ATIVIDADE DE PEROXIDASES (EC 1.11.1.7) E TEOR DE PROLINA em FEIJOEIRO Phaseolus vulgaris L. CULTIVADO em CONDIÇÕES DE SALINIDADE

Alterações nos níveis de prolina e na atividade da peroxidase foram estudadas em folhas e raízes de feijoeiro em função da resposta à salinidade do meio. A atividade da peroxidase (E.C. 1.11.1.7) e o teor de prolina das folhas foi maior do que nas raízes. Os resultados mostraram que a atividade da peroxidase diminuiu, enquanto os teores de prolina aumentaram gradualmente nas plantas cultivadas em meio salino. Ocorreu diminuição do teor de potássio e aumento de sódio nos órgãos analisados, com o aumento da concentração salina.

ISOENZYMATIC POLYMORPHISM and ACTIVITY of PEROXIDASES of COMMON BEAN(Phaseolus vulgaris L.) UNDER SALINE STRESS

Uma das utilizações da técnica de cultura de tecidos para o melhoramento vegetal é a identificação de linhas de células que apresentem tolerância ao estresse salino. Para se estudar os mecanismos bioquímicos envolvidos na expressão genética da tolerância a salinidade, calos oriundos de eixos embrionários de quatro cultivares de feijão (Phaseolus vulgaris L.; cultivares IAC - carioca, IAPAR 14, JALO-EEP 558, BAT - 93), foram cultivados em meio sólido Murashige & Skoog (1962), suplementado com NaCl nas concentrações de 0, 20, 40, 60 e 80 mM. Após 14 dias de incubação, os calos foram coletados e analisados quanto aos padrões isoenzimáticos e de atividade das peroxidases. Os cultivares BAT e IAPAR apresentaram duas zonas de atividade em comum na região anódica e apenas uma zona enzimática específica a cada um deles (migração mais rápida).Possivelmente as duas zonas anódicas intermediárias sejam produtos do mesmo loco enzimático, porém com alelos diferentes, consequentemente diferentes mobilidades eletroforéticas. O cv. JALO apresentou duas zonas anódicas de atividade em comum com os cultivares IAC e IAPAR com uma zona anódica exclusiva de migração mais lenta, a qual apresentou atividade mais intensa de todos os cultivares analisados. Este cultivar revelou ainda uma zona catódica provavelmente dimérica e heterozigota nos indivíduos de todos os tratamentos aplicados. Provavelmente, esta é a mesma zona que ocorre em homozigose com fixação do alelo lento para os indivíduos de todos os tratamentos efetuados nos cultivares BAT e IAPAR. O cv. IAC apresentou duas bandas anódicas em comum com os cv. IAPAR e JALO. Apresentou também a banda anódica mais rápida em comum com o cv. IAPAR e uma banda anódica exclusiva de migração mais lenta. Curiosamente, os indivíduos deste cv. mantidos em meio suplementado com 20 mM de NaCl não apresentaram atividade nas três zonas anódicas mais lentas. Ocorreu no cv. IAC uma única zona de atividade catódica, dimérica e heterozigota para os indivíduos provenientes de todos os tratamentos, composta provavelmente de dois alelos diferentes da zona correspondente ao cv. JALO. Amostras provenientes dos tratamentos 40 e 60 mM de NaCl, desta zona catódica, apresentaram maior atividade enzimática. A análise da atividade da peroxidase no extrato bruto, revelou que os cultivares responderam diferentemente ao aumento da concentração salina no meio de cultura, com aumento pronunciado dessa atividade nos cultivares IAC e JALO.

WATER NEEDS FOR WINTER BEAN CROP

Um estudo sobre o uso de água do feijoeiro de inverno (Phaseolus vulgaris L. cv. Carioca) foi realizado num solo Latossol Vermelho Amarelo de textura argilosa. Um sistema de sulcos de infiltração foi usado para proceder a irrigação com o intuito de manter o solo em potenciais de água superiores a -40,0 KPa. Duas doses de aplicação de N em cobertura (0 a 30 Kg N/ha) foram colocados 25 dias após o plantio. Os principais objetivos do estudo foram: avaliar a interação entre as duas doses de N com a evapotranspiração e medir os coeficientes de cultura (Kc). A evapotranspiração média máxima (ETm) foi 1,71 mm/dia, ou 157,16 mm nos 92 dias de observações; os valores de ETm para as fases vegetativa (1), florescimento (2) e formação de vagens (3) foram 1,48; 2,35 e 1,50 mm/dia, respectivamente, para a dose de 30 Kg/ha e 1,48, 1,88 e 1,45 mm/dia para o tratamento sem aplicação de N em cobertura. Os coeficientes de cultura (Kc = ETm/ETo) foram 0,62 e 0,78 para a fase 1, 0,80 e 1,10 para a 2, 0,45 e 0,55 para a 3 e 0,61 e 0,80 para o ciclo todo, respectivamente, baseados no método de FAO-Penman e do Tanque Classe A. Este mostrou melhores resultados para estimar o máximo uso de água pelo feijoeiro de inverno. Os tratamentos de N não afetaram a evapotranspiração significativamente. Entretanto, a evapotranspiração, medida pelo método do balanço de água, foi 59,78 e 27,12% maior no estágio do florescimento que no estádio vegetativo, respectivamente, nas doses de 30 e 0 Kg N/ha.

