Elias Fernandes de Sousa

Estimação da evapotranspiração de referência no estado do Rio de Janeiro usando redes neurais artificiais

This work was performed with the aim of proposing an artificial neural network (ANN) to estimate the reference evapotranspiration (ETo) as a function of geographic position coordinates and air temperature in the State of Rio de Janeiro. Data used for the network training were collected from 17 historical time series of climatic elements located in the State of Rio de Janeiro. The daily ETo calculated by Penman-Monteith (FAO-56) method was used as a reference for network training. ANNs of multilayer perceptron type were trained to estimate ETo as a function of latitude, longitude, altitude, mean air temperature, thermal daily amplitude and day of the year. After training with different network configurations, the one showing best performance was selected, and was composed by only one intermediary layer (with twenty neurons and sigmoid logistic activation function) and one output layer (with one neuron and linear activation function). According to the results obtained it can be concluded that, considering only geographical positioning coordinates and air temperature, it is possible to estimate daily ETo in 17 places of Rio de Janeiro State by using an ANN.

Estimating the total leaf area of the green dwarf coconut tree (Cocos nucifera L.)

Leaf area has significant effect on tree transpiration, and its measurement is important to many study areas. This work aimed at developing a non-destructive, practical, and empirical method to estimate the total leaf area of green dwarf coconut palms (Cocos nucifera L.) in plantations located at the northern region of Rio de Janeiro state, Brazil. A mathematical model was developed to estimate total leaf area values (TLA) as function of the average lengths of the last three leaf raquis (LR3), and of the number of leaves in the canopy (NL). The model has satisfactory degree of accuracy for agricultural engineering purposes.

Determinação do coeficiente cultural (Kc) do feijoeiro (Phaseolus vulgaris L.), em Campos dos Goytacazes, RJ

The evapotranspiration of a crop is one of the main information required for proper irrigation management and to develop an efficient water usage plan. Among the methods to estimate the amount of water that is consumed by plants, the use of crop coefficients (Kc), associated with estimates of the reference evapotranspiration (ETo), stands as one of the most promising. This work aimed to deterime the values of Kc for different phenological phases of common bean plants (Phaseolus vulgaris L.) of the cultivar UENF-47. Determination of Kc values was performed using a weighing lisimeter and results were compared with values obtained through the FAO 56 standard. Results showed that the adjustment equations proposed by Allen et al. (1998) were adequate for fitting the values of Kc obtained in this experiment. It has been shown that the crop coefficients for phenological phases 3 and 4 proposed by Allen et al. (1998) are adequate for the conditions of crop growth observed in Campos dos Goytacazes, Rio de Janeiro state, Brazil, during the autumn/winter period.

Avaliação da taxa de crescimento de frutos de mamão (Carica papaya L.) em função das épocas do ano e graus-dias acumulados

The monitoring of the vegetable organ development, as the fruit, is a great scientific interest. The knowledge of the different phases of growth of these fruits can indicate the critical points of nutritional requirements and water, and its relation with climatic factors effect, as the temperature. The aim of this work was to evaluate the growth rate of the hybrid papaya fruit UENF/CALIMAN 01 at different times of the year, in function of the number of degree-day (DD) accumulated. The fruits had reached the harvest point varying in accordance to the different times of development throughout the year. Fruits developed in periods with high temperatures had in smaller time its point of harvest, and it was inverse in fruits developed in colder periods. However, when reaching around 800 DD after anthesis, the fruits had tended to stabilize its growth invariably. After this growth period, the maturation process was as fast as the monthly temperature of the period is bigger.

Total leaf area of papaya trees estimated by a nondestructive method

Leaf area estimation is an important feature in physiological research involving predominantly photosynthesis, transpiration and growth. This study was carried out to develop a practical and nondestructive empirical mathematical model to estimate the area of one leaf and the total leaf area for papaya trees (Carica papaya L.). Two irrigated commercial orchards were evaluated over a period of 50 to 550 days after transplanting, during which the length of the leaf midrib (LM) varied from 0.04 to 0.60 m. A mathematical model was developed to estimate the area of one leaf for the papaya tree, taking into account LM and the age of the plant measured in days after transplanting. The model was considered satisfactory. Based on the average length of the last two leaves of the crown and the total leaf number of the plant, it was possible to satisfactorily estimate the total leaf area of the papaya tree.

Response coefficient of papaya yield to water stress (ky) in Northern Rio de Janeiro

The objective of this study was to determine the response coefficient to water stress in the commercial and total yield of papaya fruits grown in the northern region of the State of Rio de Janeiro. The experiment was conducted in an area of UENF/PESAGRO-RIO in the municipality of Campos dos Goytacazes, Rio de Janeiro, from 25/04/2006 to 18/05/2007, using the papaya cultivar Hybrid UENF/CALIMAN01. The experiment had a randomized block design with five treatments [replacement of reference evapotranspiration (ETo) by 50% (T1), 75% (T2), 100% (T3), 125% (T4) and 150% (T5)], with four replications. The highest real commercial yield of the crop after 13 months of growth and four harvest months was 38.78 t ha-1 (T3) and the highest total real yield was 49.42 t ha-1 (T5). After 13 months of growth and 4 harvest months of the papaya cultivar Hybrid UENF/CALIMAN01 the response coefficient for commercial fruit yield (ky) was 1.4581 and 0.5674 for total yield.

