Photosynthetic Performance and its Relationship with Leaf Water Potential in <i>Desmodium gangeticum</i> L. DC. (Shalaparni) Genotypes under Field Conditions

Abstract

Desmodium gangeticum L. DC. (Family - Fabaceae) is a medicinal legume that grows in dry hilly areas and dried roots are used as general tonic and aphrodisiac. It has a calming, sedative effect and is also used to control inflammation, fever and neurological imbalances. Genetic variability for leaf water potential and photosynthetic activities which attributes for biomass was assessed in 31 accessions collected from various agro climatic zones of India. The accessions were screened for three gas exchange parameters viz ., photosynthetic rate (P n ), stomatal conductance (g s ) and transpiration rate (E) during active photosynthetic period and leaf water potential (Ψ) during pre-dawn, noon and dusk. Plant biomass was recorded for the accessions during harvest. There were considerable variations in leaf water potential of genotypes during pre-dawn and noon. The genotypes differed significantly for the gas exchange parameters studied. High positive correlation was observed between P n and g s (R 2 = 0.68) with E (R 2 = 0. 75) and significant negative correlation with noon ψ w (-0.26). The genotypes were categorized into 2 main clusters namely, A and B with 4 sub clusters. Cluster A contained 13 genotypes of which 6 had higher photosynthetic performance with superior water relations and cluster B contained 18 genotypes of which 3 accessions (DDG 3, DDG 22 and DDG 33) formed a sub group and exhibited poor photosynthetic performance. The positive correlation of g s and E with photosynthesis can be helpful for improvement of D. gangeticum .