Cultivar BRS Guariba Research Articles

Strategies for Improving Cowpea Grain Yield in the Eastern Amazon: Biological Nitrogen Fixation, Phosphorus Nutrition, and Molybdenum Seed Enrichment

ABSTRACT This work aimed to evaluate the use of phosphorus (P) fertilizer, rhizobia inoculation, and seed enrichment with molybdenum (Mo) as tools for enhancing the cowpea yield in the Brazilian eastern Amazon. A set of field and greenhouse experiments were carried out in cerrado and upland forest environments. Four levels of P fertilization, eight rhizobia strains, and the application of mineral nitrogen (N) were evaluated for the cultivar BRS Tumucumaque (BR = Brasil e S = Sementes), and two levels of Mo seed enrichment were assessed for the cultivars BRS Tumucumaque and BRS Guariba. Grain yield increased linearly with the level of P applied. Inoculation with the rhizobia strain BR 3267 increased the shoot and nodule mass of the cultivar BRS Tumucumaque. There was no difference in grain yield and grain N accumulation between inoculation with seven rhizobia strains, N mineral fertilization and the control (without inoculation and N fertilization) in cerrado and upland forest environments. Cowpea grain yield and grain N accumulation were higher in the cerrado than in the upland forest environment and when the seeds were enriched with Mo. Phosphorus fertilization and seed enrichment with Mo are efficient tools to enhance cowpea yield in the Brazilian Amazon.

Viabilidade agrobioeconômica de combinações de cultivares de feijão caupi imaturo e de beterraba em ambiente semiárido

ABSTRACT The objective of this work was to evaluate the agro-bioeconomic feasibility of immature cowpea and beet cultivar combinations in intercropping systems in a semi-arid environment. Experiments were carried out in two cropping years using a randomized block design with four replicates. The treatments consisted of four cowpea cultivars (‘BRS Tumucumaque,’ ‘BRS Cauamé,’ ‘BRS Guariba,’ and ‘BRS Itaim’) and two beet cultivars (‘Early Wonder’ and ‘Fortuna’). In each block of the experiments, plots in monocropping of the cultivars were sown as additional treatments to obtain the following agronomic and competition indexes and economic indicators: land equivalent ratio (LER), area time equivalent ratio (ATER), land use efficiency (LUE), beet equivalent production (BEP), competitive ratio (CR), crop aggressivity (A), gross income (GI), net income (NI), rate of return (RR), and corrected monetary advantage (CMA). The highest agro-bioeconomic efficiency of the tested intercropping systems was achieved in the combination of cowpea cultivar BRS Guariba and beet cultivar Fortuna. Beet behaved as the dominant crop, and cowpea as the dominated crop in all evaluated intercropping systems. The indexes and indicators demonstrated the complementarity and sustainability of the combination of cowpea cultivar BRS Guariba with beet cultivar Fortuna.

Single inoculation with arbuscular mycorrhizal fungi promotes superior or similar effects on cowpea growth compared to co-inoculation with Bradyrhizobium

