Characterization of candidate plus trees(CPTS) of pongamia pinnata(L), a versatile legume from North Guwahati, Assam

Abstract

Plant source for fuel that replaces fossil fuels is a topical subject and has gained prominence as DDBiofuel cropsDD. Pongamia pinnata, commercially important tree species used to produce biofuels, is known for its multipurpose benefits and its role in agro-forestry. Pongamia development as a multi-potent legume crop in IIT Guwahati in collaboration with Sila Forest Range, North Guwahati, Assam was attempted in the present study. The overall objectives of the thesis were divided into 6 distinct chapters that includes systematic candidate plus tree (CPT) identification, growing nursery, mass multiplication of identified CPTs using vegetative propagation and tissue culture approach, diversity evaluation among elite genotypes using SDS-PAGE, RAPD, ISSR and AFLP, collecting seeds from identified CPTs, extracting oil, examining medicinal and biodiesel aspects, morpho-biomolecular characterization of seeds by exploitation of advanced biotechnological tools and exploring symbiosis between Rhizobium and Pongamia by identification of novel Rhizobium pongamiae from root nodules CPT. In first chapter, 10 CPTs belonging to populations 6 and 10 were identified based on morphological markers (vegetative and reproductive) using combined analysis over locations by CROPSTAT software. Identified CPTs were then multiplied using seed propagation technique in nursery bed. The best genotype identified was NGPP 46 with respect to pod-seed traits and total oil content. Hexane extraction yielded maximum oil content from seeds (33 %) compared to petroleum ether (30 %). When varying the seed to solvent ratio, no significant difference was noticed on the total oil yield for an individual tree, although the recovery of solvent and time taken for oil extraction reduced to significant level at higher ratio. Identified CPTs can be further included in programmes aimed at genetic improvement of the species. Second chapter has been divided into two sub-objectives. First one includes examining the amenability of vegetative propagation and effect of maturation in CPT, NGPP 46 through rooting of stem cuttings treated with varying concentrations and combinations of auxins. All auxin treatments promoted sprouting and at lower concentrations triggered/enhanced rooting of cuttings. The effectiveness was in the order of IBA>NAA>IAA when applied singly. IBA at 4.92 mM was found to be most effective as the rooting percentage and number of roots were significantly higher (p0.01) than in control. However higher concentrations of auxins above 7 mM in general inhibited the rooting of cuttings. The interaction among auxins was found to be effective in root induction and differentiation and the most stimulating effects were observed in three-component mixture (IAA 1.42 mM + IBA 4.92 mM + NAA 1.34 mM). For further study mature stem cuttings of ten CPTs were subjected to the best responding auxins application to compare their adventitious rooting ability. Significant differences were observed for sprouting (26 - 86.67%) and rooting (56.67 - 93.33%) behaviour. Rooting after nine weeks was more than 96% from NGPP 26, 27 and 46, in IAA 1.42 mM + IBA 4.92 mM + NAA 1.34 mM and was approximately 4 times that of control. Auxin treatment increased number of roots (2.32) and root length (22.23 cm) but has negligible effect in the number of shoots per rooted cuttings. Cuttings harv...