Shoot Growth Parameters Research Articles

Impact of salt strength on in vitro propagation and rebaudioside A content in Stevia rebaudiana under semi-solid and liquid MS media.

Stevia rebaudiana (Bertoni), commonly known as stevia, is a sought-after natural sweetener, but its conventional propagation methods are slow and inefficient. This study aims to enhance the in vitro culture for stevia by investigating the impact of different Murashige and Skoog (MS) medium salt strengths and plant growth hormones on growth and rebaudioside A content. Apical bud-containing shoot segments were used as explants and cultured on various semi-solid and liquid MS media formulations, incorporating cytokinins (BAP and Kin), auxins (NAA and IAA), and different MS major salt concentrations (MS full, ½ MS, and ¼ MS). Assessments of shoot growth parameters, root formation, and HPLC analysis for rebaudioside A content were conducted. The optimal conditions for in vitro growth was found to be in the ¼ MS + Kin 3mg/L + NAA 0.1mg/L (semi-solid) medium, resulting in significantly improved shoot growth and enhanced 30.04% rebaudioside A content. Genetic fidelity of regenerated plants was confirmed using RAPD and ISSR markers. These findings offer valuable insights for optimizing in vitro propagation of stevia and potentially enhancing rebaudioside A content.

The effects of humic substances application on the phytohormone profile in Lactuca sativa L.

AbstractHumic substances (HS) are commonly employed as plant biostimulants to enhance crop yields. However, the HS mechanisms of action, as well as the differences between radicular and foliar modes of application, remain unclear. Here, we explored the changes in phytohormonal balance as possible mechanism of HS to enhance lettuce (Lactuca sativa L.) growth, and the difference between both modes of application. For this purpose, BLACKJAK®, a HS‐based product was applied as radicular (R) and foliar (F) at the concentrations (mL/L): 0.20 (R1), 0.40 (R2), 0.60 (R3), 0.80 (R4), 5.00 (F1), 7.50 (F2), 10.00 (F3), and 12.50 (F4). The experiment was performed in pots filled with vermiculite:perlite (3:1) and HS were applied three times with a periodicity of 10 days. Shoot and root growth parameters were measured. In addition, the phythormones indole‐3‐acetic acid (IAA), gibberellins (GAs), trans‐zeatine (tZ), isopentenyl adenine (iP), 1‐aminocyclopropane‐1‐carboxylic acid (ACC), abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA), were analysed by U‐HPLC‐MS. BLACKJAK® application resulted in higher shoot growth at doses R1, R2, R3, F2, and F3, whereas root biomass was increased at R2, R3, F2, F3, and F4, showing radicular better plant growth than foliar applications. Furthermore, HS changed phytohormonal balance in shoots and roots. However, it was with radicular applications, especially at R2, where phytohormonal profile was best associated with plant growth due to the increases observed in IAA, GAs, JA, SA, tZ, and decreased ABA. However, further research is needed to clarify the involvement of hormones in the growth‐promoting action of HS.

Fertigation with Nitrogen and Phosphorus Improve Plant Growth, Root Growth, and Buddability of Containerized Citrus Nursery Plants

ABSTRACT Large-scale multiplication of quality planting material is needed to meet the huge demand of planting material in fruit crops. Little information is available on the effect of fertigation on rootstock growth, budding success, and buddling growth in containerized citrus nursery. The present studies were undertaken to study the effect of eight fertigation treatments viz. control (N0P0), N60, N80, N100, N0P100, N60P100, N80P100, and N100P100 on the growth of rough lemon rootstock and subsequently budded three citrus varieties. Among the treatments, N60P100 significantly improved seedling height, diameter, leaf number, root growth, leaf area in rough lemon, Blood Red orange, Kinnow mandarin, and Daisy mandarin over the control. The stomatal conductance was higher with treatments N60, N80, N60P100, and N80P100. While higher photosynthetic rates were observed with N60P100 and N80P100, N60P100 also improved the budding success in Blood Red, Kinnow, and Daisy. Fertigation treatments increased the nutrient concentration in leaves of all the varieties. The principal component analysis revealed that plant height and diameter were positively correlated with root length, root diameter, root number, photosynthetic rate, stomatal conductance, and chlorophyll content in rough lemon. In all the varieties, the sprout length and diameter showed a positive correlation with leaf area, leaf number, root length, root diameter, fibrous root number, photosynthesis rate, stomatal conductance, and chlorophyll content. Among different treatments, N60P100 was the best treatment in improving the shoot growth, root growth, and physiological parameters of rough lemon rootstock. Besides, it also improved budding success and buddling growth in all three citrus varieties.

