Showing papers in "Bragantia in 2019"

Forage sorghum-legumes intercropping: effect on growth, yields, nutritional quality and economic returns

Abstract: Cereal-legumes intercropping is among the most economical and effective agronomic strategies to boost forage biomass production, nutritional quality and monetary returns. This review synthesizes the research findings on how intercropping affects productivity, quality, competitiveness and economic viability of sorghum-legumes mixed, row and strip intercropping systems under varied pedo-climatic conditions. Though component crops show yield reductions in row (additive and row-replacement series), mixed (seed blended crops) and strip intercropping systems, in general overall productivity per unit land area increases to a great extent. The significantly higher resource capturing with better utilization efficacy by intercrops in temporal and spatial dimensions helps explain their greater productivity. In addition, forage intercrops result in improved nutritional quality as legumes contain protein in double quantity than cereals. Cereal-legumes intercropping systems yield higher quantities of lush green forage with improved quality traits, which ultimately increase monetary benefits. Furthermore, legumes inclusion as an intercrop with cereals has the potential to serve as a nitrogen-saving strategy due to the biological nitrogen fixation (BNF) process. Moreover, cereal-legume intercropping systems are effective in reducing weed infestations and soil erosion by providing extended soil cover, as well as in increasing water use efficiency and improving soil fertility. However, despite a significant increase in overall productivity, component crops suffer yield losses in intercropping systems owing to competition for the finite divisible pool of growth resources. Thus, there is a dire need to optimize spatial and temporal arrangements in sorghum-legumes intercropping systems to achieve maximum productivity and economic returns.

Effects of cover crops on soil hydraulic properties and yield in a persimmon orchard

Abstract: This study evaluated the effects of cover crops on yield and soil hydraulic properties of a persimmon orchard in Turkey. Soil samples were taken from 0-20 and 20-40 cm. Profiles of a clay soil and field capacity, permanent wilting point, available water capacity and saturated hydraulic conductivity of the samples were determined. Festuca rubra subsp. rubra, Trifolium repens, Festuca arundinacea, a mixture of them [Trifolium repens (40%) + Festuca rubra rubra (30%) + Festuca arundinacea (30%)], Vicia villosa R., and Trifolium meneghinianum were used as the cover crops. The experiment was conducted in a randomized complete blocks design with four replications including a mechanically cultivated and herbicide treated control plots. The greatest mean persimmon yield (16.2 Mg·ha-1) was observed in the Vicia villosa treatment and the lowest mean yield (3.6 Mg·ha-1) was observed in the bare control. The cover crops increased soil hydraulic properties, with increased aggregate stability, total porosity, reduced bulk density, and penetration resistance. The greatest increases in organic matter contents at 0-20 cm soil depth in the persimmon orchard were observed in the Vicia treatments (73.4% in the first and 74.5% in the second year). The highest aggregate stability (67.4%) and total porosity (60.9%) values were obtained on the Vicia treatments. To increase persimmon yield and improve soil physical and hydraulic properties, cover crops, especially Vicia villosa and Trifolium repens are suggested for clay soils.

Evaluation of common bean genotypes for drought tolerance

Abstract: The aim of this study was to evaluate twelve genotypes of common bean for intermittent drought stress and for root growth angle. The water deficit experiments were conducted in 2015 and 2016in a randomized block experimental design with split plots and three replications. Two treatments were applied: an irrigated treatment and a water deficit treatment, in which irrigation was suspended in pre-flowering and remained suspended up to the time at which the matrix potential of the soil was measured to be near –199 kPa. Atthe maximum point of water deficit, physiological and morphological traits were evaluated, and at physiological maturity, the yield compounds and grain yield. To evaluate root growth angle in 2016, a growth pouch system was used in a randomized block design, with five replications. Water deficit reduced genotype performance for all the traits except leaf temperature and first pod height. In relation to grain yield, the genotypes SEA 5 and Carioca Precoce performed better under water restriction conditions in both evaluations. The genotype Gen TS 4-7 performed better in the 2015 evaluation, and Gen TS 3-1 andGen TS 3-3 in 2016. SEA 5, Gen TS 3-1, and Carioca Precoce had the highest harvest indexes in 2015; and Gen TS 3-1, Gen TS 3-2,Gen TS 3-3, Gen P5-4-3-1, IAPAR 81, Carioca Precoce, and SEA 5 in 2016. SEA 5 and Carioca Precoce had the best root growth angle and were considered sources of tolerance to water deficit.

Drought stress mitigation with humic acid in two Cucumis melo L. genotypes differ in their drought tolerance

Abstract: Different responses of two melon (Cucumis melo L.) genotypes (Semame, drought and salt-tolerant and Ananas, drought and salt-sensitive) to drought stress with or without humic acid (HA) treatment were studied. The experiment was carried out under greenhouse conditions. The experimental design was two factorial randomized block with 4 replicates. HA treatment increased the shoot fresh and dry weights and leaf area of both genotypes under drought stress. HA stimulated accumulation of K and Ca ions, chlorophyll (SPAD value) and antioxidant enzyme activity (superoxide dismutase-SOD, catalase-CAT and glutathione reductase-GR) in both genotypes. This effect was more clear in the Semame genotype than in Ananas.As a result, HA treatment has been proved to influence the ability of melon genotypes to cope with drought stress and to increase their tolerance.

Development of superior lines of papaya from the Formosa group using the pedigree method and REML/Blup procedure

Abstract: Developing superior lines based on a simultaneous response from many traits of agronomic importance is a fundamental strategy to expand papaya cultivar supply, mainly the much-needed cultivars belonging to group Formosa. Our goal was to associate the pedigree method with REML/Blup procedure to select plants of progenies F2:3 with superior agronomic performance. The variance components and genetic parameters were estimated using REML approach, and the genetic values were predicted using Blup methodology. The combined selection was performed using the IG2 selection index based on weights associated with agronomic values to indicate the best progenies and lines. The heritability estimates of progeny mean were high in most traits and evidenced significant genetic variability between progenies. The narrow-sense individual heritability was moderate in traits such as commercial fruits and soluble solid contents, which indicates a favorable condition for selections within progenies. The index was consistent in the selection of six superior progenies according to the assessed traits. This index also enabled promising genetic gains in traits of great interest such as yield and pulp thickness. Although the progenies are derived from self generations, they proved to be superior in traits of significant importance such as yield, commercial fruits, and pulp thickness when compared to the Tainung-01 hybrid, which is a worldwide-planted cultivar used as a reference to Formosa representatives. Six lines were selected within the superior progenies to continue the Formosa group-lines development program. The association of the pedigree method with REML/Blup procedure can be useful to assist breeders in an autogamous breeding program.

Bayesian analysis of growth, stem straightness and branching quality in full-sib families of Eucalyptus globulus

Abstract: Eucalyptus globulus is one of the most commonly planted hardwood species for industrial use in various temperate regions around the world. The present study aimed to evaluate 62 full-sib families of E. globulus in one of the southernmost progeny trials of the species in the south of Chile. Estimates of genetic parameters for stem straightness, branching quality and growth traits were based on a Bayesian modelling approach using Gibbs sampling. A Bayes Factor (BF) analysis supported the hypothesis of significant additive genetic variation for all traits under study. Conversely, the BF supported a model with significant dominance effects for the diameter at breast height and stem volume, which explained up to 25% of the phenotypic variation. The greatest narrow-sense heritability estimates were found for the tree height and stem straightness, which were 0.15 (0.08 to 0.26) and 0.18 (0.10 to 0.28), respectively (mean of posterior distributions and 90% credible sets). In turn, the branching quality had a low heritability (narrow-sense) that varied from 0.05 to 0.10 (90% Bayesian credible region). The mean posterior estimate of genetic correlation between both quality traits was 0.22 (0.01 to 0.63, 90% credible set from a bi-trait threshold model), which indicates that stem straightness is positively related to branching quality. Our findings reveal that the study population responds to common patterns of breeding populations of E. globulus. This information is valuable for the development of improved seeds in the southern zone of Chile.

Phytodesalination of a moderately saline soil combined with two inorganic amendments

Abstract: The shortage of water and the increasing salinity are the main limiting environmental factors that directly affect the establishment and the development of crops. In this research, phytodesalination capacity of Sesuvium verrucosum was evaluated alone and in combination with agricultural gypsum (CaSO4·2H2O) and Polisul-C, in order to remedy a moderately saline soil at greenhouse level and under nonleaching conditions. The treatments studied were the following: T1 (soil), T2 (soil + S. verrucosum), T3 (soil +S. verrucosum + Polisul-C), T4 (soil + S. verrucosum + CaSO4·2H2O). Polyvinyl chloride (PVC) tubes filled with 8 kg of clay soil with an electrical conductivity of the saturation paste extract (ECe) of6.21 dS.m-1 were used. Soil samples were analyzed to determine the ECe, and the soluble and interchangeable cations (Na+, K+, Ca2+ and Mg2+) content. Then, the halophytic plants were divided into root and aerial parts and the content of Na+, K+, Ca2+ and Mg2+ was determined. In summary, S. verrucosum showed potential to desalinate its rhizosphere. Moreover, S. verrucosum desalination capacity significantly increases when used in combination with either of the tested amendments. This increase occurred mainly in the upper layers of the clay soil (0-30 cm). CaSO4·2H2O was shown to be the most effective amendment, since a greater gain in biomass and a large accumulation of sodium (Na+) in the aerial part of S. verrucosum was observed as a consequence of the soil improved physico-chemical properties caused by this chemical.

Weed interference period and economic threshold level of ryegrass in wheat

Abstract: The study of weed interference periods and the economic threshold level (ETL) of weeds on crops allows the adoption of management methods and the rationalized use of herbicides. The objective of this study was to determine the periods of interference and to test mathematical models to determine the economic threshold level of ryegrass in the wheat crop. Two experiments were carried out in a randomized block design with four replications. The first experiment was conducted in the 2014/2015 agricultural season. The periods of interference and control of ryegrass were studied in wheat. The periods of interference and/or control were: 0, 10, 20, 30, 40, 50 and 120 days after emergence (DAE). The second experiment was conducted in the 2016/2017 agricultural season. The ETLs were studied, being the treatments composed of wheat cultivars and 12 populations of ryegrass, in competition with the respective cultivars. The results allowed concluding that the management methods of weed ryegrass must be adopted in the period between 11 and 21 days after crop emergence, which is described as a critical period of control of this weed. The wheat grain yield loss competing with ryegrass reached 59% when grown with ryegrass. For ETL, the linear regression model of the rectangular hyperbola adequately estimates grain yield losses in the presence of ryegrass. The cultivar presenting the lowest values of ETL, that is, less capacity to live with the weed, was TBIO Alvorada. The other cultivars presented similar ETL values.

