CHLOROPHYLL FLUORESCENCE IN WHEAT GENOTYPES WITH DIFFERENT HEAT TOLERANCE

Abstract

In order to know the relationship between chlorophyll fluorescence and the heat tolerance of wheat (Triticum aestivum L.), initial chlorophyll fluorescence (Fo), maximum fluorescence (Fm), variable fluorescence (Fv=Fm-Fo), and the ratio Fv/Fm, were evaluated in 16 wheat cultivars with different heat tolerance, when growing under field conditions at Tlaltizapán, Morelos, México. Measurements were practiced at noon (38 oC), and daybreak (8 oC) 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 produced during anthesis or with the aerial biomass, grain yield, and grain number per spike at the grain physiological maturity