Evaluation of hydroponic systems for organic lettuce production in controlled environment.

Organic farming methods, including the use of organic substrates, fertilizers, pesticides, and biological control, are gaining popularity in controlled environment agriculture (CEA) due to economic benefits and environmental sustainability. However, despite several studies focusing on the preparation and evaluation of liquid organic fertilizers, none have explored the compatibility of these fertilizers with different hydroponic systems. Therefore, the objective of this study was to evaluate lettuce production using a liquid organic fertilizer under different hydroponic systems. Four distinct hydroponic methods were selected: nutrient film technique (NFT), deep water culture (DWC) (liquid culture systems), and Dutch bucket (DB), regular plastic container (RPC) (substrate-based systems). 'Green Butter' lettuce was grown using a liquid organic fertilizer (Espartan) for four weeks. Shoot growth parameters (e.g., shoot width, number of leaves, leaf area, foliar chlorophyll content, fresh weight, and dry weight) and root growth parameters (e.g., root length, fresh weight, and dry weight) were measured. The growth difference of lettuce under the DB and RPC systems was negligible, but the growth in RPC was 29% to 60% and 15% to 44% higher than the NFT and DWC systems, respectively, for shoot width, number of leaves, leaf area, shoot fresh weight and dry weight. Root parameters were nearly identical for the NFT and DWC systems but significantly lower (21% to 94%) than the substrate-based DB and RPC systems. Although lettuce grown in the NFT system showed the least growth, its mineral content in the leaf tissue was comparable or sometimes higher than that of substrate-based hydroponic systems. In conclusion, the tested liquid organic fertilizer is suitable for substrate-based hydroponic systems; however, further evaluation of different liquid organic fertilizers, and crop species is required.

Salicylic acid and iron-oxide nanoparticles improved the growth and productivity of ajowan under salt stress

Two factorial experiments with randomized complete block design in three replicates were conducted in a greenhouse at the University of Tabriz to investigate the individual and combined effects of SA and Fe2O3-NPs spray (1 mM and 3 mM, respectively) on cations contents, root and shoot growth, seed filling and yield parameters of salt-stressed ajowan plants (0, 4, 8 and 12 dS m-1 NaCl; as non-saline and low, moderate and high salinities, respectively). Salt stress enhanced Na+ contents and reduced K+ and Ca2+ contents, and K+/Na+ and Ca2+/Na+ ratios, leading to a reduction in root and shoot growth, particularly under high salinity. Reduction in plant growth parameters under salt stress had a negative impact on yield components and seed yield of ajowan. These deleterious impacts of salinity on plants were largely overcome by foliar treatments, particularly by SA + Fe2O3-NPs. The improvement of seed yield by these treatments was highly correlated with enhanced root and shoot growth, seeds per plant, and 1000-seed weight, especially under moderate and high salinities. Thus, the simultaneous application of SA and Fe2O3-NPs was the best foliar treatment for enhancing the growth and productivity of ajowan plants under normal and saline conditions.

Unlocking the diversity and plant‐growth promoting potential of the bulk soil bacteria associated with the Saharan tree Vachellia tortilis subsp. raddiana

AbstractIn this study, we investigated the bacterial diversity and plant growth‐promoting (PGP) properties of bulk soil bacteria of Vachellia tortilis subsp. raddiana collected from the Taidalt and Amazloug nature preserves area in southern Morocco. Using repetitive extragenic palindromic polymerase chain reaction fingerprinting and 16S rDNA sequencing, 93 strains were identified. They belonged mainly to the genera Bacillus and Peribacillus. In vitro tests for PGP traits showed high levels of activity for strains belonging to the genera Bacillus and Pseudomonas. It was relevant that several Bacillus strains produced auxin (maximum amount 262.61 µg mL−1 for Bacillus sp. LMR1097), solubilized phosphate (maximum amount 22.10 µg mL−1), or produced siderophores, while three strains were able to fix atmospheric nitrogen (LMR1145, LMR1013, and LMR1015). Inoculation of V. tortilis subsp. raddiana plants with selected bacterial strains (LMR881 and LMR1097) increased shoot and root growth parameters. The strain Pantoea sp. LMR881 had the highest mean values for shoot and root length (24.60–14.80 cm) and shoot dry weight (1.31 g), whereas Bacillus sp. LMR1097 showed the lowest mean shoot dry weight. Overall, these results highlight the potential of using selected native bacterial inoculants for improving growth of candidate tree plants to be used in restoration programs of arid degraded areas.

