Root Dry Mass Research Articles

The Allelopathic Activity of Aqueous Extracts of Helianthus annuus L., Grown in Boreal Conditions, on Germination, Development, and Physiological Indices of Pisum sativum L.

Evaluation of the allelopathy relationship between different crops is a sensible strategy fallowing the correct use of positive effects and to avoid the disadvantageous effects among plants. This study aimed to detect the allelopathic effect of aqueous extracts of sunflower (Helianthus annuus L.), grown in a boreal climatic zone, on the growth, subsequent development, and physiological traits of pea (Pisum sativum L.). Three factors have been studied: donor plant fertilization (unfertilized and fertilized), aqueous extracts from donor plant organs (leaves and stems (L+S), heads (H) and roots (R)); four concentrations of extracts (0%, 25%, 50% and 75%). The aqueous extracts from fertilized sunflower donor plant at 25% and 50% concentration acted as potential biostimulants that stimulated pea seed germination (SG), whereas L+S and R extracts at 75% concentration from unfertilized donor plant inhibited SG, at 4 days after sowing. The aqueous extracts demonstrated a stimulating effect on above-ground and root dry mass, compared to the control. The concentration of extracts demonstrated a significant inhibitory effect on SPAD. R extract revealed the strongest allelopathic effect on physiological traits of pea. L+S and H extracts at 25% concentration had stimulating effects, while 50% and 75% concentrations showed inhibiting effects on the photosynthetic rate. The water use efficiency, stomatal conductance, and stomatal limitation were inhibited, whereas, the transpiration rate, photosynthetic water use efficiency and intercellular CO2 concentration were stimulated, with an increasing of extract concentrations, comparatively to the control.

Seleção de caracteres para programas de melhoramento genético do mamoeiro sob estresse hídrico e térmico

ABSTRACT Papaya cultivation is widespread in Brazil, particularly in the states of Bahia and Espírito Santo, where most commercial plantations are concentrated. Owing to the economic and social importance of papaya, the present study aimed to determine the explanatory variables between the genotypes of two cultivars: Golden (from the Soil group) and Tainung Nº 1 hybrid (from the Formosa group), cultivated under high temperatures and hydric stress. The genotypes containing more desirable agronomic characteristics were identified for use in plant genetic improvement programs. Principal component analysis (PCA) was applied to select the desirable genotypes for Golden and Tainung Nº 1 cultivars based on specific variables analyzed for two groups of variables; for group 1, the plant height, stem diameter, leaf length, leaf width, and leaf number were analyzed, whereas for group 2, the leaf and root dry mass, stem dry mass and fresh mass of 10 discs, fresh mass, and stem and root fresh mass were analyzed. When exposed to hydric and thermal stress, the Tainung Nº 1 cultivar outperformed the Golden cultivar for the evaluation characteristics selected for use in genetic improvement programs.

Do Stimulate® and Ascophyllum nodosum seaweed promote the morphophysiological characteristics of Cordia alliodora seedlings?

Biostimulants in native forest seedlings, when absorbed and assimilated by plants, can function as activators or inhibitors of their metabolic and physiological processes. In view of the above, the present study establishes the following research problem: Can doses of Ascophyllum nodosum seaweed extract and Stimulate® be effective in the promotion of initial growth and morphophysiological indices of Cordia alliodora seedlings? The experimental design used was completely randomized, in a 4 x 2 factorial scheme, corresponding to four doses (0, 0.2, 0.4 and 0.6 ml L-1) and two hormones (Ascophyllum nodosum and Stimulate®), with five replicates, each of which composed of five seedlings (one in each container). The morphological variables evaluated were shoot height (H), stem diameter (SD), increments in stem diameter (ΔSD) and shoot height (ΔH), shoot dry mass (SDM, g plant-1), root dry mass (RDM, g plant-1), total dry mass (TDM, g plant-1), and Dickson Quality Index (DQI). Physiological variables were: net assimilation rate (EA, g.m-2.day-1), leaf relative growth rate (RA, g.m-2.day-1), leaf area ratio (FA, m2.g-1), specific leaf area (SA, cm2.g-1) and leaf mass ratio (Fw, g.g-1). The bioregulator Ascophyllum nodosum at dose of 0.2 ml L-1 promotes increments in height (ΔH) and stem diameter (ΔSD) of Cordia alliodora seedlings. Ascophyllum nodosum at dose of 0.2 ml L-1 has positive influence on the physiological indices studied in Cordia alliodora seedlings at 120 days after transplanting. The bioregulator Stimulate® at dose of 0.6 ml L-1 is not indicated to obtain Cordia alliodora seedlings with better quality and sturdiness and shorter nursery time. The bioregulator Ascophyllum nodosum at dose of 0.2 ml L-1 is recommended to obtain increments in height (ΔH) and stem diameter (ΔSD) in Cordia alliodora seedlings

