666 plants ha−1), an experiment was accomplished as split plot with three replicates during 2018 and 2019 on plant yield, nutrients concentration, essential oil (EO) yield and composition, and also stomatal properties of Bakhtiari savory in the dryland farming conditions. The maximum plant weight was observed with manure application at HPD plant density in the second year. The greatest concentrations of N, Ca, and Mg were obtained in the plans treated with manure application and HPD. The increase of plant density led to decreased EO content and increased EO yield. The highest EO yield was observed in second-year plants supplied with manure at HPD. The GC and GC/MS analysis showed that the main constitutes of Bakhtiari savory EO were p-cymene (18.6–43%), carvacrol (32.3–59.3%), γ-terpinene (5–14.3%), thymol (0.6–17.8%), and linalool (2–4.3%), representing different concentrations under the manure and plant densities. Leaf stomatal density and length at LPD was lower compared with HPD and MPD, while increased density of EO glands was obtained at LPD. To sum up, cattle manure and HPD can result in higher plant production.

Improvement of clonal micropropagation technique of promising Lonicera caerulea L. cultivars

The work is focused on enhancement of in vitro propagation technique of valuable Lonicera caerulea L. cultivars. The impact of some nutrient medium components at main cultivation stages of the genus Lonicera L. representatives was studied. Some cultivars showed the positive effect of substituting sucrose for glucose in the medium at the multiplication stage (Diana (30 or 40 g L−1), Moskovskaya 23 (20 g L−1) and Yugana (40 g L−1)). When studying the influence of different auxin types on honeysuckle rhizogenesis, Solovey and Yugana preferred addition of 1.0 mg L−1 IBA into the medium. During the research of influence of different auxin concentrations on L. caerulea rooting the increased number of rooted microshoots of Goluboy Desert was demonstrated with the increasing of IAA concentration (from 0.5 to 3.0 mg L−1). Meanwhile, Diana and Yugana better rooted on the medium containing 1.0 mg L−1 IAA but Zolushka reached its highest rooting percentage on the medium supplemented with 0.5 mg L−1 IAA. The assessment of second-year plants undergone the whole cycle of clonal micropropagation was carried out 85% of these plants began to bear fruits.

Bio-organic and inorganic fertilizers modify leaf nutrients, essential oil properties, and antioxidant capacity in medic savory (<i>Satureja macrantha<i/> L.)

The present study was carried out to assess the effects of bio-organic and inorganic fertilizers on plant nutrients, essential oil composition and antioxidant capacity of Satureja macrantha L. The experiment included nine treatments viz., NPK (50:25:25 kg ha−1), Vermicompost (VC) (5 t ha–1), NPK +VC, Thiobacillus (T), T+VC, T+sulfur (S) (250 kg ha−1), T+S 500 kg ha−1, Glomus mosseae, and control (untreated plants). The results showed the highest Essential Oil (EO) content and yield were respectively observed in plants treated with the combination of VC and NPK. Total Phenol Content (TPC) in first-year plants treated with VC and second-year plants under NPK+VC were higher than other experimental plants. Total Flavonoid Content (TFC) in second-year plants under the combination of NPK was greater than other plants. N content in first year plants treated with NPK fertilizer / combination of NPK and VC was higher compared to other experimental plants. The highest P content was observed in the NPK application in first year. Gas Chromatography—Mass Spectrometry (GC/MS) analyses revealed that the main constitutes of S. macrantha EO were p- Cymene (16.30-34.64%), γ-terpinene (15.46-33.6%), and Thymol (14.82-43.09%), which had different responses to sampling time and fertilizer treatments.

