Root Dry Mass Research Articles

Morph-physiology and development of soybean cultivars under irrigation shift

During certain periods of the year, some Brazilian regions impose water restrictions, initiating the growth cycle of the soybean crop. Thus, this work was conducted aiming to evaluate the morphophysiology and development of soybean cultivars under irrigation intervals. The experiment was conduct in January 2021, in a rural property, located in the municipality of Lavínia, state of São Paulo, Brazil. The design was completely randomized, in a 2×5 factorial scheme, with two soybean cultivars, M7110IPro (Monsoy®) and Desafio RR8473RSF (Brasmax®), interacting with the irrigation intervals (i.e., 24 h (Control); 48 h; 72 h, 96 h and 120 h) totalizing 10 treatments. We used four repetitions per treatment, which totalizes 40 plots or pots. Our results revealed that intervals longer than 48 h already negatively influence in morphophysiology of the soybean crop. Intervals of 96 h caused greater negative interferences on plant height (PH); number of leaflets (NL); number of pods (NP); dry mass of aerial part (DMAP) and root (DMR) in the soybean crop when grown in pots. Water stress did not influence the stomatal density of soybean grown in pots. Water stress harms soybean physiological parameters. No soybean cultivar showed tolerance to water stress.

Toxic effect of elements on the germination and initial development of barley seeds (Hordeum vulgare L.)

Barley (Hordeum vulgare) is an agricultural vegetable from the Poaceae family used in food and beer production. The study aimed to evaluate the toxic effect of Aluminum (Al) and Copper (Cu) on germination and initial development in barley seeds cultivar KWS Irina. Different concentrations (0, 35, 85 and 125 mg L-1) of aqueous solution of Al and Cu were produced from their chlorides. The toxicity experiment was carried out in a germination box maintained in a germination chamber with a 12-h photoperiod. After 15 days of germination, the seedlings were measured using a millimetric ruler (cm) where they were evaluated for plant length, root length, and fresh and dry mass of plant and root determined on a digital analytical scale (g). Barley seedlings cultivar KWS Irina demonstrated to be intolerant to concentrations of the toxic elements Al and Cu in all plant parameters analyzed, except for plant dry mass. Future studies should be carried out comparing the initial and reproductive development of this barley cultivar in terms of the presence and absence of toxic elements.

The impact of PEG-induced drought stress on early vigour traits of bread wheat

ABSTRACT A total of 11 genotypes from the collection of 101 bread wheat genotypes, with desirable traits in terms of increased tolerance to drought, were chosen for parents and eight crosses were performed. Number of seminal roots (NSR), total root length (TRL), root dry mass (RDM), number of shoots per plant (NS), main shoot length (MSL), shoot dry mass (SDM), number of leaves per plant (NL), leaf area per plant (LA), leaf dry mass (LDM), aboveground dry mass (ADM), SDM/LDM, RDM/ADM were analysed at the boot stage (Z45). The F1 progeny had on average higher mean values (P < 0.001) than parents for four traits: RDM, NS, LA and RDM/ADM. The highest broad sense heritability values were determined for RDM (97.6%) and NSR (93.9%). Factor analysis indicated that a large root system, higher RDM and TRL are associated with higher NS, NL, LA and LDM. For Euclid x CHI-4 and WWBMC2 x Ingenio combinations the highest heterosis values were observed for TRL (34.1%) and SDM (23.7%), for RDM (28.6%) and LA (26.8%), respectively. PEG-induced drought stress in the seedling stage, in most of the new germplasm, caused an increased redistribution of dry matter in the root compared to the stem.

