Resumo em Inglês:

ABSTRACT Climate change is already affecting life on Earth and mitigation measures must be taken, which require proper identification of the regions most vulnerable to these changes. This study assesses the impact of climate change on water availability (water surplus, water deficit and precipitation minus evapotranspiration) and climate classification across the Caatinga biome, located within the Brazilian semiarid region. To obtain the water surplus and water deficit, the water balance of Thornthwaite & Matther (1955) was applied considering the current scenario (historical series from 1961 to 2015); the optimistic scenario, considering the Representative Concentration Pathway (RCP) for a radiative forcing of 4.5 W.m-2 (RCP4.5), i.e., considering a temperature increase of 1.5 ºC and a reduction in rainfall from 15%; and pessimistic, considering a radiative forcing of 8.5 W.m-2 (RCP8.5), i.e. taking an increase in temperature of 4.0 ºC and a reduction in rainfall from 20%. The results showed that the Caatinga was strongly impacted, especially in the pessimistic scenario, with no water surplus and a negative water balance. For the optimistic scenario, only a small portion presented a water-surplus and a positive water balance. Projections also showed that a large part of the Caatinga changed from semiarid to arid climate.

Resumo em Inglês:

ABSTRACT Adjuvants mayimprove control efficiency of volunteer RR® corn with ACCase inhibiting herbicides. Thus, the aim of this study was to evaluate the effects of adjuvant addition to the herbicides clethodim and quizalofop, on surface tension, spray deposition and efficiency of volunteer RR® corn control. The surface tension of clethodim (96 g a.i. ha-1) and quizalofop (60 g a.i. ha-1) herbicides with and without a mineral oil, a vegetable oil and an organosilicon adjuvant was evaluated at concentrations of 0.01; 0.05; 0.1; 0.5; 1.0 and 2.0% v v-1. To evaluate deposition and visual control efficiency, the same herbicides associated or not with the mineral oil (0.5% v v-1), the vegetable oil (0.5% v v-1) and the organosilicon adjuvant (0, 05% v v-1) were used. For this, volunteer RR® corn plants were grown in a greenhouse until stage V2-V3. The adjuvants reduced the surface tension of the herbicides clethodim and quizalofop, organosilicon was the most efficient. Adjuvants does not alter spray deposition of herbicides on corn plants. Mineral oil increases potential control of clethodim herbicide and anticipates control with quizalofop herbicide.

Resumo em Inglês:

ABSTRACT The objective of this work was to assess the effects of A. brasilense inoculation on seeds on the yield performance of maize and black oat as a function of nitrogen rate over a 3-year succession. The experiment was conducted from 2015 to 2018 under field conditions. Maize was grown for three growing seasons in rotation with two seasons of black oat at the same experimental site. A randomized block design with a split-plot arrangement was used. Main plots consisted of A. brasilense inoculation (inoculated and uninoculated plants) and subplots of four nitrogen rates (0, 40, 80, and 120 kg ha−1). Maize plants were evaluated for biometric parameters, yield, and yield components at flowering. Black oat plants were analyzed for dry matter yield at flowering. The inoculation of A. brasilense in maize and black oat seeds in succession does not promote productivity nor does it favor the nitrogen fertilization of these cultures.

Resumo em Inglês:

ABSTRACT Species of the Amaranthus genus are very versatile and have potential for the application in the development of commercial products. The near infrared spectroscopy (NIR) is an efficient tool that can help in the quality control of products, quickly and non-destructive to the sample. The goal of this study was to carry out the distinction of seed and oils of different Amaranthus species using the near infrared spectroscopy. Three species were used: A. viridis L., A. hybridus L. e Amaranthus sp. (commercial). The spectra acquired from the sample using the near infrared spectroscopy were submitted to the partial least squares discriminant analysis (PLS-DA) and to the principal component analysis (PCA). Through PCA, it was possible to differentiate the Amaranthus species both for seeds and oils. Through PLS-DA, it was possible to predict the classes of the species with high degree of correct classification, with 96.67% of correct classifications for seeds and 98.89% for oil. Thus, with the use of the near infrared spectroscopy associated with the multivariate statistical analysis, it is possible to classify the different Amaranthus species, especially when using the oil.