• The single inoculation of R. clarus and C. etunicatum promoted the accumulation of nitrogen in the aerial part of both cultivars. • Inoculation with C. etunicatum resulted in higher phosphorus content in the shoot of the BRS Guariba cultivar. • Plants inoculated with C. etunicatum had similar or superior performance to plants fertilized with NPK or P. This study evaluated the efficiency of arbuscular mycorrhizal fungi (AMF) and the effect of co-inoculation with Bradyrhizobium on mineral accumulation and growth of two cowpea cultivars. The experimental design was a 12 × 2 factorial arranged in a completely randomized design, with four replications. The first factor consisted of 12 nutrient treatments: one control, four with AMF ( Rhizophagus clarus and Claroideoglomus etunicatum , inoculated individually and as a mixture, and AMF-based commercial inoculum) and four with AMF + rhizobia ( Bradyrhizobium sp. BR 3262); the second factor included two cowpea cultivars (BRS Novaera and Guariba), totaling 96 plots. Morphophysiological traits of plants, nitrogen and phosphorus accumulation in the aerial part, and symbiotic efficiency of microorganisms were evaluated. Double inoculation with C. etunicatum and R. clarus and the co-inoculation with Bradyrhizobium had no effect on height, shoot dry mass and N contents in the shoot of cowpea when compared to single inoculation with AMF. Positive effects of co-inoculation with Bradyrhizobium were verified for root dry mass in the treatments CE+B.BR 3262 and RC+CE+B.BR 3262, and for chlorophyll index and phosphorus content of the cultivar BRS Novaera in the nutrient treatment RC+CE+B .BR 3262. The nutrient treatment with single inoculation of R. clarus and C. etunicatum promoted the accumulation of nitrogen in the shoot for both cultivars. For the BRS Guariba cultivar, inoculation with C. etunicatum also resulted in higher phosphorus content. Overall, plants inoculated with C. etunicatum had a performance similar or superior to plants fertilized with NPK or P, resulting in greater mycorrhizal efficiency, which may be an alternative to conventional fertilization for cowpea cultivars BRS Novaera and BRS Guariba.

Weed Dynamics and Yield of Cowpea Inoculated in Mulching (Crushed Capoeira)

Mulching (crushing capoeira) is an alternative system for the use of fire for cultivation in the Northern region of Brazil. Cowpea is considered an important food crop in this region; however, weeds might limit its productivity. This study aimed to evaluate the population dynamics of weeds and the productivity of cowpea with different habit of growth inoculated with Bradyrhizobium sp in mulching. The experiment was carried out in randomized blocks with the cultivars BRS Guariba and BR 17 Gurgueia, with and without inoculation of Bradyrhizobium sp and nitrogen fertilization as a control. Twenty-seven species and three genera of weeds were identified, distributed into 12 botanical families in the BRS Guariba cultivar and 25 species in ten families in BR 17 Gurgueia cultivar. The results revealed that the significative species were Vismia guianensis (Aubl.) Pers, Cyperus sp, Scleria melaleuca Rchb. ex Schltdl. & Cham, and Spermacoce verticillata L. Inoculation with Bradyrhizobium sp reduced the infestation of the most important species and presented higher productivity (1965.09 kg ha-1) than the treatment without inoculation (987.14 kg ha-1). The growth habit of cowpea cultivars in mulching (crushing capoeira) system did not affect crop yield, but longer studies are needed to validate the information obtained.

Genetically related genotypes of cowpea present similar bacterial community in the rhizosphere

Plant breeding reduces the genetic diversity of plants and could influence the composition, structure, and diversity of the rhizosphere microbiome, selecting more homogeneous and specialized microbes. In this study, we used 16S rRNA sequencing to assess the bacterial community in the rhizosphere of different lines and modern cowpea cultivars, to investigate the effect of cowpea breeding on bacterial community assembly. Thus, two African lines (IT85F-2687 and IT82D-60) and two Brazilian cultivars (BRS-Guariba and BRS-Tumucumaque) of cowpea were assessed to verify if the generation advance and genetic breeding influence the bacterial community in the rhizosphere. No significant differences were found in the structure, richness, and diversity of bacterial community structure between the rhizosphere of the different cowpea genotypes, and only slight differences were found at the OTU level. The complexity of the co-occurrence network decreased from African lines to Brazilian cultivars. Regarding functional prediction, the core functions were significantly altered according to the genotypes. In general, African lines presented a more abundance of groups related to chemoheterotrophy, while the rhizosphere of the modern cultivars decreased functions related to cellulolysis. This study showed that the genetic breeding process affects the dynamics of the rhizosphere community, decreasing the complexity of interaction in one cultivar. As these cowpea genotypes are genetically related, it could suggest a new hypothesis of how genetic breeding of similar genotypes could influence the rhizosphere microbiome.

