Chlorophyll fluorescence and photosynthetic gas exchange in submergent tolerant CO 43 Sub1 lines

Abstract

The study was aimed at developing submergence tolerant version of popular rice variety of Tamil Nadu namely CO 43, through marker assisted introgression of Sub1 locus from a submergence tolerant FR13A. Selfed progenies of BC2 generations were genotyped and phenotyped for submergence tolerance. Foreground selection was done using rice marker RM219 and ART 5. Background Selection (BGS) was done using 25 genome wide SSR markers with three markers covering per chromosome. BGS resulted in the identification of superior six BC2F2 plants possessing > 80% of CO43 genome. These lines were selfed to generate BC2F3 progenies for further phenotyping studies under simulated submergence conditions. Most of the BC2F3 progenies and FR13A plants exhibited 100% survival for flooding stress of 13 days. All the survived plants of BC2F3 generations were evaluated for plant height, chlorophyll contents, chlorophyll fluorescence, photosynthetic rate, stomatal conductance and transpiration rates before and after flooding. The findings of the study showed that the backcross progenies (BC2F3) with minimum underwater elongation were associated with increased survival percentage, higher chlorophyll contents and comparable fluorescence values as that of FR13A. Most of the BC2F3 individuals recorded higher photosynthetic rate coupled with higher conductance and transpiration rates.