Organic fertilization and mycorrhization increase copper phytoremediation by Canavalia ensiformis in a sandy soil

Organic fertilization and mycorrhization can increase the phytoremediation of copper-contaminated soils. The time of vermicomposting alters the properties of vermicompost, which can affect copper's availability and uptake. Therefore, this study sought to evaluate the effect of different organic fertilizers and mycorrhization on copper-contaminated soil phytoremediation. The soil was contaminated with 100 mg Cu kg-1 dry soil and received mineral fertilizer (MIN), bovine manure (CM), and vermicompost produced in 45 days (V45) or 120 days (V120), all in doses equivalent to 40 mg kg-1 dry soil of phosphorus. Half of the jack bean (Canavalia ensiformis) plants were inoculated with the arbuscular mycorrhizal fungus Rhizophagus clarus. At plant flowering, the dry mass and concentrations of Cu, Zn, Mn, Ca, Mg, P, and K in the soil, solution, and plant tissue were determined, in addition to mycorrhizal colonization, nodulation, photosynthetic pigments, and oxidative stress enzyme activity. Organic fertilization increased plant growth and copper accumulation in aerial tissues. These effects were more evident with the V120, making it suitable for use in copper phytoextraction. Mycorrhization increased root and nodule dry mass, making it recommended for phytostabilization. C. ensiformis nodulation in Cu-contaminated soils depends on vermicompost fertilization and mycorrhization. Hence, the copper phytoremediation by C. ensiformis is increased by using organic fertilization and mycorrhization.

Superior salt tolerance in wild soybean (G. soja) is associated with better ion ‘exclusion’ ability from leaves and mesophyll cells than cultivated soybean genotypes (G. max)

Soybean (Glycine max) is a salt-sensitive crop. However, wild soybean (Glycine soja) is a potential source of germplasm to improve salt tolerance in G. max. This study evaluated the response of cultivated soybean (G. max cv. Bunya and Lee) and wild soybean (G. soja) to ionic components of salt stress to test the hypothesis that wild and cultivated soybean genotypes differ in leaf tissue tolerance to Na+ and/or Cl–. The soybean genotypes were subjected to NaCl, Na+ salts, and Cl– salts at 50, 75 and 100 mM, and a non-saline control to analyse the effect of salts/ions on growth, tissue ion concentrations and photosynthesis. Cryo-SEM X-ray microanalysis was used to evaluate cellular [Na], [Cl] and [K] in various cell types within leaflets. NaCl and Na+ salts reduced shoot and root dry mass more than Cl– salts in the three genotypes. Soja maintained higher photosynthetic rates (84 % of control) than Lee (70 % of control) and Bunya (60 % of control) in the 75 mM treatments. Soja had lower [Na+] in leaves and mesophyll cells than Lee and Bunya. G. soja had greater tolerance to salinity than G. max due to better ‘ion exclusion’ from leaves and photosynthetically active mesophyll cells.