The Effect Of Shoot Cuttings And Vermiwash Concentration On Orchid Growth (Onchidium sphacelatum Lindl.) Aeroponically

The Oncidium sphacelatum orchid, commonly propagated vegetatively through pseudobulb separation, presents opportunities for further research into propagation methods and organic fertilizer application. This study, conducted in Batu City, aimed to explore the interaction between vermiwash concentration and shoot number on aeroponically cultivated Orchid sphacelatum Lind cuttings, as well as individual treatment effects. Employing a factorial RKLT design with shoot number (one or two) and vermiwash concentration (100, 200, or 300 ml/L) as factors, the study evaluated plant height, leaf count, stem length, shoot length, root count, and root length as variables. Data analysis involved ANOVA and BNJ tests. Results revealed that cuttings with two shoots and a 200 ml/L vermiwash concentration promoted optimal leaf growth. The number of shoots influenced shoot length, with two shoots demonstrating superior growth compared to single shoot cuttings. Interestingly, vermiwash concentration did not significantly impact shoot growth parameters, indicating that its effects may be limited in this context. This study sheds light on the potential benefits of using vermiwash in orchid cultivation, particularly in enhancing leaf growth when combined with multiple shoot cuttings. However, further investigation is needed to understand the nuanced effects of vermiwash on other growth aspects and its interaction with different propagation methods.Overall, the findings contribute to the optimization of orchid propagation techniques, providing valuable insights for orchid growers seeking to enhance plant growth and productivity sustainably. Further research could delve deeper into the mechanisms underlying the observed effects and explore additional variables to refine cultivation practices for Oncidium sphacelatum orchids.

Unveiling the silver lining: examining the effects of biogenic silver nanoparticles on the growth dynamics of in vitro olive shoots

The current study aimed to evaluate the effects of biogenic silver nanoparticles (AgNPs) on growth behavior and leaf anatomy of in vitro growing shoots of ‘Picual’ and ‘Dolce’ olive cultivars. Biosynthesis of AgNPs was carried out using the cell-free filtrate of Fusarium oxysporum. The dimension and shape of the synthesized AgNPs have been analyzed using spectroscopy and topography analysis tools, confirming that the biosynthesis of AgNPs is a crystalline nanostructure with an average particle size of 37 nm. The shoots of the selected olive cultivars were cultured on Rugini olive medium-supplemented AgNPs at 0, 10, 20, and 30mg L− 1. The effect of genotypes on shoot multiplication was significant, ‘Picual’ recorded higher values of shoot growth parameters compared with ‘Dolce’ cultivar. Adding AgNPs to the culture medium significantly affected the growth of in vitro olive shoots. AgNPs at 20 and 30mg L− 1 produced higher values of the number of shoots, shoot length, and leaf number of Picual cv. compared with the control treatments, but the higher AgNPs concentration harmed the growth parameters of Dolce cv. and recorded lower growth values compared with the lower concentration (10mg L− 1). AgNPs had a significant effect on leaf morphology and their anatomical structure. The current results showed that the stimulatory effect of AgNPs on shoot growth of in vitro olive shoots is highly dependent on plant genotype and nanoparticle concentration.

Shoot Growth Parameters of Potato Seedlings are Determined by Light and Temperature Conditions

Raising quality hybrid potato true seedlings — derived from hybrid true potato seeds (TPS) — for field transplanting is a critical aspect contributing to the success in cultivating field-transplanted hybrid potato seedling-based crops. Various critical seedling vigour attributes must be defined and enhanced to improve plant performance as well as plant response and adaptation to field conditions after field transplanting. Moreover, additional attributes besides leaf number and stem length should be defined to design selection criteria for “transplantability” of potato seedlings. To assess these attributes and their robustness under different environmental conditions, seedlings of hybrid genotypes were raised under contrasting daylengths, light intensities and temperature regimes, and combinations of these factors, and the effects of these factors (or factor combinations) on seedling vigour and its attributes were quantified. Increased light intensity and daylight integral (DLI) enhanced leaf parameters and increased biomass under long-day conditions, but seedlings did not show conclusive responses under short-day conditions in most attributes. Higher temperatures increased biomass and constant day and night temperatures enhanced compaction of shoot architecture as did higher light intensities — to a greater extent. These results highlight additional seedling vigour attributes including leaf area parameters and seedling biomass which should be utilised to determine “transplantability” of hybrid potato seedlings. Additionally, the results provide a starting point for further research on optimising hybrid seedling production for field transplanting.

