Priscila Fratin Medina

Influência da colheita e do armazenamento na qualidade fisiológica de sementes de mamona

Sabe-se que ao longo do ciclo da mamoneira sao produzidos racemos de varias ordens que se desenvolvem sob diferentes condicoes ambientais, as quais podem provocar variacoes na qualidade das sementes no campo e durante o armazenamento. Assim, objetivou-se avaliar o efeito de diferentes tratamentos de colheita (ordens de racemos e epocas) e da armazenagem na qualidade fisiologica de sementes de mamona, cultivar IAC-2028. Foram instalados testes de germinacao, emergencia de plântulas em areia, velocidade de emergencia e crescimento de plântulas, logo apos a colheita e aos 3, 6, 9 e 12 meses de armazenamento em ambiente de laboratorio, sem controle de temperatura e umidade relativa do ar. O delineamento experimental adotado foi em blocos ao acaso, com cinco repeticoes, em esquema de parcela subdividida, onde as parcelas foram constituidas por cinco periodos trimestrais de avaliacao e as sub-parcelas de 11 tratamentos de colheita. Com base nos resultados obtidos, conclui-se que a colheita dos racemos de mamona da cultivar IAC-2028, nas condicoes deste experimento, pode ser realizada em uma unica etapa sem que ocorram perdas de qualidade fisiologica das sementes e o armazenamento manteve satisfatoriamente a qualidade das mesmas.

Descrição de características agronômicas e avaliação de épocas de colheita na produtividade da mamoneira cultivar IAC 2028

DESCRIPTION OF AGRONOMIC CHARACTERISTICS AND HARVEST TIME EVALUATION IN THE YIELD OF CASTOR BEAN CULTIVAR IAC 2028 The crop of castor bean can be used like raw material for renewable energy, however, becomes necessary the use of agricultural machines adapted to its harvest. During the crop growth racemes are produced under different environmental conditions which can cause variations in productivity of the crop. The purpose of this work was to evaluate important agronomic characteristics to mechanical harvest as well as the effect of time of harvest in productivity of castor bean. The experimental design was arranged in a randomized block design with eleven treatments and five replications, with cultivar IAC 2028 , during the agricultural year of 2005/06 at the Centro Experimental Central, Instituto Agronomico (IAC), Campinas, Sao Paulo State, Brazil. Seed yield, number of fruits and seeds per raceme and mass of a thousand seeds were evaluated. In the evaluation of the agronomic characteristics was observed a great variability among the plants, what can complicate mechanical harvest. The results showed that the secondary raceme was the most influence to total productivity and the harvest of the racemes, fruits and seeds, in the conditions of this experiment, can be performed at only time with no decrease in yield.

Teste de envelhecimento acelerado para avaliação da qualidade de sementes de alface e almeirão

O uso de testes de vigor para avaliacao da qualidade dos lotes de sementes e uma ferramenta imprescindivel para producao e comercializacao. No entanto, para sementes de alface e almeirao as pesquisas relacionadas a avaliacao de sua qualidade ainda sao escassas. Para sementes de alface, apenas o teste de germinacao e considerado padronizado, enquanto os demais devem ser aprimorados visando fornecer informacoes mais precisas. Com intuito de adequar a metodologia do teste de envelhecimento acelerado para avaliar a qualidade de lotes de sementes de alface e almeirao, foram utilizados quatro lotes de sementes de alface das cultivares Maravilha e Verdinha e quatro lotes de sementes de almeirao das cultivares Catalonha e Pao-de-Acucar. Na conducao do teste de envelhecimento acelerado as sementes foram submetidas ao envelhecimento tradicional, e ao envelhecimento com solucao saturada e diluida de NaCl; usaram-se tres periodos distintos: 48, 72 e 96 horas. Para caracterizar a qualidade dos lotes foi determinado o grau de umidade das sementes, e realizados os testes de germinacao, primeira contagem de germinacao e emergencia de plântulas em casa de vegetacao. Concluiu-se que o teste de envelhecimento acelerado aos 41 °C possibilita a separacao dos lotes em diferentes niveis de vigor, podendo ser utilizado em sementes de alface e almeirao, considerando-se o periodo de envelhecimento de 48 horas pelo metodo tradicional ou o de 72 horas pelo metodo com solucao saturada de NaCl. Quanto ao metodo modificado pelo uso da solucao diluida de NaCl, o periodo de 48 horas e adequado para as sementes de alface e o de 72 horas, para as de almeirao.

Survival of seed-borne fungi associated to the physiological quality of triticale (X. triticosecale Wittmack) stored seeds.

Triticale seeds of the IAC-2 cultivar presented germination of 85% after harvest and natural incidence of the following pathogenic fungi: 34.5% Pyricularia grisae, 12% Bipolaris sorokiniana, 15% Fusarium graminearum and 35% Alternaria alternata. The seeds were stored at 10 oC and under natural ambient conditions for twelve months. The seed physiological quality was evaluated at bimonthly intervals by the germination, accelerated aging, tetrazolium and field emergence tests and fungi survival was evaluated by the blotter test. The seeds stored at 10 oC maintained the same level of germination, viability and vigor for twelve months even though the fungi incidences also remained almost unchanged too. The germination and viability of seeds stored under natural ambient conditions decreased and the level of dead seeds increased due to a higher speed of deterioration and an increased level of storage fungi, mainly Penicillium spp.. The pathogenic fungi levels decreased, reaching very low values at the end of the storage period. However, the pathogen survival was still harmful at the time of the planting season (April).

