GENETIC ANALYSIS OF THE STRUCTURE AND FUNCTION OF THE PHOTOSYNTHETIC APPARATUS AND ITS EFFICIENCY-A REVIEW

Abstract

Scientific research towards improving the biomass productivity of crops has become inevitable because of the inherent constraints t()wards improving the biomass partitioning. This factor alone So far has been of great significance for rapid spurt in economic yield. Photosyn thetic efficiency is expected tobe directly related to biomassproduction. Hitherto, this traithas not been affectedbyselectionand genetic improvement.Asubstantial number of photosynthetic mutants have been isolated and characterised but it remains an open question yet as to what component or step(s) in photosynthesis are rate limiting under specified conditions. In the absence of this knOWledge, screening of genotypes for maximum photosynthesis rate (PmaJ has been resorted to, but it may not be directly correlated with yield. Adequate genetic variability has been reported for this trait along with fair degree of genetic advance. Further, where the factors responsible for diluting the assodation of biomass prod\1ctivity with photosynthetic efficiency were taken care of, perfect relations ,have been established. The incorporation of photosynthetic indices in breeding protocols is, therefore, strongly advocated and depending on the nature of gene action appropriate breeding programme formulated. Further stability and adaptability studies are unavoidable as photosynthetic indices are labile to the environmental conditions. Integration of the tools of classical genetics and molecular biology in manipulating the photosynthetic efficiency for improving biomass productivity will become an absolute necessity in the years to come.