Successful Grafting of Two Indonesian Clones of Piper nigrum L. with P. colubrinum Link.: Effects of IBA and NAA on Rooting and Effects of BA on Grafting

<p>This study aimed to investigate the effects of auxin types and their concentrations on rooting of the rootstock cuttings and BA on grafting. First, IBA, NAA or IBA+NAA, each at 0, 1000, 2000, and 3000 ppm were used as treatments to study rooting of <em>P</em><em>iper colubrinum</em>. In the second experiment, BA (0 and 50 ppm) was applied to <em>P. nigrum</em> scion clones of Natar-1 and Petaling-2, before being grafted to the rootstocks. Results showed, that all types of auxins (IBA, NAA or IBA+NAA) induced rooting and shoot growth, and the increase of auxin concentrations led to the increase of rooting. However, their effectiveness was different. NAA and IBA+NAA were superior to IBA, and at 2000 ppm, IBA+NAA resulted in the best plant growth, as indicated by higher values of both rooting and shoot growth parameters. Compared to control, BA treatment on scions resulted in higher grafting success (80% vs. 93%) for Natar-1, and (73% vs.100%) for Petaling-2 clones. BA treatment on scions also induced more calluses in the graft union and better shoot growth. To our knowledge, this is the first report on the use of BA to increase success of grafting between <em>P. nigrum</em> and<em> P. </em><em>colubrinum</em>.</p>

The impact of dynamic meteorological conditions in the ATU Gagauzia on the growth and development of grapevines

The southern region of the Republic of Moldova, specifically ATU Gagauzia, offers highly favourable conditions for cultivating diverse grape varieties with multiple harvest utilization options, including wine, brandy, juices, and fresh or dried consumption. Grapevines, adaptable yet sensitive to environmental changes, were the focus of our analysis regarding meteorological fluctuations' impact on the growth of grape shoots and the development of leaf surfaces. Our research aimed to assess the changes in meteorological conditions in the ATU Gagauzia and their impact on the growth dynamics of grapevine shoots, as well as the development of leaf surfaces, yields of introduced clones of European selection. Temperature and precipitation levels significantly impacted the growth of grapevine shoots and the development of shoot leaf surfaces, vines, and vineyards. Aligning these factors with the requirements of grapevines optimizes the growth and development of the annual grapevine growth. Meteorological conditions varied across study years, benefiting grapevine growth in certain years (2017-2018) but proving less favourable in others due (2019-2020) to reduced precipitation and higher temperatures during the growing season. The research findings indicate that the growth parameters of shoots, the development of leaf surfaces, LAI, and yield of clone R5 Cabernet Sauvignon in the agroecological conditions of ATU Gagauzia depend on both the rootstock variety and the fluctuating meteorological conditions. It has been established that when grafting the investigated clone onto RхR 101-14, growth indicators, the development of annual shoot growth, leaf surface and yields were lower compared to the vines grafted onto BxR Kober 5BB. This difference was evident throughout the entire research period but was particularly pronounced during periods of adverse meteorological conditions. Specifically, in 2020, these indicators decreased by 1.1-1.2 times compared to the experimental option BxR Kober 5BB.