Post-harvest physicochemical profile and bioactive compounds of 19 bananas and plantains genotypes

Abstract: Nineteen genotypes of bananas and plantains were analysed in order to differentiate the subgroups and/or groups of consumption or industrial use. Genotypes of banana and plantain from different genomic groups and in three ripening stages (2, 5 and 7) were studied in relation to physical and physicochemical characteristics, including bioactive compounds. Furthermore, with the obtained data analysed by multivariate statistical analyses (Principal Component Analysis) it was possible to relate all analysed characteristic profile of samples with the different genotype. The three ripening stages were differentiate by total soluble solids, titratable acidity, chrome (C*) and the carotenoids contents. ‘Ney Poovan’ contain high total soluble solid content and pulp-to-peel ratio, an interesting result for the promotion of this genotype for in natura consumption. ‘Ney Poovan’, ‘Ouro da Mata’, ‘Pelipita’ and ‘Tiparot’ are sources of antioxidant compounds. The genotypes ‘Pelipita’ and ‘Samura B’ are promising for the industrial use, mainly for the processing of banana chips, for both green and ripe fruit.

Oxidative stress and differential antioxidant enzyme activity in glyphosate-resistant and -sensitive hairy fleabane in response to glyphosate treatment

Abstract: Biochemical assays in a time-course were employed to evaluate stresses induced by glyphosate treatment in resistant and sensitive biotypes of Conyza bonariensis. Two experiments were conducted assessing glyphosate doses and time-course after treatment. The doses of glyphosate ranged from 0 to 11840 g ae·ha–1 and assessments performed until 552 h after glyphosate treatment (HAT). The objectives of this study were to evaluate the oxidative stress and differential antioxidant enzyme activity in glyphosate-resistant and -sensitive biotypes of hairy fleabane after glyphosate treatment. After treatment, both studied biotypes accumulated similar levels of shikimic-acid until 96 h. The sensitive biotype died at192 HAT. Shikimic-acid and hydrogen peroxide (H2O2) accumulation in glyphosate-resistant biotype were transient and did not differ from untreated plants at 288 and 500 HAT, respectively. In both glyphosate-resistant and -sensitive biotypes, a correlation analysis established a cause-and-effect relationship after glyphosate treatment, which leads to shikimic-acid and hydrogen peroxide accumulation, lipid peroxidation (indicates tissue damage) and an enhancement in the activity of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) enzyme. However, in the glyphosate-resistant biotype, the oxidative stress and tissue damage were lower, and antioxidant enzyme activities SOD, CAT, and APX were higher than in the -sensitive biotype. It indicates that antioxidant enzyme in glyphosate-resistant biotype might be related to the glyphosate-resistance process in Conyza bonariensis. This study is the first report of differential antioxidant enzyme activity in hairy fleabane.

Aluminum stress tolerance in potato genotypes grown with silicon

Abstract: Potato cultivation is widespread around the world, being exposed to several abiotic stresses, including soils with high aluminum (Al) availability. Silicon (Si) is recognized for alleviating the stress caused by Al in various plant species. Thus, the aim of this study was to investigate the potential of Si to mitigate the oxidative stress caused by Al in potato genotypes, exhibiting differential sensitivity toward this element. Plants of the Al-sensitive genotype (SMIJ319-7) and Al-tolerant genotype (SMIF212-3) were grown for two weeks in a hydroponic system with the nutrient solution containing combinations of Al (0 and 1.85 mM) and Si (0, 0.5 and 1.0 mM). At the end of the experiment, photosynthetic parameters, pigment content, root and shoot growth, superoxide dismutase and guaiacol peroxidase activity and lipid peroxidation were evaluated. In both potato genotypes Al inhibited root and shoot growth and decreased all photosynthetic parameters and superoxide dismutase activity. Silicon was able to partially alleviate the damage caused by Al in parameters of root growth in the Al-tolerant genotype while increasing the activity of antioxidant enzymes and mitigating the Al-induced damage to membrane lipids in roots and shoot in both genotypes. The Al-tolerant genotype showed greater water use efficiency and transpiration rate in control conditions as compared to the Al-sensitive genotype. These data indicate that Si application can improve the defense ability of the tested potato genotypes against Al toxicity and that the Al-tolerant genotype is more responsive to Si.