Resumo em Inglês:

ABSTRACT Light is a determining factor in plant morphophysiology, as it influences the growth and development of agricultural crops. Thus, the objective was to investigate the effects of light sources on the growth and development of “biquinho” pepper cultivars. The experiment was performed in two stages (Exp1 and Exp2), evaluating two cultivars (BRS Moema; Airetama biquinho) in five light sources (white LEDs, red LEDs, blue LEDs, red/blue LEDs, and fluorescent lamps). In Exp1 the plants were kept in a controlled condition, with a completely randomized design, in a 2x5 factorial scheme (cultivars x light sources) until 76 days after emergence (DAE), in which growth variables and photosynthetic pigments were evaluated. In Exp2, the plants were removed from the above conditions and transplanted in pots, being kept in greenhouse for more 76 DAE. At 152 DAE, the same variables as Exp1 were evaluated, as well as gain of shoot fresh and dry mass, and gain of root fresh and dry mass. In both experiments, growth variables were affected by cultivar and the light sources, however, the behavior did not follow the same trend for all variables, indicating that the light quality influences the growth of the crops, and impacting during greenhouse conditions.

Resumo em Inglês:

ABSTRACT Remote monitoring of the management of coffee crops is necessary as the demand in decision-making, where the aim is to rise production based on sustainable management is in a constant growth. In this work, it was evaluated the potential of images obtained by low-cost sensors in the discrimination of sources and doses of mineral and organomineral fertilizers in coffee. The experimental design was in randomized blocks, with five blocks and six treatments, as follows: (T1) - 100% of the organomineral treatment; (T2) - 70% of the organomineral treatment; (T3) - 50% of the organomineral treatment; (T4) - 100% of mineral fertilization; (T5) - standard treatment of the farm and (T6) - 70% of mineral fertilization. After management, we used the Mapir 3 Survey3W camera coupled to an ARP drone – Phantom4 to take images of the experiment over a 12-month vegetative period. Combined with image taking, it was collected agronomic parameters of coffee growth and productivity for two crops and concluded that different fertilization doses did not significantly affect the analyzed parameters. Based on the supervised classification of multispectral images, it was possible to discriminate treatments with a higher degree of accuracy (86.66% accuracy) than when analyzing coffee growth parameters.

Resumo em Inglês:

ABSTRACT Campomanesia adamantium (Cambess.) O. Berg (guavira) is a native plant of the Cerrado and Pantanal, which has several medicinal activities and fruits with a unique flavor rich in vitamin C. The species does not have defined cultivation methods, requiring studies to increase biomass production. An alternative is the use of organic residues that can influence the chemical, physical and biological characteristics of soils and consequently increase plant production. Thus, the objective was to evaluate the effect of different organic residues and bokashi, on the biomass production of plants and on the levels of phenols, flavonoids and antioxidant activity of tea from the leaves of guavira. Five substrates were studied in pots and protected environment: soil; soil + rice husk chicken manure; soil + sawdust chicken manure; soil + castor bean cake; soil + Organosuper® with or without the use of Bokashi in a 5x2 factorial scheme, in a randomized block experimental design. It was observed that the rice husk chicken manure can be used to increase the initial growth and biomass production of guavira keeping the leaves antioxidant activity tea stable. The use of bokashi benefits the growth of guavira only when no other organic residue is added to soil.

