Morpho-phenological and Antibacterial Characteristics of Aconitum spp.

Aconitum species have been traditionally used as ethnomedicine to cure various ailments. The present study reveals the morpho-phenology and antibacterial property of alkaloid extracts of the two Aconitum species. The morpho-phenological characteristics will be helpful for determining the resource availability. Aconitum nagarum is erect type, whereas, Aconitum elwesii is a climber. Aconitum elwesii grows in advance of A. nagarum in terms of growth, flowering and senescence. Towards the end of the year, when the fruits have ripened, the parent tuber dies off. As a result, the daughter tuber becomes independent and in the following spring, takes over the function of the parent tuber. Aconitum nagarum and A. elwesii were found to contain 4-5 aconitine equivalent (AE) mg/g of alkaloid. These alkaloids showed antibacterial activity against different bacterial species including human pathogens, namely, Staphylococcus aureus, Salmonella typhimurium, Bordetella bronchiseptica, Escherichia coli, Bacillus subtilis, