Joaquim Teófilo Sobrinho

Isoenzimas na identificação precoce de híbridos e clones nucelares no melhoramento de citros

Um dos problemas relacionados ao melhoramento de citros e a poliembrionia e a consequente dificuldade, apos cruzamentos controlados, de distinguir clones nucelares dos hibridos. Estudou-se um metodo para eletroforese de isoenzimas em gel de amido para doze sistemas isoenzimicos, desenvolvendo-se procedimento apropriado para a resolucao simultânea dos sistemas fosfatase acida, peroxidase anodica e catodica, glutamato oxaloacetico transaminase, fosfoglucoisomerase, fosfoglucomutase e enzima malica. Caracterizaram-se por esses sistemas 31 clones de citros com possivel interesse para o programa de melhoramento do IAC. Estao envolvidos 7 locos e 25 alelos, permitindo uma identificacao precoce de hibridos antes do plantio no campo para avaliacoes agronomicas. Implicacoes desses estudos basicos no melhoramento e na determinacao da taxa de seedlings nucelares de porta-enxertos comerciais sao discutidas.

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.

Viabilidade de pólen em clones de laranja pêra e outras variedades assemelhadas

Sterility limits sexual hybridization, but on the other hand, it is of economic importance by inducing fewer seeds per fruit in some citrus varieties. Pera sweet orange is the main cultivar in Brazil, around 50% of all sweet oranges produced in the country. This variety has good processing quality as well as for the fresh market. The importance of this cultivar for the brazilian citriculture and the necessity to search for new cultivars, which combine the good characteristics from Pera with others desirable agronomic characters, has induced new basic studies aiming at a better knowledge of genetics and reproduction of this elite variety. In this way, in this work, was studied the pollen viability for eleven clones of Pera and five others sweet orange varieties, morphologically similar to Pera, budded in Rangpur lime (Citrus limonia Osbeck). The percentile of pollen viability was evaluated using acetic carmine stain and optic microscopy. It was observed that Corsa Tardia, Pera Olimpia and Ovale San Lio varieties, presented larger quantity of viable pollen, with 65.5, 57.3 and 53.6%, respectively, most of studied genotypes showed this values varying from 30 to 50%, and those that presented fewer values were Pera Bianchi and Pera Pirangi, with approximately 28% of viable pollen as well as Ovale de Siracusa variety, which did not present pollen.