BIOLOGY OF THE EPHEMERAL GEOPHYTE, STEER'S HEAD (DICENTRA UNIFLORA, PAPAVERACEAE) IN THE SOUTHERNMOST CASCADE RANGE, BUTTE COUNTY, CALIFORNIA

Dicentra uniflora Kellogg (Papaveraceae), a small, single-flowered, ephemeral geophyte, was studied at three main and several secondary forest sites at the southern end of the Cascade Range in California (2009–2018). Emergence was closely linked to snowmelt, with flowering to senescence taking six to seven weeks, at elevations ranging from 1350–2575 m. Plants transitioned from flowering to fruit maturation within three weeks. Percent seed set in this perennial was high, ranging from 81–93% over five sites; seeds per fruit ranged from 44–83. In 2018, weekly field observations quantified the fate of flowers on plants staked when flowers appeared: only 27–43% of the flowers produced mature fruits with seeds, 23–24% dried up, and 25–30% disappeared, often leaving the pedicels. Black-tailed deer are suspected to be the primary herbivore, although nocturnal larvae of the butterfly Parnassius clodius, known to consume Dicentra leaves, may also be responsible at higher elevations. Each seed bears an easily-dislodged elaiosome, but little of the expected seed dispersal by ants was seen throughout the study. Field plantings of seeds illustrated that germination can occur in winter, below the snow, with seedlings bearing only a single cotyledon emerging from the ground in the spring. A seedling quickly produces a tiny food-storing, belowground bulblet before disappearing with the summer drought of the Mediterranean-type climate. The second-year plant produces a new bulblet and sometimes a tiny tuber, but only a single leaf, and plantings in the field suggest that it may take up to 10 years or more before an individual reaches flowering stage. A flowering plant has one or two fusiform tubers approximately 21 mm long and a cluster of ∼9 whitish bulblets approximately 4 mm long. Published research in the closely-related D. cucullaria (L.) Bernh. indicates that bulblets are undeveloped food-storage leaf bases unique to four species of Dicentra, capable of giving rise to small plants and providing food for plant development. Bulblets planted in this field study clearly indicate they are capable of asexual reproduction. As in some other geophytes, dry weight of D. uniflora tubers was significantly greater in June at the beginning of the summer drought than in November when the plants began renewed root growth early in the fall wet season. The depth to the tops of tubers on plants occurring in clusters varied from 3.2–10.7 cm in the rocky, loamy or sandy-loamy soils of these sites.

Measuring short distance dispersal of Alliaria petiolata and determining potential long distance dispersal mechanisms.

IntroductionAlliaria petiolata, an herbaceous plant, has invaded woodlands in North America. Its ecology has been thoroughly studied, but an overlooked aspect of its biology is seed dispersal distances and mechanisms. We measured seed dispersal distances in the field and tested if epizoochory is a potential mechanism for long-distance seed dispersal.MethodsDispersal distances were measured by placing seed traps in a sector design around three seed point sources, which consisted of 15 second-year plants transplanted within a 0.25 m radius circle. Traps were placed at intervals ranging from 0.25–3.25 m from the point source. Traps remained in the field until a majority of seeds were dispersed. Eight probability density functions were fitted to seed trap counts via maximum likelihood. Epizoochory was tested as a potential seed dispersal mechanism for A. petiolata through a combination of field and laboratory experiments. To test if small mammals transport A. petiolata seeds in their fur, experimental blocks were placed around dense A. petiolata patches. Each block contained a mammal inclusion treatment (MIT) and control. The MIT consisted of a wood-frame (31 × 61× 31 cm) covered in wire mesh, except for the two 31 × 31 cm ends, placed over a germination tray filled with potting soil. A pan filled with bait was placed in the center of the tray. The control frame (11 × 31 × 61 cm) was placed over a germination tray and completely covered in wire mesh to exclude animal activity. Treatments were in the field for peak seed dispersal. In March, trays were moved to a greenhouse and A. petiolata seedlings were counted and then compared between treatments. To determine if A. petiolata seeds attach to raccoon (Procyon lotor) and white-tailed deer (Odocoileus virginianus) fur, wet and dry seeds were dropped onto wet and dry fur. Furs were rotated 180 degrees and the seeds that remained attached were counted. To measure seed retention, seeds were dropped on furs and rotated as before, then the furs were agitated for one hour. The seeds retained in the fur were counted.ResultsFor the seed dispersal experiment, the 2Dt function provided the best fit and was the most biologically meaningful. It predicted that seed density rapidly declined with distance from the point source. Mean dispersal distance was 0.52 m and 95% of seeds dispersed within 1.14 m. The epizoochory field experiment showed increased mammal activity and A. petiolata seedlings in germination trays of the MIT compared to control. Laboratory studies showed 3–26% of seeds were attached and retained by raccoon and deer fur. Retention significantly increased if either seed or fur were wet (57–98%).DiscussionWithout animal seed vectors, most seeds fall within a short distance of the seed source; however, long distance dispersal may be accomplished by epizoochory. Our data are consistent with A. petiolata’s widespread distribution and development of dense clusters of the species in invaded areas.