Biomass partitioning reveals the adaptability of tiger nut (Cyperus esculentus L.) in an arid ecosystem in Inner Mongolia, China

AbstractTiger nuts (Cyperus esculentus L.) have been widely cultivated as a bioenergy crop in northern China. The value of tubers is receiving special attention, but the lack of information on how organs of tiger nuts coordinate resources to adapt to arid environments has limited the potential tuber production and diverse use. To address this knowledge gap, we experimented in the Ulan Buh Desert, Inner Mongolia (106° 33′ 28″ E, 40° 27′ 32″ N). Three fertilizer treatments were applied: zero fertilizer (N:P = 0:0), traditional fertilizer (N:P = 15:15), and additional nitrogen fertilizer (N:P = 60:15). Investigations were conducted at seedling, rhizome production, tuber formation, and tuber maturation stages. The results showed that under zero fertilizer, tiger nuts allocated biomass predominantly to propagative organs, namely rhizomes and tubers. However, an increase in leaf area or root surface area would necessitate more investment in leaf or root dry mass, resulting in diminishing returns. For biomass allocation, tiger nut responded the same way to traditional fertilizer treatment and zero fertilizer treatment, but the tuber number and yield increase under traditional fertilizer application. Additional nitrogen fertilizer stimulated shoot production through accelerated rhizome production aided by leaf area increasing. Fertilizer application can significantly increase both the number of tiger nuts and tuber yield. Nitrogen addition positively influenced aboveground biomass and enhanced rhizome tillering. Strong adaptability of tiger nuts makes the plant a suitable pioneer crop for developing marginal lands. The robust aboveground growth after nitrogen application enhances suitability for pasture utilization.

Supplementary Light on the Development of Lettuce and Cauliflower Seedlings

The production of seedlings is one of the main activities for implementing agricultural crops. Many factors are involved in producing quality seedlings, including nutrition, health, genetics, and climatic factors such as temperature, humidity, and light. To evaluate the effect of light supplementation, a study was conducted using supplementary artificial light to produce lettuce and cauliflower seedlings. Sowing was carried out in styrofoam trays under a floating irrigation system. Part of the experiment containing the two species, received treatment with LED light for an additional 4 h per day, in addition to solar radiation (10 h∙day−1). The remaining seedlings received only solar radiation (without supplementation). After 37 days, the seedlings’ biometric (leaf area, root length, aerial dry mass, and root dry mass) and biochemical parameters (phenolic compounds, flavonoids, chlorophyll a/b, and total chlorophyll) were analyzed. The data showed that the complementary light enhanced the performance in all the biometric parameters evaluated in the experiment for lettuce and cauliflower. The biochemical parameters in lettuce were also higher in seedlings with light supplementation. For cauliflower, supplementary light did not differ from the natural photoperiod for biochemical parameters except for a reduction in the levels of total phenolic compounds. Considering the enhanced biometric and biochemical parameters and greater dry weight and leaf area of the seedlings grown with supplemental light, using such a tool can optimize seedling development, possibly reducing production time in the nursery and providing greater productivity.

MORPHOPHYSIOLOGICAL CHANGES IN SEEDLINGS OF Eugenia uniflora L. AFTER CHEMICAL HARDENING

Using quality seedlings increases the chances of survival and development after planting. Hardening aims to modify the morphology of seedlings to acclimatize them to stressful field conditions. The objective of this study was to quantify the effects of chemical hardening with methyl jasmonate on the morphophysiology of Eugenia uniflora L. seedlings subjected to 12 days of water deficit. Seedlings were hardened with doses of 0, 50, 100, and 150 μmol L-1 of methyl jasmonate (MeJA). Afterward, they were transplanted into pots with soil and subjected to water deficit for 12 days. During that period, we assessed shoot height (H), stem diameter (SD), leaf area (LA), leaf dry mass (LDM), stem dry mass (SDM), root dry mass (RDM), total dry mass (TDM), relative water content (RWC), robustness index (RI), Dickson quality index (DQI), shoot/root ratio (S/R), stomatal conductance (Sc) and evapotranspiration (ET). The experiment was conducted in a randomized block design with five blocks. Variables RI, DQI, LA, RWC, and TDM values presented a quadratic trend, with promising results from the 50 and 100 µmol L-1 doses. Sc and ET values were influenced by water deficit. Under conditions of water restriction, application of MeJA in adequate doses promoted morphophysiological changes and induced defense strategies in E. uniflora seedlings. Doses of methyl jasmonate between 50 and 100 µmol L-1 resulted in seedlings with greater tolerance to water deficit for 12 days.

