Ademar Spironello

Calagem para a cana-de-açúcar e sua interação coma adubação potássica

SUGARCANE RESPONSE TO LIMING AND POTASSIUM FERTILIZATION Six experiments were carried out in the main sugarcane regions of the State of Sao Paulo, Brazil, in order to study sugarcane response to liming and potassium and its interactions. The treatments consisted of four rates of liming and tree rates of potassium, setup in factorial experiments, summing up twelve treatments, with four replications, organized in randomized block design. In four sites, the experiments were conducted during the first season and in two others, the ratoons were also evaluated. Four sites were cropped with the variety SP70-1143 and in the others, the varieties SP71-6163 and SP71-1406 were planted. Despite the high soil acidity in all sites, the response of sugarcane to liming was significant only in two sites, showing high tolerance of planted varieties to soil acidity conditions. The sugarcane response to potassium was linear in seven out of the 10 evaluated seasons. Significant interactions between liming and potassium were not observed in any studied site.

AVALIAÇÃO AGROTECNOLÓGICA DE VARIEDADES DE ABACAXIZEIRO, CONFORME OS TIPOS DE MUDA, EM CORDEIRÓPOLIS (SP)

Seven pineapple varieties were tested in field trials in Cordeiropolis, State of Sao Paulo, from May 1991 to February 1994, in four experiments, each one using different planting materials: sucker or shoot, slip, crown and stem section plants (developed from bud stem in sand box). The varieties were: Rondon (RD), Roxo de Tefe (RT), Turi Verde (TV), Natal Queen (NQ), Guiana (GN), Perola (PR) and Smooth Cayenne (SC).The followings characteristics were evaluated: the periods for natural inflorescence emission, the time between the emission until the flowering completed, and from then until the ripped-fruit; also, the fruit diameters (the base, the top and the largest diameter), the mass production (fruit and crown), and in the pulp, the soluble solid content (Brix), texture, acidity, ascorbic acid content and pH. The main results were: (1) RD and PR had the earliest uniform natural inflorescence emission, and SC and TV had the latest ones; (2) NQ had the shortest and SC and GN the longest period from the emission to the harvest; (3) SC and GN yielded fruits with mean weight (g) 52% and 24% higher than the mean weight of RD, PR and TV together. NQ had the lowest mean weight; (4) GN had the highest number of slips and suckers, and SC had the lowest number of slips; (5) The plants from bud-stem had lower number of slips and suckers than from the other three planting materials; (6) The pulp soluble solid content (Brix) of SC and NQ and the acidity of TV had higher values, and NQ had the highest value for the Brix and acidity ratio; (7) PR had the highest ascorbic acid content and RD had higher content than SC. It was concluded that some of the varieties cultivated in Brazil may replace the Smooth Cayenne and Perola, what is desirable, because SC and PR are highly susceptible to Fusarium subglutinans.

Potencial de produção de sementes de cultivares e clones de abacaxi visando ao melhoramento genético

Open-pollinated and artificial crosses have been carried out throughout three years among 18 cultivars and clones of pineapple, Ananas comosus (L.) Merrill, aiming at the future selection of new hybrids with desirable agronomic and fruit quality traits, in segregating progenies. The genetic materials have been evaluated as to their seed yield potentials in order to provide basic information for the choice of parentals to be used in future crosses. The amount of viable seeds produced in different crosses has been higly variable. Cultivar Perolera and clones Amarelo-de-uaupes, Roxo-de-tefe, Rioja, and Boituva have been the best seed producers in open-pollinated crosses whereas cultivar Perolera and clones Amarelo-de-uaupes, Natal Queen, and Rioja outyielded the others in artificial crosses. A significant correlation (r = 0.82**) was observed between the seed yields obtained in the two pollination systems used.

Características da atividade da peroxidase de abacaxis (Ananas comosus (L.) Merrill) da cultivar IAC Gomo-de-mel e do clone IAC-1

In the present work, the biochemical characteristics of peroxidase enzymes from new pineapples, cultivar IAC Gomo-de-mel and clone IAC-1, were studied. The peroxidases obtained from the juice of this pineapples presented optimum activities from 45 oC to 50 oC and 50 oC to 55 oC, respectively. These peroxidases showed maximum activity at pH 4.5 and showed stability at pH 4.0 to 9.0, retaining after 24 hours of incubation at 50 oC more than 80% of initial activity. Partial regeneration of peroxidase activity was observed after treatment at 75 oC for 10 minutes. The peroxidases from pineapple juices studied were inactivated after treatment at 90 oC for 2 minutes.