Using climate change models to assess the probability of weather extremes events: a local scale study based on the generalized extreme value distribution

Abstract: Regional climate models (e.g. Eta) nested to global climate models (e.g. HadGEM2-ES and MIROC5) have been used to assess potential impacts of climate change at regional scales. This study used the generalized extreme value distribution (GEV) to evaluate the ability of two nested models (Eta-HadGEM2-ES and Eta-MIROC5) to assess the probability of daily extremes of air temperature and precipitation in the location of Campinas, state of Sao Paulo, Brazil. Within a control run (1961-2005), correction factors based on the GEV parameters have been proposed to approach the distributions generated from the models to those built from the weather station of Campinas. Both models were also used to estimate the probability of daily extremes of air temperature (maximum and minimum) and precipitation for the 2041-2070 period. Two concentration paths of greenhouse gases (RCP 4.5 and 8.5) have been considered. Although both models project changes to warmer conditions, the responses of Eta-Hadgem2-ES to both RCPs are significantly larger than that of Eta-Miroc5. While Eta-Hadgem2-ES suggests the location of Campinas will be free from agronomic frost events, Eta-Miroc5 indicates that air temperature values equal to or lower than 5 and 2 °C are expected to present a cumulative probabilityof ~0.20 and ~0.05, respectively (RCP 8.5). Moreover, while the Eta-Miroc5 projected a reduction in the extreme-precipitation amounts, the Eta-Hadgem2-ES projected implausible large daily precipitation amounts. The Eta-Miroc5 performed better than the Eta-Hadgem2-ES for assessing the probability of air temperature and precipitation in Campinas. This latter statement holds particularly true for daily-extreme precipitation data.

Hybrid maize selection through GGE biplot analysis.

Abstract: The cultivation of genotypes non-adapted to the cultivation region of interest is among the main factors responsible for low yield. The aim of the present study is to select hybrid maize through GGE biplot analysis and to assess its adaptability and stability in different environments in Northeastern Brazil. Twenty-five hybrid maize cultivars were assessed in ten different environments in Northeastern Brazil in 2012 and 2013 based on the randomized block design, with two replications. The analysis of variance and assessment of genotype adaptability and stability were made through GGE biplot analysis, based on grain yield. Analysis of variance results showed different performances depending on the genotype, as well as genotype/environment interaction. The biplot analysis was efficient on data interpretation and represented 63.73% of the total variation in the first two main components, it also allowed classifying the ten environments into three macro-environments. Most environments were positively correlated. Hybrids 2 B 604 HX, 30 A 95 HX, 2 B 587 HX and 2 B 710 HX were responsive and stable. Hybrid 30 A 16 HX was recommended for macro-environments2 and 3. Cultivar 30 A 68 HX was recommended to environment 1. Sao Raimundo das Mangabeiras and Nova Santa Rosa counties were discriminating and representative. Nossa Senhora das Dores, Umbauba, Teresina, Brejo, Frei Paulo, Colinas and Balsa counties were ambiguous and non-recommended for further evaluations.

Physiological and toxic effects of selenium on seed germination of cowpea seedlings

Abstract: Selenium (Se) is considered a beneficial chemical element for plants, but in high concentrations it may present symptoms of toxicity. The present study aimed to evaluate 11 concentrations of Se (0; 0.1; 0.5; 1; 5; 10; 20; 40; 80; 400; 800 mg.L-1) to determine the low and high (toxicity) critical levels to seed germination of cowpea (Vigna unguiculata). In addition, alterations in the rate of photosynthetic pigments, lipid peroxidation and sugars during the initial growth development of seedlings were analysed. Seeds exposed to 800 mg.L-1 of Se showed a decrease of 20% of seed germination index compared to the control treatment. The decrease in seedling growth reflected in the increase of total sugars and sucrose concentration in both the shoot and root in response to exposure to Se concentration. There was a decrease in the concentration of leaf chlorophyll, carotenoids and pheophytin from seedlings exposed to high Se concentration. The rate of lipid peroxidation and the hydrogen peroxide concentration in the shoot was reduced up to the concentration of 1 mg.L-1 with subsequent increase in response to Se concentration applied. In the roots, the lipid peroxidation rate increased at concentrations higher than 80 mg.L-1. The highest oxidation rate of the cellular lipid membrane in response to Se occurred in the shoot, due to oxidation reactions in the chloroplast. Degradation of photosynthetic pigments and accumulation of total sugars and sucrose can be considered efficient biomarkers to indicate the toxicity of Se in cowpea seedlings and probably in other crops.

Gypsum application, soil fertility and cotton root growth

Abstract: Since there is no consensus on phosphogypsum (PG) rates to be used in agriculture, a better understanding of its effects on the soil solution is needed. Cotton root growth was evaluated as related to Al and Ca activity in soil solution affected by PG. The experiment was carried out in rhizotrons filled with30∙dm–3 of soil. PG rates were estimated by multiplying the soil clay content by 0.0, 1.5, 3.0, 6.0 and 12.0, and it was mixed to the sub-soil.In the upper soil layer, limestone was applied. After 90 days, samples were taken for analysis, and cotton was planted. After27 days, plants were harvested. PG increased soil pH and decreased Al content and activity. Without PG, dissolved organic carbon concentration was high in the soil solution, which explains the predominance of carbon Al-complexed with PG application. From 1,680 kg∙ha–1 of PG (corresponding to 6 × clay content), sulphur and calcium had the highest concentrations, increasing the SO4 Al-complexed. Cotton root length decreased in the upper layer and increased in the subsoil up to 2,324 kg∙ha–1 (corresponding to 8.3 × clay content) of PG. Cotton root growth is better related with soil properties than with soil solution attributes, and the present recommendations for PG use based on soil clay content underestimate the rate to be applied.

