Number Of Inflorescences Research Articles

Variation in reproductive organ functionality among a population of tomato genotypes reveals the importance of pollen viability and fruit set in response to heat stress

ABSTRACT High temperature limit crop productivity as a consequence of global warming and climate change. In particular, high temperature interferes with sexual reproduction and thus fruit and seed formation in crops. In the present study, phenotypic evaluation of a tomato population, including 21 tomato genotypes, was carried out under high-temperature stress (35°C). Several reproductive and yield-related traits, including the number of inflorescences, number of flowers per inflorescence, pollen viability, fruit set, number of fruits per plant, and number of fruits per inflorescence, were investigated. Significant positive correlations between pollen viability and fruit set were observed (r = 0.83). Based on the obtained findings, the fruit set, pollen viability, number of fruits per plant, and number of fruits per inflorescence were recognized as markers for heat tolerance screening of tomato genotypes. These traits effectively separate tolerant and sensitive genotypes, which can be used in breeding program. At the same time, the number of inflorescences and the number of flowers per inflorescence did not separate between tolerant and sensitive genotypes. In conclusion, heat stress, through influencing pollen viability and fertilization, imposes its effects on reproductive organ development in tomato genotypes.

Plant traits and seasonality shape coexistence and niche segregation patterns among spider species.

Understanding the mechanisms that enable species coexistence is a central question in ecology, as it helps to comprehend species diversity. One of the most common stabilizing mechanisms of coexistence is niche segregation, which can prevent the competitive exclusion of the fittest competitor. Niche segregation can manifest itself at various temporal and spatial scales, allowing provide essential insights into understanding the stabilizing mechanisms facilitating the coexistence of species. We assessed coexistence patterns among flower-dwelling spiders in two ways, in the first set of analyses, we investigated the factors influencing the quantity of spider individuals and species. The second approach we investigate the spatio-temporal segregation between species, effectively examining the coexistence patterns. We observed that the presence of inflorescences per plant, the number of flowers per inflorescence, and the presence of EFNs play a significant role in increasing spider abundance and richness. We find only a marginal seasonal effect, suggesting that spiders have constant access to resources throughout the year. Our niche overlap analysis demonstrated synchrony in the spatial occupation of niches by different spider species. The coexistence patterns appeared to be unaffected by the number of inflorescences. The greater number of inflorescences will enable a greater availability of niches, and consequently more abundance and richness of species of spiders the plant can sustain. Our results suggest that, to mitigate the adverse consequences of competitive interactions, spiders tend to adopt spatial partitioning as a strategy to facilitate the coexistence of spiders living in reproductive structures on plants in the Brazilian savanna.

Exploring the Role of Endophytes in Cannabis sativa L. Polyploidy and Agricultural Trait Improvement

Here, we examine the effects of ploidy variation in Cannabis sativa L. cell lines on the plant host genotype-associated microbiome. The endophytic microbiome has a protocooperative role in improving plant health and productivity and represents an alternative to synthetic chemical fertilizers and pesticides in sustainable agriculture. This study assessed the effects of seed endophytes on diploid and triploid Haze hemp cultivars. Key phenotypic characteristics were evaluated, revealing significant differences in seed germination in vitro as well as vegetative growth and flowering in phytotron conditions. Endophyte-treated triploid plants exhibited significantly taller heights compared to diploids (p < 0.01). These treated triploid plants also showed longer leaves at nodes 2, 6, and 8, except at node 4, indicating a plant in transition from vegetative growth to the generative developmental stage. Additionally, triploids treated with endophytes displayed the highest number of axillary branches, while endophyte-treated diploids had the fewest (p < 0.05). Both cultivars treated with endophytes exhibited a higher number of inflorescences compared to untreated control plants. This study revealed for the first time a direct correlation between the shifts in diameter of the stem and the biomass in both tested hemp hosts, in association with endophytic microbiomes.

