ABSTRACT


Víctor Volke H.1
 
Considering the results; from 47 field experiments, conducted during the seasons1966/67 ta 1968/69 and in which the response of wheat to nitrogen and phosphorus
was observed, the main production factors affecting this crop and their relative importance as limitants of the productivity of "trumao" soils in the provinces of
Malleco and Cautin was studied.
The soils considered in this study can be grouped in: a) trumaos in slopingland (Santa Barbara), and b) trumaos in plains (Victoria, Agua Fría and Vilcún).The varieties were: Cappelle Desprez (winter) and Chifen and Pumafen(spring).The determination of the production factors was based on the yield in grainfor the tester plots (no fertilizers) and the maximum yield, obtained with levelsof nitrogen and phosphorus non limitant to the productivity of wheat. A regressionanalysis was used for this.From all the soil, biological and weather factors considered, the following werefound to be relevant for the production of wheat on the soils and areas envolvedin the experiments: Soil content in assimilable nitrogen and phosphorus; Soil contentin organic matter; Rain fall during the period between the stalk forming stageand the milky grain stage of wheat; Field infestation with weeds; The potential productionof the wheat variety (the winter variety was superior to the spring varieties);Soil depth; Wind (lodging); and Low temperatures in late spring (frosts during flowering) . The fungus diseases, Ophiobolus graminis Sacc. and Puccinia striiformisWest., apparently were not important; though they are important, in general,under certain conditions.
Key words:
1Ing. Agr., M. S., Centro Suelos y Riego. Estación Experimental Carillanca, Instituto de Investigaciones Agropecuarias (INIA), Chile.