Effect of mini-sprinkler irrigation system on Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juvenile

Entomopathogenic nematodes (EPNs) are currently being used as successful biological control agents of soil-dwelling insect pests. Previous field and greenhouse studies demonstrated that application techniques and non-biotic factors (temperature and pressure) have a significant effect on EPNs efficacy. The objective of this study was to evaluate the influence of an irrigation spray application system on the viability, infectivity and host search capability of Heterorhabditis baujardi LPP7 (Nematoda: Heterorhabditidae) infective juveniles (IJ). Two assays were proposed. Their viability was evaluated under the microscope after the IJ passed through the irrigation system. Infectivity on Galleria mellonella larvae, and host search capability, as evidenced by larval mortality, were evaluated in containers (Experiment 1). In the field (Experiment 2), mortality of G. mellonella larvae was evaluated under different nematode concentrations (0, 100,000, 300,000 and 500,000 IJ per tree). No differences were recorded on the viability, infectivity and host search capability of the IJ in Experiment 1. In Experiment 2, differences were recorded among the different concentrations used (p < 0.05), and a higher mortality was observed at the highest nematode concentration (28.3% and 37% in each one of the two experiment repetitions). This irrigation system did not affected adversely the viability, infectivity and host search capability of H. baujardi LPP7.

Produtividade e qualidade de frutos de mamão cultivar 'Golden' sob diferentes lâminas de irrigação e doses de potássio no norte de Espírito Santo

This work aimed to study the effects of different irrigation depths and potassium doses on yield and fruit quality of papaya cv Golden. The experiment was carried out in an area of commercial and agricultural production situated in Linhares - ES, Brazil. The design employed was randomized blocks, arranged in subdivided parcels and having three replications. The treatments consisted of five irrigation depths in the parcel and four potassium doses in the subparcel, totalizing 20 treatments. The five programmed irrigation depths were 50; 70; 90; 110 and 130% of the reference evapotranspiration and the four potassium doses were 30; 42; 54 and 66 g of K2O plant-1month-1. The high rainfall rates in the experimental period (February-2005 to June-2006), greatly overcame the plant water requirements, interfering in the treatments, not allowing significant variation in the variables analyzed, particularly in function of the applied depths. During the 11 months and 21 days of harvest, the average yield was 79.41 t ha-1, with an average of 96 fruits per plant which, in the first stage of ripening, presented a mass of 404 g, average total soluble solids content (SST) of 10.11 oBrix and pulp and fruit firmness of 79.80 N and 126.19 N, respectively.

Evapotranspiração e coeficiente da cultura do mamoeiro

This study aimed to determine the crop evapotranspiration (ETc) and the crop coefficient (Kc) for of UENF/CALIMAN01 papaya hybrid (Carica papaya L.). The experiment was conducted in an area of UENF/PESAGRO-RIO, in Campos dos Goytacazes, RJ, Brazil, from 4-25-2006 to 8-20-2007. To determine the ETc and Kc, a weighing lysimeter (6 m2) was used. The reference evapotranspiration (ETo) was determined by the Penmam-Monteith (FAO) method. The maximum crop evapotranspiration was of 2.9 mm day-1, 229 days after the transplant (DAT), and the medium crop evapotranspiration during the experiment was of 1.8 mm day-1. The value of crop coefficient (Kc) varied linearly from 0.63 to 1.05, the transplant to 206 DAT. After this period, the variation of Kc presented inversely relation with the canopy diameter, being reduced to a value medium minimum of 0.81, to 300 DAT. Considering the whole period of study, it was obtained an average Kc of 0.87.

Avaliação da dissimilaridade genética em genótipos de bananeira (Musa spp.) via marcadores RAPD

Banana is a very important social and economic crop. The introduction of of banana cultivars was initiated through the Plant Genetics Laboratory at UENF. Cultivars from Embrapa Cassava and Tropical Fruits and Western Amazon were introduced. The objective of the present work was to analyze the genetic dissimilarity between 21 cultivars and obtain the correct identification of the possible genotypes introduced at UENF. The following genotypes were evaluated: Fhia 18, Prata Ana, UENF 1526, Pacovan, Caipira, Maca, UENF 1527, Nanicao, Thap Maeo, UENF 1528, UENF 1529, Grande Naine, Ambrosia, Bucaneiro, Calipso, PV42-68, PV42-85, PV42-142, ST12-31, Calcutta and BB da Franca. The genetic dissimilarity was carried out using RAPD molecular markers. Thirty-one primers were used, generating a total of 94 bands. The RAPD molecular markers were capable to accurately reveal the existence of genetics diversity among the 21 banana genotypes. For data interpretation, the Jaccard index was used. Based on cluster analysis UPGMA and the Tocher method, the dissimilarity could be observed by the presence of similar and dissimilar genotypes.