THE INFLUENCE OF FERTILIZER TYPE AND Trichoderma harzianum INOCULATION ON THE GROWTH AND PHYSIOLOGY OF YOUNG PLANTS OF Cordia americana

In this study, we sought to determine the influence of combined treatments with different types of fertilizer and inoculation of the fungus Trichoderma harzianum on the growth and physiological characteristics of young plants of Cordia americana. To this end, we adopted a completely randomized experimental design, comprising six replications in a 5 × 2 factorial scheme, to assess the effects of five different types of fertilizer applied with or without T. harzianum inoculation. At 180 days post-planting, we performed measurements of plant height, stem diameter, leaf dry mass, root dry mass, stem dry mass, total dry mass, leaf area, Falker’s chlorophyll index, and chlorophyll fluorescence. It was found that the combined application of T. harzianum and a controlled-release fertilizer or manure-based organominerals was effective in enhancing the growth of C. americana plants under conditions similar to those in the field. The use of controlled-release fertilizer as a base fertilization was found to have a positive influence on all evaluated variables and was effective in maximizing the initial development of C. americana plants. Granulated fertilizers derived from swine manure were established to promote plant growth and photosynthetic efficiency, thereby confirming their efficacy as a fertilizer for the cultivation of C. americana.

Composted Sewage Sludge as a Substrate for Commercial Seedlings of Peltophorum dubium (Spreng.) Taub.

Sewage sludge in natura is rich in nutrients, water, and organic matter and is essential for plant development. However, sewage sludge is diluted with water when composted, which could hamper plant growth. Therefore, supplementation with chemical fertilization may be necessary. This study evaluated the performance of composted sewage sludge (CSS) in producing Peltophorum dubium (Spreng.) Taub. seedlings with and without chemical fertilization via fertigation. The experiment was completely randomized in a 3 × 4 factorial scheme, with four fertigation (Ca(NO3)2(H2O)x: 0.87; (NH4)(H2PO4): 0.21; KCl: 0.47; (NH4)2SO4: 0.11; CH₄N₂O: 0.54; MgSO4: 0.52; Fe (13%): 0.03; B(OH)3: 6.00; CuSO4: 0.60; ZnSO4: 1.40; MnSO4: 6.00; Na2MoO4: 0.16 g L−1) doses: zero, standard, duplicate, and quadruplicate. In addition, three substrates were used: commercial substrate as the control, sewage sludge composted with sugarcane bagasse (LBC), and sewage sludge composted with Eucalyptus bark (LCE). The development of the seedlings was measured through the following variables: height, stem diameter, shoot/root ratio, leaf dry mass, root dry mass, total dry mass, green color index, the Dickson Quality Index, and the accumulation of nutrients in plant tissue. The seedlings produced with LCE that were subjected to the standard dose (1×) and the quadruplicate dose (4×) had the statistically highest mean values for most variables. Nevertheless, supplementation with chemical fertilization was necessary. Composted sewage sludge with eucalyptus bark, at the standard dosage, can be used for the commercial production of P. dubium seedlings, thus preventing the dangerous disposal of waste and strongly decreasing associated environmental hazards.

Salt stress and organic fertilization on the growth and biochemical metabolism of Hylocereus costaricensis (red pitaya) seedlings.

Red pitaya (Hylocereus costaricensis) is a promising species, with high cultivation potential due to the organoleptic and functional qualities of its fruits. However, irrigation water salinity can affect the crop yield. Therefore, materials rich in organic substances can minimize the damage caused by excess salts in soil and/or water. Thus, the objective of this study was to evaluate the influence of organic matter sources as attenuators of salt stress on the production and biochemical responses of red pitaya seedlings. A completely randomized design in 4 × 5 factorial scheme, with five sources of organic matter (humus, sheep manure, biofertilizer, organic compost and sand + soil) and four salinities (0.6, 2.6, 4.6 and 6.6 dS m-1) with four replicates and two plants per plot was used. The shoot length, root length, cladode diameter, number of cladodes, number of sprotus, root volume, shoot dry mass, root dry mass and total dry mass, root and shoot dry mass ratio, chlorophyll a, b and total, amino acids and soluble sugars were evaluated at 120 days after the treatments began to be applied. Red pitaya is moderately tolerant to salinity (ECw from 4.0 to 6.0 dS m-1). Organic compost and sheep manure attenuate the harmful effects of salinity on red pitaya seedlings. Under salt stress conditions, red pitaya plants increase their levels of proline, amino acids and total sugars.

