Root Dry Mass Research Articles

Metal accumulation, growth and nutrition of Vernonia polyanthes exposed to lead nitrate and arbuscular mycorrhizal fungi

The association between plants and arbuscular mycorrhizal fungi (AMF) can be used to bioremediate areas contaminated by metals. The objectives of this work were to evaluate the lead (Pb2+) phytoaccumulation capacity, morpho-physiology and nutrition responses of Vernonia polyanthes exposed to a solution amended with concentrations of lead nitrate and arbuscular mycorrhizal fungi. The treatments consisted of increasing doses of Pb2+ as lead nitrate [Pb(NO3)2], two strains of AMF and an absolute control without lead and AMF. Lead negatively affected some morphophysiological variables, reduced 27.3, 25.63, 30.60, and 56.60% shoot length, root collar diameter, number of leaves and leaf area, respectively, besides reducing decreasing chlorophyll a. Lead accumulated in the shoot and roots, the latter at the highest concentrations. However, the translocation factor was above 1, indicating low efficiency. The bioaccumulation factor referring to the roots were above 1. The fungi colonization rate was low, 3.31% for Gigaspora margarita and 2.33% for Acaulospora morrowiae. However, the absorption of lead increased, reflecting in lower values of chlorophyll a, dry mass of root and diameter. Results indicated that the arboreal species V. polyanthes tolerate high concentrations of lead and can accumulate significant amounts in the roots. AMF increase the accumulation of lead in the shoot and can be used in projects aimed at the phytoextraction of metals.

Propagation of herbaceous unrooted cuttings of cold-tolerant species under reduced air temperature and root-zone heating

Vegetative propagation of herbaceous cuttings mostly occurs in greenhouses during late winter and early spring when outdoor radiation intensities and average daily temperatures (ADT) are seasonally low. To promote rapid callus induction and rooting, supplemental lighting and air and root-zone heating (RZH) can be utilized. Given that cold-tolerant crops have base temperatures <4 °C, reducing the air temperature is a potential energy saving strategy. Therefore, the objective of this study was to quantify how reduced air ADT and increased RZH temperatures influence root initiation and development of cold-tolerant herbaceous annual and perennial crops propagated by cuttings. Shoot-tip cuttings of calibrachoa ‘Callie Coral’ (Calibrachoa ×hybrida), campanula ‘Birch Hybrid’ (Campanula portenschlagiana), nemesia ‘Aromatica Royal Blue’ (Nemesia fruticans), nepeta ‘Junior Walker’ (Nepeta × faassenii), osteospermum ‘Voltage Yellow’ (Osteospermum ecklonis), petunia ‘Sanguna Patio Blue’ (Petunia ×hybrida), phlox ‘Glamour Girl’ (Phlox paniculata), and rosemary ‘Arp’ (Rosmarinus officinalis) were inserted into a soilless medium and grown in a greenhouse with an air ADT and RZH temperature of 21 and 24 °C, respectively, for callusing. After 6 d, trays of cuttings were placed in two greenhouse compartments with air ADTs of 16 or 21 °C. Three benches within each compartment had RZH set points of 21, 24, or 27 °C. After 14 d, the interaction of air and RZH temperatures influenced stem length of nepeta, petunia, phlox, and rosemary. For example, increasing the air ADT from 16 to 21 °C and RZH set points from 21 to 27 °C increased stem length of nepeta by 2.5 to 3.7 cm. As air ADT increased from 16 to 21 °C at an RZH set point of 27 °C, shoot dry mass increased by 32% and 24% for calibrachoa and phlox, respectively. Root dry mass and liner pullability for osteospermum increased as air ADT increased from 16 to 21 °C at an RZH set point of 21 °C by 14 mg and 70%, respectively. Overall, the results from this study identify cold-tolerant crops that can be propagated with genera-specific RZH set points under a reduced air ADT without sacrificing liner quality or propagation time and highlights the importance of RZH for growers.

Response of Mungbean (cvs. Celera II-AU and Jade-AU) and Blackgram (cv. Onyx-AU) to Transient Waterlogging.