PRODUÇÃO DE SEMENTES DE CULTIVARES PRECOCES DE SOJA EM DUAS ÉPOCAS E DOIS LOCAIS PAULISTAS: I. CARACTERÍSTICAS AGRONÔMICAS E PRODUTIVIDADE

The main objective of this research work was to determine early-maturing soybean cultivar (IAC-100, IAC-16, IAC-Foscarin-31, BR-4 and IAS-5) seed production in the dry season, under irrigation. Field experiments were carried out in Campinas and Votuporanga, Sao Paulo State, Brazil, during the dry season (Autumn/Winter) as well as during the traditional growing season (late Spring/Summer) to compare sowing time effects on seed quality. Plant height, number of nodes per plant, first pod insertion height, number of seeds per plant, weight of 1,000 seeds and yield, were evaluated at harvest maturity (R8 development stage). Seed germination was evaluated right after harvesting and at the onset of the following sowing season. Viable seed yields were also estimated at those times. Results showed that early-maturing soybean cultivars can be sown in the dry season, mainly in regions where traditional sowing (wet season) does not result in proper seed quality, not allowing the maintenance of reasonable seed germination potential up to the following sowing season. The decision of delaying sowing time should be based on total and viable seed yields, taking into account the estimated seed viability at the following sowing season.

PRODUÇÃO DE SEMENTES DE CULTIVARES PRECOCES DE SOJA EM DUAS ÉPOCAS E DOIS LOCAIS PAULISTAS: II. QUALIDADE FISIOLÓGICA

Early soybean cultivars, produced in the traditional season (sowed in November) in Sao Paulo State, Brazil, often show poor physiological seed quality. IAC-100, IAC-16, IAC-Foscarin-31, BR-4 and IAS-5 early cultivars were sown in November and March/April in Campinas and Votuporanga counties. The physiological quality of the seeds was evaluated immediately after harvesting and at the time of next planting season. Seeds had better vigour and viability when sowing time was delayed until the end of Summer or beginning of Autumn. The advantages of this procedure were greater in Votuporanga than in Campinas.

Viabilidade de sementes de trigo tratadas com fenitrotion e infestadas por Sitophilus oryzae (L.) (Coleoptera: Curculionidae) durante o armazenamento

Clarifying aspects of the weevils (Sitophilus spp.) behavior on stored wheat seeds, considering the seed quality, is essential to improve the seed management during storage. In order to evaluate the efficiency of the insecticide fenitrothion as protecting wheat seeds against Sitophilus oryzae (L.) (Coleoptera: Curculionidae) and to measure the seed germination during storage, wheat seeds of IAC-120 and IAC-350 cultivars were treated or not with the insecticide fenitrothion three months after harvest and stored in laboratory ambient conditions, in Campinas, SP, Brazil, during 15 months. S. oryzae adults were trimonthly placed on seed samples from the replications of the treatments with insects. The survival of the insects was evaluated, as well as the resulting progeny. The insects were eliminated and seed moisture content, germination and insect infestation were measured at the seed samples from the replications of all the treatments with or without insects. It was concluded that fenitrothion, in the recommended dose, does not protect wheat seeds, against S.oryzae infestation, even in short-term storage of two months. Wheat seeds with high initial germination level can keep their viability, for 14 to 17 months after harvest, when stored in ambient conditions, in regions, which have the climate similar to Campinas.

Influência da colheita e períodos de armazenamento na qualidade sanitária de sementes de mamoneira

As atuais preocupacoes quanto a escassez das reservas de petroleo e o agravamento do efeito estufa, pela emissao de CO2, levam a cultura da mamona a ser uma das fontes para energia renovavel. Sabe-se que ao longo do ciclo da mamona sao produzidos racemos de varias ordens, que se desenvolvem sob diferentes condicoes ambientais, podendo provocar variacoes na qualidade das sementes. Assim, objetivou-se avaliar a interferencia da colheita e de cinco periodos de armazenamento na qualidade sanitaria das sementes de mamona, cultivar IAC-2028. Para tanto, foram instalados os testes de germinacao e sanidade, logo apos a colheita e aos 3; 6; 9 e 12 meses de armazenamento em condicoes nao controladas de temperatura e umidade relativa do ar. As avaliacoes foram feitas em esquema de parcela subdividida no tempo, onde as parcelas foram constituidas por cinco epocas trimestrais de avaliacao e as sub-parcelas por 11 tratamentos. Os resultados sugerem que todos os racemos podem ser colhidos em uma unica etapa, sem que ocorram perdas de qualidade das sementes.

Damage caused by fungi and insects to stored peanut seeds before processing

The aim of this study was to gather data on the incidence of fungi associated with peanut seeds stored in their pods, before being processed by the State of Sao Paulo seed-producing companies, and the relation of the fungi to the seed damage caused by insects and to the quality of the stored seeds. Samples were taken from seed lots of cultivars IAC 886 and IAC 503 stored by these companies at the beginning and end of a six-month storage period. The peanut seeds were shelled and half of each sample was treated with fludioxonil + metalaxyl. Untreated and treated seeds were analyzed for moisture content, germination, vigor and health. The following insects were found to damage the peanut seeds: Cyrtomenus mirabilis (Perty) (Hemiptera: Cydnidae) and Corcyra cephalonica (Stainton) (Lepidoptera: Pyralidae). Both species reduced seed quality. When present, fungi of the genera Aspergillus, Fusarium, Penicillium and Rhizopus infected seeds and seedlings during the germination process and were considered the main limiting factor for obtaining normal seedlings. Nevertheless, despite their presence, peanut seeds maintained their germination capacity and vigor after six months of storage in their pods.