ATIVIDADE DE PEROXIDASES (EC 1.11.1.7) E TEOR DE PROLINA NO EMBRIÃO E COTILÉDONES DE FEIJOEIRO Phaseolus vulgaris L. em CONDIÇÕES DE SALINIDADE

Os efeitos da salinidade sobre a atividade de peroxidases foram acompanhadas no embrião e em cotilédones de feijoeiro Phaseolus vulgaris L. cv. Carioca, observando-se em ambos, aumento na atividade das enzimas. Com relação ao teor de prolina, ocorreu decréscimo constante no embrião de feijoeiro cultivado em condições salinas, entretanto, nos cotilédones, verificou-se aumento progressivo em condições de presença ou ausência de salinidade.

Cádmio e a atividade de peroxidase durante a germinação de sementes de feijoeiro

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of salt stress on polyamine metabolism in bean cell culture

The adaptive capacity of bean (Phaseolus vulgaris L.) calluses (cultivars IAC-carioca, JALO EEP-558, BAT-93 and IAPAR-14) to salt stress (0-80 mM) was verified to determine the existence of biochemical markers such as organic and inorganic compounds, and metabolism of polyamines. The results obtained demonstrate that salt (NaCl) interfered with all the parameters analyzed and its intensity ranged due to the salt concentration and the cultivars used.

Effect of pre-imbibition and osmoconditioning on seed-germination in Phaseolus-vulgaris L. under water-stress

The effect of osmoconditioning and controlled water sowing was analysed in seeds of Phaseolus vulgaris L. cv. carioca on germination under water stress conditions. The pre-sowing in water at low temperature to limit germination resulted in the increase in the tolerance to water stress. The osmoconditioning with PEG for 48 hours increased the tolerance of bean seeds to water stress of -0.51MPa. The osmoconditioning or controlled water sowing can be used as a practice to increase the tolerance of bean seeds to water stress before planting in the field.

PLANT-TO-SEED TRANSMISSION of CURTOBACTERIUM FLACCUMFACIENS pv. FLACCUMACIENS IN A DRY BEAN CULTIVAR

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Thermal structure, heat content and stability of two lakes in The National Park of Rio Doce Valley (Minas Gerais, Brazil)

The thermal structure, heat content and stability were studied in Lakes Dom Helvécio and Carioca during an annual cycle. It was found that the maximum heat content, stability and work of the wind in Lake Dom Helvécio correspond to two, four and four times, respectively, the values for the Lake Carioca. These difference can be attributed to morphometric differences in the lakes. A long-term record of heat content and stability for lake Carioca is also presented. Diel variations were studied in summer and winter. The tropicality of the lakes is discussed and compared with other lacustrine systems. © 1989 Kluwer Academic Publishers.

Incorporação de mucuna-preta e de restos culturais de milho antes da cultura do feijão (Phaseolus vugaris L.) de inverno

The experiments were conducted during two years (1990/91 and 1992/93), to study the effects of the incorporation of bengal velvetbean and of residues on the development and yield of the winter bean crops. The trial was developed in experimental field at the Faculdade de Engenharia de Ilha Solteira, UNESP, located in Selvíria, MS, Brazil, in dark red latosol covered by savanna vegetation. It was concluded that: the incorporation of residues of corn or corn + bengal velvetbean or only bengal velvetbean had no effects on soil chemical characteristics, evaluated 80 days after the residues incorporation; in yield and bean crop development, no statistical differences were observed among treatments.

Produção de matéria seca de feijoeiros submetidos a diferentes níveis de magnésio em solução nutritiva

The effect of Mg levels in nutrient solution upon root, stem, leaf, fruit and total dry matter production of common bean (Phaseolus vulgaris L. cv. Carioca) was studied. Bean plants were grown in Hoagland & Arnon n. 2 solution modified to obtain 2.4, 24.3, 48.6, 72.9 and 97.2 ppm of Mg. The experimental design was a split-plot factorial replicated three times with five Mg levels and five samplings which were done fortnightly. Results were compared with those observed in plants submitted to a nutrient solution with 48.6 ppm of Mg concentration, considered the ideal Mg content. Only a mild prejudicial effect was observed with Mg excessive levels. Stem, leaves and total dry matter were higher when 2.4 ppm were used, suggesting this level as the concentration chosen for the culture of common bean.