Chrysanthemum ×hybridum MN 98-89-7 Shrub Garden Chrysanthemum

A new garden chrysanthemum with a shrub plant habit is released as a descendent of a cross involving two hexaploid species: Chrysanthemum weyrichii (Maxim.) Tzvelv. (female) × C. ×grandiflorum Tzvelv. (male). Chrysanthemum ×hybridum Anderson MN 98-89-7 [U.S. Plant Patent (PP) 14,495] is a vigorously growing shrub chrysanthemum for garden culture, exhibiting extreme hybrid vigor. Single daisy reddish-purple flowers cover the foliage in the fall, numbering >3000 on second-year plants. This selection displays excellent winterhardiness in U.S. Department of Agriculture (USDA) Z3b+ (–34.4 to –37.2 °C) as well as frost-tolerant flowers. In its second and subsequent years of growth after planting, MN 98-89-7 grows into a fall flowering (August–October), herbaceous shrub ranging in plant height from 61.0 to 91.4 cm with a diameter of 76.2 to 152.4 cm. Its spherical plant shape is achieved naturally with self-pinching, creating a highly manicured appearance; it also attracts honey bees and butterflies as pollinators. MN 98-89-7 is a vegetative product and this unnamed selection is being released for germplasm purposes as well as for potential licensing and naming.

Fine roots – functional definition expanded to crop species?

Fine roots – functional definition expanded to crop species?

Identification and Characterization of Salvia miltiorrhizain miRNAs in Response to Replanting Disease.

Replanting disease is a major factor limiting the artificial cultivation of the traditional Chinese medicinal herb Salvia miltiorrhiza. At present, little information is available regarding the role of miRNAs in response to replanting disease. In this study, two small RNA libraries obtained from first-year (FPR) and second-year plant (SPR) roots were subjected to a high-throughput sequencing method. Bioinformatics analysis revealed that 110 known and 7 novel miRNAs were annotated in the roots of S. miltiorrhiza. Moreover, 39 known and 2 novel miRNAs were identified and validated for differential expression in FPR compared with SPR. Thirty-one of these miRNAs were further analyzed by qRT-PCR, which revealed that 5 miRNAs negatively regulated the expression levels of 7 target genes involved in root development or stress responses. This study not only provides novel insights into the miRNA content of S. miltiorrhiza in response to replanting disease but also demonstrates that 5 miRNAs may be involved in these responses. Interactions among the differentially expressed miRNAs with their targets may form an important component of the molecular basis of replanting disease in S. miltiorrhiza.

Identification and expression analysis of Rehmannia glutinosa mediator complex genes in response to continuous cropping

The mediator complex, a conserved assembly of multi-functional proteins, is required for the transcription of almost all protein-encoding genes in eukaryotes. In this report, 36 mediator complex subunit transcripts in Rehmannia glutinosa were identified from a leaf and tuberous root EST database. Nine of these transcripts had integrated open-reading frames (ORFs). A comparison of predicted amino acid sequences with putative mediator complex subunit homologues from another six flowering plants revealed high identities and several conserved domains. Phylogenetic analysis of the nine mediator complex genes in seven flowering plants revealed a closer evolutionary relationship between R. glutinosa and Solanum lycopersicum. The relative abundances of the 36 transcripts were analysed in the leaves and tuberous roots of R. glutinosa. qRT-PCR analysis revealed that the transcripts of approximately one-third of the mediator complex genes investigated in this study were expressed at similar levels. This result suggested that these transcripts might contribute to the formation, maturation or functions of the analysed tissues. The effects of consecutive monoculture on the transcription of R. glutinosa mediator complex genes were also analysed by qRT-PCR. This analysis revealed that one-third of the mediator complex genes presented differential expression patterns in the leaves of second-year plants, whereas over half of the mediator genes were differentially expressed in the tuberous roots of second-year plants. These patterns suggest that one of the subunits of the mediator complex regulates the consecutive monoculture problem in R. glutinosa.