Assessing the growth, yield, and biochemical composition of greenhouse cherry tomatoes with special emphasis on the progressive growth report

The growth of plants hinges on a complex interplay of biochemical and physiological activities across various growth stages. These intricate processes dynamically adapt to different environmental conditions, shaping both plant development and productivity. This study explores the impact of greenhouse climate on the growth, yield, and biochemistry of winter-grown cherry tomatoes ‘Cheramy F1’. A randomized complete block design (RCBD) under split plot arrangements (3 Rows) with three replications (3 plants from each row) was adopted. The data were collected on various dates during the period extending from December to March of two consecutive growing seasons in 2022 and 2023, and presented as averages. An analysis of variance was applied to statistically analyze the collected data at a confidence level of p < 0.05. The climatic conditions in the greenhouse were calculated as temperature ranging from a minimum of 10.5 °C to the maximum of 41.3 °C by an average of 21.2 °C during the vegetative stage and from 8.2 °C to 32.3 °C by an average of 20.9 °C during the fruit-bearing stage, with an average CO2 concentration fluctuated within the range of 385.61 ppm to 510.30 ppm and an average light intensity of 94.62 to 240.45 W/m². This study assessed various growth parameters such as plant height, leaf growth, stem diameter, leaf spacing, leaf count, leaf area, and inflorescence count per plant, and suggested the optimum range of greenhouse conditions for each stage. The key results of this study revealed the Progressive Growth Report (PGR), predicting daily potential growth rates of plants: plant height, 2.86 to 3.81 cm/day; growth rate of mature older leaf: 0.003988 m2/day; middle younger leaf: 0.008733 m2/day; top nascent leaf: 0.010722 m2/day; three to five leaves per week; and one inflorescence per week. In our accidental observation, we noticed unusual plant growth and yield responses because of the various growing postures and positions that the plants adopted in the greenhouse. An exceedingly significant difference among the inflorescences was found in view of their growth, productivity and biochemical composition. A non-significant interaction was found between the fruit keeping quality (shelf days), fruit height, fruit diameter, and inflorescence number. The present study results highlight the possible responses of greenhouse-grown cherry tomatoes to different ranges of temperature, light intensity, and CO2 concentrations, offering valuable insights for optimizing greenhouse cherry tomatoes cultivation.

Morphological and molecular characterization of some Chrysanthemum (Dendranthema grandiflora) cultivars

The diversity and genetic relationships among seven commercial chrysanthemum cultivars were analyzed using morphological and molecular markers. Vegetative growth, flowering, flower yield, and flower quality parameters were evaluated to assess genetic variability across the cultivars. Cultivars Crystal Red, Kodiack, and Crystal White exhibited superior vegetative growth, while Abrun, Crystal Red, and Kodiack displayed better flowering characteristics, particularly in terms of the number of inflorescences per plant and mass of colored flowering. Crystal White, Coca Bleach, and Crystal Red cultivars demonstrated the highest inflorescence stalk length, while cvs. Crystal Red, Crystal Yellow, Crystal Pink, and Kodiack Yellow recorded the maximum number of ray floret inflorescences. Other quality parameters such as inflorescence diameter and ray floret length were found to be optimal in Kodiack, Crystal White, Crystal Pink, Coca Bleach, and Crystal Yellow cultivars. Simple Sequence Repeat (SSR) markers were employed to distinguish and identify standard-type chrysanthemum cultivars, utilizing twelve SSR markers from the chrysanthemum SSR database. The results suggest that these SSR markers hold promise for identifying additional chrysanthemum cultivar types and assessing genetic relationships among them. Association studies combining morphological and molecular data offer a valuable approach to identifying informative markers for plant breeding purposes.

Pollination‐related plant traits under environmental changes: Seasonal and daily mismatches produce temporal constraints