Agronomic performance of cowpea cultivars (Vigna unguiculata (L.) Walp) under application of limestone doses

Evaluating agricultural management practices, such as liming, is essential in regions with acidic soils to increase the yield of agricultural crops. The aim was to evaluate soil fertility, agronomic performance, and grain quality of cowpea cultivars under application of limestone doses. The experiment was carried out in Argissolo Vermelho Amarelo (Ultisol), with initial base saturation of 26%, during two agricultural years. A randomized block design was used, in split plots, with four replications. The plots were composed of five limestone doses (0, 1, 2, 3 and 4 times the recommended rate to reach 50% base saturation), and the subplots were formed by two cowpea cultivars (BR 17 Gurgueia and BRS Guariba). The applied doses of limestone, with relative total neutralizing power (RTNP) of 91%, were 0, 1.3, 2.6, 3.9 and 5.2 t ha-1. Liming increased soil fertility, increasing pH, calcium, magnesium, and base saturation, and decreasing soil acidity. Maximum grain yields were obtained with limestone doses between 3.1 and 3.2 t ha-1 for the cultivar BR 17 Gurgueia and between 3.3 and 3.4 t ha-1 for the cultivar BRS Guariba, reaching average base saturation values of approximately 48 and 55%, respectively.

Late harvest and chemical treatment of cowpea seeds

Reduced quality ofcowpea due to late harvest and therefore pathogen incidence may influence the results of the germination test, whenever losses are associated with the agentsadhered to seed coat;in that context, chemical treatmentof seeds during the evaluations may reflect more accurately physiological quality of the samples, which in turn may assurethe emergence results of healthy seedlings and establishment of appropriate plant populations inthe field. This study had the objective ofevaluating the effects of fungicide treatment on minimizing physiological quality losses of cowpea seedsdue to lateharvestin germination and seedling development tests. The experimental design was the completely randomized with four replications. Treatments consisted of cowpea, cultivar BRS Guariba, harvested at different times (0, 3, 6, 9, 12 and 15 days after physiological maturity)andtreated or not with fungicide carboxim+thiramfor seed quality tests. Seeds were initially characterized by seed moisture and mass. Afterwards, sampleswere evaluated by tests ofgermination percentage, germination first count, seedling length and dry matter. Data was submitted to variance analysisand means were analyzed as a 2x6 factorial. Means from chemical treatment and harvest times were compared by the Tukey test and regression analysis (p≤0.05), respectively, with subsequent unfolding of any significant interactions. Delayed harvest of cowpea seeds sharply reduces germination and vigor; fungicide treatment before performing physiological tests enables to establish thatseed quality losses can bein part caused by pathogen vehiculationonthe seed coat.

Modelling to obtain expanded cowpea products in a twin screw extruder

Abstract Cowpea grains are nutritious and beneficial to health, contain about 25% of proteins, in addition to carbohydrates, vitamins, minerals, and bioactive compounds. Soaking the beans followed by cooking requires time availability that is incompatible with the current lifestyle. Consumers have opted for read-to-eat, attractive, healthy, nutritious and convenient foods, thus, transforming cowpeas into crispy expanded product is promising. This research aimed to evaluate the effect of the extrusion conditions, moisture, and temperature, on the physical characteristics of the extrudates developed from cowpea cotyledons flour (CCF): from cultivar BRS Guariba (Sorriso, MT, Brazil). The CCF was processed using twin-screw thermoplastic extruder ZSK 30 (Werner & Pfleiderer Co.) varying the moisture (16.2% to 21.8%) and temperature (124 to 166 °C) using Central Composite Rotatable design 22. The expansion index values ranged from 3.01 to 3.98, the regression model was not predictive, with the determination coefficient (r2) equal to 0.67. The independent variables studied presented significant effects, being water solubility index affected by the CCF moisture, compression force (15.63 to 47.72 N) affected by the extruder temperature, the water solubility index (28.34% to 43.67%) by moisture, while the specific volume (2.41 to 4.58 mL g-1) and the water absorption index (5.34 to 6.54 g g-1) were affected for both variables. By simulation, the maximum value of 1 was obtained through the global desirability test in the combination of an extrusion temperature of 124.21 °C and conditioning moisture of CCF of 16.28%. This condition favors obtaining extrudates with greater values for a specific volume and water absorption index, and lower values for compression force and water solubility index.

