João Bosco Carvalho da Silva

Production and testing of lettuce seed pellets.

Para este trabalho, os peletes foram confeccionados em betonei ras, onde as sementes rolam umas sobre as outras, recebendo aos poucos e alternadamente os ingredientes de enchimento e cimentante, ate atingirem o tamanho desejado, sendo entao secados e classifica dos. Foram confeccionados peletes de semente de alface com areia fina, areia grossa, calcario fino e calcario grosso, utilizando como cimentante, bentonita diluida em agua a 7,5% ou cola a base de acetato de polivinila (PVA) a 30%. Parte dos peletes recebeu acaba mento com calcario calcifico mais cola a base de PVA. Os peletes pequenos, confeccionados com areia fina ou com a mistura de areia e calcario, com ou sem acabamento, apresentaram os melhores re sultados, nao diferindo da germinacao e da velocidade de cresci mento de plântulas obtidas de sementes nuas. A utilizacao de calcario prejudicou o crescimento das plântulas e o prejuizo foi mais acentu ado para os peletes grandes. Os peletes confeccionados com calcario e cola a base de PVA foram os mais resistentes ao esmagamento e os peletes confeccionados com areia, utilizando bentonita como cimentante, os de menor resistencia. A cola a base de PVA atuou como cimentante mais forte que a bentonita e a aplicacao da camada de acabamento com cola a base de PVA aumentou a firmeza dos peletes. Os peletes confeccionados com areia apresentaram maior velocidade de dissolucao, mas todos os peletes testados se dissolveram em me nos de um minuto. Todos eles apresentaram baixo grau de umidade (media de 0,45%) e baixa higroscopicidade (cerca de 0,6%).

Desempenho de sementes peletizadas de alface em função do material cimentante e da temperatura de secagem dos péletes

Seeds of lettuce cv. Grand Rapids Nacional were pelleted using as a filler, a mixture of sand and microcellulose in equal volume parts, and as a glue, different volumes of water suspension of bentonite and polyvinyl acetate at five proportions (%): 100+0; 75+25; 50+50; 25+75; and 0+100 applied apart, betonite being applied in the first coat layer. After pelleting, seeds were dried at 15 or 36°C and evaluated for germination and seedling emergence. Seed pelleting compound and drying temperature did not affect total germination. Only two pellet formulations showed reduced rate of seedling emergence indicating that differences were not due to the coat formulation and drying process. Independently of seed pellet formulation and drying temperature, the germination of pelleted seed delayed in relation to raw seeds. When sowed in organic substrate and placed under greenhouse conditions, pelleted seeds showed similar germination rate to raw seeds. In this environment, seedlings from pelleted seeds showed normal growth. The fresh and dry matter were similar to those from raw seeds at 20 days after sowing.

Desempenho de sementes de pimentão revestidas com diferentes materiais

The technique of covering seeds has been used mainly for the species which have small seeds, such as vegetables, forage, forest and ornamental species, because besides increasing the size of the seeds for direct sowing, it is possible to add other elements which are necessary for the good development of the plant in its early stages. In this context the objective of the present study was to covered green-pepper seeds in different types of materials and to evaluate their behavior during storage. Seeds treated and not treated with Rovrin at the dosage of 200g/100kg were submitted to pre-conditioning for the imbibing of seeds in KNO3 in -1,1Mpa solution, in an aired system for 5 days. After drying the seeds were covered in a mixture of sand + microcellulose and another of limestone + microcellulose. The covered seeds and those not covered were dried and packed in paper envelopes (permeable pack) and in aluminum envelopes (impermeable pack) and stored at room temperature in the Seeds Analysis Laboratory at UFLA. The seed quality was evaluated once every four months, for a period of 20 months, using the following parameters: water content, germination test, accelerated aging, controlled deterioration and emergency in soil + sand. From the results, it was possible to conclude that the covering of seeds slows but does not affect the germination rate of the green pepper seeds before storage, but the covered seeds deteriorate faster than the seeds not covered, when stored in permeable packs. The nature of the materials used did not affect the quality of the green pepper seeds stored in impermeable packs.