Abstract Pollination is a key tenet of ecosystem sustainability and food security, but it is threatened by climate change. While many studies investigated the response of plant‐pollination traits to temperature, few attempted multifactorial and integrative approaches with multiple floral traits. We determined which plant‐pollination traits were disrupted by environmental changes and the consequence for plant fitness. We focused on the thermogenic plant, Arum italicum, which relies on floral scent and heat production to attract its pollinators with a deceptive strategy. In a field mesocosm, we measured the response of floral phenology, thermogenesis traits, scent and plant fitness to experimental changes in shade level, water supply and soil temperature. In the laboratory, we exposed plants to extreme heat to determine the thermoregulation ability at high temperatures. Plant fitness decreased dramatically in response to soil warming and the level of shade. While both factors caused a lower number of inflorescences, soil warming was mostly responsible for the crash in number of fruits. The plant traits related to thermogenesis and scent were relatively resilient to the environmental changes in the mesocosm and were unlikely to produce the observed decrease in plant fitness. First, environmental changes only weakly modified the scent composition. Second, the appendix regulated its maximal temperature almost perfectly, while stamen regulated imperfectly. In the laboratory experiment, the appendix maintained a thermal gradient supposedly to improve scent emission while stamen became cooler than ambient air, possibly preventing the pollinators from overheating within the floral chamber. By contrast, the phenology of flowering was drastically modified. Flowers appeared earlier in the season in response to soil warming (by 39 days) or absence of shade (by 19 days). At the daily scale, flowering hour did not change across the season resulting in plants flowering before sunset late in the season and before the pollinator activity window (mostly nocturnal). The strong shift observed in the flowering period may induce a temporal mismatch with this pollinator both early and late in the season when the insects may not be active so early in the spring and during daytime, respectively, thereby altering plant fitness. Read the free Plain Language Summary for this article on the Journal blog.

Seasonal Climatic Variation and Flowering Intensity of Garcinia kola (Heckel) in a Humid Forest Plantation

Aim of study: The study designed to assess seasonal climatic variation and flowering intensity in G. kola in a humid forest plantation. Area of study: The study was conducted in the mono-plantation of Garcinia kola in the Swamp Forest Research station of the Forestry Research Institute of Nigeria, Onne, Rivers state, Nigeria. The plantation consists of 103 trees at 5×5m spacing. Material and methods: Climatic data were sourced from meteoblue.com. Flowering intensity was determined by the estimation of the total flower production per tree: total number of flower buds per inflorescence was determined by visual counting and then extrapolated for the total number of inflorescences per twig, total number of twigs per branch and total number of branches per tree to determine the average flowering intensity per tree. A total of 9 trees and twenty-five inflorescences per tree, were sampled. Data was analysed using covariance and analysis of variance. Main results: Rainfall, wind speed, and flowering intensity varied significantly (p ≤ 0.05) between seasons; seasonal rainfall variation influence on flowering intensity varied with tree gender. Research highlights: Rainfall is the flowering cue of the plantation; we recommend that farmers target low to moderate rainfall seasons for high fruit and seed yields.

Impact of rising CO2 and temperature on grass phenology, physiology, and pollen release patterns in northern latitudes

Climate change has complex effects on vegetation, including native grasses and those used as fodder plants. Like many other plant species, grasses respond to climate change by altering their phenology and physiological behavior, leading to changes e.g. in growth, reproduction and metabolic processes. Our study is the first to explore how Phleum pratense and Alopecurus pratensis respond to rising CO2 and temperatures projected for northern latitudes for two growing seasons. We investigated growth, phenology, pollen release, and physiological parameters in plants cultivated under these conditions, simulated within environmentally controlled chambers.Treatment with elevated temperature reduced the number of generative tillers and, consequently, decreased both the number of inflorescences and the season pollen integrals. Pollen release from P. pratense started up to 17 days earlier, and the daily peak concentration of released pollen was observed 1–2 h earlier in chambers with elevated temperatures when compared to the present climate conditions. Similar effects were noted in A. pratensis. Elevated CO2 (EC) increased net photosynthesis of P. pratense, but this effect was reduced under elevated temperature (ET), suggesting an antagonistic interaction. In A. pratensis, both elevated CO2 and temperature had an additive effect on increasing net photosynthesis, with the highest rate observed under the combined ETEC treatment. The elevated temperature or CO2 did not affect the plant biomass.Our findings propose that the rising temperatures in northern latitudes decrease the flowering of studied grasses and shift the seasonal and daily start of the pollen release. Changes in tiller proportions, reduced pollen integrals, and fewer inflorescences suggest that a warmer climate may negatively impact reproductive success, ecological fitness, and allergenic burden of these grasses.