Assessing the vigor of cowpea seeds using the Vigor-S software

Abstract: The use of computational resources to assess the physiological potential of seeds has attracted the attention of researchers and professionals in the seed sector. The aim of this study was to evaluate the vigor of cowpea seeds using the Vigor-S software (Automated Seed Vigor Analysis System), in comparison to the information provided by traditional vigor tests that are recommended for the species. Seven seed lots of the cultivar BRS Guariba were used. They underwent germination and seed vigor assessment by testing first germination count, accelerated aging, electrical conductivity, seedling emergence, speed of seedling emergence and use of Vigor-S, an automated image system for seedling assessment, in two evaluation periods. The data underwent analysis of variance, in a completely randomized design and their means were compared by the Scott-Knott test (p ≤ 0.05). An analysis was made of the correlation between the vigor tests traditionally used and the variables provided by Vigor-S. Using the Vigor-S software for automated image analysis of cowpea seedlings three days after sowing is an efficient alternative to detect differences in vigor between seed lots, similarly to traditional seed vigor evaluations.

Sources of resistance to black aphid in cowpea varieties used as green grains

Evaluation of resistance of Vigna unguiculata L. landraces, used as green beans, to Aphis craccivora Koch was tested. Eleven landraces and standard genotypes were used in a free choice protocol: BR 17-Gurguéia, VITA 7 (susceptible), BRS Guariba and TVu 408P2 (resistant). A completely randomized blocks design was used with six replicates. Seedlings were infested with five six-day-old adult insects. The number of alive adults after 48 h and of alive nymphs after 96 h was evaluated. The results evidenced that there are high genetic diversity among the landraces, the antibiosis as the main mechanism of resistance. By means of multivariate analysis we suggest crosses among the commercial cultivar BRS Guariba and the most dissimilar varieties CCE-088, CCE-075, CCE-013 and CCE-062 to obtain superior hybrids.

Sources of resistance to black aphid in cowpea varieties used as green grains

Evaluation of resistance of Vigna unguiculata L. landraces, used as green beans, to Aphis craccivora Koch was tested. Eleven landraces and standard genotypes were used in a free choice protocol: BR 17-Gurguéia, VITA 7 (susceptible), BRS Guariba and TVu 408P2 (resistant). A completely randomized blocks design was used with six replicates. Seedlings were infested with five six-day-old adult insects. The number of alive adults after 48 h and of alive nymphs after 96 h was evaluated. The results evidenced that there are high genetic diversity among the landraces, the antibiosis as the main mechanism of resistance. By means of multivariate analysis we suggest crosses among the commercial cultivar BRS Guariba and the most dissimilar varieties CCE-088, CCE-075, CCE-013 and CCE-062 to obtain superior hybrids.

Herbicide weed control – induced differential tolerance and productivity in cowpea plants

The use of herbicides is a represents an efficient way to control the infesting plant population, since it is associated with low operational cost, and it does not demand large amounts of labour. An obstacle to growing cowpea (Vigna unguiculate) is the absence of herbicides registered for this crop. The objective of this work was to evaluate the tolerance of cowpea to herbicides. The experiment was carried out in a randomised block with treatment controls with and without weeding, Bentazon (720 g ha-1), Fluazifop-p-butyl (250 g ha-1), Fomesafen and a tank mix between Fluazifop-p-butyl + Fomesafen (250 + 187.5 g ha-1) with treatment replicates. The herbicides were applied on vegetative (V3 – stage) cowpea plants using a CO2-pressurised backpack sprayer with four spray tips TT 110.02 operating at a pressure of 2.5 bar and applying 240 litres of syrup per hectare. The cultivar BRS Guariba, with five planting lines per plot, was tested with the three central lines of the useful area, scoring 0.5 m of the ends. The species Oxalis latifolia was difficult to control. The Fluazifop-p-butyl + Fomesafen mixture presented better control of weeds. The herbicides caused phytotoxicity to cowpea and reduced leaf area and dry mass. The productivity of the crop was affected due to the low control of weeds. It was concluded that the cowpea presented differential tolerance to the herbicides tested doses.