Mungbean [Vigna radiata (L.) Wilczek] and blackgram [Vigna mungo (L.) Hepper] are important crops for smallholder farmers in tropical and subtropical regions. Production of both crops is affected by unexpected and increasingly frequent extreme precipitation events, which result in transient soil waterlogging. This study aimed to compare the waterlogging tolerance of mungbean and blackgram genotypes under the varying duration of waterlogging stress at germination and seedling stages. We evaluated the responses to different durations of transient waterlogging in a sandy clay loam under temperature-controlled glasshouse conditions. Waterlogging durations were 0, 1, 2, 3, 4, 5, 6, 7, and 8 days during germination and 0, 2, 4, 8, and 16 days during the seedling stage. We used two mungbean genotypes (green testa), Celera II-AU (small-seeded), and Jade-AU (large-seeded), contrasting in seed size and hypocotyl pigmentation, and a blackgram genotype (black testa), Onyx-AU. Waterlogging reduced soil redox potential, delayed or even prevented germination, decreased seedling establishment, and affected shoot and root development. In the seedlings waterlogged (WL) at 15 days after sowing (DAS), adventitious root formation and crown nodulation varied between the genotypes, and 16 days of waterlogging substantially reduced growth but did not result in plant death. Plants in soil with waterlogging for 8–16 days followed by drainage and sampling at 39 DAS had reduced shoot and root dry mass by 60–65% in mungbean and 40% in blackgram compared with continuously drained controls, due at least in part to fewer lateral roots. Soil plant analysis development (SPAD) chlorophyll content was also reduced. Onyx-AU, a blackgram genotype, was more tolerant to transient waterlogging than Jade-AU and Celera II-AU in both growth stages. Of the two mungbean genotypes, Celera II-AU had a greater seedling establishment than Jade-AU post waterlogging imposed at sowing. In contrast, Jade-AU had more plant biomass and greater recovery growth than Celera II-AU after waterlogging and recovery during the seedling stage. Both species were delayed in emergence in response to the shorter periods of transient waterlogging at germination, and with the longer waterlogging germination and emergence failed, whereas at the seedling stage both showed adaptation by the formation of adventitious roots.

Morphological divergence of seedlings Calophyllum brasiliense cambes collected in São Paulo and Tocantins

Objective: The objective was to quantify the morphological diversity of Calophyllum brasiliense Cambes from four municipalities of the State of Tocantins employing morphological characteristics, to strengthen information on conservation and future breeding of the species. Methodology: Seeds were collected from four municipalities in the State of Tocantins and one in the State of São Paulo. The following were evaluated: plant height, stem diameter, root length, number of leaves, leaf area, root dry mass, shoot dry mass, total dry mass, and Dickson´s quality index. The data were subjected to univariate analysis of variance, Tocher grouping method, and UPGMA, obtaining a dendrogram through the generalized Mahalanobis distance. Results: The results showed a statistical difference of 1 and 5% probability. Dueré stood out in stem diameter(5.52 mm), Sandolandia in height (34.84 cm) and root length (42.13 cm). Formoso stood out in the number of leaves (34 leaves). Lagoa da Confusão in leaf area (856.28 cm 2 ) and São Paulo in root dry mass (16.20 g), shoot dry mass (12.38 g), total dry mass (16.20 g), and Dickson´s quality index (1.57). Implications: Variations in morphological characteristics can be used as a tool for genetic studies of guanandi progeny accordingto their similarity and/or differences. Conclusions: The morphological divergence evidenced that among the five studied areas it is possible to direct the collection of seeds to subsidize conservation strategies and future breeding of the species.

Rearranging the sugarcane holobiont via plant growth-promoting bacteria and nitrogen input

The development and productivity of plants are governed by their genetic background, nutrient input, and the microbial communities they host, i.e. the holobiont. Accordingly, engineering beneficial root microbiomes has emerged as a novel and sustainable approach to crop production with reduced nutrient input. Here, we tested the effects of six bacterial strains isolated from sugarcane stalks on sugarcane growth and physiology as well as the dynamics of prokaryote community assembly in the rhizosphere and root endosphere under two N fertilization regimes. All six strains, Paraburkholderia caribensis IAC/BECa 88, Kosakonia oryzae IAC/BECa 90, Kosakonia radicincitans IAC/BECa 95, Paraburkholderia tropica IAC/BECa 135, Pseudomonas fluorescens IAC/BECa 141 and Herbaspirillum frisingense IAC/BECa 152, increased in shoot and root dry mass, and influenced the concentration and accumulation of important macro- and micronutrients. However, N input reduced the impact of inoculation by shifting the sugarcane microbiome (rhizosphere and root endosphere) and weakening the co-dependence between soil microbes and sugarcane biomass and nutrients. The results show that these beneficial microbes improved plant nutrient uptake conditioned to a reduced N nutrient input. Therefore, reduced fertilization is not only desirable consequence of bacterial inoculation but essential for higher impact of these beneficial bacteria on the sugarcane microbiome.

