Juarez C. Rodrigues Júnior

Comportamento de cultivares de alface tipo americana em Boa Esperança

The experiment was carried out at green house, in Boa Esperanca, Brazil, to evaluate lettuce cultivars (Cassino; Legacy; Lucy Brown; Lorca; Lady and Raider), crisphead group, in two planting seasons (October and March). The experimental design was of randomized blocks with four replications. For the first season (October), the commercial yield, varied from 29.3 t.ha-1 to 37.6 t.ha-1 and head circumference from 40.07 to 42.95 cm, without significant difference among cultivars. At the second planting season (March), cvs. Raider, Cassino, Lady, Legacy and Lorca presented a commercial yield of 42.6; 41.6; 39.3; 37.3 and 32.5 t.ha-1. Cvs. Lady, Raider Lucy Brown and Cassino, were superior to the other cultivars, without significant differences among themselves, with 48.15; 46.69; 45.90; and 45.67 cm respectively.

Efeito de composto orgânico sobre a produção e características comerciais de alface americana

Doses of organic compost were evaluated on crisp head lettuce production and quality in an experiment conduced in Tres Pontas, Brazil, from July 8>th to August 30th. The experimental design was in randomized complete blocks with four replicates, the treatments being constituted by five doses of organic compost (0.0; 20.0; 40.0; 60.0 and 80.0 t ha-1). Total fresh matter showed a quadratic effect, in which the maximum yield of 914.2 g plant-1 was obtained with the dose of 59.4 t ha-1 of organic compost. For commercial fresh matter, the maximum yield (634.3 g plant-1) was obtained with the dose of 56.1 t ha-1. The greatest commercial head circumference (41.4 cm) was obtained with the dose of 53.7 t ha-1. The dose of 42.7 t ha-1 caused a maximum stem length of 3.9 cm. These results permit to conclude that the use of 56.0 t ha-1 of organic compost applied in pre plant provides an increase in yield and commercial quality of crisp head lettuce.

Efeitos de tipos de bandejas e idade de transplantio de mudas sobre o desenvolvimento e produtividade da alface americana

This study was carried out from March to July, 2002 at Tres Pontas, Brazil, to evaluate the influence of tray types and transplanting age of seedlings over the development of crisphead lettuce (Lactuca sativa L.). Three types of tray (128; 200, and 288 cells) and five transplanting ages (22; 26; 30; 34 and 38 days after the sowing) were evaluated in a randomized complete block experimental design (3 x 5 factorial), with three replications. The 128 cells tray and the transplantation at 38 days after sowing date showed the highest fresh mass, driest weight, highest leaf number and highest plant height. The highest commercial yield was obtained with 128 cells tray, followed by the one with 200 cells. The lowest yield was obtained with the 288 cells tray. The transplanting age varied from 22 to 38 days after sowing date depending on the use of the 128 or 200 cells tray, with preference for the smaller periods (22 to 30 days). Using the tray with 288 cells, the seedlings should be transplanted at 38 days after sowing date.

Produtividade e qualidade pós-colheita da alface americana em função de doses de nitrogênio e molibdênio

The influence of nitrogen and molybdenum doses was evaluated on the productive characteristics and postharvest quality of crisphead lettuce (Lactuca sativa L.), at Tres Pontas, Minas Gerais State, Brazil, from October to December 2002. A randomized complete block design in a 4 x 5 factorial arrangement with three replications was used. The factorial consisted of four doses of nitrogen (0; 60; 120 and 180 kg/ha) in top dressing, in addition to the usual farmers doses (60 kg/ha), and five doses of molybdenum in foliar application (0.0; 35.1; 70.2; 105.3, and 140.4 g/ha). The highest total fresh weight was obtained with the doses of 86.9 kg/ha of nitrogen in top dressing and 87.4 g/ha of molybdenum. Highest commercial fresh weight was obtained using the doses of 89.1 g/ha of nitrogen in top dressing, while the doses of 94.2 g/ha of molybdenum resulted in the highest yield. The doses of 85.3 kg/ha of nitrogen in top dressing and 72.9 g/ha of molybdenum were the best for highest commercial head circumference. There was no significant effect of the treatments on stem length and post-harvest conservation. The highest percentage of dry matter was obtained with the doses of 89.9 kg/ha of N in top dressing and 77.2 g/ha of Mo in foliar spray.

Produção de alface americana em função da aplicação de doses e fontes de fósforo

Avaliou-se o efeito de doses e fontes de fosforo na producao de alface americana em experimento no municipio de Santo Antonio do Amparo, MG, de junho a setembro/98. O delineamento utilizado foi blocos ao acaso em esquema fatorial 2x4, com tres repeticoes, compreendendo duas fontes de fosforo [superfosfato simples (18% de P2O5) e termofosfato magnesiano (17% de P2O5)], e quatro doses (0, 300, 600, 900 kg ha-1de P2O5). Avaliou-se a producao total e comercial de alface, comprimento do caule e circunferencia da cabeca comercial. Observou-se para a producao total e comercial efeitos significativos na interacao entre doses e fontes. Para o superfosfato simples houve regressao quadratica em que as doses de 672 e 617 kg ha-1 de P2O5, apresentaram as maiores producoes total e comercial, respectivamente. Quanto ao termofosfato magnesiano verificou-se aumento linear na produtividade. Com o uso da dose de 583 kg ha-1de P2O5 obteve-se o maior comprimento de caule (6,7 cm), sem no entanto, prejudicar o valor comercial. As doses, bem como as fontes de fosforo utilizadas nao apresentaram o efeito significativo com relacao a circunferencia da cabeca comercial.