Plant growth-promoting bacteria in sorghum development in coppercontaminated soil

Copper (Cu) is a metal that can become toxic to sorghum when present in high concentrations in the soil. The use of plant growth-promoting rhizobacteria can be an alternative for the development of sorghum [Sorghum bicolor (L.) Moench] in soil contaminated with copper. The objective of this study was to determine the effect of Azospirillum brasilense inoculation on the development and copper levels of sorghum cultivated in soil contaminated with Cu, enabling the reuse of these areas. The experimental design was randomized blocks in a factorial arrangement (9 × 2), with nine doses of copper [(0: natural content of the soil), 30, 60, 90, 120, 150, 180, 240, and 300 mg of copper kg-1 of soil] with and without A. brasilense inoculation, with six replicates. In the treatment without inoculation, a dose of 200 kg-1ha was applied. Plant height (PH), stem diameter, dry mass of the air part (DMAP), volume, length, and root dry mass (RDM), relative index of chlorophyll a and b, and copper contents in DMAP and RDM were evaluated. The inoculation with A. brasilense allows a higher index of chlorophyll a and b and the development of the aerial part of the sorghum, reducing copper content in the aerial part, enabling the reuse of soil containing 52.5% clay, contaminated with up to 300 mg of copper kg-1 of soil. Inoculation with A. brasilense increases the specific surface area (SSA) of sorghum roots compared with non-inoculated plants grown only with nitrogen fertilization in soil contaminated with copper.

Redução do crescimento de begônia envasada via tratamento com etanol

Abstract The application of plant growth regulators is a viable tool to produce potted plants, but its use is limited due to the risk of toxicity. Alternative treatment with ethanol has shown potential in restricting growth, but its morphological effects on ornamental plants are not yet well-explored. This study evaluated the application of different concentrations of ethanol (0, 2%, 4% and 6%) on the growth of potted Dragon Wing Begonia, a hybrid of great ornamental potential that presents vigorous growth, seeking to select the best concentration to reduce plant height. The experiment was conducted in a 2x4 factorial scheme, with two varieties, ‘Red’ and ‘Pink’, and four concentration levels of ethanol treatment. Plant growth and development aspects were evaluated. Ethanol showed great potential to reduce plant size, as it linearly restricted all growth variables (height, diameter, number of leaves, leaf area, shoot, and root dry mass) and flowering variables (dry mass and number of flowers and buds). The highest concentration (6%) caused phytotoxic symptoms and senescence in plants. On the other hand, treatments with concentrations of 2% and 4% resulted in compact plants with great market quality. In conclusion, ethanol treatment can be a viable alternative to reduce the growth of potted ornamental plants.

Regimes hídricos nas respostas morfofisiológicas e bioquímicas de Croton blanchetianus (Euphorbiaceae)

ABSTRACT Plant species occurring in the Caatinga biome, when subjected to different water fluctuations, may have their morphophysiological and metabolic performance altered. Depending on the level of stress, the production of quality seedlings is affected. Therefore, the objective of this study was to evaluate the responses to different water availability levels in the morphophysiological and biochemical development of Croton blanchetianus Baill. The experiment was carried out in a greenhouse, evaluating four water regimes: 25%, 50%, 75% and 100% of pot capacity, and conducted in a randomized block design, with a total 5 blocks. The variables analyzed were: branch height and branch diameter; leaf area, number of leaves, root volume; root dry mass, shoot dry mass, total dry mass and root/shoot ratio; relative water content, proline, total soluble proteins, malondialdehyde, hydrogen peroxide, and photo synthetic pigments (chlorophyll ɑ, chlorophyll b, and carotenoids). The species Croton blanchetianus Baill. shows drought tolerance mechanisms, demonstrated by the reductions of growth, leaf area, dry mass of seedlings and photo synthetic pigments. It adjusts osmotically with increments in the production of proline, which acts in osmoprotection when there is water deficit, and in the production of proteins under the lower and higher water regime. The species has full development of seedlings under water regimes between 75% and 80% and adapts to different water fluctuations.

