Abstract:Studies were made on photosynthetic rates, chlorophyll contents and chl a/b ratio,chlorophyll-protein complexes and chlorophyll induction fluorescence kinetics in two rice hybrid progenies in comparison with their parents. Two rice hybrids used were Qingyou 159(F1) and its parents Qing A(♀) and R159(♂), Guangyou No. 4(F1) and its parents Guang A(♀) and Qingliuai(♂). It was found that the photosynthetic rates of both hybrids were much higher than their parentS (18% heterobeltiosis, 26%-30% mid-parent heterosis). The chlorophyll contents in leaves of both hybrids were not much different from that of their parents and showed only a low mid-parent heterosis, while chl a/b ratios were lower in these two hybrids than in their parents. Statistical analysis showed no correlation between photosynthetic rates and chlorophyll contents, and the chl a/b ratio showed significant negative correlation with photosynthetic rate. Determination of the chlorophyll-protein complex content by SDS-electrophoresis followed by scanning of the electrophoretogram at 650nm and 675nm showed that the peak area of OD values in both hybrids were much higher than that of their respective parents with marked heterobeltiosis, and was significantly correlated with photosynthetic rate. Chlorophyll fluorescence induction kinetics studies showed that the characteristic parameters (Fv/Fo and Fv/Fm) in the hybrids were higher than those of their respective parents, indicating a higher photosystem Ⅱ activity and high primary photochemical efficiency of photosystem Ⅱ in these two rice hybrids than that in their respective parents.