Exploring the quantitative genetics of traits associated with drought tolerance and yield in Pimpinella anisum L. under different water regimes

Genetic improvement of seed yield and drought resistance could be simultaneously gained in anise when breeding for drought resistance. Improving the water use efficiency of anise is a primary objective of anise breeding programs aimed at mitigating the impacts of drought stress. This study aimed to determine the predominant mechanisms involved in drought tolerance and investigate the genetic control of associated traits with drought tolerance and higher grain yield. According to these aims, 10 half-diallel hybrids and their five parents were evaluated in both field and greenhouse lysimetric experiments under well-watered and water deficit stress conditions. The results indicated that the inheritance of grain yield is complex and affected by water deficit stress. Similar heritability and genetic architecture were detected for flowering time and percentages of photosynthate partitioned to grain (PPPG) in both well-watered and water deficit stress treatments. Significant negative genetic correlations were observed between grain yield and flowering time, root dry mass, root diameter, root volume, root number, percentages of photosynthate partitioned to shoot, and percentages of photosynthate partitioned to root. Therefore, the selection of low values of these attributes can be used to improve grain yield under drought conditions. In contrast, a positive significant genetic linkage between grain yield and PPPG, chlorophyll content, cell membrane stability, and leaf relative water content reveal selection for high values of these attributes is favored. These attributes could be used as surrogate selection criteria in the early segregating generations. The P1 parent (early ripening parent) contained key genes associated with PPPG and drought escape. It was concluded that improvement of drought tolerance and grain yield could be simultaneously achieved in anise breeding programs.

Selenium does not ease growth inhibition caused by aluminum in Schinus terebinthifolius seedlings

Aluminum (Al) toxicity is observed in several crops in the world and affects the yield of many cultures. Using beneficial elements such as selenium (Se) has been the object of studies focused on finding an alternative to mitigate the toxic effects of metals on crops. Thus, the aims of the current study were to assess the tolerance/sensitivity to Al, and Se mitigating effects on morphological, photosynthetic and biochemical variables recorded for Schinus terebinthifolius seedlings exposed to Al. Schinus terebinthifolius seedlings in hydroponics were subjected to the following Al and Se combinations added to the nutrient solution in mM: 0 Al + 0 Se; 0 Al + 0.0025 Se; 1.85 Al + 0 Se; 1.85 Al + 0.0025 Se; 3.71 Al + 0 Se and 3.71 Al + 2.5 Se. The study followed the completely randomized experimental design, with three repetitions. Al reduced the leaf area, shoot and root dry mass, root increment, as well as root length, surface area, volume and diameter. Seedlings’ photosynthetic activity decreased possibly due to the presence of Al in them; and even when Se was present, it was not able to mitigate the effects of Al. The enzymatic and non-enzymatic antioxidant system was not able to avoid the oxidative stress caused by the presence of Al, as well as the Se was not able to minimize the effects from different Al concentrations on S. terebinthifolius seedlings. Therefore, species S. terebinthifolius is sensitive to Al in hydroponic systems and Se addition, in general, did not mitigate the toxic effects from different Al concentrations.

Comparison of Hydraulic and Aeration Properties of Peat Substrates Used to Produce Containerized White Spruce Seedlings (1+0) in Forest Nurseries

The physical properties of peat substrates from eight tree nurseries were characterized to determine bulk density, air-filled porosity, saturated hydraulic conductivity, pore effectiveness, relative gas diffusivity and chemical properties. There were significant variations among nurseries both in growth of white spruce [Picea glauca (Moench) Voss] seedlings (1+0) and substrate properties. Shoot dry mass and root collar diameter were negatively correlated with air-filled porosity and saturated hydraulic conductivity, whereas root dry mass was positively correlated with bulk density. Seedling growth increased with increasing substrate bulk density up to ~0.11 g cm−3, above which value conditions may become limiting to plant performance. Our results suggest that there was no growth limitation due to restricted aeration (Ds D0−1 > 0.005 m2 s−1 m−2 s for all substrates except one) and that over-aeration reduced seedling growth under dry irrigation management.

