Processo infeccioso de Pseudocercospora musae e severidade da Sigatoka Amarela da bananeira em função do silício, potássio e cálcio em solução nutritiva

Yellow Sigatoka leaf spot, caused by Pseudocercospora musae (Mycosphaerella musicola), is one of main threats to banana production around the world. However, information regarding the infection process of P. musae and the influence of mineral nutrition on the disease severity could help with cultural control strategies and increase the fruit yield. Therefore, this work aimed to characterize the infectious process of P. musae in banana leaves, to study the effect of silicon (Si) and the interaction between potassium (K) and calcium (Ca) on the Yellow Sigatoka leaf spot severity. In the first study, samples were inoculated on the abaxial leaf surface with P. musae and analyzed at 12, 24, 36, 48, 72, 96, 120, 144, and 168 hours after inoculation (HAI) as well as 36 and 50 days after inoculation (DAI). The conidia germinated between 24 and 36 HAI and penetrated through the stomata between 96 and 120 HAI, or usually from 144 HAI. P. musae colonized intercellularly the spongy parenchyma at 36 DAI and inter- and intracellularly the palisade parenchyma at 50 DAI. The sporulation occurred at 50 DAI on the adaxial leaf surfaces. In the second study, banana plants grown in nutrient solution with 0; 0.5; 1.0; 1.8 and 3.6 mmol L -1 of silicic acid (H 4SiO 4) were inoculated with conidial suspension. The disease severity was assessed and data were integrated in the area under the disease severity progress curve (AUDSPC). The lower AUDSPC was 49.27% for the concentration of 3.05 mmol L -1 of H 4SiO 4 compared to plants grown without Si addition. Regarding silicon accumulation, at 3.6 mmol L -1 H4SiO 4, leaf Si content was 23.53% higher compared to the control. In the third study, plants grown in nutrient solution with 5 K concentrations (1, 2, 4, 6, and, 8 mmol L -1 ) combined with 5 Ca concentrations (1, 3, 5, 7, and, 9 mmol L -1 ), forming 25 treatments, were inoculated with conidial suspension. The disease severity was assessed and the data were integrated in the AUDSPC. There was no interaction between concentrations of K and Ca for AUDSPC, although the AUDSPC increased with the increase of K concentrations from 1 to 6 mmol L -1 . The K increase led to a reduction in chlorophyll a and b contents and in the N, P, Mg, B, Cu, Zn, and, Mn nutrients as well as increased the total plant dry weight.

Compartimentos de K, Ca e Mg em solos e sua relação com o crescimento inicial, fisiologia e produtividade do eucalipto

Forestry has grown in a continuous and accelerated manner in Brazil, constituting a strategic activity for the generation of employment, income and tributes, favoring social and economic development of Brazilian agribusiness. The objectives of this study were: (1) evaluate the contents of K, Ca and Mg in the reserve compartments, non-interchangeable, interchangeable, available and the speed of its release, its correlations and its effects over productivity (annual average increment – AAI) of eucalyptus plantations, in forest sites cultivated in soils of the state of Rio Grande do Sul; (2) evaluate the initial growth, nutrition and physiological aspects of eucalyptus plants, cultivated with and without the addition of mineral sources of potassium (K), calcium (Ca) and magnesium (MG), in soils obtained from forest sites in the state of Rio Grande do Sul. In the first study, contents of K, Ca and Mg were evaluated in sulfuric digestion extract, boiling nitric acid, ammonium chloride, Mehlich-1 (only K), potassium chloride (Ca and Mg), as well as the release speed of these nutrients in the soil. In the second study, growth variables, nutritional aspects, photosynthetic rate (A) and transpiration rate of the plants (E) grown in distinct soils were evaluated under controlled conditions. The contents of K, Ca and Mg varied between compartments and depths in the studied soil classes, with the highest proportions found in the reserve compartment, indicating the importance of this compartment for the supplement of these nutrients at average and long terms. The great majority of K, Ca and Mg compartments presented significant correlations between each other, showing the dependence between them and the importance of evaluating the contents of these nutrients in the different compartments to adapt the nutritional management of the plants to each soil class, and to obtain continuous productions, minimizing the negative effects to the environment. Plants cultivated in soils that present larger reserves, availability and K, Ca and Mg release kinetics, presented similar height (H), stem diameter (SD) and shoot dry mass (SDM), with or without fertilization with K, Ca and Mg. The plants presented higher leaf content and accumulation of K in all soils fertilized with K, Ca and Mg.

Nutrição do feijoeiro e intensidade da antracnose em função da aplicação de silício e cobre

The objective of this work was to evaluate the effect of calcium silicate and copper sulfate on anthracnose intensity and nutrition of bean plants. The experiment was conducted using an experimental design in randomized blocks following a 4 x 4 factorial arrangement, (four levels of calcium silicate and four levels of copper sulfate) and two additional treatments (plants without inoculation and plants sprinkled with Benomyl). Four evaluations of the incidence and severity of anthracnose were done, in addition to measuring total leaf area. At the end of the evaluations, incidence and severity data were integrated over time, obtaining the area under disease progress curve (AUDPC). Contents of N, P, K, Ca, Mg, B, Cu, Fe, Mn, Zn, Si and lignin were determined in the aerial part. A linear decrease of the intensity AUDPC was observed with the increase of the doses of calcium silicate. The severity AUDPC was influenced by the doses of copper, obtaining a reduction of 35% on the higher dosage. The supply of silicon and copper altered the content of the K, Mg, S, Zn, Ca and Si in the aerial part of the bean plants.