Changes in anatomical structure and cell wall composition during male inflorescence development of Castanea mollissima

The Chinese chestnut ( Castanea mollissima Blume) is a dioecious plant in which the number of male inflorescences far exceeds that of female inflorescences. Therefore, it is of interest to study the differentiation of male flowers in C. mollissima. In this study, the male inflorescences of “Yanshanhongli” C. mollissima were observed. Then, the main components of the cell wall were stained by fluorescence and immunofluorescence labeling techniques to examine the changes in cell wall components. The results showed that the development of the male inflorescence of C. mollissima had different transverse elongation and longitudinal elongation. In addition, the development of male inflorescences and anthers were divided into five and four major stages, respectively, according to the microstructural changes. Immunostaining indicated that the fluorescence intensity of cellulose increased with the development of male inflorescences of C. mollissima. The fluorescence intensity of low-esterified homogalacturonan (HG) was stronger in the early stage, while the fluorescence intensity of high-esterified HG was stronger thereafter. This research provides new insights into the changes in cell wall components during the growth and development of male inflorescences of C. mollissima and important clues for exploring the growth and development mechanism of male inflorescences of C. mollissima.

Plant growth and physiological responses of the invasive plant Acmella radicans to contrasting light and soil water conditions

Acmella radicans (Jacquin) R.K. Jansen is a new invasive species record for Yunnan Province, China, as of 2017 and little is known about its invasion mechanisms. To better understand its invasive strategies, we investigated the growth, physiological and soil nutrient use parameters of the invader under combined conditions of light (25%, 50%, 75%, and 100% of light availability) and soil water content (full, high, medium, and low soil water content) in the glasshouse. The results showed that light level, soil water content and their interaction had a significant effect on all plant morphological, physiological and soil nutrient parameters for A. radicans (P < 0.05). For the most part, plant height, total branch length, leafstalk length, leaf area, inflorescence number, seed number, leaf biomass, stem biomass, aboveground biomass, and total biomass of A. radicans were significantly increased with increased shading rate and soil water content and were generally greater at intermediate light levels and intermediate to high soil water levels. Under high-irradiance conditions, the chlorophyll content was greatly reduced compared to other treatments. We also observed that leafstalk length, leaf area, Pn, chlorophyll a, and chlorophyll b of A. radicans were markedly increased with increased shading rate and soil water content, and were generally highest under intermediate irradiance and soil water conditions, but many plant physiological parameters also exhibited relatively high values under waterlogging conditions. The concentrations of organic matter, available N and available K of A. radicans soils at high-irradiance and full-high soil water content treatments and medium-irradiance and high-medium soil water content treatments were often less than those of other treatments indicated that hypothetically soil absorption was increased by moderate shading and high soil water. This was the first study demonstrating that A. radicans thrives best under moderate light conditions in combination with high soil water. Furthermore, we surmised that its higher phenotypic and physiological plasticity contributes to its invasion success.

Flowering phenology patterns promotes pollination facilitation in coexisting Anthurium species from a mountain forest in Colombia

AbstractCo-flowering congeneric plant species may either experience competition for the services of shared pollinators or facilitation when together, they attract a higher number and diversity of pollinators. In this study, we evaluate whether temporal segregation in flowering time and temporal partition of shared pollinators operate among sympatric Anthurium species as mechanisms to reduce competition to attract potential pollinators. We investigated flowering phenology, the intra-e interspecific synchrony, and the composition of the flower visitor community of seven coexisting Anthurium species biweekly for a whole year in Native and Pine forests. We also analyzed the structure of Anthurium -flower visitor networks and the functional role of species. Flowering was continuous thorough the year for most Anthurium species, but their flowering peaks were segregated significantly in time. Although the flowering periods of these species overlapped, flower visitor communities were very dissimilar among Anthurium species, sharing only a tiny fraction of insects that function as connectors among species in the network. The partition of potential pollinators in a fine temporal scale occurred through the rewiring of shared flower visitors to the most abundant flowering Anthurium species. On the other hand, a high number of inflorescences attracted larger abundance and richness of insect visitors. Facilitation occurred almost throughout the year, while competition occurred during the flowering peak, where a particular species was the best competitor increasing the constancy of pollinators. This study highlights the role of facilitation and competition as mechanisms that together shape the use of potential pollinator resources between sympatric congeneric plant species.

Polyamine oxidase induces flower formation by promoting spermidine and ABA accumulation in cherry (Cerasus pseudocerasus Lindl.)

