Resumo em Inglês:

The occurrence of polyembryonic seeds in Mangifera indica has been known for a long time, but nothing is known with reference to the forms cultivated in Brazil. It was found impossible to count the number of embryos in the seed, in spite of the size of both seed and embryo. But the cotyledons are in such a way twisted around each other that it is impossible to separate them. Thus it was necessary to take into acount only the embryos which were able to germinate and their number was determined after 3 and 7 months. It was necessary to dig up the seedlings and wash off all soil in order to distinguish ramifications of shoot and root from the actual polyembryony. In 7 months old seedlings a new complication arises owing to the complete fusion of their base. Evidently there is a pronounced variation in the occurrence of polyembryonic seeds. In 30 resp. 40 germinated seeds, taken from one tree each oí the varieties "Santa Alexandrina" and "Itamaracá", all had one embryo only, while in "Pêssego" (one tree), "J. F. da Silva" (two trees) and "Oliveira Neto" (one tree) from 46 to 84% of the seeds contained more than one embryo. "Oliveira Neto", with 24 polyembryonic seeds out of the 25 germinated, had 4 seeds with four embryos and 1 with five.

Resumo em Inglês:

Observations were made with tobacco plants which, after being naturally infected in the field by the virus of "vira-cabeça", a disease identical to spotted wilt (3), not only resisted to it, but exhibited complete recovery. Several trials were carried out in order to ascertain the following points : 1) whether the recovery means a greater degree of individual constitutional resistance ; 2) whether it represents an acquired immunity or ; 3) whether it is just of pure accidental nature. Plants showing recovery were selfed and seeds collected from them sown in separate rows. The same procedure was always applied with the new recovered plants. Thus, strains of plants were obtained representing several succeeding generations of recovered plants. In 1940-41 recovery progenies were planted at two different transplanting periods. During the next season 1941-42 these progenies, which represented already one more generation in comparison with those of 1940-41, were planted in two districts where the average occurrence of "vira-cabeça" was different. The percentages of "vira-cabeça", observed in all trials, were submitted to statistical analysis, comparing the errors obtained for difference of districts, transplanting time, varieties and progenies representing several generations of recovered plants. Comparing the calculated errors it was found that the greatest effect in the occurrence of ' Vira-cabeça" observed should be attributed to different transplanting times or different districts. The selection of recovered plants showed no influence in lowering the incidence of * vira-cabeça" : hence the impossibility of getting types of tobacco resistant to "vira-cabeça" through selection of recovered plants. Plants were observed in the field that after the first recovery exhibited symptoms of the disease, and then completely recovered from it again. This is in accordance with the results of Smith (11) in the reinoculation of tobacco plants after recovery from spotted wilt and of Costa (4) who reinoculated "vira-cabeça" - recovered tobacco plants with it. Therefore, as far as our knowledge is concerned districts should be selected where the disease does not appear very frequently; transplanting periods should be chosen, tc guarantee the lowest possible incidence of the disease.

Resumo em Inglês:

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.

Resumo em Inglês:

In the present work were studied several varieties of manihot of the Ubatuba area on the north coast of the State of São Paulo. The experiments were carried out at the Experiment Station of that locality with a view to compare the production of roots and meal of each variety with that of the variety "Vassourinha", introduced in that district in 1938 by the Division of Roots and Tubers of the Instituto Agronômico. Said variety ("Vassourinha") is the most cultivated all over the State of São Paulo. Results have shown that among the eleven varieties studied the following exceeded the others as regards production of roots and meal: N.° 1 ("Vassourinha") and N.° 120 ("Santa"). Comparing these two one with another, it was found that N.° 1 surpassed N.° 120, not only with regard to production of roots but also in regard to manufacture of meal. Through the study of production of cuttings it was found that in no variety whatever there is a relationship between the production of stems and roots. Finally, analyses are mentioned of meal obtained from each variety both of one and two vegetative cycles.