G. M. de Resende

Doses de nitrogênio e molibdênio no rendimento e teor de micronutrientes em alface americana

The trial was carried out in Tres Pontas, Minas Gerais State, Brazil, from October to December, 2002, to evaluate the influence of doses of nitrogen and molybdenum on yield and macronutrient uptake of crisphead lettuce (Lactuca sativa L.). A randomized complete block design scheme with three replications was used, in which the treatments were a factorial combination of nitrogen rates (0, 60, 120 and 180 kg ha-1 of N) in top dressing in addition to the dose used by farmers (60 kg ha-1 of N) and five foliar molybdenum rates (0.0; 35.1; 70.2; 105.3 and 140.4 g ha-1). The highest yield of commercial fresh mass was obtained using the dose of 89.1 kg ha-1 of nitrogen in top dressing and 94.2 g ha-1 of molybdenum. The results indicated an increase in the levels of Ca, Zn, Fe and Mn as a consequence of the application of higher doses of nitrogen and molybdenum. Significant effect of the interaction N x Mo on the Cu level was verified and it was evidenced, for the highest molybdenum level (140.4 g ha-1), a linear reduction due to the application of increasing doses of nitrogen.

Produtividade de cultivares de tomate industrial no Vale do São Francisco

Two field trials were carried out to evaluate processing tomato cultivars in the Experimental Field of Bebedouro, Petrolina, Brazil, in the periods of May to October 1996 and 1997. The experimental design consisted of randomized blocks with 18 cultivars (IPA-5, XPH-5720, XPH-12066, XPH-12045, XPH-12068, XPH-12044, Spectrum-151, Spectrum-153, Spectrum-385, Nema-512, Nema-1435, Hypeel-153, Hypeel-108, PSP-58494, PSP-22210, Latino, Zenith and Condor), with four replications. The commercial yield ranged from 70.85 to 96.68 t/ha. The cultivars IPA-5, XPH-5720, Spectrum-151, Nema-512, XPH-12044, Spectrum-385, Hypeel-153 and XPH-12066 showed the highest commercial yields above 86.0 t/ha, the lowest yield being shown by the cultivar Spectrum-579, with 70,85 t/ha. When the yield was adjusted in function of oBrix, similar results were observed, Zenith and XPH-12045 being included among the highest yielding cultivars. The cultivars Nema-1435 (110.96g/fruit) and Hypeel-108 (101.54 g /fruit) showed the highest average weight of fruits. The soluble solids (Brix) contents ranged from 4.3% to 6.0%, and all hybrids showed higher contents than the open-pollinated variety IPA-5, which showed the lowest brix (4.30), the highest contents being from PSP-22210 (6.00) and Zenith (5.80). The results regarding fruit yield and quality allow us to recommend the cultivars XPH-5720, Spectrum-151, Nema-512, XPH-12044, Spectrum-385, Hypeel-153, XPH-12066, XPH-12045 and Zenith for the farmers, besides the traditional cultivar IPA-5.

Evaluation of onion cultivars at Petrolina-PE.

With the objective of identifying high productive and better quality onion cultivars for the tropical semi-arid region of Brazil, field trials were conducted at Petrolina, Pernambuco State, Brazil, from February until July of 1996.The experimental design was a randomized complete blocks with four repetitions and twenty treatments (Cultivars Granex-429, Texas Grano-PRR, Brownsville, Houston, Texas Grano-502, Texas Grano-438, Conquista, Composto IPA-6, Belem IPA-9, Franciscana IPA-10, Valeouro IPA-11, Alfa Tropical (CNPH-6179), CNPH-5898, CNPH-6074, CNPH-6040, CNPH-6067, Bola P. Empasc, XP-1, XP-2 and Crioula Mercosul). Production of commercial bulbs ranged forms 21.41 to 61.78 ton/ha. Texas Grano-PRR had the highest yield (61.78 ton/ha), followed by Granex-429 (58.28 ton/ha), Texas Grano-438 (56.97 ton/ha), Brownsville (55.38 ton/ha), Texas Grano-502 (53.97 ton/ha) and Houston (53.35 ton/ha).

Yield and postharvest storage of onion bulbs using doses of nitrogen and potassium.