CHEMICAL CONTROL OF Colletotrichum gloeosporioides ON SEEDLINGS OF SINGLE ASSAI PALM

Anthracnose (Colletotrichum gloeosporioides) is the main disease affecting single assai palm seedlings and, therefore, a limiting factor to the production of quality seedlings. So far, there are no fungicide recommendations for the control of C. gloeosporioides in Euterpe precatoria. Thus, this study aimed to investigate the action of fungicides, such as pyraclostrobin + fluxapyroxad, as a possible alternative for controlling anthracnose in single assai palm seedlings. The experiment was installed in the nursery at Embrapa Acre, in a randomized block design, with seven treatments (0 – 0.155 – 0.187 – 0.218 – 0.250 – 0.281 – 0.312 μl of fungicide), with four replications of five plants. Evaluations were conducted for ten months regarding seedling height, stem diameter, number of leaves, shoot dry mass, root dry mass, total dry mass, and Dickson Quality Index. A visual scale ranging from 1 to 9 was used to assess the severity of the disease. The data were submitted to analysis of variance and regression analysis. Under the study conditions, the application of the active ingredient pyraclostrobin + fluxapyroxad reduced anthracnose severity by an average of 36.94% in single assai palm, providing better quality seedlings in the nursery.

Nicotinamida e Azospirillum brasilense melhoram a qualidade de mudas de Coffea arábica

ABSTRACT The use of biostimulants in coffee seedlings can promote gains in their growth and quality. Thus, this study aimed to evaluate the growth and quality characteristics of Coffea arabica seedlings under the effect of the nicotinamide and Azospirillum brasilense application. The experimental design was randomized blocks with treatments arranged in a 5 × 2 factorial scheme, with four replicates. The treatments resulted from the use of five doses of nicotinamide (0, 30, 60, 90, and 120 mg L-1 of water) combined with the absence and presence of Azospirillum brasilense applied to Coffea arabica seedlings from Catuaí Vermelho 144 cultivar. Plant height, stem diameter, number of leaves, leaf area, shoot dry mass, root dry mass, plant height:stem diameter ratio, shoot:root dry mass ratio, plant height:shoot dry mass ratio, and Dickson quality index were evaluated. The combined or isolated use of A. brasilense and nicotinamide, up to a dose of 33.5 mg L-1, increased the biometric characteristics and dry mass accumulation. However, using nicotinamide doses between 30 and 61.8 g L-1 increased the quality of Coffea arabica seedlings. The synergistic effect of the use of A. brasilense and nicotinamide was verified for the growth and quality of Coffea arabica seedlings.

English

In vitro cultivation is widely used for micropropagation of several plant species; however, the increase in the gas concentration, such as ethylene gas, inside the growth vials can cause physiological changes. Thus, 4 experiments were carried out at the Federal University of Minas Gerais to evaluate the biochar use from sugarcane bagasse in vials with or without caps with porous membrane in the in vitro growing of pitaya (Hylocereus undatus Haw) (experiment 1) and strawberry (Fragaria x ananassa Duch) (experiment 2) and evaluating in combination of the use of biochar from sugarcane bagasse and AgNO3 in the in vitro growing of pitaya (experiment 3) and strawberry (experiment 4). The types of caps did not affect the growth and number of pitaya and strawberry; however, using caps with porous membrane obtained more magnificent roots dry matter yield. The addition of 4 g L-1 of biochar, regardless of cap type, favored the pitaya and strawberry roots' growth and development. AgNO3 alone contributed to the higher length and dry mass of pitaya roots and greater dry mass of strawberry roots. Adding biochar decreases the AgNO3 effects in vitro culture. Biochar is an alternative to improve the in vitro environment of plant species. Key words: Fragaria x ananassa Duch, Hylocereus undatus Haw, Tissue culture, AgNO3, gas exchange.

Growth and development of Paspalum virgatum L.

The objective of the work was to evaluate the growth and development of the razor-blade grass (Paspalum virgatum L.). The experimental design was a randomized complete block design with 17 treatments, and the growth evaluations were performed at 20, 27, 34, 41, 48, 55, 62, 69, 76, 83, 90, 97, 104, 111, 118, 125, 132 days after sowing (DAS) and five replications, considering as sowing date the day the seeds were placed in the plastic boxes. The evaluated characteristics were: total dry mass (Mt), shoot dry mass (Ma) and dry mass of roots (Mr), number of leaves and number of tillers per plant. The quantitative variables related to plant growth were analyzed by applying the F test on the analysis of variance followed by non-linear log-logistic regressions, with the objective of modeling the data in the form of equations. The razor-blade grass (Paspalum virgatum L.) is a weed with slow initial development and growth, but with high dry mass production at the end of the cycle.