Relationship between the normalized difference vegetation index and leaf area in vineyards

Abstract: In vineyards, the monitoring of leaf area is used to guide management practices in order to produce grapes with quality and enological potential. Remote sensing has been used to estimate leaf area by means of vegetation indices. This work aimed at determining the temporal evolution of the Normalized Difference Vegetation Index (NDVI) while associating it with leaf area of vineyards in the Serra Gaucha region, Brazil. To this end, between 10 and 20 plants were evaluated monthly (September to May) in three vegetative seasons. NDVI data were obtained using the remote sensor Greenseeker while the following leaf area related parameters were obtained non-destructively: unit leaf area (ULA), average number of leaves per branch (NLB), plant leaf area (PLA), leaf area index (LAI) and chlorophyll index (CI). Data correlation was assessed by joint temporal analysis and Pearson correlations (p < 0.05). The results indicated that NDVI variation over time is coherent with the leaf area dynamics and expresses biomass variations due to phenology and management actions. The NDVI evolution pattern is described by a quadratic regression equation: the index increases rapidly at first (September to November), followed by a relative stabilization (December to February), and decreases in the final stage (March to May). The correlations were higher in the initial and final stages of the cycle, especially for NLB (r = 0.73 and 0.77), PLA (r = 0.60 and 0.61) and CI (r = 0.48 and 0.84), which are promising parameters for characterizing leaf area in vineyards by remote sensing.

Compatibility and horticultural performance of Pera sweet orange clones grafted to Swingle citrumelo rootstock

Abstract: Despite its interesting agricultural traits, Swingle citrumelo (Citrus paradisi Macfad. ‘Duncan’ × Poncirus trifoliata L. Raf.) rootstock exhibits severe incompatibility when grafted with Pera sweet orange [Citrus sinensis (L.) Osb.] scions, and this fact limits its use for propagation purposes. Nonetheless, the existence of certain Pera sweet orange clones that are compatible with Swingle citrumelo represents a substantial gain for the entire citrus industry. This study investigated the compatibility between seven Pera sweet orange clones and Swingle citrumelo rootstock, regarding the presence of a necrotic line at the graft union junction, the difference in diameter between rootstock and scion, the influence of clonal cleaning by micrografting, and the horticultural performance of the selected combinations. No trees died because of grafting incompatibility, even after twenty years (trial I), except for clone CV1, or after six years and nine months (trial II) from planting. The rootstock/scion trunk diameter ratio was not related to the presence of a necrotic line in the graft-union region. Additionally, these variables did not influence fruit yield and quality, and they were not affected by clonal cleaning or pre-immunisation of the old Pera sweet orange clones.

Microbial biomass and organic matter in an oxisol under application of biochar

Abstract: The aim of this study was to investigate the short- and medium-term effect of biochar on soil microbial properties, organic carbon and nitrogen in an Oxisol from Brazil. The experiment was conducted in a randomized block design consisting of five levels of biochar (0, 2, 4, 8 and 16 Mg∙ha–1) with and without of synthetic fertilizer: 0 and 200 kg.ha–1 of synthetic fertilizer N-P-K (00-20-20). The following soil properties were determined: microbial biomass carbon (MBC) and nitrogen (MBN), microbial respiration (MR), metabolic quotient (qCO2) and microbial quotient (qMIC), total organic carbon (TOC) and nitrogen (TN). The MBC, qCO2 and carbon management index (CMI) were not altered by doses of fertilizer and biochar. The presence of biochar reduced the MBN by 11% and 5% with the application of16 Mg∙ha–1 compared to control in the third and sixth year, respectively. The qMIC was reduced exponentially with the application of biochar, but was within normal limits as a proportion of total organic carbon. There was an increase in TOC and TN with the application of biochar. The use of biochar did not cause significant negative changes in soil microbial properties or contribute to carbon sequestration in the soil.

Differential expression of the genes involved in responses to water-deficit stress in peach trees cv. Chimarrita grafted onto two different rootstocks

Abstract: Water deficit is responsible for a negative impact on agricultural systems. Several physiological, biochemical, and molecular processes are initiated as a response to water-deficit stress. Quantifying the differential expression of the genes involved in the response to water-deficit stress plays a key role in the development of molecular strategies for engineering water-stress tolerance in plants. Therefore, the present study aims to evaluate the expression of key genes involved in the water-deficit response process in peach trees cv. Chimarrita grafted onto two different rootstocks. The experimental design was completely randomized, with four treatments that correspond to the evaluation periods: day zero (control), the fourth, seventh, and ninth days of water-deficit stress. Leaf samples of each Chimarrita/rootstock combination were analyzed separately. The expression of the genes related to ethylene biosynthesis, osmotic adjustment, and carbohydrate metabolism, namely ACC oxidase, GTL, SDH, SIP1, SOT1, S6PDH, and P5CS was quantified by real-time quantitative polymerase chain reaction (RT-qPCR). A differential response was observed in the expression of the SDH, GTL, P5CS, and SIP1 genes between Chimarrita/rootstock (Aldrighi 1 and Tsukuba 2)combinations. In both combinations of grafting, the S6PDH gene presented the highest level of expression at the fourth day of stress. These results show that genes related to carbohydrate and proline metabolism are important molecular markers to identify variability to water-deficit tolerance in Prunus persica.

