Expedito Paulo Silveira

Atividade de peroxidase e polifenoloxidase na resistência do feijão à antracnose

The objective of this work was to evaluate the influence of peroxidase and polyphenol oxidase enzymes in anthracnose resistance of four bean cultivars. Seedlings were sprinkled with salicylic acid and delta race of Colletotrichum lindemuthianum (inducer fungus) and after three days they were inoculated with 33/95 virulent pathotype of C. lindemuthianum. Enzyme activity and phenol levels were evaluated three days after inducer fungus application and five days after inoculation with virulent pathotype. Plants treated with salicylic acid and inducer fungus presented higher activity increases of both enzymes, in all cultivars. Higher impulses in enzymatic activity were observed in cultivars with higher disease resistance. One isoperoxidase appeared in treatments with inducer fungus, salicylic acid, after inoculation with virulent pathotype, and in control plants, in AB 136, Rio Tibagi and Macanudo cultivars. Positive correlation was observed among peroxidase and polyphenol oxidase activity, phenolic compound levels and anthracnose resistance.

Assessment of spacing and plant density of beans for mechanical harvesting.

8 RESUMO - O trabalho foi conduzido na safra 1992/93, no Centro Agropecuario Palma (CAP)/Univer- sidade Federal de Pelotas (UFPel), objetivando avaliar o efeito da variacao do espacamento entre linhas e da populacao de plantas sobre caracteristicas agronomicas relacionadas com a colheita mecanizada de feijoeiro (Phaseolus vulgaris L.). Foram testados tres espacamentos entre linhas (25, 50 e 75 cm) e quatro populacoes de plantas/ha (100, 200, 350 e 500 mil), utilizando como reagente a cultivar Pampa, de habito de crescimento indeterminado, tipo II. O delineamento experimental foi em blocos casualizados, com quatro repeticoes. Somente ocorreu interacao entre os fatores para o indice de acamamento, onde o aumento da populacao tendeu a reduzi-lo. A combinacao do maior espacamento com a menor populacao provocou o maior acamamento. A reducao no espacamento entre linhas, apesar de reduzir a altura de plantas, a altura de insercao de vagens e o rendimento de graos, provocou aumento na altura da ponta da vagem mais baixa ate o solo, e reducao na porcentagem de plantas com vagens encostando no solo. O aumento na populacao de plantas, apesar de nao afetar a maioria das caracteristicas agronomicas das plantas, provocou reducao na porcentagem de plantas com vagens encostando no solo, e nao provocou modificacoes no rendimento de graos. Termos para indexacao: Phaseolus vulgaris, acamamento, insercao de vagens. SPACING AND PLANT POPULATION FOR DRY BEAN HARVEST MECHANIZATION ABSTRACT - The experiment was conducted in 1992/93 season at Centro Agropecuario da Palma (CAP) of the Universidade Federal de Pelotas (UFPel), in Pelotas, Brazil, to evaluate the effect of spacing variations between rows and plant populations on agronomic characteristics related to mechanized harvest for dry bean (Phaseolus vulgaris L.). Three different row spacing (25, 50 and 75 cm) and four different plant populations/ha (100, 200, 350 and 500 thousand) were used, utilizing the cultivar Pampa, indeterminate growth habit type II as reagent. The field trial was in randomized blocks, with four replications. Positive interaction between factors was observed for the lodging index, where the increase in the plant population tended to reduce it. The combination of larger spacing with smaller plant population resulted in a higher lodging index. The reduction in the row spacings, in spite of reducing the plant height, the pod insertion height and the grain yield, resulted in an increase of the lowest pod tip height and in a reduction of the percentage of plants with pods touching the soil surface. The increase in the plant population, despite of not affecting the majority of the agronomic characteristics of the plant, resulted in a reduction of the percentage of plants with pods touching the soil and did not cause any alteration in the grain yield.The experiment was conducted in 1992/93 season at Centro Agropecuario da Palma (CAP) of the Universidade Federal de Pelotas (UFPel), in Pelotas, Brazil, to evaluate the effect of spacing variations between rows and plant populations on agronomic characteristics related to mechanized harvest for dry bean (Phaseolus vulgaris L.). Three different row spacing (25, 50 and 75 cm) and four different plant populations/ha (100, 200, 350 and 500 thousand) were used, utilizing the cultivar Pampa, indeterminate growth habit type II as reagent. The field trial was in randomized blocks, with four replications. Positive interaction between factors was observed for the lodging index, where the increase in the plant population tended to reduce it. The combination of larger spacing with smaller plant population resulted in a higher lodging index. The reduction in the row spacings, in spite of reducing the plant height, the pod insertion height and the grain yield, resulted in an increase of the lowest pod tip height and in a reduction of the percentage of plants with pods touching the soil surface. The increase in the plant population, despite of not affecting the majority of the agronomic characteristics of the plant, resulted in a reduction of the percentage of plants with pods touching the soil and did not cause any alteration in the grain yield.