Roberto Pedroso de Oliveira

Bap concentration and tetraploid banana micropropagation efficiency (AAAB group)

The objective of the present work was to establish an efficient procedure for the in vitro production of tetraploid banana plantlets (Musa sp. cv. FHIA-01, AAAB group). The cloning effect on the in vitro development of the explants, the rates of contamination and multiplication, and the level of oxidation in culture media with five benzylaminopurine (BAP) concentrations were studied. In the phase of in vitro introduction of explants, a high level of contamination (22.32%), caused mainly by bacteria, was observed. However, the degree of contamination decreased along the subcultures, reaching 1.07% in the eighth subculture. Higher multiplication rates were obtained, averaging 2.65 per subculture, on the MS media supplemented with 4.0 mg L-1 BAP, leading to an estimated production of 584 and 3451 plantlets/initial explant after the 6th and 8th subculture, respectively. A pronounced effect of the cloning on multiplication was observed. Acclimatization efficiency of plantlets was 94%. Somaclonal variations were not observed among in vitro micropropagated plantlets under greenhouse conditions.

Desempenho produtivo de mudas nacionais e importadas de morangueiro

The aim of this work was to compare the agronomic performance of national and imported strawberry plants, using Aromas and Camarosa cultivars at the climatic conditions of Rio Grande do Sul. The experiment was carried out in Pelotas, using tunnel system and fertirrigation. In June of 2005, the strawberry plants from three regions (Chile, Serra Gaucha and Pelotas) and two cultivars (Aromas and Camarosa) were transplanted at the distance of 35 cm between lines and between plants. The treatments were disposed according to a randomized complete block design and a factorial arrangement with four replications. The experimental units were composed by 20 plants. Weekly, from August to December, the variables fruit fresh weight and number of fruits produced in each experimental unit were studied. Camarosa cultivar (569,6 g plant-1) was more productive than Aromas (510,4 g plant-1). Independently of the cultivar, the imported plants from Chile showed greater production of commercial fruits (724,5 g plant-1) and fruits of bigger average weight (15,5 g) than those produced in Pelotas region (493,3 g plant-1 and 12,6 g fruit-1) and in Serra Gaucha (402,3 g plant-1 and 11,7 g fruit-1).

Production of strawberry fruits depending on vernalization periods of the transplants

The yield of strawberry fruits cv. Camarosa was evaluated as affected by different vernalization periods of the transplant, in comparison with imported ones. The experiment was carried out in Pelotas, Rio Grande do Sul State, Brazil, using a tunnel as production system. The plants were transplanted on May18, 2006, using transplants produced in the south of Rio Grande do Sul, which were vernalized during 0; 7; 14; 21 and 28 days (4±1oC, 94±2% RH), and transplants without vernalization coming from Chile. The treatments were disposed according to a randomized complete block design with four replications. The experimental unit were composed of 21 plants. The yield, number of fruits per plant and average fruit mass were analyzed during 20 weeks (August to December). The Chilean transplants provided greater production and number of fruits than transplants produced in Rio Grande do Sul (1,038.3 and 491.7 g plant-1; 55.1 and 34.3 fruits plant-1, respectively). The vernalization of the national transplants during approximately 24 days optimized the yield and number of fruits significantly (1,023.1 g plant-1; 55.6 fruits plant-1). Transplants produced in Rio Grande do Sul presented higher production in November and December, while Chilean ones in October and November.

Escarificação química da semente para favorecer a emergência e o crescimento do porta-enxerto Trifoliata