Agronomic performance and genetic dissimilarity of second-harvest soybean cultivars using REML/BLUP and Gower’s algorithm

Abstract: The cultivation of second-harvest with soybean crop after first-harvest with maize crop has become an alternative to aggregate income to farmers in the South region of Brazil. However, there is little information about this cropping system in this region. The aims of this study were to: (i) evaluate the agronomic performance of soybean (Glycine max L.) cultivars growing in second-harvest during the summer; and (ii) evaluate the genetic divergence of the cultivars based on qualitative and quantitative traits. To do this, 18 soybean cultivars were evaluated in three field trials, sown during January in the northwestern region of Rio Grande do Sul state, Brazil. In each experiment, a randomized block design with four replicates was used. Five quantitative traits (representing the agronomic performance of the cultivars) and 12 qualitative traits (morphological descriptors) were assessed aiming at studying the genetic divergence. Variance components and genetic parameters were estimated using mixed models and BLUPs for genotypes were estimated for each quantitative trait. The cultivars FPS Iguacu RR and BMX Turbo RR have good agronomic performance and are, based on quantitative and qualitative traits, genetically distant. These cultivars have shown agronomic features that allow their cultivation in the second-harvest in the northwestern of Rio Grande do Sul in addition to be potential genitors for future soybean breeding programs.

Soil conservation management with cover crops: effects on critical energy levels, release and dispersion of aggregates

Abstract: The normalized dispersion index (NDI) and the b/a index are commonly used to express the stability of aggregates measured by ultrasound. However, few studies have used the critical energy (CE) extracted from modeling to explain the effects of soil use and management on soil aggregation. The objective of this study was to evaluate the influence of soil cover on the CE level required for dispersion of aggregates of a Typic Hapludalf. Soil samples collected from the 0.0-0.05 m depth were evaluated in five different managements with cover plants: perennial soybean (PS), peanuts (P), spontaneous vegetation (SV), black oat/forage turnip (BOFT), and black oat/hairy vetch (BOHV). Aggregates ? 2 mm of the treatments were exposed to ultrasonic irradiation during 0, 30, 60, 120 and 180 s. The specific applied energies were calculated based on sonification time and potency: 0, 745, 1490, 2980, and 4470 J·g–1. After each sonification, sand (2000-53 ?m), silt (53-2 ?m) and clay (< 2 ?m) were quantified. The mass of aggregates of each size class was modeled as a function of the ultrasonic energy. The CE, the NDI and the b/a indexes were coefficients extracted from these models. Cover crops influenced the critical energy levels required for dispersion of aggregates of the Typic Hapludalf. However, our methodology did not prove management systems with intercrops of the cover crops, as black oats and vetch, contribute more effectively to the increase of soil aggregation.

Longer crop cycle lengths could offset the negative effects of climate change on Brazilian maize

Abstract: Maize (Zea mays) is considered one of the most important crops for world food security. Globally, Brazil is the second largest maize producer and the fourth largest maize consumer. The climate variables is one of the main determining factors for crop yield. Given the possibility of future climate changes, our objective was to evaluate the impact of climate change on maize crop growth and development, assessed strategies to cope with the future crop and to quantify the impacts on various producing regions of Brazil. The DSSAT/CERES-Maize model was calibrated with field data and then used to simulate current and six future climate scenarios, according to the AgMIP protocols. We selected three regional climate AGROMETEOROLOGY Article Longer crop cycle lengths could offset the negative effects of climate change on Brazilian maize Tamires Teles de Souza*, Luís Alberto Silva Antolin, Vitor de Jesus Martins Bianchini, Rodolfo Armando de Almeida Pereira, Evandro Henrique Figueiredo Moura Silva, Fábio Ricardo Marin Universidade de São Paulo Escola Superior de Agricultura “Luiz de Queiroz” Departamento de Engenharia de Biossistemas Piracicaba (SP), Brazil. *Corresponding author: tamiresteles@usp.br Received: Feb. 26, 2019 – Accepted: June 13, 2019 circulation models (GCMs) and two representative concentration pathways (RCPs) for the period of 2040-2069. For most of the producing regions, the simulations showed a decreasing trend during both the summer and autumn sowing seasons, except the autumn crops in Southern Brazil. We found the air temperature rise as the main factor for yield decreasing, and this finding provides an adaptation option to cope with future climate, as the country has a great latitudinal range for crop management, meaning genotypes with extended cycles could compensate the climate change, and thereby avoid the yield loss for maize crops.

Selection and genetic parameters for interpopulation hybrids between kouilou and robusta coffee

Abstract: Selection of hybrid coffee plants coming from crosses between divergent populations is particularly relevant for the success of breeding programs. This study aimed to outline the best selection strategy in a hybrid population of Coffea canephora var. kouilou and robusta by estimating intrapopulation genetic parameters. Twenty full-sib progenies obtained by North Caroline II were installed in a randomized complete blocks design, with one plant per elementary plot. The following traits were evaluated: vegetative vigor, reaction to rust, plant height, diameter of canopy projection, maturity time, and bean yield. Significant individual genotypic variance and heritability estimates lead to an effective selection. The multi-trait selection index carried out between progenies and at individual level provided 5% and 40% gain, respectively. Thus, intrapopulation selection in a hybrid population is a viable strategy for the selection of superior individuals to compose new crosses and clones for cultivars in the breeding program of C. canephora, even with unbalanced data.