Population and plant community dynamics involving garlic mustard (Alliaria petiolata) in a Minnesota Oak Woodland: a four year study1

Garlic mustard, Alliaria petiolata (M. Bieb.) Cavara & Grande, a European biennial, has become common in many Midwestern and eastern North American forests. Researchers have sometimes documented a two-year (two-point) population cycle in which the vegetative and reproductive phases alternate in abundance. However, little research has been conducted on the scale dependence of the two-point cycle and the extent to which the cycle is dependent on the density of A. petiolata. In addition to this interest in A. petiolata's population dynamics, researchers have investigated A. petiolata's effects on other plant species, often concluding that it displaces native herbs and inhibits tree seedling growth and survival through the production of allelochemicals. In order to examine both the population dynamics of A. petiolata and its possible effects on North American native plants, we conducted a four year study in which we monitored A. petiolata in a 6.2 ha portion of a Minnesota oak (Quercus) woodland at two spatial scales (0.5 m2, 400 m2). We also conducted an indoor seedling pot study to investigate whether any soil inhibitory effects associated with A. petiolata may be exacerbated under drought conditions. We found that a two-point cycle was not sustained during the four year study throughout the entire study site. However, the two-point cycle was exhibited in high A. petiolata density areas in the study site, providing support for the hypothesis that the cycle is driven by competition between first-year (rosette) and second-year (stem) plants. Both the monitoring study and the pot experiment yielded little evidence that A. petiolata is a major agent of ecological change in the woodland. Rather, the data indicate that over the four years of this study A. petiolata and the other plant species in the woodland we studied are changing in abundance largely independent of one another.

Induced Variation in Tetraploid Rudbeckia subtomentosa ‘Henry Eilers’ Regenerated from Gamma-irradiated Callus

Rudbeckia subtomentosa ‘Henry Eilers’ is an adaptable and popular garden plant; however, reduction in height and increased novelty in flower color would be desirable. The effect of gamma radiation dose on in vitro survival and development, and ex vitro fertility, phenology, and morphology of tetraploid Rudbeckia subtomentosa ‘Henry Eilers’ was investigated. In vitro embryogenic callus was treated with gamma radiation (0, 5, 10, 20, or 40 Gy). Rooted microshoots were established ex vitro and evaluated for morphology (plant height, number of flowers, diameter of the terminal flowers, diameter of the secondary flowers, number of stems, number of nodes, and internode length), date of first anthesis, winter survival, and pollen fertility on mature, second-year plants. Callus survival had no response to dose 2 months after treatment; however, microshoot number was significantly reduced with increasing dose. In vitro microshoot survival continued to decline at higher doses up to 4 months after treatment. Plant height, average stem height, number of flowers, flower diameter, percent winter survival, and pollen viability were all reduced with increasing radiation dose. Date of first anthesis was also delayed with increased radiation dose. Several off phenotypes were recorded including increased apical splitting of the ray florets in several plants. Gamma radiation was somewhat effective for reducing the height of R. subtomentosa ‘Henry Eilers,’ but flower morphology, flower number, and plant overwintering survival were often negatively affected with increasing radiation dose. Treating callus with low levels of gamma radiation (5–10 Gy) resulted in relatively high in vitro and field survival while inducing a range of other mutations that could be selected.

Age dependency of the meiotic process in an F1 interspecific hybrid of Solanum lnnaeum L. × Solanum incanum

A study of the meiotic process in first- and second-year plants of an F1 interspecific hybrid of Solanum linnaeum L. × Solanum incanum L. has been carried out. Fruits with seeds were obtained during the second year of vegetation. The numbers of univalents and tetravalents, as well as the percentage of basic impairments, decreased as the age of plants increased. The process of meiosis in the parental forms was normal. A conclusion was made regarding the connection between the regularity of meiosis in the F1 heterozygotes of Solanum lynnaeum L. × Solanum incanum L., on the one hand, and the hybrid nature of the genotype and age and the influence of environmental factors, on the other hand.