Rhizobacteria modify root architecture and improve nutrient uptake in oil palm seedlings despite reduced fertilizer

The oil palm (Elaeis guineensis Jacq.) is one of the most economically important oilseeds due to the production of two types of vegetable oils: palm oil and palm kernel oil. Due to the commercial plantations expansion, its necessary to produce seedling of agronomic quality, with low cost and proper management, which express all the productive potential of this culture. The objective was to evaluate the changes in the root system, in the nutrients acquisition and allocation in oil palm seedling inoculated with rhizobacteria. The study was carried out in the field in the seedling nursery of the company Agropalma Group S/A. Treatments was C-: no inoculation with ½ fertilizer; BRM 32113: Burkholderia pyrrocinia inoculated plants with ½ fertilizer; UFRA 92: Bacillus subtilis inoculated plants with ½ fertilizer; C+: no inoculation and complete fertilization. The inoculation positively influenced the root volume with an average increase of 46.7%, 28.4% total root length, 42.5% total surface area, 43.7% average diameter, 203% number of tips and 115% ramifications when comparing the mean of BRM 32113 and UFRA 92 against the mean of C- and C+. The results showed that inoculation modified the root architecture, increased the root system, and this favored the nutrients accumulation, in addition to obtaining quality seedlings for permanent planting with low production costs, highlighting the potential of rhizobacteria as a bioinoculant in agriculture. Rhizobacteria BRM 32113 and UFRA 92 also induced an increase in nutrient accumulation in the root, root dry mass, shoot and total dry mass in oil palm seedlings, with half the fertilizer compared to the controls. Rhizobacteria can be used as a mechanism to reduce the current high rates of synthetic fertilizers, without leaving chemical residues inherent to environmental problems and without compromising plant growth and productivity.

English

The specific objective of the study was to evaluate effect of inoculation with Azospirillum brasilense and nitrogen (N) doses on vegetative growth and gas exchange in Zea mays L. The experimental design adopted was the completely randomized, in a 4 2 2 factorial scheme, in the following way: four doses of N (0 60 120 and 180 kg ha-1 of N), two sources of N (common urea and urease inhibitor-treated urea) and absence and presence of inoculation with A. brasilense, with four replications. The evaluations were made for vegetative growth of the plant (plant height, stem diameter, leaf area, number of leaves, dry mass of stem, root, leaves and aerial part and total dry mass) and photosynthesis, stomatal conductance, transpiration, internal carbon, relationship between internal and external carbon and content of chloroplast pigments. The application of N provided an improvement in plant growth, and, in general, the dose of 180 kg ha-1 N associated with A. brasilense, promoted an increase in stem diameter, photosynthesis, stomatal conductance, transpiration and internal carbon ratio of the corn. The treatment with urease inhibitor, greatly promoted the stem diameter, transpiration, Ci/Ca ratio and chlorophyll (Chl) a, b, total compared to urea treatment. The inoculation of the corn seeds with the bacteria and the use of N fertilization, regardless of the source, promoted an improvement in the vegetative growth of the hybrid, improving the vegetative growth and the physiological responses of corn when applied to the highest dose of 180 kg/ha N. © 2021 Friends Science Publishers

Effects of Phosphorus on Different Genotypes of Wheat and Canola Differing in P-Efficiency in Acidic Soils of Western Australia

We hypothesized that phosphorus addition would result in plant morphological changes and changes in rhizosphere carboxylates among wheat and canola cultivars in different acidic soils. Concentration of carboxylates in the rhizosphere extracted with 0.2 mM CaCl2, expressed per unit root dry mass. Dry weight of root and shoot were measures after harvest; total root length, and average root diameter were determined using a scanner. Also, the concentration of phosphorus (Colwell P) in rhizosphere and bulk soil was measured using UV-VIS Spectrophotometer. Shoot and root dry mass of wheat and canola increased significantly with increasing P supply. There was significant difference in total root length and average root diameter between treatments and genotypes in both acidic soils. Citrate was the dominant carboxylate in the rhizosphere of wheat genotypes, and malate was the second one. In canola genotypes, concentration of carboxylates in the rhizosphere were at least 10 times higher than rhizosphere of wheat genotypes. Surprisingly, malonate which there was not in the rhizosphere of wheat genotypes, was the most important carboxylate in the rhizosphere of canola genotypes followed by malate and citrate. This study showed there were significant differences between plant P-efficient and non-efficient in acidic soils when we used different level of P.