Characterization and report of binucleate Rhizoctonia AG‐Fb affecting soybean in Brazil

AbstractRhizoctonia root rot is a disease that can affect soybean leading to plant death usually in bare patches. Frequently, Rhizoctonia solani has been reported as the main causal agent of the disease. However, due to the great genetic diversity of the genus Rhizoctonia, there are other species that could also attack soybean plants. Thus, the objective of this study was to determine the pathogenicity and characterize an isolate of binucleate Rhizoctonia obtained from a soybean plant with symptoms of root rot cultivated in soil from southern Brazil. The isolate was identified based on the morphology and phylogenetic analysis of the internal transcribed spacer region (ITS) of the rDNA. Pathogenicity tests were then performed on seeds and roots of soybean and the optimum temperature for mycelial growth was determined. The isolate was identified as binucleate Rhizoctonia AG‐Fb and it was pathogenic to soybean seeds and roots. In the pathogenicity assay in soybean seed, the isolate reduced seed germination by 20% and caused seed rot index of 69.3. In the pathogenicity assay in soybean root, the inoculation of binucleate Rhizoctonia AG‐Fb caused 67.3 root rot severity index, and reduced the emergence speed index by 19%, seedling height by 31%, root dry mass by 25% and root volume by 43% in soybean seedlings. The optimum temperature for the mycelial growth of the isolate was 26°C. To the best of our knowledge, this is the first report of binucleate Rhizoctonia AG‐Fb associated with soybean root rot in Brazil.

Metagenomics and vegetative growth of Salvia hispanica inoculated with Trichoderma harzianum.

The soil is a dynamic environment, influenced by abiotic and biotic factors, which can result in changes in plant development. This study aimed to assess the impact on vegetative growth of chia (Salvia hispanica L) inoculated with Trichoderma harzianum and on the rhizosphere microbiome. The experimentation was conducted in a greenhouse under controlled conditions growing chia plants in pots containing soil with a clayey texture. Different concentrations of T. harzianum (0; 2.5; 5.0; 10.0; 20.0 µL. g-1 of seed) were applied to the chia seeds before planting. Morphological parameters, including plant height (cm), number of branches, stem diameter (mm), number of days to flowering and shoot and root dry masses (g) were quantitatively assessed. After the cultivation period, soil samples from the rhizosphere region were collected for subsequent chemical and metagenomic analyses. These samples were also compared with the control soil, collected before installing the experiment. The results showed that increasing doses of T. harzianum promoted a significant increase in the diameter of the stem, number of branches, dry biomass of the root system and the number of days to flowering, without modifying the overall height of the plants. Soil metagenomics indicated that T. harzianum inoculation modified the microbial diversity of the rhizosphere environment, with more pronounced effects observed in samples treated with higher concentrations of the inoculant. Furthermore, there were changes in the chemical composition and enzymes related to soil quality in correlation with the concentrations of the applied inoculant. This study demonstrated that inoculating chia seeds with T. harzianum not only promotes specific morphogenetic characteristics of the plant, but it also has a significant impact on the microbial diversity and biochemical functionality of the soil, including an observed increase in the populations of T. harzianum and T. asperellum.

Restoring South African subtropical succulent thicket using Portulacaria afra: root growth of cuttings differs depending on the harvest site during a drought.