Polyamines are important small molecules that play a crucial in flower formation in plants. Polyamine oxidases (PAOs) have a significant function in regulating flower development by influencing polyamine homeostasis. Treatment with exogenous Spd resulted in a significant increase in the Spd content in cherry flower buds, which was accompanied by an increase in abscisic acid (ABA) levels and a decrease in gibberellin (GA) levels, as well as a notable rise in the expression of genes associated with flower formation. Polyamine oxidases are essential for maintaining endogenous polyamine homeostasis. Based on the sweet cherry genome and the ‘Manaohong’ cherry transcriptome data, four polyamine metabolism enzyme genes (CpPAO1/2/3/4) were identified. Sequence comparisons of PAO proteins revealed a high degree of sequence similarity between ‘Manaohong’ cherry and sweet cherry, with only a single amino acid variation. Phylogenetic analysis classified CpPAOs into three subclasses. The expression patterns of CpPAOs were significantly tissue-specific, exhibiting higher levels of expression in flowers and young leaves. Exogenous Spd significantly increased the expression abundance of CpPAOs, as well as ABA-related and flower-forming genes. The function of CpPAO2 was subsequently verified through genetic transformation, which demonstrated that the expression levels of ABA synthesis, signal transduction genes, and flower formation genes were substantially elevated in CpPAO2 transgenic lines. These transgenic lines exhibited earlier flowering and a greater number of inflorescences compared to wild type (WT). Yeast single-hybrid and dual-luciferase assays revealed that CpABF5 binds to the promoter of CpSOC1, promoting its expression. Collectively, these results indicated that exogenous Spd increases the content of Spd and Spm while enhancing ABA levels by promoting the transcript level of CpNCEDs in flower buds, thereby facilitating flower formation through the CpABF5-CpSOC1 pathway.

ЭФФЕКТИВНОСТЬ ИСПОЛЬЗОВАНИЯ НОВЫХ МОРФОБИОТИПОВ ГРЕЧИХИ В СЕЛЕКЦИИ ДЛЯ ЗАСУШЛИВЫХ УСЛОВИЙ СРЕДНЕГО ПОВОЛЖЬЯ

The research was carried out to evaluate the effectiveness of using fasciated buckwheat morphobiotypes in the breeding process when creating varieties for the conditions of the Middle Volga region. The single-factor experiment was laid in 2018-2023 on gray forest soils of the Republic of Tatarstan. The soil of the experimental plot contained 3.2...4.4% humus (according to Tyurin), 110...123 mg/kg of potassium and 145...377 mg/kg of phosphorus (according to Kirsanov), pH - 5.3...6.6. The objects of the study were Batyr variety, which in plant habit corresponds to “Krasnostreletskiy” variety, Yashlek variety and the hybrid population of K-990, with a predominance of forms with fasciations of the stem and generative zone in the population. The inclusion of fasciated genotypes with reduced branching in hybrid populations forms a compact plant habit, compared to the “Krasnostreletskiy” variety, due to a decrease in plant height by 5.6...9.1%, a 1.3...1.6 times reduction in the number of laterals first order branches. At the same time, due to an increase in the number of inflorescences on the main stem by 25...30%, the productivity of the plant increases by 1.2 times. The grain yield of the hybrid population K-990 was the highest in both unfavorable and favorable years (1.68 t/ha and 2.17 t/ha, respectively). As for Batyr variety, it directly depended on the amount of precipitation that fell during the interphase period “the beginning of fruit formation - the beginning of fruit browning” (r = 0.77) and had a strong inverse relationship with the average daily temperature during the period of grain ripening (r = -0.77). The productivity and grain size of Yashlek variety depended on average daily temperatures, while in the hybrid population K-990 there was a direct strong relationship between the yield and the amount of precipitation that fell in the initial growing season (r = 0.93).

Reproductive strategies in the persistence of polymorph clover, an amphicarpic species

Amphicarpic plants produce aerial and subterranean fruits on the same plant. Trifolium polymorphum Poir. is an amphicarpic legume that also reproduces vegetatively by regrowing storage roots. Because of this, resource allocation information for different reproductive strategies is of great interest. In this study, the production of aerial and subterranean seeds and storage roots was evaluated in populations of T. polymorphum. The Pinheiro Machado and Eldorado do Sul populations produced on average the highest (165.50) and lowest (61.87) number of inflorescences per plant, respectively. Total aerial seed production did not differ between populations. Aerial flowers produced more seeds than subterranean flowers. There were positive correlations between number of inflorescences and total aerial seeds (r = 0.73), the number of subterranean legumes and total subterranean seeds (0.94) and between number and weight of storage roots (r = 0.83). Amphicarpy associated with vegetative reproduction is an important strategy for the persistence and increase frequency of T. polymorphum in the natural pastures of the Rio Grande do Sul, where intense grazing and trampling can destroy periodically the aerial part of the plants.