Varietal Response of Cola Species to Fertilizer Application on Field Establishment, Growth, Development and Canopy Characteristics

Responses of Cola nitida and Cola acuminata to NPK and Super-gro fertilizers on seedling development, field establishment, and canopy characteristics were investigated in 2019-2020. Seedlings of the two Cola species were transplanted as a randomized complete block design with three replications on the field. Fertilizer treatments were imposed and the shoot and root growth parameters of the cola were monitored for two growing seasons. From the results, application of NPK fertilizer positively enhanced leaf and stem branch development as well as canopy features of the cola species compared to super-gro and the control treatments. Seedling height and leaf area development were higher significantly through application of super-gro compared with other treatments. Seedlings establishment were enhances by the application of super-gro over NPK and the control plots. Leaf production, stem branch number, stem girth development and leaf area development in Cola nitida were significantly higher than in Cola acuminata. Cola acuminata seedlings height were significantly higher compare to Cola nitida during the two growing seasons. The interactions of fertilizers and crop species reveals that NPK and super–gro application significantly influenced leaf production in C acuminata over C nitida. Stem branch production in C acuminata was better significantly under the treatment of NPK than that of C nitida under super-gro and the control plots. Canopy development was significantly higher under Cola acuminata treated with Super-gro followed by NPK with the control having the least. Canopy development in Cola nitida were significantly lower compared with Cola acuminata across the fertilizer treatments.

Improvement of rooting and growth in kiwifruit (Actinidia deliciosa) cuttings with organic biostimulants

Seaweed extracts have shown profoundly positive effects on crop growth, quality and reproduction in diverse agricultural and horticultural crops. Seaweed extracts can be used to promote the rooting and growth of cuttings in perennial fruit species like kiwifruit (Actinidia deliciosa). In this study, the cuttings were treated with 1, 5, 10 and 50% solutions of G Sap (Gracilaria edulis), K Sap (Kappaphycus alvarezii), AN (Ascophyllum nodosum), EM (Ecklonia maxima), HA (Humic acid) and control (water) for 6 h as base dipping. Subsequently, the treatments of G Sap, K Sap, AN, EM, HA and control were repeated every 15 days for a period of six months as application of 50 ml solutions in the potted cuttings. All the treatments exhibited significant effects on the rooting percent in all the kiwifruit cultivars, namely ‘Monty’, ‘Abott’, ‘Hayward’, ‘Allison’ and ‘Bruno’ (P ≤ 0.01) as compared to the control. Shoot and root growth parameters including leaf number per cutting, number of roots per cutting, number of branches, plant height, shoot diameter, root length, root diameter and root weight were all positively increased with the application of seaweed extracts (P ≤ 0.05). Cuttings treated with seaweed extract exhibited significantly higher levels of pigments (chlorophyll a, chlorophyll b and total carotenoids), metabolites (total carbohydrates and soluble phenols) and less electrolyte leakage as compared to the control cuttings. Significant positive and negative correlations were observed between biochemical parameters combined with plant nutrient concentration. Principal component analysis (PCA) revealed that PC1 and PC2 (first two principal components) accounted for 75% of the entire variation. While, PC1 accounted for 63% of the total variation, PC2 accounted for 11% of the total variation. The leaves and the roots of kiwifruit cultivar ‘Hayward’ treated with G Sap at 10%, K Sap at 10%, AN at 10%, EM at 10%, HA at 10% exhibited higher expression of all four root promoting candidate genes (GH3-3, LBD16, LBD29 and LRP1) compared to the control. Therefore, it can be concluded that, seaweed extract and humic acid can be used as a suitable alternative to synthetic hormones for promoting the rooting and growth of kiwifruit cuttings.

Use of Liquid Culture with the ElecTIS Bioreactor for Faster Recovery of Blackberry (Rubus fruticosus L.) Shoots from Conservation at 4 °C

ElecTIS is a new single container bioreactor which does not require forced air blowing, instead making the culture material mobile and the liquid medium stationary. The timed up-and-down movement of the basket containing the shoot culture ensures periodic contact with the liquid medium positioned at the base of the container. In this study we tested for the first time its use in the recovery of blackberry shoot cultures (Rubus fruticosus L., cvs Thornfree and Chester), coming from 5 months of slow growth storage (SGS), at 4 °C and in the dark. The shoot recovery at standard culture conditions was performed on two different types of ElecTIS, i.e., one with a smaller basket (ElecTISS, 234 cm2 of culture area), and one with a large basket (ElecTISL, 336 cm2), comparing the culture in TIS (cycle of 8 min every 6 h, equal to 32 min/day) with the traditional one in a gelled medium in glass jars (500 cc). After each one of the three 4-week subcultures, the shoot growth parameters and the relative growth rate highlighted a clear superiority of ElecTIS in promoting the recovery of shoot cultures coming from SGS. The analyses of chlorophyll content and stoma functionality confirmed the superior quality of shoots cultured in the ElecTIS bioreactor, and these shoots were afterwards easily rooted and acclimatized ex vitro.

