Avaliou-se o comportamento de dezesseis introduções, consideradas resistentes à broca no Sul dos E.U.A., e quatro clones 'IAC' de cana-de-açúcar em relação ao ataque de Diatraea saccharalis (Fabr., 1794) (Lepidoptera:Pyralidae) em ensaio delineado em blocos ao acaso, com dez repetições, instalado na Estação Experimental de Ribeirão Preto, do Instituto Agronômico. As introduções utilizadas foram CP57-614, CP62-258, CP66-491, CP70-321, CP70-330, CP71-321, Tainan 2n = 96, US74-103, TJS76-9, US-76-14, US76-15, US76-20, US76-22, TJS76-25, US76-26 e US76-34 e, os clones, 'IAC50-134', 'IAC52-150', 'IAC71-1001' e 'IAC1006'. Decorrido um ano do plantio, efetuado em setembro de 1979, procedeu-se à avaliação. Vinte colmos por parcela foram cortados e, individualmente, mediu-se o diâmetro e contaram-se os internódios sadios e broqueados. A partir desses dados, calcularam-se a infestação e a sua intensidade. Os dois índices evidenciaram o mais baixo ataque de D. saccharalis na introdução Tainan 2n = 96, cujo diâmetro médio foi l,03cm, e o ataque mais alto no cultivar IAC52-150, de diâmetro médio 2,83cm. Correlacionando-se o diâmetro com os índices de infestação nos vinte clones, verificou-se que a infestação é diretamente proporcional ao diâmetro (r² = 0,91) e, a intensidade, ao quadrado do diâmetro (r² 0,82). No Brasil, a possibilidade de utilização desse germo-plasma introduzido dos E.U.A. como fonte de resistência a D. saccharalis é incerta, em face da associação observada entre infestação e diâmetro das plantas.

Sixteen clones of sugarcane resistant to the sugarcane borer, D. saccharalis in Houma, Louisiana, USA, were introduced and tested in Brazil against the same insect species. The sixteen introduced germplasm were CP57-614, CP62-258, CP66-491, CP70-321, CP70-330, CP71-321, Tainan 2n = 96, US74-103, US76-9, US76-14, US76-15, US76-20, US76-22, US76-25, US76-26 e US76-34. These sixteen introductions plus 4 IAC clones, namely 'IAC50-134', 'IAC52-150', 'IAC71-1001' and 'IAC1006', were planted on September 26, 1979, in Ribeirão Preto, State of Sao Paulo, Brazil. The experimental design used was a complete randomized block with 20 treatments and 10 replications. Evaluation was made on September 9, 1980. Twenty culms per plot were split lenghtwise and the numbers of internodes bored and not bored were registered. The variation of infestation among the clones was highly correlated with the diameter of the plants. The least infested germplasm was Tainan 2n = 96 with a culm diameter of 1.03cm. The most infested, IAC52-150 had a diameter of 2.83cm. The infestation (percentage of culms infested) was linearly correlated with the diameter (r² = 0.91) and the intensity of infestation (percentage of internodes infested) was linearly correlated with the square of the diameter (r² = 0.82). These results show the possibility of the use of thinner less infested clones introduced from USA as source of resistance to the sugarcane borer in Brazilian breeding programs.

The development of the root system on five varieties of rice grown under upland conditions, has been studied. It has been found, with the rice varieties used and under the conditions tested, that 66 percent of the roots occured within 5 centimeters and 95 percent within 15 centimeters of the surface of the ground. A few roots were found to reach a depth of 1 meter, and occasionally to a depth of 1.35 meter. The Iguape-catete variety of rice showed a tendency to develop a somewhat deeper root system than the other varieties studied. Recognition of the fact that development of the roots of the rice plant is largely within the plowed layer of soil, suggests that deep plowing prior to planting with frequent and shallow cultivation following planting, to eliminate weed competition, would be desirable.

A description is given of a new method for the production of seedlings in planting of rice strains. This method has been used these three last years in connection with the improvement work on rice in the "Instituto Agronômico". Perforated cylinders, 14 cm high and 18 cm diameter, are distributed over the seed bed and the seeds of each strain sown inside. A week afterwards the cylinders are pulled up and used again. With this method seedlings are obtained with great facility and perfect separation between strains thus avoiding mixture of seeds.