The study was conducted in greenhouse at horticulture department of the Instituto Federal do Espírito Santo, Campus Itapina, Colatina, northwestern Espírito Santo state, Brazil, with the objective of evaluating the effect of cooling and electrical conductivity of nutrient solution on growth and development of lettuce cv. Vitória de Santo Antão in hydroponics. The study was conducted in a completely randomized design with two factors (control of the maximum temperature of the nutrient solution: 26ºC and without control; and electrical conductivity, EC, of the solution: 1, 2 and 3 dS m-1) with three repetitions. The plants were harvested fifty-two days after sowing (DAS). We evaluated the dry and fresh mass of leaves, stems and roots, stem and root length, root volume and plant water content (%). The temperature of the nutrient solution influenced the behavior of lettuce influenced by the electrical conductivity, showing that the increase of the EC did not reduce the lettuce productivity when the maximum temperature of the nutrient solution is limited, which in this experiment was tested at 26ºC. The cooling of the nutrient solution provided greater accumulation of mass and a higher water percentage in plants, increasing the productivity of hydroponic lettuce in tropical climate.
Organic matter is a fundamental component of a substrate. However, different organic matter sources can provide different physiological responses from seedlings as a result of different types and concentrations of humic substances, which influence the functioning of the plant and the structuring of the soil. The objective of this work was to quantify photosynthetic pigments, gas exchange, and secondary metabolite indices in the abaxial and adaxial parts of leaves of Conilon coffee clonal plantlets grown in different sources of organic materials. The experiment was arranged in a randomized block design with five treatments and five replications. The treatments consisted of different sources of organic matter added to the substrate: 85% soil + 15% urban waste compost; 85% soil + 15% mature cattle manure; 85% soil + 15% dairy residue; 85% soil + 15% tannery sludge; and a Control: 100% soil, without addition of organic material. The contents of chlorophylls a, b, and total, carotenoids, and their ratios were analyzed by destructive methods. Indirect measurements of nitrogen and chlorophyll (SPAD) were performed by non-destructive methods. Fluorescence indices of flavonoids, anthocyanins, total chlorophyll, and nitrogen balance were estimated using a Multiplex® sensor. The substrate added with dairy residue provided the highest chlorophyll a production in the adaxial part, which was confirmed by the SPAD index. Tannery sludge provided the highest production of flavonoids. The comparison between the two forms of evaluation showed that the abaxial part of the leaf had greater sensitivity and that the Multiplex® sensor showed higher sensitivity for detection of indices. No changes were found in plant photosynthesis. However, greater stress was detected in the treatment with tannery sludge.
The objective of this study was to determine mathematical equations that estimate the leaf area of jackfruit (Artocarpus heterophyllus) in an easy and non-destructive way based on linear dimensions. In this way, 300 leaves of different sizes and in good sanitary condition of adult plants were collected at the Federal Institute of Espírito Santo, Campus Itapina, located in Colatina, municipality north of the State of Espírito Santo, Brazil. Were measured The length (L) along the midrib and the maximum leaf width (W), observed leaf area (OLA), besides the product of the multiplication of length with width (LW), length with length (LL) and width with width (WW). The models of linear equations of first degree, quadratic and power and their respective R2 were adjusted using OLA as dependent variable in function of L, W and LW, LL and WW as independent variable. The data were validated and the estimated leaf area (ELA) was obtained. The means of ELA and OLA were compared by Student’s t test (5% probability) and were evaluated by the mean absolute error (MAE) and root mean square error (RMSE) criteria. The choice of the best model was based on non-significant comparative values of ELA and OLA, in addition to the closest values of zero of EAM and RQME. The jackfruit leaf area estimate can be determined quickly, accurately and non-destructively by the linear first-order model with LW as the independent variable by equation ELA = 1.07451 + 0.71181(LW).
RESUMO Em relação às diversas doenças que reduzem a produção da cultura do tomateiro, destaca-se a ocorrência da virose conhecida como “vira-cabeça”. Epidemias dessa doença são frequentes com altas taxas de progresso e danos significativos. Nesse caso, estudos sobre a variabilidade espaço-temporal podem auxiliar em propor estratégias de manejo. Portanto, o objetivo desse estudo foi mapear a distribuição espacial da incidência do “vira-cabeça” ao longo do tempo em lavoura de tomateiro, para entender os mecanismos de dispersão do patógeno e progresso da doença. Para isso, a presença ou ausência de sintomas da doença foi monitorada ao longo do tempo em 120 plantas georreferenciadas, dispostas em malha regular e distribuídos num espaçamento de 1,0 x 0,5 m. Os dados de incidência da doença foram submetidos à análise geoestatística. Após o ajuste dos semivariogramas foi realizada a interpolação dos dados por krigagem. Houve epidemia da doença na lavoura de tomate, e a taxa de progresso (Dy/Dt) variou de 4,7 a 6 plantas doentes/dia, e 100% das plantas apresentaram sintomas aos 20 dias após a primeira detecção da doença na lavoura. Houve dependência espacial forte da distribuição das plantas de tomateiro com sintomas de “vira-cabeça” em todas as avaliações, e valor de alcance variando de 4,3 a 1,69 m. Ao longo do tempo surgiram focos secundários da doença, expansão lateral e coalescência desses, caracterizando dispersão por ação do agente vetor associado às fontes de inóculo inicial, internas e externas à lavoura. O padrão aleatório de distribuição da doença evoluiu para agregado, e posteriormente regular.
Brazil is the largest producer of Conilon coffee (Coffea canephora) in the world. The use of organic matter in substrates for clonal plant propagation is essential to promote favorable conditions for the development of both shoots and roots. Therefore, it is important for production systems to test new sources of organic matter such as solid urban waste. The objective of this study was to evaluate the effect of different proportions of composted urban waste on the propagation of Conilon coffee plants. The experiment was arranged in a randomized block design, with five replications and seven treatments. The treatments consisted of different proportions of composted urban waste (0, 15, 30, 50, 70, 90 and 100%), and biometric and quality characteristics of the clonal plants were evaluated. The results showed that proportions of composted urban waste higher than 50% added to the soil substrate promoted the highest plant growth rates, and even the lowest proportion of organic matter (15%) showed better results for all characteristics than the treatment without organic matter.
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