Bernadete Radin

Deficit hídrico e produtividade na cultura do milho

O objetivo deste trabalho foi avaliar o impacto do deficit hidrico, no rendimento de graos de milho, e a eficacia da irrigacao em todo ciclo e, especificamente, no florescimento. Os dados foram obtidos em dez anos de experimentacao, durante os quais doses variaveis de irrigacao foram aplicadas por um sistema de aspersao, localizado no centro da area experimental. Foram calculados balancos hidricos, tendo como variaveis a agua precipitada (chuva e irrigacao) e a evapotranspiracao maxima do milho. Foram ajustados modelos de regressao para 27 condicoes hidricas, relacionando-se rendimento de graos com deficit hidrico e razao evapotranspiracao real sobre evapotranspiracao maxima (ETr/ETm). A maior reducao na producao ocorre em consequencia do deficit hidrico na polinizacao, formacao do zigoto e desenvolvimento inicial do grao, numa relacao quadratica. Nesse periodo, a razao ETr/ETm explica quase 80% das variacoes na producao de graos, que se estabiliza acima de uma razao de 0,7. A irrigacao aumenta e estabiliza a producao do milho; doses de rega de aproximadamente 60% daquela necessaria para elevar a umidade do solo a capacidade de campo aumentam a eficiencia de uso da irrigacao.

Crescimento de cultivares de alface conduzidas em estufa e a campo

The growth of lettuce cvs. Veronica, Marisa and Regina was analised through an experiment carried out under plastic greenhouse and under field conditions, from April 15th to June 03rd 1999, in Eldorado do Sul, Rio Grande do Sul State, Brazil. Sampling of plants started one week after transplanting and proceeded until the end of the plant cycle on a weekly basis. The lettuce cultivated under greenhouse presented more fresh and dry mass, leaf area, specific leaf area and greater number of leaves. In addition, plants cultivated under greenhouse presented a shorter cycle when compared to the plants cultivated in field conditions. The cvs. did not show any difference when cultivated under greenhouse environment, but, in field conditions, the cv. Regina presented a larger number of leaves and a larger leaf area index than the cultivars Marisa and Veronica.

Desempenho de quatro cultivares de morangueiro em duas regiões ecoclimáticas do Rio Grande do Sul

The choice of cultivars has important significance in achieving success in strawberries cultivation. However, the experiments with cultivars are usually carried out in conventional systems of production and not in soilless growing systems. Due to this, the present research intended to assess the performance of some strawberry cultivars in soilless growing system, inside the greenhouse, in two regions with different ecoclimatic conditions, in Eldorado do Sul (Depressao Central) and Caxias do Sul (Serra do Nordeste), in Rio Grande do Sul State. Four strawberry cultivars were tested: Aromas, Camarosa, Oso Grande and Tudla. The planting was in May 2005, and the seedlings were placed in bags containing substrate composed of 50% of peat and 50% charred rice hulls. The fertilizer was supplied by fertirrigation. Fruits were harvested when 70% of them presented red color up to fully mature. The results showed that the cultivation of strawberries in this system led to lower yield per plant than in a traditional system, but provides better use of internal greenhouse, with positive consequences in yield per area, due to the high density of plants and the facility to manage the crop. The highest productivity was obtained in Caxias do Sul (235.8 g plant-1) compared to Eldorado do Sul (196.4 g plant-1) without interaction between locations and cultivars. In Caxias do Sul, the cultivars Aromas, Oso Grande and Camarosa presented highest yield when compared to Tudla, but there was no difference in Eldorado do Sul.

Número de colheitas e comparação de genótipos de tomateiro cultivados em estufa de plástico

The objective of this study was to determine the number of harvests necessary to predict the performance of tomato (Lycopersicon esculentum) genotypes under greenhouse conditions. The genotypes Empire, Fanny, Floradade and Olympo were transplanted on October 3, 2002 and submitted to 11 harvests. The genotypes Empire, Rodas, Floradade and Olympo were transplanted on February 28, 2003 and submitted to 14 harvests. Harvests were carried through in three intervals of four days. The mass and the number of fruits and the ratio mass/number were evaluated for commercial and discarded fruits. Repeatability estimates were obtained through variance, structural, and principal component analysis. Seven harvests are sufficient to identify supe- rior genotypes for all characteristics, with 90% accuracy of the real value, in both grown conditions.

Eficiência de Trichoderma harzianum e Gliocladium viride na redução da incidência de Botrytis cinerea em tomateiro cultivado sob ambiente protegido

A producao de tomates no Estado do RS ocupa um importante papel socio-economico, que pode ser constatado pelo crescimento do cultivo dessa hortalica em ambiente protegido. Essa tecnica permite a producao de tomates em periodo de entressafra; no entanto, ocorrem tambem condicoes favoraveis para o desenvolvimento de doencas fungicas como o mofo cinzento provocado por Botrytis cinerea. O surgimento de racas de patogenos resistentes a fungicidas quimicos vem fazendo com que o controle biologico torne-se uma alternativa necessaria. Neste trabalho foi realizada selecao in vitro de 24 isolados do fungo Trichoderma harzianum e 12 de Gliocladium viride que inibiram o desenvolvimento do patogeno B. cinerea. Foram selecionados dois isolados (TRIC-30 e GLIO-10) para serem testados em experimentos em condicoes de campo com tomates cultivados sob ambiente protegido, nos quais a pulverizacao foliar semanal com uma suspensao com 2x107 conidios mL-1 reduziu significativamente a incidencia do mofo cinzento, enquanto a aplicacao dos antagonistas nas sementes, no substrato e na cova, no momento do plantio, nao reduziu a incidencia do patogeno.