Efeito de diferentes materiais de peletização na deterioração de sementes de tomate durante o armazenamento

The pelleting of vegetable seeds is a very common technique, mainly for the species which have small seeds. One of its functions is to increase the seed size for direct sowing. The present study verified the pelleting of tomato seeds with different types of materials and to evaluated the performance during seed storage. The materials used as pelleting coats were sand + microcellulose and limestone + microcellulose, with and without Rovrin fungicide (200g/100kg of seeds). Raw seeds were covered, and treated with or without fungicides. Then, seeds were dried and put in paper envelopes (permeable) and in aluminum foil (impermeable) and stored at room temperature at the Universidade Federal de Lavras Seed Lab. The evaluation of seed quality was done once every four months, for 24 months, using the following determinations: germination test, accelerated aging and emergence on soil + sand. Covered seeds presented slower germinatnion than the raw seeds. Seeds covered with limestone + microcellulose deteriorated faster than the ones with sand + microcellulose and seeds treated with fungicides in association with the pelletting

Produtividade, florescimento prematuro e queima-das-folhas em cenoura cultivada em sistema orgânico e convencional

Four experiments were carried out with carrots genotypes during summer season in Distrito Federal, Brazil, to evaluate yield, bolting and leaf blight under organic and conventional conditions. The experiments were carried out in two locations and in each one two experiments were established, considering both crop systems. The experimental design was a random block with eight treatments and five replicates. The treatments consisted of the cvs. Alvorada, Brasilia RL, Brasilia Bionatur, Kuronan, Nantes 3 Tip Top, Carandai AG 106, Brazlândia and Pop. 0212246. The soil was fertilized with organic compost for the organic trial and with chemical fertilizer for the conventional trial. Plants were evaluated for leaf blight incidence, 70 days after sowing date, through visual observation. Roots were harvested 95 days after sowing, washed, classified and weighted. Bolting was more frequent in Brasilia Bionatur, under conventional condition, in Brazlândia. A difference of susceptibility to leaf blight among genotypes was observed in plants cultivated in the organic system. Nantes was the most susceptible while Pop. 0212246 was the most resistant. Alternaria dauci was observed more frequently at Brazlândia, while Cercospora carotae was observed at both locations, similarly, under organic conditions. For commercial and total yield, commercial and total root number, Pop. 0212246 and Brazlândia were the best materials in both crop systems. Total and commercial yield, total and commercial root number, number and weight of refused roots were higher in the conventional area, compared to the organic area. Brasilia and Brazlândia can be recommended for Distrito Federal, independently of crop system, during summer season. Pop. 0212246 showed desirable agronomical characteristics and can be, in the future, available for farmers in Distrito Federal.

Germinação de sementes de cenoura osmoticamente condicionadas e peletizadas com diversos ingredientes

Germination of carrot seed primed and pelleted with several ingredients Carrot seeds are small and the distribution in the field by seeders is generally very difficult. Seed pelleting has been used to improve sowing and consequently the stand establishment. Pelleted seeds generally present lower germination rate than raw seeds from the same seed lot. Seed priming has been used to increase germination rate of several species. Various binder materials for seed pelleting were evaluated and the relation between the osmoconditioning and germination of pellet seeds verified, using ‘Alvorada’ carrot cultivar. The pellet was obtained through a mixture of equal parts of microcelulose and sand as filling materials; five binder materials were also evaluated: bentonite, methocel, opadry, rhoximat and arabic gum. Part of the pelleted seeds received an external coat treatment (iriodin). Raw seeds were included as control. In another study, seeds were primed in an aerated solution of polyethylene glycol, dried and then pelleted. Rhoximat and opadry showed better characteristics as binder materials presenting pellets with smooth surface, uniform and excellent external appearance. In general, seed pellets showed a slight decrease of the germination rate and total germination compared to raw seeds, with greather differences for pellets finished with iriodin. Priming enhanced the germination rate of pelleted carrot seeds.