The restoration of succulent thicket (the semi-arid components of the Albany Subtropical Thicket biome endemic to South Africa) has largely focused on the reintroduction of Portulacaria afra L. Jacq-a leaf- and stem-succulent shrub-through the planting of unrooted cuttings directly into field sites. However, there has been inconsistent establishment and survival rates, with low rates potentially due to a range of factors (e.g., post-planting drought, frost or herbivory), including the poor condition of source material used. Here we test the effect of parent-plant and harvesting site on the root development of P. afra cuttings in a common garden experiment. Ten sites were selected along a ∼110 km transect, with cuttings harvested from five parent-plants per site. Leaf moisture content was determined for each parent-plant at the time of harvesting as a proxy for plant condition. Root development-percentage of rooted cuttings and mean root dry weight-was recorded for a subset of cuttings from each parent-plant after 35, 42, 48, 56, and 103 days after planting in a common garden setting. We found evidence for cutting root development (rooting percentage and root dry mass) to be strongly associated with harvesting site across all sampling days (p<0.005 for all tests). These differences are likely a consequence of underlying physiological factors; this was supported by the significant but weak correlation (r 2=0.10-0.26) between the leaf moisture content of the parent-plant (at the time of harvesting) and dry root mass of the cuttings (at each of the sampling days). Our findings demonstrate that varying plant condition across sites can significantly influence root development during dry phases (i.e., intra- and inter-annual droughts) and that this may be a critical component that needs to be understood as part of any restoration programme. Further work is required to identify the environmental conditions that promote or impede root development in P. afra cuttings.

Crescimento e atributos fisiológicos de mudas de mirtileiro inoculadas com fungos micorrízicosarbusculares

ABSTRACT: High-quality seedlings are one of the key factors in achieving high yield and precocity of blueberries. The inoculation of arbuscular mycorrhizal fungi (AMF) can enhance the development of seedlings in the nursery, ensuring more vigorous seedlings in a shorter time. This study evaluated the effect of inoculation of arbuscular mycorrhizal fungi on the development of ‘PowderBlue’blueberryseedlings. The treatments were arranged in a 4 x 2 factorial scheme, in which the first factor was the arbuscular mycorrhizal fungi Gigaspora rosea, Glomus clarum, G. rosea + G. clarum, and a control level without mycorrhizae, while the second factor consisted of usingindole-3-butyric acid(IBA) and a control level without IBA. Semi-hardwood cuttings were planted in pots containing sterilized soil and kept in a greenhouse for 660 days. The percentage of rooted cuttings, plant height, root system length, shoot dry mass, root dry mass, total dry mass, peroxidase (POD) and superoxide dismutase (SOD) enzyme activities, SPAD index, mycorrhizal efficiency and dependence, number of spores, and soil basal respiration were evaluated. Plants inoculated with G. clarum without IBA and inoculated with G. rosea with IBA showed higher dry matter and SOD and POD enzyme activities, but the use of IBA had a negative effect on the fungus. The inoculation of blueberry cuttings with G. clarummay help seedlingdevelopment, thus improving biometric and biochemical parameters. Furthermore, the plant regulator IBAwas essential in establishing the symbiosis between blueberry and the AMF G. rosea.

Intensidades de poda e volumes de recipiente na produção de mudas avançadas de maracujazeiro-azedo

Abstract: The objective of this work was to evaluate the production of advanced seedlings of sour passion fruit (Passiflora edulis Sims.) in pruning intensities at different volumes of containers. The experiment was carried out in a production nursery, in Pedras Grandes, Santa Catarina state. The experimental design was a randomized block design and the treatments were arranged in a factorial scheme of five pruning intensities (control and pruning from the emission of 2, 4, 6, and 8 defined leaves) x 3 container volumes (1.0; 1.7 and 3.6 liters), with three replications and six plants per plot. The height and number of leaves (NF) of the seedlings were evaluated throughout the experiment and, at the end, the percentage of plants with a twisted root system (PSRE), root volume (VR), root dry mass (MSR), aerial part (MSPA) and total were measured (MST). The control treatment (without pruning) showed greater height, NF, MSPA and MST, regardless of container volume. The production of advanced sour passion fruit seedlings under pruning intensities reduced height, NF, MSPA and MST. Seedlings formed in larger volume containers provided greater height, NF, VR, MSR, MSPA and MST, in addition to the lowest PSRE. Therefore, pruning at an intensity of 6 leaves in a 1.7 liter container is recommended.