Rendimento e teores de macronutrientes em alface tipo americana em função de doses de nitrogênio e molibdênio em cultivo de verão

Conduziu-se o trabalho, no municipio de Tres Pontas, Sul de Minas Gerais, no periodo de outubro a dezembro de 2002, objetivando avaliar a influencia de doses de nitrogenio e molibdenio no rendimento e teor de macronutrientes da alface americana (Lactuca sativa L.). Utilizou-se o delineamento de blocos ao acaso em arranjo fatorial 4 x 5, compreendendo quatro doses de nitrogenio em cobertura adicionais a dose aplicada pelo produtor de 60 kg/ha de N (0, 60, 120 e 180 kg/ha) e cinco doses de molibdenio via foliar (0,0; 35,1; 70,2; 105,3 e 140,4 g/ha) e tres repeticoes. A maior massa fresca comercial foi obtida com a dose de 89,1 kg/ha de nitrogenio em cobertura e 94,2 g/ha de molibdenio. Os resultados indicaram incremento no teor de nitrogenio e fosforo com as doses de nitrogenio e molibdenio. Os teores de potassio reduziram-se com o aumento das doses de nitrogenio e molibdenio. Para os teores de calcio, magnesio e enxofre verificou-se efeito significativo da interacao N x Mo, cujas concentracoes na parte aerea aumentaram com as doses de nitrogenio e molibdenio.

Produção de alface americana em função de doses e épocas de aplicação de Supa Potássio

Three trials were carried out in Tres Pontas, Brazil, from November 2002 to January 2003, to evaluate the effects of Supa Potassio® doses on yield and quality of crisphead lettuce. Five doses of Supa Potassio® (0.0; 4.5; 9.0; 13.5 and 18.0 L/ha), with 20% SiO2 and 15% K and three foliar application times (14; 21 and 28 days after planting date) were tested using a randomized complete blocks design with four replications. Each application time was considered one trial. The total fresh mass presented quadratic effect and the dose 9.1 L/ha of Supa Potassio® resulted in the largest revenue. There were significant differences between time of foliar application for plant fresh weight and plants with 706,0 g were harvested when Supa Potassio® was applied 14 days after transplant. The application of 10.5 L/ha of Supa Potassio® promoted the highest commercial fresh matter. Applications at 21 and 28 days after planting date showed a quadratic effect and the doses of 4.3 and 9.8 L/ha of Supa Potassio® presented the best post-harvest storage of the crisphead lettuce. Supa Potassio® had no significant effect on head circumference and stem length.

Comportamento da alface americana em função do uso de doses e épocas de aplicação de boro em cultivo de inverno

The influence of doses of borax on yield and post harvest quality of crisp head lettuce (Lactuca sativa L.) was evaluated. Three distinct trials were conducted in Tres Pontas, Minas Gerais State, Brazil, from June to August 2002. The randomized block design with five doses of borax (0.00; 0.75; 1.50; 2.25 and 3.00 kg.ha-1) and four replicates, applied foliarly at different times (14; 21 and 28 days after transplanting) was evaluated. The total fresh matter presented a quadratic effect, where the dose of 1.58 kg ha-1 of borax resulted in a greater yield. A range of 795 to 829 g plant-1 between different application times, with no statistical significant differences was observed. The application of 1.71 kg ha-1 of borax resulted in greater commercial fresh matter production. The best results (563 g plant-1) were obtained when the application was performed at 21 days. Applications at 21 days also resulted in greater head circumference (41.7 cm), being statistically superior to the applications at 28 days (40.6 cm). Stem length did not present any significant effects between treatments. The dose of 1.55 kg ha-1 of borax presented best lettuce conservation in cold-chamber (20 days).

Resposta da alface americana (Lactuca sativa L.) a doses e épocas de aplicação de cobre

Foram conduzidos tres ensaios distintos no periodo de dezembro de 2002 a fevereiro de 2003, no municipio de Tres Pontas - MG, com o objetivo de avaliar a influencia de doses de cobre sobre a producao de alface americana (Lactuca sativa L.). Utilizou-se o delineamento de blocos ao acaso com cinco tratamentos, sendo uma testemunha e quatro doses de cobre (0,15, 0,30, 0,45 e 0,60 l/ha); e 4 repeticoes, aplicadas em tres diferentes epocas via foliar (14, 21 e 28 dias apos o transplantio). A maior massa fresca comercial por planta foi constatada na dose de 0,35 l/ha de cobre, com um incremento de 20,5% no rendimento, comparativamente a testemunha. A aplicacao aos 21 e 28 dias apos o transplante promoveu os maiores comprimentos de caule com 5,7 e 6,1 cm, respectivamente. A dose de 0,45 l/ha de cobre elevou a circunferencia da cabeca comercial. Para sanidade das folhas constatou-se efeito quadratico, no qual a dose de 0,41 l/ha de cobre proporcionou a melhor sanidade das folhas externas, quando aplicada aos 21 e 28 dias. Nao se observou efeito significativo dos tratamentos para massa fresca total.