Resumo em Inglês:

ABSTRACT Integrated agricultural production systems have been improved with the introduction of Urochloa grasses aiming at obtaining straw for a no-tillage system (NTS) and the increase of legumes, which promote physicochemical improvements in soils and guarantee intensification and sustainability of production. This study aimed to evaluate the agronomic traits and yield of soybean in succession to the intercropping of corn with marandu grass and/or pigeonpea in five populations of plants harvested for silage production. The experiment was carried out in the Cerrado region of Selvíria, MS, Brazil, during the 2016/17 and 2017/18 agricultural years, in an Oxisol. The experimental design consisted of randomized blocks, with four replications. The treatments were arranged in a 2×5 factorial scheme, consisting of off-season corn intercropped with pigeonpea (Cajanus cajan (L.) Millsp.) and off-season corn intercropped with marandu grass (Urochloa brizantha) and pigeonpea, in addition to five sowing densities (0, 6, 12, 18, and 24 seeds m-1). Soybean was planted in succession aiming to evaluate the effect of remaining straw on crop performance. Soybean grown in succession to the triple intercropping of corn with marandu and pigeon pea shows increased productivity.

Resumo em Inglês:

ABSTRACT The efficiency of recurrent selection depends, among other factors, on the estimation of parameters that guide the breeder to obtain genetic gains for multiple traits. The aim of this research was to estimate genetic and phenotypic parameters of maize populations during the third cycle of recurrent selection for traits of interest. The populations CRE-01 and CRE-02, potential for resistance to corn stunt, were described using genetic and phenotypic parameters of variance components, heritability, variation indices and correlation between 16 agronomic traits. Direct and indirect selection gains were estimated for each trait and considering the Smith and Hazel, Mulamba and Mock and Z index. Both populations have genetic variability for the traits. High heritability estimates were obtained for most of the traits, which associated with the genetic variability, indicate that these populations may show continuous gains with recurrent selection. All selection indexes provided satisfactory genetic gains, but the Z index was the most promising considering the results of both populations.

Resumo em Inglês:

ABSTRACT The objective of this work was to characterize reference bacteria strains, belonging to the genus Bacillus and species of correlated genera, by simplified morphological and biochemical methods. The morphological characterization is based on the aspects of the colonies, as well as cytomorphology of the species, by optical and scanning microscopy. For biochemical characterization, the sensitivity test to antimicrobials by disk-diffusion is performed. Moreover, the strains were characterized by extracting intracellular proteins. Characteristics such as shape, color, and consistency of the colonies, in addition to the type of spore and production of protein crystals were determinants for the morphological characterization of these species. The antibiogram revealed high resistance to β-lactam group antibiotics, in species of Bacillus cereus s.l group. In Bacillus subtilis s.l. group there was high susceptibility to antibiograms, mainly for species of B. subtilis. The protein profile provided specific protein patterns for some species, mainly bands of 130 e 65 kDa for B. thuringiensis, 140 e 130 kDa for Lysinibacillus sphaericus, and 115 kDa for Brevibacillus laterosporus. Our results showed that the morphological and biochemical characterizations, provided a simple identification, with easy interpretation, and low cost.

Resumo em Inglês:

ABSTRACT Searching for novel sources of resistance to head blast is essential to strengthen wheat production in the Cerrado´s biome. The objective of this work was to evaluate disease intensity measures and yield for 2NS and non-2NS carriers wheat genotypes with varying heading times in Minas Gerais, Brazil. A total of fourteen wheat genotypes, two susceptible and twelve resistant to head blast, were sown in 2014, 2015, and 2017 at the Sertãozinho Experimental Station of Empresa de Pesquisa Agropecuária de Minas Gerais (Epamig) during three sowing dates without fungicide applications. The experimental design was a randomized complete block with three replicates. Blast incidence, severity, disease index and grain yield were influenced by the cycle of wheat genotypes and the sowing date, with the highest disease intensities and the lowest yields in the earliest sowing date. Blast incidence and disease index correlated negatively with grain yield and positively with percent yield losses. The group of wheat genotypes with higher grain yield (between 2,104.7 and 2,917.8 kg ha-1) and lower yield losses (between 44.3 and 54.8%) includes BR 18 as well as other five that do not carry the 2NS/2AS translocation: BRS Angico, PF 909, BRS 229, Embrapa 27, and CPAC 07340.