Production of barueiro seedlings in different substrates

Barueiro (Dipteryx alata Vog.) is one of the species native to the Brazilian cerrado that has economic potential. Thus, for the implantation of commercial orchards of this fruit tree, it is important to produce quality seedlings. This study aimed to evaluate the growth of barueiro seedlings under different substrates containing organic residues in the municipality of Nova Xavantina-MT. The experimental design used was randomized blocks (RBD), with 7 treatments (soil (control); soil + bovine manure (2: 1); soil + coffee husk (3: 1); soil + humus (2: 1); soil + coffee husk + humus (3: 1: 1); soil + coffee husk + bovine manure (3: 1: 1); and soil + humus + bovine manure (3: 1: 1)) and 4 replicates, with ten plants per plot, totaling 280 seedlings. Treatments consisted of substrates formulated with different proportions of soil, bovine manure, coffee husk and earthworm humus. Substrate containing only soil (control) provided greater plant height, stem diameter, number of leaves, number of leaflets, shoot and root fresh and dry mass and Dickson Quality Index. In general, residues tested did not favor the growth parameters evaluated, possibly because barueiro is a species native to the Cerrado, not very demanding in soil fertility. Under the conditions of this work, it is recommended the use of soil in the formulation of substrates to produce barueiro seedlings. The addition of organic matter to the soil had negative effect on seedling development.

Morphophysiology and quality of yellow passion fruit seedlings submitted to inhibition of gibberellin biosynthesis

The aim of this study was to verify if a growth reduction of yellow passion fruit seedlings’ growth morphophysiology and quality could be changed by paclobutrazol applied through seedling immersion. The experiment was conducted in a greenhouse, with seedlings grown in polyethylene tubes (290 cm3), with substrate. At 40 days after sowing, the seedlings were immersed in an aqueous solution of paclobutrazol at concentrations of 0, 50, 100, 150, and 200 mg L-1. The experiment was conducted in a randomized block design, with five treatments (paclobutrazol concentrations) and four replicates. At 15 and 30 days after treatment, growth characteristics were evaluated. At the end of the assay, destructive evaluations related to mass determination, total leaf area, and seedling quality index were performed. Paclobutrazol treatment induced restrictions in seedling growth, except for fresh and dry mass of root and total fresh mass. Based on these characteristics, the increase in values induced by paclobutrazol was verified. The seedling quality, defined by the major value of the Dickson quality index and a smaller robustness index, was higher when submitted to paclobutrazol treatment.

Growth analysis of schizolobium parahyba var amazonicum (huber ex ducke) barneby under different proportions of rock dust

The Cerrado is a biocore biome that occupies about 25% of the Brazilian territory, located mainly in the central region. Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby is a species of the Fabaceae family, occurring in primary and secondary terra firme forests of the Amazon region. This paper aims to evaluate the development of the species Schizolobium parahyba var. amazonicum (Huber ex Ducke) Barneby under different proportions of alternative substrate. Four treatments were used, distributed as follows: T1- Prepared Substrate (SP) 100% (Black soil, cattle manure and rice straw), control, T2- 80% SP + 20% Rock Powder (PR), T3- 65% SP + 35% PR, T4-50% SP + 50% PR. The design used was randomized blocks with 5 replications and the parameters used were: height, diameter, chlorophyll content, root dry mass (MSR), shoot dry mass (MSPA), total dry mass (MST), ratio root dry mass and shoot dry mass (MSR / MSPA), and Dickson quality index. The analysis of variance and means were compared by Tukey test at 5% probability using the Sisvar program. In all variables analyzed there was no significant difference for all treatments tested. The use of rock dust as fertilizer had no significant effects on the development of the studied species.

