Marcelo Calgaro

Physiological and technological responses of sugarcane to different irrigation systems.

O objetivo do trabalho foi avaliar a influencia de tres sistemas de irrigacao sobre as trocas gasosas e as qualidades tecnologicas da cana-de-acucar, variedade RB 92579, por tres ciclos consecutivos, cultivada em dois tipos de solos na regiao do Submedio do Sao Francisco. Os experimentos foram instalados utilizando delineamento experimental em blocos casualizados, com seis repeticoes, em areas com solo arenoso e argiloso. Os sistemas de irrigacao foram: sulco, gotejamento superficial e gotejamento subsuperficial. Avaliaram-se as caracteristicas fisiologicas das plantas: fotossintese liquida, condutância estomatica, transpiracao e temperatura foliar. Para analises tecnologicas foram determinados o teor de solidos soluveis, porcentagem de fibra industrial, pureza do caldo, porcentagem de acucar bruto, acucares redutores e umidade. Verificou-se que a irrigacao por gotejamento subsuperficial em solo arenoso interfere negativamente nas trocas gasosas da cultura. Os sistemas de irrigacao nao influenciaram na qualidade tecnologica dos colmos quando cultivada em solo arenoso e, no argiloso, o sulco interfere negativamente no processo de maturacao dos colmos.

Temporal and spatial variation of parameters for the random modeling of daily rainfall in the state of Rio Grande do Sul, Brazil

Rio Grande do Sul is one of the largest grain producer states in Brazil, since most of the crops grown in non-irrigated systems, thus making them extremely dependent on the climatic conditions and on the pluviometric regime. This fact has inspired several research studies in the attempt of characterizing the spatial and temporal behavior of the rainfall. The objective of this research was to study the spatial and temporal variation of alpha and beta parameters of the gamma function for the generation of daily rainfall data in the state. The pluviometric precipitation data were obtained from the National Water Agency (ANA). The modeling of the daily rainfall was divided into the events of occurrence and quantity. Estimation of alpha and beta parameters of the gamma function was accomplished on the basis of historical series followed by the adjustment of these parameters as a function of time and space, and then the comparison between estimated and observed values. According to the results, one can conclude that the proposed methodology can be applied for the generation of synthetic series of daily rainfall in the different pluviometric stations of Rio Grande do Sul.

Growth of sugar cane varieties under salinity

Large salty areas in the Brazilian semi-arid region have limited farming in Northeastern Brazil. One example is the sugar cane cultivation, which reinforces the need of selecting varieties that are more tolerant to salinity. The objective of this study was to evaluate the effect of salinity on growth of ten varieties of sugar cane. The experiment was conducted in a greenhouse, set in the experimental field of Embrapa Semiarido, in Petrolina, Pernambuco State. The experimental design was randomized blocks arranged in a 6 X 10 factorial arrangement, comprised of six levels of salinity (0, 1.0, 2.0, 4.0, 6.0 and 8.0 dS m-1) and ten sugar cane varieties (VAT 90212; RB 72454; RB 867515; Q 124; RB 961003; RB 957508; SP791011; RB 835089; RB 92579 and SP 943206). Salt levels of irrigation water were obtained by adding NaCl, CaCl2.2H2O and MgSO4.7H2O to achieve an equivalent ratio among Na:Ca:Mg of 7:2:1. Sixty days later, plant height, stem diameter (base), number of leaves, stalks and sprouts, leaf area and fresh and dry mass of the aerial part and roots were all measured. The varieties of sugar cane showed similar responses for growth reduction as soil salinity increases, being considered moderately sensitive to salinity.

Aspectos fisiológicos de variedades de cana-de-açúcar submetidas a estresse salino.

As areas salinizadas tem limitado a producao de culturas como a cana-de-acucar, sendo a selecao de variedades mais tolerantes ao estresse salino uma das alternativas para os produtores. Objetivo do presente trabalho foi avaliar as respostas fisiologicas de tres variedades de cana-de-acucar a salinidade. O experimento foi realizado em vasos, numa casa de vegetacao localizada no campo experimental da Embrapa Semiarido, em Petrolina-PE. O delineamento experimental utilizado foi em blocos casualizados dispostos em arranjo fatorial de 6 X 3, sendo seis niveis de salinidade da agua de irrigacao (0; 1,0; 2,0; 4,0; 6,0 e 8,0 dS m-1) e tres variedades de cana-de-acucar (VAT 90212, RB 867515 e RB 835089). As variedades de cana-de-acucar demonstraram alteracao nas trocas gasosas com o aumento da salinidade, com destaque a maior tolerância para as variedade RB 867515 e RB 835089.