Pasting properties of raw and extruded cowpea cotyledons flours

Abstract There is little research on the viscosity profile analysis of cowpea cotyledon flour (CCF). Due to the new ways of using pulses grains in the diet, it is important to evaluate the viscoamylographic behavior of raw and processed CCF. The CCF was obtained from the cultivars BRS Guariba and BRS Novaera and evaluated in the Rapid Visco Analyzer (RVA). For raw CCF it was used the “Standard 1” program. The extruded CCF was obtained from the cultivar BRS Guariba, which was processed following a central rotational composite design, combining thermoplastic extrusion temperatures (124; 130; 145; 160; 166 °C) and conditioning moisture (16.2%; 17%; 19%; 21%, 21.8%). The obtained extrusions were ground (Ø > 0.5 mm) and evaluated in the RVA using the program “Extrusion 2”. The raw CCF from BRS Guariba presented higher protein, lipid and mineral content and lower carbohydrate content than BRS Novaera. The raw CCF from BRS Guariba showed lower values of pasting temperature (79.35 °C), viscosity breakdown (103.00 cP) and seatback (1447.33 cP) compared to raw CCF from BRS Novaera. The extrusion process drastically changed all viscosity parameters, increasing the initial viscosity value and decreasing the value of other parameters. The extruded CCF had different pasting properties. CCF extruded at 166 °C and 19% moisture resulted in flours with higher initial viscosity and lower retrogradation values, which can be used as a thickener in food products, in addition to increase nutritional value.

Physiological Quality of Cowpea Beans (Vigna unguiculata L.) Seeds in the Function of Cultivars and Planting Times

Germination and vigour evaluation of improved cultivars and creole of cowpea bean seeds as a function of different planting seasons. A completely randomized design in a factorial scheme, with six treatments and two planting periods, with four replications, each repetition with 25 seeds. The treatments consisted of six cowpea bean (Vigna unguiculata L.) cultivars, and two improved (BRS Tumucumaque, BRS Guariba) and four creoles, (Governor, Passagem, Chico Joaquim and Espírito Santo). The experiment place and timing was carried out under greenhouse on a riparian zone of the Federal Rural Semi-Arid University (UFERSA), located in the municipality of Mossoró-RN, Brazil. The first sowing season comprised the period from April 3 to April 18, 2017, and the second one from January 15 to 30, 2018. The sowing was done in plastic trays. Was used the sand washed and sterilized as a substrate. The trays were kept in a greenhouse at room temperature. Two irrigations were realized daily. In order to avoid the local effect, the trays were changed position each day. The evaluated characteristics were: Germination percentage, emergence speed index, seedling height, leaf number, root length, stem diameter, fresh and dry mass of seedlings. Creole cultivars showed superior quality to those improved in the second season. In the first season, the cultivars BRS Guariba and BRS Tumucumaque were the most outstanding. It was concluded that the physiological quality of cowpea beans is directly influenced by the cultivars and the planting season, as well as by the interaction of these two factors.

Silicon foliar application attenuates the effects of water suppression on cowpea cultivars