EFFECTS OF SALINITY ON GROWTH AND PROLINE CONTENT ON BEAN AND ALFALFA

Soil salinity is a major agricultural constraint in many countries. Plants’ response to salinity depends on the species and the salt concentration in the soil. The objective of this study was to test the resistance of three leguminous plants - common bean (variety ‘El-Jadida’), broad bean (variety ‘Claro de Luna’), and alfalfa (variety ‘Diamon’) - to several salinity rates and to show which one was more resistant to salt stress. This study was carried out under controlled conditions, with six NaCl concentrations (0, 1, 3, 6, and 9 g/kg) added to a mixture of potting soil and sand. A completely randomised design was used, where the three legumes were cultivated with different salt concentrations to determine the effect of these doses on fresh biomass, dry mass, and physiological parameters (sodium and proline content). The results showed the negative effect of salinity on fresh biomass and dry mass of shoots and roots. Claro de Luna, the broad bean variety, was more adapted to salinity than alfalfa and common bean. The amount of sodium in the shoots and roots of the three species increased with increasing salinity. Alfalfa may play a role in soil desalination; at 53.33 mM NaCl, 100 mg alfalfa dry mass absorbed 4.5 mg Na per pot, which corresponded to the uptake of about 0.6 kg Na per hectare of soil. Proline content increased with increasing salt concentrations.

Salinidade da água e ácido salicílico no crescimento de plantas de tomate

The tomato is one of the most important vegetables in Brazilian market. The production of this vegetable can be limited by the excess of salts in the water used for irrigation. The use of phytohormones, such as salicylic acid (SA), is used to minimize the negative effects of excess salts on plants. The objective of this paper was to evaluate the attenuating effect of salicylic acid on tomato plants growth irrigated with saline water. The experimental design was the randomized blocks in an incomplete factorial scheme 5 (SA doses: 0.0, 0.29, 1.0, 1.71 and 2.0 mM) x 5 (electrical conductivities of irrigation water - ECw: 0.5, 1.3, 3.25, 5.2 and 6 dS m-1), combined according to the experimental matrix Central Compound of Box, with four replicates and two plants per experimental plot. Growth evaluations were performed 45 days after the beginning of irrigation with saline water. Plant height, number of leaves, stem diameter, absolute and relative growth rate for plant height, root dry mass, shoot dry mass, total dry mass, Dickson's quality index, leaf area, specific leaf area and specific leaf weight were evaluated. The tomato plants growth was reduced by the increase in ECw. Salicylic acid, applied exogenously up to 2.0 mM, did not promote attenuating effect of salinity on tomato plants.

SUBSTRATES AND LIGHT CONDITIONS IN THE GROWTH OF SEEDLINGS OF Parkia multijuga BENTH.

The forest species Parkia multijuca Benth. occurs in the Northwest Region of Mato Grosso State, Brazilian Amazon region, important for the recovery of degraded areas of permanent preservation, mainly due to its rapid growth. The aim of this study was to identify the best combinations of substrates and light conditions for the development of Parkia multijuga seedlings in nursery. The experimental design was in randomized blocks, arranged in a plot scheme subdivided 4 x 11, with four replications. The light conditions were full sun, 30%, 50% and 70% shading. The substrates were: 1 - Soil; 2 - Soil + limestone "filler"; 3 - Soil + limestone + cattle manure; 4 - Soil + limestone + simple superphosphate; 5 - Soil + limestone + simple superphosphate + catlle manure; 6 - Solo + thermophosphate and 7 - Soil + thermophosphate + bokashi. The morphological parameters used were shoot height, diameter, number of leaves, total dry mass, shoot mass, dry mass of roots, relationship between height and diameter, height and dry shoot mass, between dry shoot mass and root dry mass, and the Dickson quality index (IQD). The seedlings of Parkia multijuga can be produced in a nursery with higher quality in full sun and in substrate with 25% cattle manure. Shading should not be used in the production of Parkia multijuga seedlings.