Magnésio, cálcio e potássio em sementes e cotilédones de feijoeiros e sua transferência para plantas jovens

Magnesium, calcium and potassium concentration in the seeds and cotyledons of Phaseolus vulgaris L. cv. Carioca and its translocation from the cotyledons to the plant were evaluated. For such an evaluation plants were cultivated during the cotyledons phase and were irrigated with deionized water. Three samplings of cotyledons completely randomized were done and replicated ten times, before its senescence and fall, at 8, 12 and 15 days after the germination of the seeds. Fresh and dry matter of the cotyledons and its magnesium, calcium and potassium content were determinated in every sample. These parameters were also determined in the seeds from the same lot. Potassium concentration was higher than magnesium in both seeds and cotyledons. Calcium presented the lesser concentration both in seeds and cotyledons. These minerals were translocated from the seeds and cotyledons to the young plants. Eight days after germination 59% of the magnesium, 78% of the calcium and 71% of the potassium were translocated to the plants. Fifteen days after germination these percentages were respectivaley 73%, 82% and 91%. Thus, magnesium was the less and potassium was the most translocated mineral at the end of the study.

Virulência de isolados Dexanthomonas campestris pv. Phaseoli (Smith) dye em feijoeiro

The objective of this research was to evaluate de reaction of leaves and pods of five cultivars of bean (Phaseolus vulgaris L.) plants to twenty strains of Xanthomonas campestris pv. phaseoli. The strains were inoculated onto leaves in a greenhouse, and onto pods in a growth chamber. The results obtained were analyzed and the strains classified into three groups: low, medium, and high virulence. Most of the strains showed high virulence on leaves of Carioca and Rio Negro cultivars, as opposed to only low to medium virulence on leaves of IAPAR 14, IAPAR 16, and G. N. Nebraska # 1 sel. 27 cultivars. There were, however, individual strains powerful enough to overcome the leaf resistance of IAPAR 14, IAPAR 16, and G. N. Nebraska # 1 sel. 27. With regard to pods, most strains showed high virulence on all bean cultivars, with exception of IAPAR 14 where virulence was at medium level. A correlation between leaf and pod symptoms was found to exist in Carioca, Rio Negro, and IAPAR 14 cultivars. No such correlation was observed in IAPAR 16 and G. N. Nebraska # 1 sel. 27. Comparing strains producing melanine in vitro with those not producing this pigment, no difference was observed with regard to virulence.

Reação de genótipos de feijoeiro comum a Fusarium oxysporum f. sp. phaseoli, Macrophomina phaseolina e Xanthomonas campestris pv. phaseoli

The behavior of dry bean (Phaseolus vulgaris L.) genotypes PI 150414, PI 163117, PI 175829 white, PI 175829 purple, PI 175858, PI 197687, A 417, A 420, A 429, Xan 160, Xan 161, WISHBR 40, and IAC Carioca inoculated with Fusarium oxysporum f. sp. phaseoli, Macrophomina phaseolina, and Xanthomonas campestris pv. phaseoli was evaluated under greenhouse condition. The bean genotypes Xan 160, PI 150414, A 417, PI 175829 purple, Xan 161, A 420, PI 163117, and PI 175829 white were resistant to F. oxysporum f. sp. phaseoli, and only PI 155829 white had a good level of resistance to M. phaseolina. All bean genotypes were susceptible to Feij-4 strain, and only Xan 161 had some level of leaf resistance to Feij-41 strain of X. campestris pv. phaseoli.

Evaluation of naturally and artificially aged seeds of Phaseolus vulgaris L.

Seed ageing is natural phenomenon that occurs in all seeds, including those stored in dry and low temperature rooms. Phaseolus vulgaris L. cv. 'Carioca' seeds harvested in five different years were stored in at 15°C. Seed samples were germinated and evaluated according to The Brazilian Rules for Testing Seeds. The newest seed sample was submitted to artificial ageing. Small (∼1g) samples of all materials (naturally and artificially aged) were ground and proteins extracted. Equal quantities of protein were loaded onto the gels and electrophoresis carried out. Although seeds submitted to 24, 48, 72 and 96 hours of artificial ageing did not show any statistical difference (5%) in relation to unaged seeds in physiological parameters related to emergence, some statistically different parameters related to dry matter and length of shoots and roots occurred. A 24 h of artificial ageing at 41°C improved these factors. Protein patterns were changed after 72 h of artificial ageing and naturally aged seeds showed alterations after two years storage at 15°C. Aged seeds, naturally and artificially, had decreasing germination, vigour, and changes in the characteristic banding pattern of proteins. Physiological parameters and electrophoresis examination showed that for naturally aged seeds physiological parameters were more sensitive while artificially aged seeds, (41°C/100% RH), had electrophoretic profiles that were more efficient for seed lot discrimination.