Plant growth stimulants and defense activators fail to control phony peach disease in mature peach orchards

The bacterium Xylella fastidiosa subspecies multiplex causes phony peach disease (PPD), a serious disease of peach in the southeastern United States. The current management strategy for PPD is removal of symptomatic trees, but other management options should be explored. Field efficacy trials with plant growth stimulants and plant defense activators were conducted in orchards of ‘Julyprince’ in 2021 and 2022, and ‘Springprince’ in 2021. Treatments were applied either as a foliar or root drench application once a month for three consecutive months during the growing season. Treatments included Rio, ProGibb 40SG, Maximizer, Actigard 50WG, and K-phite 7LP. In 2021, ProGibb 40SG provided increased shoot growth in both varieties, but cycle threshold (Ct) values did not suggest that any treatment affected bacterial titer. In 2022, applications were initiated one month later and no significant effects on shoot growth parameters or bacterial titer were observed among treatments. The reduction in symptoms after ProGibb 40SG application and the fact that healthy trees responded similarly indicates the growth response was due to the plant responding to the hormonal treatment, and not an effect on the pathogen, the titer of which remained similar. Thus, ProGibb 40SG may have very limited value for improving PPD tree health.

Ant13 Encodes Regulatory Factor WD40 Controlling Anthocyanin and Proanthocyanidin Synthesis in Barley (Hordeum vulgare L.)

Flavonoid compounds like anthocyanins and proanthocyanidins are important plant secondary metabolites having wide biological activities for humans. In this study, the molecular function of the Ant13 locus, which is one of the key loci governing flavonoid synthesis in barley, was determined. It was found that Ant13 encodes a WD40-type regulatory protein, which is required for transcriptional activation of a set of structural genes encoding enzymes of flavonoid biosynthesis at the leaf sheath base (colored by anthocyanins) and in grains (which accumulate proanthocyanidins). Besides its role in flavonoid biosynthesis, pleiotropic effects of this gene in plant growth were revealed. The mutants deficient in the Ant13 locus showed similar germination rates but a decreased rate of root and shoot growth and yield-related parameters in comparison to the parental cultivars. This is the seventh Ant locus (among 30) for which molecular functions in flavonoid biosynthesis regulation have been determined.

Phosphorus Use Efficiency of Leafy Brassica sp. Grown in Three Contrasting Soils: Growth, Enzyme Activity and Phosphorus Fractionation

Plant adaptations to low soil phosphorus (P) availability have been intensively studied in Brassica sp. in an attempt to identify the mechanisms involved in P uptake and utilization. The present pot experiment was conducted to evaluate the relationships between plant shoot and root growth, P uptake and use efficiency parameters, and P fractions and enzyme activity, in two species grown in three soil types. The aim of this study was to determine whether adaptation mechanisms are soil-dependent. Two kale species were grown in soils typical for coastal Croatia (terra rossa, rendzina, and fluvisol) with low P availability. Plants grown in fluvisol had the highest shoot biomass and accumulated most P, whereas plants developed the longest roots in terra rossa. Phosphatase activity differed among soils. P use efficiency differed among soils and species. Genotype IJK 17 showed better adaptation to low P availability, which was related to better uptake efficiency. In general, soils differed in inorganic and organic P fractions in rhizosphere soil, but no difference between genotypes was found. The activities of alkaline phosphatase and phosphodiesterase were negatively correlated with most organic P fractions, suggesting their function in the mineralization of soil organic P. Kale species activate different mechanisms of P uptake and utilization when grown in contrasting soil types, suggesting that specific responses to the soil type were more important than the genotypic difference.

Effect of biologically active TotalHumus® and Bacterbase on the growth ex vitro of strawberry, blueberry and hip rose microcuttings