Strategies for increased yellow nutsedge (Cyperus esculentus) control in turfgrass with halosulfuron, sulfentrazone, and physical removal

AbstractYellow nutsedge is one of the most widely distributed and troublesome weeds in the world. Field and greenhouse studies were conducted to optimize strategies for increased yellow nutsedge control in turfgrass with halosulfuron and sulfentrazone. In the field study in yellow nutsedge and perennial ryegrass mixture, single or sequential applications (3 wk after initial) of halosulfuron or sulfentrazone were made on June 3, June 23, July 15, or August 5 in 2013, 2014, 2015, and 2016. Percent yellow nutsedge control was rated within the same growing season on September 17 and the following year on June 3 for carryover control. Field and greenhouse studies confirm that sequential applications of halosulfuron with a 3-wk interval resulted in &gt;95% control in a yellow nutsedge–turfgrass mixture. In a greenhouse study, both herbicides reduced yellow nutsedge root and rhizome dry mass from 39% to 98%, reduced number of new tubers and tuber fresh weight from 38% to 100%, and prevented re-emergence. Sequential applications of either herbicide within a 3-wk interval early postemergence is recommended for optimal control. Herbicide application to yellow nutsedge using halosulfuron and sulfentrazone should be made as early as possible postemergence, preferably at the three- to five-leaf stage or 200 to 250 growing degree days (GDD, 10 C base). Mowing can be an effective method to reduce yellow nutsedge growth. Mowing at 7.6 cm weekly reduced yellow nutsedge rhizome dry mass by 55% and number of new tubers formed by 63% in the greenhouse study. Physical removal of yellow nutsedge plants such as hand-pulling can be an effective method to manage yellow nutsedge and is most effective at the three- to five-leaf stage (200 to 250 GDD). End-users can maximize yellow nutsedge control by integrating early herbicide treatments and cultural practices such as mowing and hand-pulling.

Production of basil (Ocimum basilicum L.) under different soilless cultures

The main aim of this paper was to investigate the possibility of growing basil under three soilless systems (aeroponic, hydroponic and peatmoss slab systems). A model was developed to predict the nutrients consumption by basil plants. Shoot and root height, fresh and dry mass of whole plant, nutrients uptake, and oil content were studied during the growth period (after 4 and 7 weeks from transplanting). The results indicated that the shoot lengths of basil plants were 71.67 ± 2.89, 65.67 ± 1.15 and 62.33 ± 2.31 cm at the end of growth period for aeroponic, hydroponic and peatmoss slabs, respectively. The highest value of root height of basil plants was 37.67 ± 6.66 cm for aeroponic system. The dry mass of shoot of basil plants ranged from 28.48 ± 0.91 to 44.77 ± 0.97 and 72.98 ± 0.83 to 117.93 ± 1.40 g plant−1 after 4 and 7 weeks from transplanting, respectively. The highest values of the N, P, K, Ca and Mg uptakes were 753.99 ± 5.65, 224.88 ± 3.05, 449.75 ± 4.59, 529.12 ± 6.63 and 112.44 ± 1.67 mg plant−1 at the end of experimental period, respectively. The basil oil content ranged from 1.129 (1.11%) to 2.520 (1.80%) and 2.664 (1.42%) to 6.318 (1.44%) g plant−1 after 4 and 7 weeks from transplanting, respectively at the same pervious order. The production costs of basil plant were 2.93, 5.27 and 6.24 EGP kg−1 of plant. The model results were in a reasonable agreement with the experimental ones.

Stimulus to rooting of Saccharum sp. mini-cuttings with talc indole-butyric acid

Sugarcane is a commercially important species for sugar and biofuel production and because of the high demand for plant material in planting, new means of propagation are being developed and require improvements. Therefore, the objective of this study was to evaluate the effect of different concentrations of indole-butyric acid (IBA) applied in the form of talc on the initial growth and emergence of sugarcane mini-cuttings used for the system of pre-sprouted plantlets (PSP). Mini-cuttings were treated with concentrations of 0, 500, 1000, 1500 and 2000 mg kg-1 of IBA in the form of talc and evaluated for emergence and initial growth. There was no difference between IBA concentrations for the physiological, biometric and dry mass variables analyzed. The sugarcane plantlets formed had emergence above 89%, functional photosynthetic apparatus, 4.4 leaves on average, stem diameter of 11.90 mm, shoot length of 12.18 cm, leaf area of 108.81 cm² and root area of 142.17 cm². Shoot dry mass and root dry mass were equal to 2.27 and 1.20 grams, respectively. Thus, concentrations of up to 2000 mg kg-1 of IBA applied in the form of talc in sugarcane mini-cuttings had no effect on rooting and initial growth of plantlets.