O objetivo deste trabalho foi avaliar a emergencia e o crescimento de plantas do porta-enxerto de citros Trifoliata [Poncirus trifoliata (L.) Raf.], provenientes de sementes escarificadas quimicamente. A semeadura foi realizada em tubetes de plastico, contendo substrato comercial, em viveiro-telado. Foram utilizados: tratamento quimico de referencia - TQR (imersao por 45 minutos em solucao 0,5 L NaClO 12%, 3 mL HCl e 20 g NaOH diluidos para 2 L de agua); metade, o dobro e quatro vezes a concentracao do TQR; metade e o dobro do tempo de imersao do TQR; omissao de NaClO; omissao de HCl; omissao de NaOH; tratamentos- controle utilizando sementes com tegumento e sem tegumento. Utilizou-se delineamento de blocos ao acaso, com quatro repeticoes e unidades experimentais constituidas por 42 tubetes contendo uma semente cada. A emergencia das plantas de Trifoliata ocorre do 6o ao 45o dia depois da semeadura. A porcentagem final de emergencia varia de 92,4 a 99,7%. Aos 65 dias da semeadura, as sementes submetidas a escarificacao no tratamento com o dobro da concentracao do TQR resultam em porta-enxertos com maior producao de materia seca total (0,52 g por planta) e bom desempenho quanto a media de altura (15,2 cm) e diâmetro do caule (2,41 mm).

Indução e desenvolvimento de calos e embriões somáticos em mamoeiro

In order to establish a protocol for induction and development of callus and somatic embryos of papaya (Carica papaya L. cv. Tainung n.1) four explant types (hypocotyl with cotiledonary leaves, hypocotyl, cotiledonary leaves and epycotyl) and two light conditions (dark and 16 h photoperiod) were used. Callus induction and development were evaluated in ½MS2, ½MS10 and HMH media, and somatic embryo induction and development in ½MS and HMH1 media. In vitro culture of hypocotyl with cotiledonary leaves in ½MS10 medium, under dark condition for 20 days, was suitable for induction (100%) and growth of embryogenic friable callus. The culture of these callus in ½MS medium, under dark condition for two subcultures of 30 days, was suitable for induction (60%) and development of papaya somatic embryos. The explant type, culture media and culture conditions were defined for papaya somatic embryogenesis.

BRS Ana: cultivar de batata de duplo propósito

The genotype BRS Ana is a new potato cultivar adequate for French fries, with potential for processing into frozen French fries and flakes, released in 2007. It was developed by the Embrapa Potato Breeding Program (Embrapa Temperate Agriculture, Pelotas-RS; Embrapa Transference of Technology, Office of Canoinhas-SC; and Embrapa Vegetables, Brasilia-DF), based on tuber appearance and yield, specific gravity and French fries quality. Tubers are red-skinned, lightly rough, oval shaped with shallow eyes. The pulp is white. Cultivar BRS Ana has high yield potential. In the subtropical ecosystem, cultivar BRS Ana showed higher yield (31.2 t ha-1) than the most used cultivars in Brazil when grown in autumn, and did not differ from them in the spring. In the tropical ecosystem, under irrigation, BRS Ana did not differ from both control cultivars. It produced higher percentage of marketable tubers (55.6%) and average tuber weight (108.4 g) than the controls in the fall crop of subtropical ecosystem. In both ecosystems, cultivar BRS Ana presented high specific gravity (1.086) and dry matter content (19.7%). The sensorial analysis showed that cultivar BRS Ana is adequate for home made French fries as well as for industrial processing. It is moderately susceptible to late blight (Phytophthora infestans) and presents good resistance to early blight (Alternaria solani). The reaction to the tuber soft rot (Pectobacterium sp.) is similar to the most used cultivars. It has low seed degeneration conferred by moderate resistance to PVY and low incidence of PLRV. Susceptibility to tuber physiological disorders has not been observed. It seems that BRS Ana has lower fertilizer and water requirements than the most planted cultivars, meaning reduction of crop cost and risk. In the subtropical ecosystem, tuberization starts later in spring, therefore BRS Ana should be planted earlier in the season.

