Resumo em Inglês:

The English resumé is given in a different form from the Portuguese "conclusões". In the former we gave mainly the results which may be of general interest, explaining the tables (quadros) and the procedure of statistical analysis, while in the other the properties of the different rootstocks are discussed in detail since they are of immediate local interest. 1. In a previous publication, Moreira (19) explained the layout and the first results of an experiment, under way since 1936 in the Limeira Exp. Sta., on the influence of twelve different types of Citrus rootstocks on three scion varieties : the oranges "Baianinha" and "Pera" and the grape-fruit "Marsh Seedless". We report here three main results obtained during the first six years of the experiment: a) all plants budded on sour and bitter-sweet oranges (C. aurantium), showed definite signs of the new disease "tristeza" ; b) other rootstocks such as citron (C. medica), ponderosa lemon (C. lemon) had such disadvantageous effect that they could be eliminated as suitable stocks ; c) the data of the first four crops permit to determine certain particularities of some rootstocks varieties used in the experiment. The present paper deals with the complete