Adubação foliar de sulfato de zinco na produtividade e teores foliares de zinco e fosforo de cafeeiros arábica

Aiming to evaluate the dose and application schedule of foliar Zn-sulfate spraying in growing and yield of Arabic coffee Mundo Novo, a field experiment was set up on Distroferric Red Latosol, at the Experimental Station of the EPAMIG in São Sebastião do Paraíso. The statistical design used was randomized blocks in s 4 x 2 factorial scheme with five replications and a 30-plant plot with six central valid or four applications per agricultural year. Phosphorus and zinc leaf levels were evaluated for eight years and the yields. It was possible to conclude that there is a positive response to the in the leaves. Four low concentrations sprayings promoted higher yields than two high concentrations. The highest yields were achieved with 10.8 and 12.6 kg ha-1 of ZnSO4 and 4 yearly applications, respectively. It is suggested as a critical range for the Zn leaves values between 10 and 28 mg kg-1 and for P/Zn ratio, between 100 and 150. ) was sprayed under 4 concentrations 0; 0.5; 1.0 and 1.5%, two applied on the leaves in terms of yield, and to Zn levels

Caracterização fisiológica e produção de metabólitos secundários em Achillea millefolium L. após aplicação de quitosana

Elicitation with chitosan is a tool used to improve the responses of plant defense by inducing secondary metabolism routs. In addition, the adequate application of this elicitor on medicinal plants can promote the increase of major components in the composition of the oil. However, we lack information concerning which are the main physiological processes responsible for the changes in the composition of the oil. Thus, we aimed at evaluating the action of chitosan and determine an ideal concentration for optimizing the production of essential oil in Achillea millefolium L. and the changes in the physiological processes responsible for this increase. The research was conducted in greenhouse of the Plant Physiology sector of the Universidade Federal de Lavras (UFLA) with A. millefolium plants. The treatments consisted of control (water); acetic acid solvent (with no elicitor); and chitosan in the concentrations of 2, 4 and 6 g L -1 . The measurements of growth, gas exchange, enzyme activity of the antioxidant system and phenylalanine ammonia lyase (PAL), in addition to the production and composition of the essential oil. We verified that the application of chitosan promoted decrease in plant growth. However, the concentration of 4 g L -1 of chitosan induced an increase in the content and yield of the essential oil. In the oil, there was predominance of sesquiterpenic compounds, including the major compounds borneol, β-caryophyllene, β-cubebene, α-farnesene and chamazulene. The elicitation with chitosan at 4 g L -1 promoted an increase of the photosynthetic rate, activity of the antioxidant system and of PAL, however, this increase occurred in short-term, only in the first days after elicitation.

Cobre via foliar na nutrição e na produção de mudas de cafeeiro

The objective of this study was to evaluate the effect of different sources and doses of copper (Cu) applied to leaves on growth and nutrition of coffee seedlings. The treatments consisted of combinations of two Cu sources (Cupric Sulfate Ammonium - CSA and Copper Sulfate - CS) and four Cu doses (0, 250, 500 and 1000 g ha-1). The sources of Cu in different doses were dissolved in water, calculated for the application volume of 400 L ha-1. The doses were divided in 3 applications at 20 days. The Cu content and concentration in the leaf, stem, and root in were measured. The dry matter of the leaf, stem, root and total and the utilization, absorption and translocation efficiency, in coffee seedlings were evaluated. In general the Cu content and concentration were obtained for the CS at doses of 250, 500 and 1000 g ha-1 Cu. The maximum increase of total dry matter was 48 and 51 g to CSA and CS, when applied 534 and 668 g ha-1, respectively. The highest utilization and absorption efficiency was found to CSA and CS, respectively. The translocation efficiency was similar for both sources.

Biofortificação com zinco, selênio e ferro, e biodisponibilidade de ferro em cultivares de feijoeiro-comum

The common bean (Phaseolus vulgaris L.), a staple food in nutritional diet of Brazilians and populations in developing countries, is a nutritionally rich legume with potential for biofortification. Approximately one third of the world population suffers from nutritional deficiencies, being necessary to increase the nutrient content in vegetables, especially iron (Fe), selenium (Se) and zinc (Zn), which are important micronutrients for plants and human health. In this context, three studies were carried out aiming to evaluate the potential of common bean cultivars to biofortification with Fe, Se and Zn, and verify the interaction between these minerals and iron bioavailability, in order to contribute to increased nutritional quality of grains, reducing the micronutrients deficiency and improving human health. In the first study, experiments were conducted in a greenhouse, with ten common bean cultivars in nutrient solution under different treatments with Fe, Se and Zn. The plant growth and the mineral content of the beans were evaluated in addition to verify the influence of polyphenol and phytate levels on Fe bioavailability in grains fortified with Zn and Se. The evaluated beans cultivars have proved promising for simultaneous biofortification with these nutrients without greatly affecting Fe bioavailability. In the second study, the aim was evaluate the interaction between Fe, Se and Zn in cultivars consumed in Brazil or in USA. Gene expression and root microscopy analysis were performed in order to understand the positive effect of Zn supply on the Fe uptake by roots. The expression of genes related to the transport and uptake of Fe and Zn did not clearly explain the influence of Zn in Fe nutrition. The roots microscopy and the evaluation of nutrient solutions used showed that, in the presence of Zn, there was Fe accumulation in epidermis of the roots and not in the vascular system, prone to be precipitated when it goes through the root membrane. In the latest study, a field experiment was conducted to evaluate the effect of Zn fertilization via soil and foliar, in the content and accumulation of Fe and Zn in grains and in the yield of common bean cultivars, in addition to verify the amount of these micronutrients supplied by biofortified beans. The fertilization with Zn did not affect the yield, but provided high levels of this nutrient in grains of the cultivars analyzed, representing 27% of the recommended daily intake of Zn. The higher Fe content in beans, obtained when there was no application of foliar Zn, supplies 56% of the daily requirement of Fe.