One of the key steps in plant micropropagation is rooting and acclimatization of microcuttings. The aim of the study was to investigate the suitability of commercial biopreparations, TotalHumus® and Bacterbase, to stimulate the growth of young fruit plants derived from in vitro propagation. TotalHumus® is made from brown coal. Bacterbase is a bacterial preparation containing Bacillus velezensis and Bacillus amyloliqefaciens (Skierniewickie Microorganisms) with antifungal properties that stimulates the growth and yielding of plants. Unrooted microshoots of strawberry ‘Grandarosaʼ and highbush blueberry ‘Chandlerʼ, and rooted in vitro microcuttings of hip rose ‘Konstancinʼ were planted in a peat substrate. Three weeks after planting ex vitro, the plants were treated with the biopreparations. Four times, at two-week intervals, the plants were drenched and simultaneously sprayed with mineral fertilizer 0.2% Hydrovit (control), 0.04% TotalHumus® and 0.03% Bacterbase, which were used separately or in combinations. In hip rose and strawberry, compared to the control, similar or better growth parameters of shoots and roots were observed after the use of TotalHumus® and/or Bacterbase. The plants were characterized by the highest fresh weight, longer shoots/runners and more shoots than in the control (mineral fertilization). In strawberry, root parameters were significantly improved by TotalHumus®, and in rose by Bacterbase. The use of both TotalHumus® and Bacterbase separately or in combination significantly reduced the occurrence of symptoms of rose leaf infection with powdery mildew. The biopreparations had no effect on highbush blueberry.

An exopolysaccharide-producing novel Agrobacteriumpusense strain JAS1 isolated from snake plant enhances plant growth and soil water retention

A peculiar bacterial growth was very often noticed in leaf-initiated tissue cultures of Sansevieriatrifasciata, a succulent belonging to the Asparagaceae family. The isolate left trails of some highly viscous material on the walls of the suspension vessels or developed a thick overlay on semisolid media without adversities in plant growth. FTIR identified this substance to be an extracellular polysaccharide. Various morphological, biochemical tests, and molecular analyses using 16S rRNA, atpD, and recA genes characterized this isolate JAS1 as a novel strain of Agrobacteriumpusense. Its mucoidal growth over Murashige and Skoog media yielded enormous exopolysaccharide (7252 mg l−1), while in nutrient agar it only developed fast-growing swarms. As a qualifying plant growth-promoting bacteria, it produces significant indole-3-acetic acid (86.95 mg l−1), gibberellic acid (172.98 mg l−1), ammonia (42.66 µmol ml−1). Besides, it produces siderophores, 1-aminocyclopropane-1-carboxylicaciddeaminase, fixes nitrogen, forms biofilms, and productively solubilizes soil inorganic phosphates, and zinc. Under various treatments with JAS1, wheat and chickpea resulted in significantly enhanced shoot and root growth parameters. PGP effects of JAS1 positively enhanced plants’ physiological growth parameters reflecting significant increments in overall chlorophyll, carotenoids, proline, phenols, flavonoids, and sugar contents. In addition, the isolated strain maintained both plant and soil health under an intermittent soil drying regime, probably by both its PGP and EPS production attributes, respectively.

COMPARATIVE ANALYSIS OF THE EFFECT OF ZINC EXCESS ON THE SHOOT GROWTH OFSINAPIS ALBA AND BRASSICA JUNCEA

The effect of zinc excess on shoot growth of white mustard ( Sinapisalba ) andsareptskaya mustard ( Brassicajuncea ) was studied. Nowadays, supposed that B.juncea is a zinc hyperaccumulator – accumulating its high concentrations in the aboveground organs. In contrast, S.alba belongs to the “excluders” and accumulate the zinc mostly in the roots. It is known, that both species are able to grow on zinc-contaminated soils, but too less known about their metal tolerance. The data about their physiological reactions to excess metal influence are contradictory.In a laboratory experiment, the effect of zinc at concentration of 5 (control), 25, 50, 100, 150 and 200 mg/kg of substrate on a shoot growth parameters in S.alba cv. Radugaand B.juncea cv. Slavanka was studied. Our studies showed, that the effect of zinc on shoot growth mostly depends on the zinc concentration in the substrate as well as the plant species. Thus, zinc at concentration of 25 and 50 mg/kg had a stimulating effect on the growth of shoots of S.alba and only higher concentration of the zinc (100-200 mg/kg) led to decrease in the studied parameters. In B.juncea, even at a metal concentration of 50 mg/kg decrease in shoot height and leaf area. In concentration dependent matter the negative effect was observed. We supposed the the stronger negative effect of zinc at the studied concentrations on the shoot growth of B. juncea as a hyperaccumulator compared to S.alba is associated with a higher content of the metal in its aboveground part. Our results demonstrate the possibility of using studied varieties of S.alba and B. juncea in phytoremediation of zinc contaminated soils.