Resumo em Inglês:

ABSTRACT Decomposition processes and mineralization are essential to determine the time to deploy and manage species in consortia or rotations. The aim of this article was study the dynamics of biomass decomposition and release of macronutrients of plant residues of Fabacea. The species used were: jack bean (Canavalia ensiformis), pigeon pea (Cajanus cajan), dwarf mucuna (Mucuna deeringiana) and sunn hemp (Crotalaria juncea). The experiment was conducted in the field in a randomized block design, 4 x 5 factorial, four species of green manure and five times (0, 30, 60, 90, and 120 days). In the results, sunn hemp and pigeon pea had lower decomposition and release of C, N, K, and Mg. All species, K and P showed similar half-lives (t1/2). For N, sunn hemp presented the lowest coefficient of mineralization (k), 0.0040 g g-1 dia-1, associated with highest t1/2 (173.3 days), already, jack bean showed the highest k (0.0122 g g-1 dia-1) associated with the lowest t1/2 (56.8 days). In edaphoclimatic conditions, use of the jack bean and the dwarf mucuna is recommended for supply of nutrients in shorter periods of time for subsequent crops. However, sunn hemp and pigeon pea are recommended for greater persistence of mulch on the soil.

Resumo em Inglês:

ABSTRACT Cultivation and commercialization of Capsicum pepper have great importance in Brazil. This work assessed the influence of omission of macro and micronutrients on the growth and mineral nutrition of sweet pepper plants (Capsicum chinense Jacquin). The research was carried out in a greenhouse with washed sand as substrate. The experimental design was completely randomized with five replications and eight treatments: complete (control), omission of N, P, K, Ca, Mg, S, and micronutrients (B, Cu, Fe, Mn and Zn). The plants were submitted to the treatments when they reached an average height of 20 cm and the nutrient solution was supplied by percolation in plastic pots and renewed every 15 days. Nutrients omission affected negatively plant growth as a whole. The omission of N, Ca, and micronutrients greatly reduced sweet pepper yield. The C. chinense plants presented the sequence by dry matter production of shoots and roots in descending order: COMP > OP > OS > OK > Omg > ON > Oca > OMicro.

Resumo em Inglês:

ABSTRACT This study aimed to identify the correlations between traits of the groups stem cutting, seedling, stem, and root of cassava. Length, diameter, and weight of stem cutting (Group 1) were measured at each growing season (July, August, September, and October). A total of 300 cuttings were collected after sprouting and planted at seasons of September 22, October 7 and 19, and November 25. Plant height at planting, number of leaves at planting, and number of leaves at 7 days after planting were measured. The number of leaves at transplanting and plant height at transplanting were determined after acclimation (Group 2). Seedling transplanting was carried out on November 9 and 24 and December 3 and 26, and the traits stem (Group 3) and root (Group 4) yield were measured at harvest. Associations between the groups stem cutting and seedling were established by stem cutting diameter and weight, and height and number of leaves at planting. Seedling traits had the greatest influence on the number of buds per stem and stem diameter. Main stem branching height and stem diameter can be used for selecting plants with an indication of the best quality and yield of root traits.

Resumo em Inglês:

ABSTRACT The aerial part distribution and arrangement can significantly affect the forage resource’s use, both for the leaves and seeds harvesting. This work aimed to verify the structure derived from different times of pasture use and the subsequent seeds production in a long-cycle ryegrass cultivar. Weekly assessments of number and length of living leaves, elongation of the internodes, tillering, plants’ height, structural components (leaf, stem, flower, and dead material), seeds yields components, and seeds yield, to determine the pasture structure along its production cycle. The ryegrass cv BRS Ponteio pasture had its structure significantly modified just after 150 days (thermal sum: 1303 degrees-days) from seeding without the defoliation. Defoliation during the vegetative period did not alter the plants’ structure until the seeds’ production. Defoliation just after the beginning of the internodes’ elongation caused a significant tillering growth, which maintained the high seeds production potential, without plants lodging, besides promoting a more significant leaves harvesting. Subsequent pasture use determined predominant stems and flower harvesting, compared to the leaves, and the significant reduction of the production seeds and potential seeds production.