Carryover effect of fomesafen, applied on edible bean, on sucessional maize

Em dois experimentos fomesafen foi aplicado em pos-emergencia em culturas do feijoeiro nas doses de 0; 0,125; 0,25; 0,375 e 0,5 kg/ha, em 1992 (abril e agosto) e em 1993 (marco e agosto) em parcelas distintas, para avaliar os efeitos de seus residuos no solo argiloso (Latossolo Vermelho-Escuro) na cultura do milho. O milho foi plantado em sucessao 65 e 198 dias apos aplicacao de fomesafen em 1992 e 65 e 212 dias em 1993. Residuos de fomesafen no solo foram determinados por cromatografia liquida e foram detectados ate 20 cm de profundidade, porem a maior concentracao encontrada foi a 0-10 cm de profundidade. Nesta profundidade, a concentracao de fomesafen variou de 21 a 24 e 55 a 60 ppb aos 212 e 65 dias apos aplicacao de 0,25 kg.ha-1 de fomesafen, respectivamente, enquanto que a aplicacao de 0, 5 kg ha-1, apresentou concentracoes de 46 a 61 e 137 a 193 ppb aos 212 e 65 dia s apos aplicacao, respectivamente . No plantio de milho aos 65 dias apos aplicacao de fomesafen, residuos do herbicida no solo reduziram o teor de clorofila na folha e volume de raiz do milho aos 10 dias apos emergencia. A diminuicao do teor de clorofila na folha e volume de raiz, entretanto, nao afetaram o rendimento de graos.

Rendimento de cultivares de tomate para processamento em Goias

Six field trials were carried out to evaluate processing tomato cultivars in four counties in the State of Goias, Brazil (Anapolis, Jatai, Porangatu and Santa Isabel, in 1990, and Anapolis and Porangatu, in 1991). The experiment was conducted as a randomized block design, with four replications, and plots of 80 plants in 1990 and 70 plants in 1991. The plant cycle was shorter in Porangatu (1990), where temperatures were higher than Anapolis. In Porangatu, plant flowering began 35 to 41 days after sowing, with the harvesting period starting 38 days later. Cultivars Petomech, IPA 6, and Improved Topmech, followed by IPA 5 and Agrocica 72, were high yielding and showed a high fruit firmness. Cultivars Roma VFN, Rossol and Agrocica 08, were also high yielding but produced fruits unsuitable for long distance transportation. With the exception of cultivar Itaparica, which showed the best adaptation to less favourable enviroments, all genotypes were responsive to enviroment improvement. Higher stability to environmental variation was observed in cultivars Agrocica 33, Calmec VF, IPA 6, Rio Fuego, Santa Adelia, Topmec Melhorado, and UC 82.

Curva de dissipação de imazapyr em água de drenos de irrigação, após aplicação para controle da taboa

O herbicida sistemico imazapyr foi usado no controle da taboa (Typha subulata Crespo & Peres-Moreau f.) em drenos de irrigacao, como alternativa ao controle mecânico. O residuo do principio ativo do herbicida na agua foi analisado por cromatografia liquida de alta performance (HPLC). A curva de dissipacao de imazapyr mostrou que o herbicida pode ser usado para o controle de taboa em drenos de irrigacao, sem causar danos a culturas vizinhas, desde que a agua seja usada, no minimo, depois de 1,6 a 3,7 dias da aplicacao das doses de 500 a 1500 g ha-1, respectivamente.

Desinfestação de substratos para produção de mudas, utilizando vapor de água

O tratamento sanitario de substratos e uma operacao importante no processo de producao de mudas e no cultivo de plantas em vasos ou outros contentores. Tradicionalmente tem-se utilizado o gas brometo de metila como agente desinfetante. Entretanto, a producao deste gas devera ser abolida ate o ano 2010, forcando-se a busca de novas opcoes. Desenvolveu-se na Embrapa Hortalicas um equipamento que utiliza o vapor de agua a baixa pressao, produzido por uma caldeira industrial, com capacidade para evaporar 30 L/h de agua, para aquecer o substrato contido em uma caixa metalica cilindrica com capacidade de 2000 L. O vapor e aplicado no fundo da caixa que contem uma camada de brita coberta com uma tela metalica de malha de 2 mm, que favorece a distribuicao uniforme do vapor por toda a massa de substrato. O tempo de aquecimento e de aproximadamente 3 horas e o calor armazenado durante este periodo mantem a massa de substrato aquecida a temperaturas pasteurizantes, por ate 4 horas apos a aplicacao do vapor. Para testar a eficacia do sistema avaliou-se a sobrevivencia dos patogenos Ralstonia solanacearum, Fusarium oxysporum, Sclerotinia sclerotiorum e Rhizoctonia solani. Aplicou-se vapor por uma hora, nao considerando o periodo de aquecimento, e coletaram-se as amostras apos uma, duas, tres ou quatro horas o inicio da aplicacao de vapor. O tratamento por uma hora, em adicao ao periodo de aquecimento, resultou na eliminacao dos patogenos.