Foliar application of silicon decreases wheat blast symptoms without impairing photosynthesis

Abstract: Considering the importance of blast, caused by Pyricularia oryzae, to impact wheat yield, this study investigated whether the foliar spray of potassium silicate (PS) could affect the photosynthesis of wheat plants and its potential to reduce disease symptoms. The Exp. 1 aimed to determine the effect of the foliar spray of PS on the photosynthetic performance of plants and was arranged in a completely randomized design with six treatments (plants sprayed with PS rates of 2.5, 5.0, 7.5, 10.0, and 12.5 g·L-1 at 35 days after emergence) and six replications. The leaf gas exchange (net CO2 assimilation rate (A), internal CO2 concentration (Ci), stomatal conductance to water vapor (gs), and transpiration rate (E)) as well as fluorescence of chlorophyll a (maximal photosystem II quantum yield (Fv/Fm), quantum yield of non-regulated energy dissipation [Y(NO)], photochemical yield [Y(II)], electron transport rate (ETR), and quenching non-photochemical [Y(NPQ)]) parameters were evaluated. The Exp. 2 was carried out to determine the effect of PS on blast control and also on the photosynthetic performance of plants. Plants at 35 days after emergence were sprayed with PS rate of 12.5 g·L-1, which did not affect photosynthesis on plants from Exp.1. This experiment was a 2 × 4 factorial and arranged in a completely randomized design with six replications. The factors studied were plants non-inoculated or inoculated plants and the spray of water, PS, fungicide (trifloxystrobin 10% + tebuconazole 20%; 0.75 L/ha), and fungicide + PS. There were no significant changes in the values of A, gs, E, Ci, Fv/Fm, Y(NO), Y(II), Y(NPQ), and ETR for plants sprayed three times (every 96 h interval) as the PS rates increased from 2.5 to 12.5 g·L-1. There was no significant relationship between the PS rates with either absorbance, reflectance or transmittance on the leaf blades. Linear regression model best described the foliar Si concentration-PS rates relationship. Foliar Si concentration significantly increased by 44 and 42%, respectively, for the PS and PS + fungicide treatments compared to water-sprayed plants. The area under disease progress curve was significantly lower by 64, 58, and 53%, respectively, for the fungicide, PS, and fungicide + PS treatments in comparison to water-sprayed plants. The photosynthetical process, primarily related to the Fv/Fm parameter, on wheat leaves was greatly impaired during the infection process of P. oryzae, but to a lesser extent on the leaves of PS-sprayed plants. In conclusion, the foliar spray of PS can be an environmentally friendly strategy to control wheat blast without causing perturbation to the photosynthetic machinery of wheat plants.

Genetic control of aluminum tolerance in tropical maize germplasm

Abstract: Aluminum (Al) toxicity is the most limiting factor to maize crop productivity in acid soils. Therefore, the understanding of inheritance of Al tolerance in maize is important for the developmentof more adequate procedures for Al tolerant genotypes selection. In this sense, the objectives of this study were to determine the inheritance, and the general (GCA) and specific combining ability (SCA) for Al tolerance in tropical maize. First, we evaluated diallel crosses of maize from landrace and hybrid germplasms for Al tolerance through the minimal solution methodology. The DIF data (root growth difference) were analyzed by Griffing diallel model. Later the additive-dominant genetic model proposed by Mather and Jinks (1971) was used to estimate the genetic effects. The results of the diallel analysis showed greater variability associated with the estimates of the SCA for both germplasm. The diallel crosses involving the V 06 (Dente de Ouro 2) landrace stood out by high SCA and GCA for Al tolerance. The generation mean analysis indicated quantitative inheritance of Al tolerance in this germplasm, with most of the variance explained by the additive effects. The heritability in the narrow sense varied from 47% to 71%, indicating the possibility of genetic gain with the selection of tolerant genotypes in F2 generation. Additive gene action associated with intermediate heritability and quantitative inheritance demonstrates the possibility of genetic gains with artificial selection for Al tolerance in this maize germplasm.

Performance evaluation of different soil water retention functions for modeling of water flow under transient condition

Abstract: ABSTRACT: Description and prediction of water flow through unsaturated soils is necessary to understand their hydraulic properties, including soil water retention curve (SWRC). Many models have been developed for estimation of SWRC and many researchers compared water retention curve derived from these models with the measured values. In this paper, in addition to comparing measured and derived SWRC, a functional evaluation of SWRC for modeling of soil water movement was carried out using van Genuchten, Brooks-Corey, Campbell and Hutson-Cass models in three sites including Loamy sand, Loam and Clay loam soils. Therefore, the functional behavior of SWRC was quantitatively compared by applying mentioned SWRC to numerical code (HydroGeoSphere) to simulate soil profile drainage under steady-state and transient conditions. The agreement between simulated and measured free drainages values was evaluated using statistical criteria including mean absolute error (MAE), modified index of agreement (d’), modified coefficient efficiency (E’), and t-test. The results demonstrated that the van Genuchten model was slightly better than the other models for estimation of SWRC (MAE 0.014 – 0.016,E’ 0.80 – 0.87 and d’ 0.90 – 0.93) while according to t-test, it was found that the measured and estimated SWRC using various models did not differ significantly. Therefore, it is expected that the simulated free drainage using mentioned SWRC models did not differ significantly with observed values. But the results demonstrated that the simulated free drainage using Brooks-Corey model for Loamy sand soil and van Genuchten and Brooks-Corey models for Loam soil differed significantly (p ≤ 0.05) with measured values.

