ABSTRACT


Víctor VoIke H.1
 
The objetive of the present study was to determine those factors of the cultivar, soil, management and climate which: 1) affect the grain yield of the wheat (Triticum aestivum L.), and 2) modify the wheat response to nitrogen and phosphorous, in some "trumao" soils of Malleco and Coutin provinces (Chile). The way followed for this, was to establish a mathematic relationship -general regression equation- that expresses the yield as a function of applied nitrogen and phosphorous as fertilizers, and some cultivar, soil, management and climate factors. the data were obtained from 42 trials of wheat response to nitrogen and phosphorous. The trials were based on a treatment desing "square double" (5 doses of each nutrient and 13 treatments). The trumao soils studied were: Santa Barbara, Victoria, Agua Fria and Vilcun. the method used for producing the general regression equation, was that based on the "prediction sum of squares" porposed by Cady and Allen.The general regression equation achieved a coefficient of multiple determination, R2, of 0.910. According with it, the factors that affected the wheat yield were: nitrogen and phosphorous applied as fertilizers; the wheat variety; the infection of Puccinia striiformis West.; the extractable nitrogen, phosphorous and potassium contents of soil; the organic matter content of soil; the soil depth; the infestation of "chépica", Agrostis sp.;the planting date; and the total rainfall since the beginning of jointing wheat stage to soft-dough graing. Those factors that modified the wheat response to nitrogen and phosphorous were: the extractable nitrogen and phosphorous contents of soil; and to nitrogen: the soil drainage. Besides, differences of wheat response to nitrogen and phosphorous among soils were observed. It was found that the amount of rainfall and the aluminum content of soils did not modify the wheat response to nitrogen and phosphorous.
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1Ing. Agr., M. S., Centro Suelos y Riego, Estación Experimental Carillanca, Instituto de Investigaciones Agropecuarias (INIA) ,Chile. Actuamente en CIMMYT. Londres 40, México 6, D. F., México.