This study was carried out from March to November 2001, in Petrolina, Pernambuco State, Brazil, to evaluate the influence of nitrogen and potassium levels applied through fertirrigation, on yield and post-harvest quality of onion bulbs. Cultivar Franciscana IPA- 10 was used in a randomized complete block design, in a 4 x 3 factorial arrangement, with four nitrogen levels (0; 60; 120 and 180 kg ha-1) and three potassium levels (0; 90 and 180 kg ha-1 of K2O) with three replications. The applied levels of nitrogen showed linear effects on the commercial yield independent of the potassium fertilization. The non-commercial yield (calls) showed linear reductions in the three potassium levels, with the increase in nitrogen levels. With the increase of applied nitrogen levels a linear effect on the fresh mass of the bulbs was observed. There were no significant effects of nitrogen and potassium application on the mass loss of the bulbs at 40 and 80 days after cure.O experimento foi conduzido de marco a novembro de 2001, em Petrolina-PE, com o objetivo de avaliar a influencia de doses de nitrogenio e potassio aplicadas via fertirrigacao sobre o rendimento e conservacao pos-colheita da cebola. Utilizou-se a cultivar Franciscana IPA-10, no delineamento experimental de blocos ao acaso, em esquema fatorial 4 x 3, compreendendo quatro doses de nitrogenio (0; 60; 120 e 180 kg ha-1) e tres doses de potassio (0; 90 e 180 kg ha-1 de K2O), com tres repeticoes. A adubacao nitrogenada apresentou efeitos lineares positivos na produtividade comercial independente da adubacao potassica. Para a produtividade nao comercial (refugos) constataram-se reducoes lineares na ausencia da adubacao potassica e nas doses de 90 e 180 kg ha-1 de K2O, com o incremento das doses de nitrogenio. O aumento das doses de nitrogenio proporcionou um incremento linear na massa fresca dos bulbos. Nao se constataram efeitos significativos para perda de massa aos 40 e 80 dias apos cura, com a aplicacao de nitrogenio e potassio.

Yield components of sweet potato cultivars harvested on two dates in Porteirinha, Minas Gerais.

Com o objetivo de avaliar a produtividade e a qualidade de raizes de cultivares de batata-doce e identificar a melhor epoca de colheita, conduziu-se um experimento no Campo Experimental do Gorutuba, em Porteirinha-MG, de novembro de 1990 a junho de 1991. Foram estudadas cinco cultivares de batata-doce (Brazlândia Branca, Brazlândia Rosada, Brazlândia Roxa, Princesa e Paulistinha) e duas epocas de colheita (150 e 200 dias apos plantio), arranjadas em esquema fatorial 5x2, no delineamento experimental de blocos casualizados, com cinco repeticoes. Verificou-se, para a colheita aos 150 dias apos o plantio, que a cultivar Brazlândia Branca foi 62,7% mais produtiva (22,84 t/ha) que a cultivar Brazlândia Roxa (14,33 t/ha), a menos produtiva. Aos 200 dias de ciclo, a cultivar Paulistinha foi a mais produtiva (54,50 t/ha), sendo a menor produtividade apresentada pela cultivar Brazlândia Rosada (55,0% menos produtiva que a cultivar Paulistinha). A cultivar Brazlândia Roxa apresentou maior producao de refugos, de 7,76 e 12,38 t/ha, respectivamente, para a colheita aos 150 e aos 200 dias apos o plantio. Para peso medio de raiz, houve uma variacao de 220,12 a 504,95 g, sendo que todas as cultivares apresentaram maior porcentagem de raizes graudas (400-800 g/raiz), quando colhidas mais tardiamente. Recomenda-se a colheita das cultivares Paulistinha, Brazlândia Rosada e Brazlândia Branca aos 150 dias apos o plantio, pelo tamanho menor de raizes preferidas pelo consumidor. Ja para a cultivar Princesa, em funcao da sua menor producao de raizes tipo 2 (400 a 800 g/raiz) comparativamente as cultivares anteriores, sua colheita pode ser feita de 150 ate 200 dias apos o plantio. A cultivar Brazlândia Roxa apresentou melhor desempenho quando colhida aos 200 dias apos o plantio.