Variabilidade temporal e espacial da precisão das estimativas de elementos meteorológicos no Rio Grande do Sul

Planning agricultural activities requires that climatic risks in each location and time of year are estimated with maximum precision. In this estudy data from15 locations of Rio Grande do Sul, Brazil, were used with the objective of studing spatial and temporal variability of the precision estimates average of monthly rainfall, sunshine, solar radiation global and temperatures minimum, mean and maximum. It was estimated the estimation error (half-amplitude of the confidence interval) (EE) in percentage of estimate average monthly rainfall, sunshine, solar radiation global and temperatures minimum, mean and maximum for each month and location, which was used as a measure of precision. From the EE, for each meteorological elements, months and locations were clustered by hierarchical method of Ward. The Pearsons linear correlation coefficient between the arrays of the standardized average euclidian distance and graphics was calculated in order to check the clusters consistency. It was concluded that the precision estimates, average of months and locations, between the meteorological elements, increases in the following order: rainfall (EE=21.66%), sunshine (EE=6.74%), global solar radiation (EE=5.52%) and temperatures minimum (EE=4.40%), mean (EE=2.63%) and maximum (EE=2.27%). Results showed that there is variability in precision estimate of monthly average rainfall, sunshine, global solar radiation and minimum, mean and maximum temperatures in Rio Grande do Sul, both in temporal and spatial scale. Estimates based on 30 years data are less precision in April, May, June, July, August and September in relation to the others.

Dimensionamento da amostra para a estimação da média de precipitação pluvial mensal em diferentes locais do Estado do Rio Grande do Sul

It was used data from 19 locations of the Rio Grande do Sul State, Brazil, collected from 1953 to 2007, with the objective to determine the sample size to estimate the average monthly rainfall. The central tendency, variability and asymmetry was calculated for each of the 228 time series (12 months x 19 locations) and the aleatory and normality data were tested. Then it was verified the homogeneity of variance among months in each locality and among places in each month and it was determined the sample size to estimate the average monthly rainfall in each month and locality. The sample size (number of years) to estimate the average monthly rainfall is dependent on the month and locality. One concluded that 51 years of data are enough to predict the average monthly rainfall, with an estimation error equal to 25% of estimated average, with a degree confidence of 95%.

Modelo harmônico para a estimativa da temperatura do ar média mensal em diferentes locais do Estado do Rio Grande do Sul

The objective of this research was to adjust the harmonic model for the estimation of average monthly air temperature, in 37 locations of Rio Grande do Sul State, Brazil, with data from the period 1931 to 2000. In each locality, data from 1931 to 1990 (60 years) was used to estimate the coefficients of the harmonic model and from 1991 to 2000 (10 years) to validate the model. It was tested the normality and homogeneity of variance among months, estimated trends and incorporated into the models harmonic based in waves annual and semiannual. The coefficients linear, angular, correlation and determination, the root mean square error and the index of WILLMOTT (1981) and CAMARGO & SENTELHAS (1997) were used to validate the models. The coefficient of determination (R2) of the harmonic model, was high in all sites (R2≥0.9867), giving reliability for future forecasts. The harmonic model generated for each of the 37 location in the the Rio Grande do Sul State, Brazil, is adequate to estimate the average monthly air temperature.

Bradysia sp. em morangueiro

This paper describes the first record of Bradysia sp. (Insecta; Diptera; Sciaridae) in strawberry (Fragaria x ananassa), cultivated in the city of Eldorado do Sul, RS, Brazil. Strawberry was planted in plastic bags filled with a mixture of burnt rice hulls and peat and cultivated in a greenhouse. The presence of Bradysia sp was noticed in the second fortnight of August, 2005. The symptoms in strawberry and the probable consequences in terms of disease arising were described in the present study, as well as the morphological characterization of Bradysia sp. and its illustrations.

Tamanho de amostra para a estimação da média mensal de insolação diária em diferentes locais do estado do Rio Grande do Sul

It was used data from 30 locations of the Rio Grande do Sul State, Brazil, collected from 1960 to 2007, with the objective to determine the sample size (number of years) to estimate the average daily month insolation . The average and variance was calculated for each of the 360 time series (12 months x 30 locations) and the aleatory and normality data were tested. Then it was verified the homogeneity of variance among months in each locality and among places in each month and it was determined the sample size to estimate the average monthly insolation daily in each month and locality. The sample size (number of years) to estimate the average monthly insolation daily is dependent on the month and locality. One concluded that 44 years of data are enough to predict the average monthly insolation daily, with an estimation error equal to ±0.5 hours days-1, with a degree confidence of 95%.