Ravi Datt Sharma

Produtividade do algodoeiro herbáceo em plantio direto no Cerrado com rotação de culturas

O experimento, instalado em um Latossolo Vermelho-Amarelo muito argiloso, teve o objetivo de avaliar o efeito da rotacao de culturas na produtividade do algodoeiro herbaceo (Gossypium hirsutum L. r. latifolium Hutch) em plantio direto sob condicoes de sequeiro no Cerrado. O delineamento experimental foi de blocos casualizados com cinco tratamentos e quatro repeticoes. Os tratamentos consistiram das rotacoes soja-milheto-soja-milheto-algodoeiro; soja-amaranto-soja-nabo forrageiro-soja-algodoeiro; soja-sorgo granifero-soja-sorgo granifero-algodoeiro; soja-aveia preta-soja-aveia preta-algodoeiro e soja-soja-algodoeiro. A maior produtividade do algodoeiro foi obtida com a rotacao de soja e milheto, em que houve melhor controle de plantas daninhas.

Effect of Meloidogyne javanica on the growth of pea

The root-knot nematode, Meloidogyne javanica commonly causes yield reduction of pea (Pisum sativum L.) in the Federal District of Brazil. The effect of M. javanica on the growth of pea cv. Triofin was studied with five inoculum levels namely 0, 10, 100, 1,000, and 10,000 eggs/kg of soil under greenhouse conditions. There was a progressive decrease in plant growth as the inoculum levels of nematode increased. The rate of nematode multiplication was inversely proportional to the inoculum level. Rhizobial nodulation was adversely affected at all the inoculum levels except for the inoculum level of 10 eggs/kg of soil which showed a 61.63% increase in number of bacterial nodules.

CONTROLE DE MELOIDOGYNE JAVANICA COM PASTEURIA PENETRANS

In a greenhouse experiment, the efficiency of Pasteuria penetrans against Meloidogyne javanica was evaluated on soybean cv. FT-Cristalina using four inoculum levels of P. penetrans viz: 0, 10x105, 50x105 and 100x105 endospores/kg of soil. Immediately after inoculating the autoclaved soil with P. penetrans, 1,000 second-stage juveniles were inoculated in each pot. After 48 hours of nematode inoculation, a 3-day old soybean seedling was transplanted in each pot. The experiment was evaluated in two steps of which the first evaluation was made after 89 days of transplanting the seedlings; and the second after 90 days of soybean sowing in sequence with a following period of 30 days. In the first evaluation, the highest fresh plant weight was observed in treatment with 100x105 endospores/kg of soil which differed significantly (P<0.05) from other treatments except the untreated control. The maximum increase in fresh pod weight of treatment with 100x105 endospores/kg of soil differed significantly (P<0.05) from the other treatments. The final nematode density in soil and roots for treatments 10x105, 50x105 and 100x105 endospores/kg of soil was significantly (P<0.05) lower than the untreated control. The nematode control obtained for treatments with 10x105, 50x105 and 100x105 endospores/kg of soil was 50.9%, 89.1% and 81.8% respectively. In the second evaluation, the control obtained for treatments 10x105, 50x105 and 100x105 endospores/kg of soil was 94.7%, 99.7% and 100%, respectively, in comparison to the untreated control. P. penetrans was highly efficient in the control of M. javanica even at the lowest concentration (10x105 endospores/kg of soil).