Arbuscular mycorrhizal fungi provides enhanced development and reduced mite incidence in Phaseolus vulgaris L. by direct root colonization and via the common mycorrhizal network

Arbuscular mycorrhizal fungi (AMF) are important to agriculture due to positive effects on development and resistance to attack by herbivores in agricultural crops. AMF can affect a single plant by directly colonizing its roots and two or more plants through the common mycorrhizal network (CMN). This work aimed to analyze the influence of AMF on the development of Phaseolus vulgaris and on the incidence of the mite Tetranychus urticae in bean plants colonized directly by mycorrhizal propagules or linked by the CMN. The root systems of two plants were either separated by an impassable barrier so that one or both plants could be colonized by the mycorrhizal propagules without forming the RMC, or they were separated by a steel mesh that allowed the outer hyphae of the AMF on the roots of one of the plants to colonize the non-mycorrhizal roots of the other plant and form the RMC. The mite infestation occurred first on one plant and at the end of the experiment on all. Percentage of mycorrhizal colonization, dry mass of aerial part and roots, number of reproductive structures and mite incidence were analyzed. The colonization by the mycorrhizal propagules and the hyphae of the MRC positively influenced the vegetative and reproductive development of P. vulgaris and resulted in lower mite incidence on the leaflets of the plants. Therefore, direct colonization of P. vulgaris roots by AMFs and via CMR improves plant development and resistance of bean plants to T. urticae mite infestation.

ROOT SYSTEM ARCHITECTURE AND STEM TRAITS OF BREAD WHEAT SEEDLINGS UNDER CONTRASTING WATER REGIMES

Differential response of bread wheat seedlings to contrasting water regimes can be used to determine traits related to drought tolerance. The F1 offspring from eight crosses and 11 selected parental genotypes were simultaneously grown in hydroponic cultivation-polyethylene glycol (PEG) induced drought stress vs. control conditions. Criteria for selection of maternal and paternal genotypes were desirable traits in terms of increased tolerance to drought: longer stem length, longer primary root, large number of seminal roots, large root dry mass and stem dry mass, beginning of root branching at the greatest possible distance from beginning of the root, contrasting angle of seminal roots. The traits were measured on 14 day old seedlings: primary root length (PRL), distance to the first branch on the primary root (DFBR), number of seminal roots (NSR), total seminal root length (TSRL), angle of seminal roots (ASR), stem length (SL), root dry mass (RDM), stem dry mass (SDM), and the ratio of root dry mass to stem dry mass (RDM/SDM). Drought stress led to a decrease in the mean values of all root and stem traits by 11% on average, except for RDM/SDM which was increased. The most sensitive trait to drought stress was DFBR (25% reduction), causing root systems to branch at a shallower depth. In conditions of induced drought stress, the strongest statistically significant correlation was found among RDM and RDM/SDM (r = 0.794), SL and ASR (r = 0.708), RDM and TSRL (r = 0.673). The stress tolerance index had the strongest positive correlation with the SDM, PRL, TSRL, SL, and the stress susceptibility index with the NSR. The highest heterosis mean value was observed for PRL (24.6%) and for SL (15.6%) under drought stress. The different directions of average heterosis in induced drought stress vs. control conditions were observed for DFBR, RDM, and SDM, indicating differential traits to account for when planning breeding bread wheat for drought tolerance. Selected traits as criteria for selection and favorable combinations can be incorporated into pre-breeding and breeding schemes, directly or indirectly, aiming to achieve drought tolerance. Keywords: bread wheat; drought stress; heterosis; hydroponics; root system architecture.