ABSTRACT Silicon and proline play important physiological, metabolic and functional roles in plants, especially under water deficit conditions. Their application can mitigate the adverse effects of stress in crops by increasing water use efficiency and antioxidant activity. The objective of this study was to evaluate silicon (Si) as attenuator of the effects of water deficit on cowpea cultivars, through physiological, biochemical and growth indicators. The experimental design was randomized blocks with four cultivars (BRS Guariba, BRS Itaim, BRS Aracê and BRS Rouxinol) and four irrigation treatments associated or not with Si application (W100 - 100% ETo; W50 - 50% ETo; W50+100Si and W50+200Si, with 100 and 200 mg L-1 silicon, respectively), in a 4 x 4 factorial scheme, with five replicates. Leaf water potential, proline concentration, antioxidant enzymes and growth indicators were evaluated in cowpea plants. Under water deficit conditions, all cultivars showed reductions in leaf water potentials, which compromised plant growth. However, Si applications of 200 mg L-1 in the cultivar BRS Guariba and 100 and 200 mg L-1 in the cultivar BRS Itaim minimized the effects of stress, by increasing leaf water potential and the activity of the enzyme ascorbate peroxidase, in both cultivars, besides increasing proline concentration in the former and reducing proline concentration in the latter, which ensured the maintenance of growth. Despite the no contribution to the increase in water potential, Si applications of 100 and 200 mg L-1 in BRS Rouxinol and BRS Aracê, respectively, reduced the deleterious effects of the stress on their growth by regulating the enzymatic metabolism and proline.

Weed Interference in Semi-Erect and Semi-Prostate Cowpea Cultivars

ABSTRACT: This study aimed to determine weed interference periods in semi-erect and semi-prostrate cowpea cultivars. Two simultaneous experiments were conducted with the cowpea cultivars BRS Guariba (semi-erect) and BRS Aracê (semi-prostrate). The experimental design was a randomized block design with four replications in a 7 × 2 factorial scheme, seven periods × two weed management (control and coexistence). Control and coexistence periods consisted of 0, 0-8, 0-16, 0-24, 0-32, 0-45, and 0-60 days after emergence (DAE) for the semi-erect cultivar and 0, 0-8, 0-16, 0-24, 0-32, 0-45, and 0-64 DAE for the semi-prostrate cultivar. Competition throughout the cycle reduced productivity by up to 39.81% for BRS Guariba and 37.27% for BRS Aracê. The cultivars BRS Guariba and BRS Aracê presented critical period of interference prevention of 9 to 41 DAE and 15 to 32 DAE, respectively. The semi-prostrate cultivar BRS Aracê was more competitive with weeds, requiring a shorter control period to express maximum productivity.

TOLERÂNCIA DO FEIJÃO-CAUPI A DIFERENTES HERBICIDAS APLICADOS EM PÓS-EMERGÊNCIA

One of the obstacles to the production of cowpea is the intensity of weed infestations that may interfere with its productivity. The objective of this work was to evaluate the tolerance of cowpea, cultivar BRS Guariba, to the herbicides Linuromand Quizalofope-P Etílico, in the initial stage of development of the crop. The experiment was conducted in sequestrationsystem, emergency irrigation underfield conditions in experimental design with randomized blocks, nine treatments and four replicates. The treatments evaluated were: 50% Quizalofope-P-Ethyl; 50% of Linurom; 100% Quizalofope-P-Ethyl; 100% of Linurom; 50% Quizalofope-P-Ethyl+ 50% Linurom; 50% Quizalofope-P-Ethyl+ 100% Linurom; 100% Quizalofope-P-Ethyl+ 50% Linurom; 100% of Quizalofope-P-Ethyl+ 100% of Linurom,and Manual weeding (control). Visual evaluations of weed control, phytotoxicity, plant height, number of leaves and stem diameter were performed. The cowpea plants, BRS Guariba cultivar, presented high tolerance tothe herbicides 50% and 50% in the post-emergence applications. The herbicide 100% Linurom and the formulation of the Quizalofope-P-Ethyl + Linurom cause severe damage to the development of cowpea. The herbicides blended with 100% of Quizalofope-P-Ethyland 100% of Linurom potentiatesthe effect of the herbicides on the cowpea crop, causing the death of the plants.