Extratos vegetais como promotores de germinação e estabelecimento de plântulas de alface e milho

ABSTRACT: Substances produced by plants have huge importance regulating multiple functions as germination, development promoter/enhancer, yield increaser and activator of plant defense system against diseases and pests. Due to diversity, each plant species produces different compounds and in different concentrations. This research evaluated the role of 20 plants extracts obtained from different plant species or plant tissues on seed germination and seedlings establishment of maize and lettuce, in concentration of 5%, 10% or 20%. For this, two experiments were carried out, the first analyzing 20 plant extracts and the effects on germination percentage and root and shoot length based on the germination test for the two species. The second was carried out in a greenhouse, in a completely randomized design with three and ten repetitions for maize and lettuce, respectively, using only the three extracts with the best results from the first experiment. Seedling height and seedling dry matter were evaluated. To germination test most of extracts showed negative or no effects in both species. Only Conyza bonariensis at 5% and Richardia brasiliensis at 5% and 20% had positive effects on early seedling growth, increasing the seedlings length for maize seedlings. To seedlings establishment, Conyza bonariensis, Leucaena leucocephala and Richardia brasiliensis extracts did not show statistical difference to shoots height but increased the dry mass of shoots and roots. The results demonstrated that these plants extract have potential as growth promoters and can be a good option to a better seedling growth and establishment, collaborating to a more effective agriculture.

Trocas gasosas e crescimento de algodoeiro colorido sob estresse salino e aplicação de ácido salicilico

ABSTRACT The occurrence of water sources with high salt content stands out as a limiting factor for the expansion of irrigated agriculture in the semi-arid region. In this context, it is essential to look for strategies to mitigate the effects of salt stress, and the application of salicylic acid stands out. The objective of this study was to evaluate gas exchange and growth of the naturally colored cotton cv. BRS Jade under saline water irrigation and foliar application of salicylic acid under semi-arid conditions. The experiment was carried out in containers adapted as drainage lysimeters, under open air conditions at the Center of Science and Agri-Food Technology of the Federal University of Campina Grande in Pombal, Paraíba, Brazil. A randomized block design was adopted, in a 5 × 5 factorial scheme, with treatments resulting from the combination of five levels of electrical conductivity of irrigation water - ECw (0.3, 1.8, 3.3, 4.8, and 6.3 dS m-1) associated with five concentrations of salicylic acid - SA (0, 1.5, 3.0, 4.5, and 6.0 mM), with three replicates. Water salinity from 0.3 dS m-1 limited the photosynthetic efficiency and therefore the growth of cotton cv. BRS Jade. Foliar application of SA at concentration of 6.0 mM mitigated the effects of salt stress on the stomatal conductance and leaf transpiration of these plants. However, SA concentrations ranging from 0 to 6.0 mM reduce the internal CO2 concentration, growth in stem diameter and plant height, and root and stem dry mass accumulation of cotton plants cv. BRS Jade.

Cultivo de abobrinha sob estresse salino e aplicação exógena de paclobutrazol

ABSTRACT Salinity is considered an obstacle to the production system that limits the growth and yield of crops around the world. Therefore, it is essential to develop strategies to minimize the effects of salinity and increase yield, especially in the semi-arid region of the Northeast, which has limited water resources of good quality for irrigation. The objective was to evaluate the effects of applying paclobutrazol on zucchini crop under salt stress. The experiment was conducted in a greenhouse, in a randomized block experimental design, in a 2 × 5 factorial scheme, with two salinity levels of irrigation water (0.6 and 4.0 dS m-1) and five concentrations of paclobutrazol - PBZ (0; 2; 4; 6 and 8 g L-1), and with four repetitions. Application of 8 mg L-1 PBZ increases stem diameter in zucchini under irrigation of 4.0 dS m-1. Chlorophyll b and total chlorophyll contents increase with PBZ concentration of 4 mg L-1 and irrigation of 0.6 dS m-1. PBZ concentration of 4 mg L-1 increases the relative water content while reducing electrolyte leakage in zucchini under salinities of 4.0 and 0.6 dS m-1 respectively. Root, stem and leaf dry mass of zucchini increases when plants are irrigated with water of 0.6 dS m-1 and subjected to PBZ concentration of 8 mg L-1. PBZ concentrations do not attenuate the effects of salinity on leaf area, crown volume and diameter, vegetative vigor index, chlorophyll a and carotenoids.