Melhoramento do milho: III - Ensaios de híbridos

摘要

Comparative trials with experimental corn hybrids are being conducted, in the State of S?o Paulo, Brazil, by the Instituto Agron?mico, at its Experiment Stations, at Campinas, Ribeir?o Prêto and Pindorama. During the years from 1938 to 1950 a total of 119 trials were planted, only twelve of them having been eliminated due to severe insect attacks. Except 21 trials in randomized blocks and 2 in incomplete block designs, all the others were planted in simple lattice, with 4 replications. The individual plots, with few exceptions, had one or usually two 5 m rows each. Among the yellow flint Unes tested, L. 483 is, no doubt, the best. It has high combining ability and also excellent agronomic characters. The performance of some other lines, as L.278-1-1, L.606, L.334, L.445 and L. 422, is also briefly described. Hybrid H.3531 [(483 x 581)x(278-1-1 x 429-2)] gave, on the average, an increase of 780 kg/ha over the "Cateto" variety, having been tested in a total of 51 trials conducted at 3 different localities. Some lines of yellow dent corn were also obtained from local and introduced varieties. Among the lines received from different places of the United States, only Hy and 38-11 furnished reasonably good results. However even these are too early for local conditions, the ears being poorly protected, exposing them to severe weevil damage. L.2051-1-2-3 derived from "Amarel?o" and L.2761, from "Tuxpan", are, so far, the best ones. At apresent, H.4624 [(2051-1-2-3 x 2761)x(278-1-1x483)J is being produced, as a good, medium dent double hybrid.