Diversity of ecotypes of five species of ryegrass from Northwestern Spain by phenotypic traits and microsatellites

BackgroundThe Agricultural Research Centre of Mabegondo (Xunta de Galicia, A Coruña, Spain) conserves one of the most important collections of phytogenetic resources of ecotypes and natural populations of grassland species from northwestern Spain, among them populations of ryegrass (Lolium spp.), one of the most cultivated forage grasses in the world. The objective of the present study was to evaluate the diversity among commercial cultivars and natural ryegrass populations with phenotypic traits and molecular markers.ResultsEleven polymorphic microsatellites loci were used to analyze 58 ecotypes and 10 cultivars (680 DNA samples in total) differentiating 673 genotypes. Two main groups were detected by the Structure analysis, one related to Lolium perenne and a second to Lolium multiflorum. The first group showed two subgroups and the second three. The cluster of L. multiflorum showed two subgroups not related with the third cluster including commercial varieties, one from the Canary Islands (with Lolium rigidum included) and a second one from northwestern Spain, which presented specific agromorphological characteristics, such as lower FES (number of days from 1 January, when three heads per plant were flowering per plot), CRE (growth in flowering, in g of dry matter), and AIN (number of inflorescences per plant).ConclusionsThis is the first time that a large amount of data on ryegrass from the Iberian Peninsula has been analyzed, obtaining a clear genetic differentiation of the autochthonous varieties from the commercial varieties analyzed. In addition, the genetic structure found in the ecotypes was related to the phenotypic variation analyzed. Being of interest in the conservation of biodiversity and in obtaining better adapted varieties of ryegrasses, due to their specific phenotypic traits, such as a lower FES, CRE and AIN.

Sexual dimorphism and pollination mechanism of Zanthoxylum armatum, a vulnerable medicinally important dioecious tree

Among dioecious species, the differential strategy of resource allocation between male and female plants is depicted in their life-history traits and reproductive features. This is classified as sexual dimorphism. The strategies of resource allocation along with the habitat of these species pose an impact on their pollination mechanism and reproductive success. Zanthoxylum armatum DC (Rutaceae) is a small tree with wide economic and medicinal value. The species is naturally distributed in tropical parts of India and other countries. Due to overexploitation of natural populations in India, the species is rapidly declining. To restore the population of the species in the wild and establish commercial plantations, detailed knowledge of its reproductive biology is essential. Thus, the present study was conducted in natural population of Z. armatum growing in the union territory of Jammu and Kashmir, India. The study revealed sex-biased allocation and sexual dimorphism both in vegetative and reproductive traits. Such traits include more height and higher number of shoots, inflorescences, and flowers in male plants than in female plants. The natural populations of Z. armatum exhibit a male-biased sex ratio, and such biasness appears to be the outcome of resource allocation strategies and other demographic characteristics. Species possibly exhibit presence of ambophilous suite, i.e., a combination of wind and insect pollination in floral features. However, pollen dispersal by wind is up to limited distance, and thus wind may or may not be effective in fruit-set.

Grafting of Cannabis – The effect of the rootstock on vegetative and reproductive indices of the scion

Among the commercial cannabis varieties, some are high yielders but characterized by a relatively poor root system. Roots absorb water and minerals from the soil, enabling vegetative development that directly affects yield, as vigorous plants have more resources to support reproduction. Moreover, healthy foliage is a primary key to high assimilation rates, leading to better production of photosynthetic products, including cannabinoids and terpenes, which are the main active components of cannabis. We grafted a high-THC variety, named 'Freud Super-Ego' (FSE) onto three chemotypes of rootstocks: high-THC (T), high-CBD (C), and Balanced (B). All the rootstocks had significantly greater root biomass compared to FSE. All the grafting treatments significantly improved FSE's vegetative indices and yield. The best overall vegetative performance – height, stem circumference, number of mature leaves - was that of plants grafted onto the Balanced and high-CBD rootstocks, resulting in high yields as well. However, the greatest number of inflorescences was counted when FSE was grafted onto a high-THC rootstock. According to leaf mineral content analysis, the highest nitrogen and phosphorus levels were found in leaves of FSE grafted on the balanced rootstock. The cannabinoid content profile analysis revealed that all grafting treatments raised the THC level in FSE's inflorescences by 8–12 % in comparison to the non-grafted control, and the THC rootstock led to the highest THC level. The results indicate the importance of grafting in cannabis as a tool to increase the productivity and quality of the product.