Comparison of the Effect of Early and Late Removal of Second-Year Garlic Mustard (Alliaria petiolata) on First-Year Plants and Deciduous Forest Spring and Summer Dominant Herbaceous Groundlayer Species in Central Illinois, USA

Garlic mustard, a biennial Eurasian species, has extensively invaded eastern North American deciduous forests. We studied effects of 3 years (2005–2007) of annual removal of second-year garlic mustard plants on first-year plants and native spring herbaceous species in upland and lowland woods. Treatments compared removal of second-year plants in mid-March (early treatment) or mid-May (late treatment) to a control. We recorded first- and second-year plants and native herbaceous species percent cover on April 19 and 20. First-year plant cover was higher on control than treatment plots; however, in the upland woods only control and late treatment plots differed significantly. First-year plant cover was less in removal than control plots, indicating reduced seed input; however, we found no difference in cover of second-year plants between late treatment and control plots. Results suggest second-year plants strongly compete with younger conspecifics, and their removal decreases first-year plant mortality. Removal of second-year garlic mustard did not significantly affect total cover of native herbaceous species. Second-year plants complete vegetative growth before late May and might impact early developing native species more than later growing species. We tested effect of removal of garlic mustard on native species in 2 phenological categories: spring- and summer-dominant species. We found no treatment effects on summer-dominant species. However, early treatment plots had significantly more cover of spring-dominant plants than late treatment and control in the upland woods. Indicator Species Analysis indicated a majority of spring (75%) and summer (50%) dominant species maximized performance in the early treatment.

Controlled-release Fertilizer Type and Rate Affect Landscape Establishment of Seven Herbaceous Perennials

Use of controlled-release fertilizers (CRF) has been recommended to the landscape service industry as a best management practice for establishing landscape plants. However, application practices vary considerably among professionals and recommendations are lacking for the appropriate type (tablet vs. granular), application rate, and timing of CRF to establish herbaceous perennials. In this study, cigar plant (Cuphea ignea), daylily (Hemerocallis ‘Stella de Oro’), gaura (Gaura lindheimeri ‘Siskiyou Pink’), lantana (Lantana camara ‘New Gold’), mexican heather (Cuphea hyssopifolia), purple coneflower (Echinacea purpurea), and rudbeckia (Rudbeckia fulgida ‘Goldsturm’) were fertilized with granular CRF (GF) 15N–3.9P–10K (8 to 9 month) at 0, 1, 2, or 4 lb/1000 ft2 nitrogen (N) at transplant (no fertilization, GF1, GF2, and GF4, respectively), a split application of GF with 1 lb/1000 ft2 N applied at transplant and 1 lb/1000 ft2 N applied 5-months later (GF2-split), or tablet CRF 16N–3.5P–10K (8 to 9 months) at two tablets per plant (7.5 g) at transplant (TF2). Plant size and visual quality (VQ) at 5 months after transplant (MAT) were improved by fertilization for all perennials except ‘Stella de Oro’ daylily. Compared to GF2, GF4 improved the growth of perennials of larger size and greater biomass production (i.e., cigar plant), but did not further improve their VQ. All perennials grown with TF2 had similar size and quality as those grown with GF2 at 5 MAT. At 15 MAT, no difference was found among fertilizer treatments for surviving perennials except cigar plant. Split application (GF2-split) did not improve overwinter survival or second-year plant growth and quality for most species when compared with GF2. On the basis of these results, we recommend applying two tablets (7.5 g) of 16N–3.5P–10K per plant at transplant to establish the perennials tested in this study.