LANZA® Tedera Is Strongly Suppressed by Competition from Lolium multiflorum and Is Best Adapted to Light-Textured Soils

Bituminaria bituminosa var. albomarginata, known as Tedera, is a promising forage for Mediterranean climates. An improved variety named LANZA® has been developed. Previous research suggests that soil water saturation in heavy-textured soils might affect its initial development. Competition from grasses could also compromise its successful establishment and persistence. We investigated the effects of soils with contrasting textures (loamy sand vs. clay) with a high soil water content and the competition from Lolium multiflorum on the development of LANZA® in a pot experiment. Dry mass (DM) production of LANZA® was strongly reduced (86%) when grown with L. multiflorum. LANZA® shoot DM was 60% higher than the total shoot DM production of the mixture of LANZA® and L. multiflorum. Soil type did not significantly affect the shoot and total root DM. However, a 44% reduction of the DM of thin roots and slower development was observed in clay soils, which may indicate a preference for light-textured soils. This study provides further information on the factors limiting the establishment and persistence of LANZA®. Future research should confirm these results at field scale and investigate measures aimed at reducing early competition in monocultures and functional complementarity with partner species in mixtures to successfully establish LANZA®.

Potential Use of Two Forest Species (Salix alba and Casuarina glauca) in the Rhizofiltration of Heavy-Metal-Contaminated Industrial Wastewater

The discharge of raw industrial wastewater (IWW) into ecosystems is a major environmental problem that adversely affects water quality, soil physicochemical properties, the food chain and, therefore, human health. Injection of treated IWW into irrigation and “fertigation” systems is an ecological, sustainable and economical approach for its appropriate disposal. Seedlings of two forest species (Salix alba, Casuarina glauca) were grown hydroponically and subjected to 25% diluted IWW and control (tap water) treatments for 35 days. Morphological and physiological traits were evaluated, including leaf symptoms, stem and root dry masses, leaf water potential, relative water content, chlorophyll content, photosystem II efficiency, hydrogen peroxide, thiobarbituric acid reactive substances, bioaccumulation and translocation factor estimates and removal efficiency for various heavy metals. Application of 25% IWW stress affected many aspects of plant morphology: chlorosis and necrosis in leaves, epinasty, leaf curling, early leaf senescence and root browning. In both species, the 25% IWW treatment reduced leaf, stem and root dry masses relative to controls. S. alba exhibited greater removal capacity for heavy metal ions and could be effective as a remediator of toxic-metal-polluted industrial effluent water.

Chromosome groups 5, 6 and 7 harbor major quantitative trait loci controlling root traits in bread wheat (Triticum aestivum L.).

Identifying genomic regions for root traits in bread wheat can help breeders develop climate-resilient and high-yielding wheat varieties with desirable root traits. This study used the recombinant inbred line (RIL) population of Synthetic W7984 × Opata M85 to identify quantitative trait loci (QTL) for different root traits such as rooting depth (RD), root dry mass (RM), total root length (RL), root diameter (Rdia) and root surface areas (RSA1 for coarse roots and RSA2 for fine roots) under controlled conditions in a semi-hydroponic system. We detected 14 QTL for eight root traits on nine wheat chromosomes; we discovered three QTL each for RD and RSA1, two QTL each for RM and RSA2, and one QTL each for RL, Rdia, specific root length and nodal root number per plant. The detected QTL were concentrated on chromosome groups 5, 6 and 7. The QTL for shallow RD (Q.rd.uwa.7BL: Xbarc50) and high RM (Q.rm.uwa.6AS: Xgwm334) were validated in two independent F2 populations of Synthetic W7984 × Chara and Opata M85 × Cascade, respectively. Genotypes containing negative alleles for Q.rd.uwa.7BL had 52% shallower RD than other Synthetic W7984 × Chara population lines. Genotypes with the positive alleles for Q.rm.uwa.6AS had 31.58% higher RM than other Opata M85 × Cascade population lines. Further, we identified 21 putative candidate genes for RD (Q.rd.uwa.7BL) and 13 for RM (Q.rm.uwa.6AS); TraesCS6A01G020400, TraesCS6A01G024400 and TraesCS6A01G021000 identified from Q.rm.uwa.6AS, and TraesCS7B01G404000, TraesCS7B01G254900 and TraesCS7B01G446200 identified from Q.rd.uwa.7BL encoded important proteins for root traits. We found germin-like protein encoding genes in both Q.rd.uwa.7BL and Q.rm.uwa.6AS regions. These genes may play an important role in RM and RD improvement. The identified QTL, especially the validated QTL and putative candidate genes are valuable genetic resources for future root trait improvement in wheat.