Germination and tolerance of cowpea (Vigna unguiculata) cultivars to water stress

ABSTRACT The objective of this study was to evaluate the tolerance of cowpea cultivars to water stress, during seed germination and seedling establishment. For this, a completely randomized experimental design was used in a factorial scheme consisting of nine cultivars of cowpea (BRS Guariba, BRS Potengi, BRS Itaim, BRS 17 Gurguéia, BRS Aracê, Paulistinha, Maratanã, Costela-de-Vaca and Canapu-Branco) and two levels of osmotic potential induced by PEG 6000 (0.0 MPa (control) and -0.4 MPa) in four replicates of 50 seeds. The variables analysed were germination, germination first count, root and shoot lengths, and dry matter accumulation of shoots and roots. The dissimilarity between the genotypes was also determined by Euclidean distance. Germination and initial development of cowpea cultivars are impaired by the reduction in the potential to -0.4 MPa. The cultivars BRS Guariba, BRS Aracê, Paulistinha and Canapu-Branco are the most tolerant to water stress, while BRS Potengi, BRS Itaim, BRS 17 Gurguéia, BRS Maratanã and Costela-de-Vaca are the most sensitive in the early development stage.

AGRONOMIC PERFORMANCE OF COWPEA ELITE LINES IN THE STATES OF MINAS GERAIS AND MATO GROSSO, BRAZIL

ABSTRACT The objective of this work was to evaluate the agronomic performance of erect and semi-erect cowpea elite lines grown in the States of Minas Gerais and Mato Grosso, Brazil. The experiments were conducted in Jaíba, Janaúba, Sete Lagoas (Minas Gerais), Primavera do Leste and Nova Ubiratã (Mato Grosso), with 20 genotypes of cowpea, arranged in a randomized block design with four replications. The data were subjected to individual and joint analyses of variance and means grouped by the Scott-Knott test (p<0.05). The plant growth habit, lodging, cultivation value, pod length and bean yield were evaluated. The lines MNC04-768F-21 and MNC04F-795F-168 had the highest bean yield in the experiments conducted in Mato Grosso, and their growth habit, lodging and cultivation value were similar to those of the cultivar BRS-Guariba. The lines MNC04-769F-30, MNC05-795F-154 and MNC04-769F-49 and the cultivar BRS-Tumucumaque had the highest bean yield in the experiments conducted in Minas Gerais. However, the cultivars BRS-Guariba, BRS-Tumucumaque, BRS-Novaera, BRS-Itaim and BRS-Cauamé and the lines MNC04-792F-143 and MNC04-792F-144 showed satisfactory bean yield and good growth habit, plant lodging and cultivation value in the State of Minas Gerais, especially in the northern region of the state (Jaíba and Janaúba), representing good alternatives for the genotypes recommended for this region.

GERMINATION AND INITIAL GROWTH OF COWPEA CULTIVARS UNDER OSMOTIC STRESS AND SALICYLIC ACID

ABSTRACT Cowpea is one of the major food crops in Northeast Brazil, where it is commonly cultivated in the semi-arid regions with limited water availability. It is important to study the elicitors associated with cowpea to mitigate any deleterious effects of abiotic stress on the initial establishment of this crop. In this study, we aimed to evaluate the morphophysiological changes in cowpea cultivars under osmotic stress with seeds soaked in salicylic acid. The germination test was conducted in B.O.D germination chambers. The seeds of three cowpea cultivars: BRS Tumucumaque, BRS Aracê, and BRS Guariba, were germinated at five osmotic potentials (0.0; -0.2; -0.4; -0.6, and -0.8 MPa) after three pre-treatments: pre-soaking in deionized water, pre-soaking in salicylic acid, and without pre-soaking. The following parameters were evaluated: germination, germination speed index, seedling height, total phytomass, contents of chlorophyll ‘a’ and ‘b’, carotenoid content, electrolyte leakage, water content, and proline content. Our results indicate that salicylic acid promotes reduction in the harmful effects of abiotic stress, which is reflected in the increase in germination percentage, seedling height, and chlorophyll and carotenoid content as well as in the adjustment of electrolyte leakage and increase in proline content under induced water stress conditions. The cultivar BRS Guariba proved to be more tolerant to water deficit during germination and initial growth stages, when the seeds were treated with salicylic acid (1 mM).