Cytokinin and reproductive shoot architecture: bigger and better?

Cytokinin (CK) is a key plant hormone, but one whose effects are often misunderstood, partly due to reliance on older data from before the molecular genetic age of plant science. In this mini-review, we examine the role of CK in controlling the reproductive shoot architecture of flowering plants. We begin with a long overdue re-examination of the role of CK in shoot branching, and discuss the relatively paucity of genetic evidence that CK does play a major role in this process. We then examine the role of CK in determining the number of inflorescences, flowers, fruit and seed that plants initiate during reproductive development, and how these are arranged in space and time. The genetic evidence for a major role of CK in controlling these processes is much clearer, and CK has profound effects in boosting the size and number of most reproductive structures. Conversely, the attenuation of CK levels during the reproductive phase likely contributes to reduced organ size seen later in flowering, and the ultimate arrest of inflorescence meristems during end-of-flowering. We finish by discussing how this information can potentially be used to improve crop yields.

Genotypic and Phenotypic Characterization of Pseudomonas atacamensis EMP42 a PGPR Strain Obtained from the Rhizosphere of Echinocactus platyacanthus (Sweet Barrel).

Plant growth-promoting rhizobacteria (PGPR) are a group of bacteria that associate with the rhizosphere of plants; one of the most abundant bacterial genera in this ecological niche is Pseudomonas, which is constantly expanding due to the emergence of new species such as Pseudomonas atacamensis, whose discovery in 2019 has led to the characterization of several strains from different environments but taxonomically related. The objective of this work was to phenotypically and molecularly characterize P. atacamensis strain EMP42, isolated from the rhizosphere of Echinocactus platyacanthus. The strain EMP42 is able to use different substrates and reduce oxidative stress in plants. It is capable of improving growth parameters such as the number of inflorescences and the height of the aerial body of Arabidopsis thaliana, as well as the germination and seedling survival of the cacti Echinocactus platyacanthus and Astrophytum capricorne. The genetic structure of P. atacamensis EMP42 consists of a closed chromosome of 6.14 Mbp, and 61.1% GC content. It has 5572 genes, including those associated with PGPR activities, such as the trpABCDE, SAP, phoABPRU and acsABC genes, among others, and three ncRNA loci, nine regulatory regions, five complete rRNA operons and three CRISPR-Cas loci, showing phylogenomic similarities with the reference strain P. atacamensis B21-026. Therefore, this study contributes to the understanding of genomic diversity within P. atacamensis and, particularly, highlights the potential application of strain EMP42 as a PGPR.

ESTABLISHMENT OF PHENOTYPIC VARIABILITY AND CORRELATIONS OF SEED YIELD AND YIELD RELATED TRAITS IN ALFALFA (Medicago sativa L.) CLONAL PROGENIES

The aim of present study was to evaluate phenotypic variability of seed yield and yield-related traits and to establish the relationships among them at eleven alfalfa clonal progenies. The study was conducted in experimental field at Institute of Agriculture and Seed Science Obraztsov chiflik - Ruse under conditions of open pollination (polycross), from 2014 to 2016. The traits plant seed yield, plant height, generative stem number, inflorescence number, pod number, seed number and 1000-seed weight were evaluated. The factors year, genotype and year x genotype interaction had a significant influence on all morphological and generative traits. There was wide range of variability for all analized traits between progenies and over study period. PM30 progeny showed superior scores regarding all traits studied and four progenies distinguished with high phenotypic expression of seed yield, pod number, seed number and 1000-seed weight. These progenies are valuable germplasm source to be used in further breeding to develop a new synthetic alfalfa variety with stable seed yield. It was found seed yield strongly and positively correlated with plant height, seed number per pod and pod number per inflorescence, wtich suggest that selection for improving alfalfa seed yield may be performed directly through selection on these three traits.