Invasive White Sweetclover (Melilotus officinalis) Control with Herbicides, Cutting, and Flaming

AbstractWhite sweetclover is invading the Alaska glacial river floodplains and roadsides adjacent to natural areas, and control methods are needed. Chlorsulfuron, 2,4-DB, clopyralid, triclopyr, and 2,4-D controlled white sweetclover seedlings below recommended rates in the greenhouse. Biomass of established plants in the field was reduced by chlorsulfuron at recommended (17.6 g ai/ha), 1/2, and 1/4 rates and was reduced by triclopyr and 2,4-D at recommended rates (1,260 and 1,600 g ai/ha). Herbicides were more effective at reducing white sweetclover viable seed production in 2007 than in 2006. Only chlorsulfuron at 17.6 g ai/ha (recommended rate) eliminated seed production in both years. Flaming killed first-year plants, but some second-year plants resprouted and produced viable seed. Cutting at the 2.5 or 10 cm height did not control first-year plants because of regrowth, and second-year plant density and seed production was reduced by cutting at 2.5 cm but not by cutting at 10 cm.

Infection by powdery mildew Erysiphe cruciferarum (Erysiphaceae) strongly affects growth and fitness of Alliaria petiolata (Brassicaceae)

Garlic mustard (Alliaria petiolata) is an invasive biennial that negatively impacts plant and animal communities throughout North America and lacks significant herbivory in its invasive range. Throughout Ohio, many garlic mustard populations support the powdery mildew fungus Erysiphe cruciferarum, although disease incidence varies among populations and environments. Effects of infection on plant growth, as well as both plant and fungal responses to drought and light conditions, were examined on greenhouse-grown, first-year garlic mustard plants. Also, the effects of the fungus on plant growth and fitness were studied in a naturally growing population of second-year plants in the field. Powdery mildew significantly reduced growth of first-year plants in the greenhouse, eventually causing complete mortality. Simulated drought slowed both plant growth and disease development, independent of light conditions. In the field, plants with little incidence of disease after their first year grew taller during their second year, producing significantly more siliques and twice as many seeds as heavily diseased plants did. Seed germination rates did not differ between plants with different levels of disease severity. Consistent reductions in survival, growth, and fitness caused by fungal infection may reduce populations of garlic mustard. These effects may be more evident in moist sites that favor fungal development.

Changing leaf litter feedbacks on plant production across contrasting sub-arctic peatland species and growth forms

Plant species and growth forms differ widely in litter chemistry, which affects decay and may have important consequences for plant growth via e.g. the release of nutrients and growth-inhibitory compounds. We investigated the overall short-term (9.5 months) and medium-term (21.5 months) feedback effects of leaf litter quality and quantity on plant production, and tested whether growth forms can be used to generalise differences among litter species. Leaf litter effects of 21 sub-arctic vascular peatland species on Poa alpina test plants changed clearly with time. Across all growth forms, litter initially reduced plant biomass compared with untreated plants, particularly litters with a high decomposition rate or low initial lignin/P ratio. In the second year, however, litter effects were neutral or positive, and related to initial litter N concentration (positive), C/N, polyphenol/N and polyphenol/P ratios (all negative), but not to decomposability. Differences in effect size among several litter species were large, while differences in response to increasing litter quantities were not significant or of similar magnitude to differences in response to three contrasting litter species. Growth forms did not differ in initial litter effects, but second-year plant production showed a trend (P<0.10) for differences in response to litters of different growth forms: evergreen shrubs<graminoids or deciduous shrubs<forbs. While long-persisting negative litter effects were predominant across all growth forms, our data indicate that even within nutrient-constrained ecosystems such as northern peatlands, vascular plant species, and possibly growth forms, differ in litter feedbacks to plant growth. Differences in the composition of undisturbed plant communities or species shifts induced by external disturbance, such as climate change, may therefore feedback strongly to plant biomass production and probably nutrient cycling rates in northern peatlands.

Genetic study of a new color of the beet Beta vulgaris L.

A new genetic character of the beet Beta vulgaris L., named stem color, was described and studied genetically. This character was shown to be dominant trait and monogenically inherited. The first-year beet plants with the genotype Stc/_have red leafstalks, weakly colored central rib, and colored storage root; however, the root itself is not colored. The second-year plants have a red-colored low third of the floral shoot. The plants with the genotype stc/stc are uncolored. The Stc gene was localized to the first linkage group at a distance of 17.5 +/- 2.1 crossing over units from the gene B (Bolting), which controls the annual-perennial habit of beet.