Vesicular arbuscular mycorrhizal influence on growth of cancer bush (Sutherlandia frutescens) and alleviation of saline stress

Lack of arable land on a global scale, agricultural malpractices and high soil salinity have prompted the development of alternative eco-friendly ways to increase crop production. The usage of vesicular arbuscular mycorrhizal (VAM) has been reported to positively improve crop production under harsh soil conditions but no such effort has fixated on traditional underutilized crops such as cancer bush (Sutherlandia frutescens). Given its significance as a versatile remedial crop, it is critical to cultivate this plant and regulate the agronomic necessities for its effective cultivation. Therefore, two separate experiments were conducted at the University of Mpumalanga, Mbombela, South Africa in 2021 and 2022, with an objective to investigate whether VAM will improve growth of cancer bush under saline soil conditions. Three weeks old cancer bush seedlings were planted in pots under microplot conditions. The in a 4 x 4 factorial treatmentarrangement in a randomized complete block design. The seedlings were grown in four geometric series of NaCl : CaCl2 (3 : 1) of artificial chloride salinity levels: 0, 0.25, 0.5 and 0.75 ds/m and four levels of VAM: 0,10, 20, and 30 g/pot, with four replications in the two successive years. At 60 days after initiation of treatments, dry root mass and number of branches were significantly affected by treatments in Experiment 1, with total treatment variation (TTV) of 11-17 and 9-34%, respectively of the variables. Dry shoot mass was significantly affected by treatments in Experiment 2, with TTV of 26-32%. In both the experiments, treatments had significant effects on soil EC, contributing 26-42% in TTV in Experiment 1, whereas in Experiment 2 the treatments contributed 4-76% in TTV of the respective variable. In conclusion, findings in the current study demonstrated that VAM in presence of salinity improved growth relative to plants under saline stress.

Potential of growth-promoting bacteria in maize (Zea mays L.) varies according to soil moisture

Climate change has caused irregularities in water distribution, which affect the soil drying-wetting cycle and the development of economically important agricultural crops. Therefore, the use of plant growth-promoting bacteria (PGPB) emerges as an efficient strategy to mitigate negative impacts on crop yield. We hypothesized that the use of PGPB (in consortium or not) had potential to promote maize (Zea mays L.) growth under a soil moisture gradient in both non-sterile and sterile soils. Thirty PGPB strains were characterized for direct plant growth-promotion and drought tolerance induction mechanisms and were used in two independent experiments. Four soil water contents were used to simulate a severe drought (30% of field capacity [FC]), moderate drought (50% of FC), no drought (80% of FC) and, finally, a water gradient comprising the three mentioned soil water contents (80%, 50%, and 30% of FC). Two bacteria strains (BS28–7 Arthrobacter sp. and BS43 Streptomyces alboflavus), in addition to three consortia (BC2, BC4 and BCV) stood out in maize growth performance in experiment 1 and were used in experiment 2. Overall, under moderate drought, inoculation with BS43 surpassed the control treatment in root dry mass and nutrient uptake. Considering the water gradient treatment (80–50–30% of FC), the greatest total biomass was found in the uninoculated treatment when compared to BS28–7, BC2, and BCV. The greatest development of Z. mays L. was only observed under constant water stress conditions in the presence of PGPB. This is the first report that demonstrated the negative effect of individual inoculation of Arthrobacter sp. and the consortium of this strain with Streptomyces alboflavus on the growth of Z. mays L. based on a soil moisture gradient; however, future studies are needed for further validation.

The Effect of Salinity on the Initial Growth of Soy Varieties

The article presents the data obtained on the study of the characteristics of soil salinity on the initial growth of different soybean varieties in the conditions of the Bukhara region. During the experiments, it was found that during the first 21 days of the plant, stem and root growth and dry mass accumulation. Based on the above results, it was noted that the above indicators vary in different degrees depending on the soil salinity and the biological and various characteristics of the varieties.