[Chlorophyll fluorescence in wheat genotypes with different heat tolerance] | Fluorescencia de clorofila en genotipos de trigo con diferente tolerancia al calor

English. In order to konow the relationship between chlorophyll fluorescence and the heta tolerance of wheat (Triticum aestivum L.), initial chlorophyll fluorescente (Fo), maximum fluorescence (Fm), variable fluoresce (Fv=Fm-Fo), and the ratio Fv/Fm, were evaluated in 16 wheat cultivars with different heat tolerance, when growing under field conditions at Tlaltizapan, Morelos, Mexico. Measurements were practiced at noon (38 degrad C), and daybreak (8 degrad C) in the flag leaf. No significant differences were found in chlorophyll fluorescence between cultivars, either at noon or daybreak; however, when the Fm and Fv obtained in the day were compared against those obtained at daybreak, significant differences were found in most of the cultivars. The variables related to chlorophyll fluorescence did not correlate with the biomass, grain yield, and grain number per spike at the grain physiological maturity

Spanish; Castilian. Con objeto de evaluar la relacion entre la fluorescencia de clorofila y la tolerancia al calor en trigo (Triticum aestivum L.), se midio la fluorescencia basal (Fo), la fluorescencia maxima (Fm), la fluorescencia variable (Fv=Fm-Fo) y la relacion Fv/Fm, en 16 variedades que diferian en su tolerancia al calor, en condiciones de campo, en Tlaltizapan, Morelos, Mexico. Las mediciones de hicieron a medio dia (38 grados C) y en la madrugada (8 grados C), en la hoja bandera. No hubo diferencia significativas en la fluorescencia de clorofila entre los cultivares al medio dia ni en la madrugada; pero al comparar los valores de Fm y Fv observados en el dia contra los de la madrugada, se detectaron diferencias significativas en la mayoria de las variedades. No hubo correlacion de las variables relacionadas con la fluorescencia con la biomasa producida durante la antesis, o con la biomasa producida durante la antesis, o con la biomasa aerea total, el rendimiento de grano y el numero de granos por espiga en la madurez fisiologica del grano