Production and biochemical responses of cowpea under thermal and water stress

Water deficit and high temperature limit agricultural productivity, affecting plant growth, development, and metabolism. Thus, the objective of this study was to evaluate the impact of the interaction between water deficit and temperature increase on cowpea production. The experiment was carried out with the cultivar BRS Rouxinol, in growth chambers, in a 4 × 2 factorial arrangement, being four soil water availability (25; 50; 75 and 100% of field capacity) and two daily temperature regimes (T°1: 20-26-33 °C and T°2: 24.8-30.8-37.8 °C). The increase in water availability favored an increase in shoot and root dry mass. The vegetative stage was prolonged in plants maintained at a temperature regime of 24.8-30.8-37.8 °C. The cowpea yield increased with higher water availability. The water availability of 90% was the one that provided the highest water use efficiency. The 4.8°C increase in air temperature promotes an increase in oxidative stress with lack of synchrony in the antioxidative defense system. The cultivar Rouxinol is sensitive to the increase in air temperature and water deficit. However, even with 100% water availability, there was no seed production with an increase in air temperature.

Sewage sludge as organic matrix in the manufacture of organomineral fertilizers: Physical forms, environmental risks, and nutrients recycling

The use of organomineral fertilizers (OMFs) has grown worldwide, mainly in tropical conditions, combining economics and environmental management. Our study used a sewage sludge (SS) rich in Zn as the organic matrix in the manufacture of OMFs, with the following objectives: i) to select the best OMF physical form; ii) to evaluate environmental risks associated with their application; iii) to recycle SS nutrients for soybean (Glycine max) production; iv) to verify their benefits to soil microbial activity and other soil functions. For each soil individually, a clay and a sandy clay loam, six treatments were tested: control (CT, without fertilization); mineral fertilization (MF); MF plus Zn and B (MFZn + B); and three distinct physical forms for the OMFs [powder (Pw), granule (G), and pellet (Pt)], all calculated to provide 100 kg of P2O5 and performed in four blocks. Amending SS-OMFs did not represent an environmental risk in terms of spreading pathogens and hazardous trace elements. In comparison with MFs, SS-OMFs enhanced nutrients accumulation, pod numbers, and nodulation, as well as soil microbial activity, but did not affect shoot and root dry masses and enzymatic activities at early stages of soybean development (60 d after planting). They were also capable to supply Zn and B to plants and their distinct physical forms did not affect microbiological indicators of soil quality or nutrients accumulation in plant tissues. Overall, SS-OMFs seems to be a promising alternative for sustainable use of SSs in soybeans avoiding their disposal in landfills, but field studies are still needed to ratify the findings under more realistic conditions.

EFFICIENCY OF VEGETATIVE PROPAGATION OF CAJÁ-DE-JABUTI UNDER CONCENTRATIONS OF INDOLEBUTYRIC ACID AND GRAFTING METHODS

ABSTRACT The objectives of the tests were to evaluate concentrations of indolebutyric acid (IBA) combined with different types of cuttings and grafting methods on the vegetative propagation of cajazeira-dejabuti (S. testudinis). The experiment with stem cuttings was conducted in a greenhouse with an intermittent misting system. The experimental design was completely randomized in a 5 x 6 factorial arrangement consisting of five cutting types: apical, medial, basal, stratified, and tanchan, and six IBA concentrations: 0, 1,000, 2,000, 3,000, 4,000, and 5,000 mg kg-1, with four replications of ten cuttings. The experiment with the root cuttings followed a randomized block design composed of six IBA concentrations (0, 1,000, 2,000, 3,000, 4,000, and 5,000 mg kg-1) with four replications, evaluating after 120 days the percentages of live, sprouted, rooted, and calloused cuttings, and the number and dry mass of roots and sprouts. Five grafting methods (chip budding, shield budding, cleft grafting, wedge grafting, and splice grafting) were tested by evaluating the graft success and sprouting percentages at 30 and 60 days after grafting, respectively. Statistical analyses were performed using the Kruskal-Wallis non-parametric test. The IBA concentrations of 0, 2,000, 3,000, and 5,000 mg kg-1 increased the number of sprouts in tanchan cuttings. The tanchan cuttings showed the highest survival and percentage of sprouts regardless of the IBA concentration. The IBA concentration of 2,200 mg kg-1 promotes higher rooting rates in root cuttings. Splice grafting provides higher graft success and sprouting rates.