Comparative performance of triticale, durum, synthetic and bread wheat for chlorophyll fluorescence traits under heat stress conditions

A set of 24 wheat genotypes comprising different genomes namely Triticum aestivum (AABBDD), T durum (AABB), synthetic wheat (AABBDD) and triticale (AABBRR) were evaluated under heat stress in field conditions. The observations were recorded for chlorophyll fluorescence traits namely minimum fluorescence (Fo), maximum fluorescence (Fm) and maximum quantum yield of photosystem II (Fv/Fm) at 10 days after anthesis. The estimates of genotypic coefficient of variability, phenotypic coefficient of variability and heritability were found moderate for Fm and grain yield while low for Fo and Fv/Fm which revealed that Fm has considerable magnitude of genetic variability and heritability. The genetic advance through selection as per cent of mean was also moderate for Fm and grain yield indicating reasonable scope of selection for these traits. Fm provides information about the maximal capacity of photo-system II to transfer electrons for reaction centre though electron transport chain (ETC) to photo-system I and in turn gives information about the potential to estimate photosynthetic performance. However the estimates of genetic advance were low for Fv/Fm and Fo which may be due to narrow total genetic variation for these traits. Keeping in view the moderate to high estimates of genetic advance, maximum fluorescence (Fm) has considerable scope for selection. Correlation coefficients revealed that genotypes having high grain yield under heat stress conditions also had high expression of Fv/Fm (r= 0.44), high Fm (r= 0.65) and high Fo (0.74). The genotypes having high Fv/Fm also had high expression of Fm (r= 0.87). This indicated that genotypes having high grain yield under heat stress were also having high Fv/Fm.