In vitro conservation of diploid banana accessions

A protocol for the in vitro conservation of diploid banana accessions based on lower temperature for culture environment was developed. Twenty four genotypes, four clones per genotype were studied. After disinfection, shoot tips (0.5 cm diameter x 0.5 cm height) were established in vitro and submitted to multiplication induced by benzylaminopurine. Twelve explants (0.6 cm diameter x 1.2 cm height) from each accession were transferred to the MS medium supplemented with 20 g L-1 sucrose and 2 g L-1 Phytagel, without growth regulators, under light intensity of 2000 lux, 16-hour photoperiod, at temperatures of: 17 ± 2oC, 22 ± 2oC and 26 ± 2oC. The development of plantlets was evaluated during 450 days and the survived plantlets were acclimated under greenhouse conditions. There were no differences among genotypes concerning the behavior during in vitro conservation; all genotypes showed potential to be conserved for a long time. The interval for transference should be 180, 360 and 450 days under the mean temperatures of 26, 22 and 17oC, respectively.

Formação do porta-enxerto Trifoliata: época de semeadura e tegumento na emergência de plântulas

This study was aimed at evaluating the effect of the time of sowing and the seedcoat in seedling emergency and production of Trifoliata rootstock. The experiment was carried out in a glasshouse, in Pelotas-RS. Sowing was performed in dibble tubes of 50cm3, containing commercial substrate. Two sowing plates (winter and spring) and three seedcoat treatments (integral tegument, with a hole in the endosperm and without tegument) were studied. The experimental design was a randomized complete block, in a factorial schedule, with four replications and experimental units composed by 42 dibble tubes with one seed each. The rootstocks were considered adequate for the transplant when they reached 15cm height. The speed and final germination percentage of Trifoliata rootstocks were significantly higher in the spring (95.6%) compared to the winter (83.6%). Regardless of the season of the year, the removal of the seedcoat improved the germination (96.9%) compared with the use of seed with integral tegument (84.8%). The period necessary for rootstock formation in dibble tubes was 70 days in the spring and 130 days in the winter.

Skewed RAPD markers in linkage maps of Citrus

The objective of this work was to analyze the effects of RAPD markers with skewed segregation on genetic linkage maps. Segregation data for 123 Citrus sinensis (L.) Osbeck cv. Pera markers and 53 C. reticulata Blanco cv. Cravo markers in F1 progeny composed of 94 hybrids were used. Genetic linkage maps of the two varieties were constructed with non-skewed markers (p < 0.05 and p < 0.01) using the program MAPMAKER 3.0 and a pseudo-testcross strategy. The maps were compared to those constructed with all markers. Alterations in the genetic distances were observed based on the location of the skewed markers within the linkage groups. Generally, the skewed markers were located at the end of the linkage groups, sometimes forming entire linkage groups, without causing significant distance modifications. However, skewed markers located between non-skewed markers caused significant distance modifications and, in some cases, altered the order of the markers. Most of the skewed markers can be included in linkage maps, but in each case the degree of distance modification caused by each marker needs to be assessed.

Sugarcane micropropagation using light emitting diodes and adjustment in growth-medium sucrose concentration

The aim of this research was to evaluate the use of light emitting diodes (LEDs) instead of white fluorescent lamps as light source and adequate growth-medium sucrose concentration for sugarcane micropropagation (Saccharum officinarum L.). Sugarcane (RB 872552 variety) bud explants were evaluated during the multiplication and rooting phases under controlled growth-room conditions. Different light sources (blue, red and green LEDs; Growlux and white fluorescent lamps) and different medium sucrose concentrations (0; 15; 30 and 45g L-1) were used, maintaining constant light intensity (20µmol m-2 s-1), photoperiod (16h) and temperature (25+2°C). The experiment was a completely randomized design, and treatments were arranged in a 5x4 factorial (five light sources and four medium sucrose concentrations) with six replications. Sugarcane bud growth was satisfactory under the three LED types studied. The presence of sucrose in growth media was essential for bud multiplication and rooting. Nevertheless, each light source requires the respective medium sucrose concentration adjustment for best results. Red LEDs provided a significantly high multiplication rate (although not the highest) with 8.5 buds per sub-culture and 34.9g L-1 of sucrose; also, the highest bud length (33.3mm) and the best plantlet acclimatization. Therefore, LED sources can advantageously substitute fluorescent lamps in laboratories of sugarcane micropropagation.