Selecting “the best” nonstationary Generalized Extreme Value (GEV) distribution: on the influence of different numbers of GEV-models

Abstract: The selection of an appropriate nonstationary Generalized Extreme Value (GEV) distribution is frequently based on methods, such as Akaike information criterion (AIC), second-order Akaike information criterion (AICc), Bayesian information criterion (BIC) and likelihood ratio test (LRT). Since these methods compare all GEV-models considered within a selection process, the hypothesis that the number of candidate GEV-models considered in such process affects its own outcomehas been proposed. Thus, this study evaluated the performance of these four selection criteria as function of sample sizes, GEV-shape parameters and different numbers candidate GEV-models. Synthetic series generated from Monte Carlo experiments and annual maximum daily rainfall amounts generated by the climate model MIROC5 (2006-2099; State of Sao Paulo-Brazil) were subjected to three distinct fitting processes, which considered different numbers of increasingly complex GEV-models. The AIC, AICc, BIC and LRT were used to select “the most appropriate” model for each series within each fitting process.BIC outperformed all other criteria when the synthetic series were generated from stationary GEV-models or from GEV-models allowing changes only in the location parameter (linear or quadratic). However, this latter method performed poorly when the variance of the series varied over time. In such cases, AIC and AICc should be preferred over BIC and LRT. The performance of all selection criteria varied with the different number of GEV-models considered in each fitting processes. In general, the higher the number of GEV-models considered within aselection process, the worse the performance of the selection criteria. In conclusion, the number of GEV-models to be used within a selection process should be set with parsimony.

Backcrosses in a segregating population of Passiflora mediated by morphoagronomic and resistance traits

Abstract: The present study aims to characterize the genetic diversity of Passiflora setacea, P. edulis, their hybrids, and first-backcross progenies, and to indicate promising recombinants for generation advancement in a breeding program for transferring resistance to cowpea aphid-borne mosaic virus (CABMV). Ninety-one genotypes were evaluated for 37 morphoagronomic descriptors. The traits were analyzed to obtain a distance matrix, based on the Gower algorithm, using the Ward-Modified Location Model (MLM) procedure for the composition of genetic groups. The adopted strategy led to the formation of five homogeneous groups, where groups I, III, and V comprised the parents P. setacea, P. edulis and interspecific hybrids, respectively, while groups II and IV consisted of 69 genotypes of BC1. Broad variability was observed among the tested genotypes, and the highest was shown by group IV. Genotypes 17, 293, 355, and 501, from group IV, were the most promising for the second backcross cycle as they showed good resistance to the disease and desirable morphoagronomictraits.

Local genotypes of dog rose from Interior Aegean region of Turkey as a unique source of pro-health compounds

Abstract: Rosehip, Rosa canina L. fruit, is valued for its flavor, taste, color and aroma, in accordance with its recognition as one of richest sources of pro-health compounds. Screening, preservation and propagation of the most valuable local populations of rosehip are performed for food, pharmacological, and cosmetic applications. Eleven native R. canina genotypes from the Interior Aegean region, Turkey, were collected and analyzed regarding organic acids, phenolic compounds, sugars, and DPPH scavenging activity within this study. Regarding biochemical profile of fruits, protocatechuic acid and quercitrin were the most dominant compounds among 12 identified phenolics. The dominant organic acids were malic and citric and fructose and glucose were the dominant sugars. There was no correlation between DPPH scavenging activity and the analyzed chemicals in fruits. Although levels of certain compounds varied significantly between consecutive years, the ranking of genotypes according to the levels of particular chemicals was maintained. Generally, the most promising chemotype regarding biological value was 64US03. The chemical composition and the presence of bioactive compounds make the native to Interior Aegean R. canina genotypes a valuable source of bioactive agents preventing oxidative-stress related diseases.

Genetic diversity, population structure and AFLP markers associated with maize reaction to southern rust

Abstract: Maize is one of the species with greater genetic diversity among cereals and possibly the most diverse crop species known. Accessing this variability is essential for maize breeding, allowing breeders to achieve progress of yield increasing, overcome environmental challenges or deal with pests and diseases. Among the maize diseases, southern rust is one of the most important, causing significant losses in yield and presenting severe epidemics worldwide. In the present study, the AFLP technique was applied to analyze population structure and genetic diversity among 145 tropical maize inbred lines, and to test for preliminary evidence of association between AFLP markers and the reaction to southern rust. Disease severity was evaluated in two crop seasons and the accessions were genotyped through AFLP using four primer combinations. The clusters obtained based on the Jaccard genetic distance and Ward’s hierarchical clustering and those achieved by structure simulations had high concordance and were capable of establish two big clusters, one predominantly of common maize and another of popcorn. The association analysis was performed using four different statistical models. The more complete model containing both population structure and genetic relatedness narrowed the number of significant associations, demonstrating its importance to control false associations. A total of 19 significant marker associations were identified from which three (EactMctg18, EactMctg205, EactMctg169) are interesting candidates for further investigations.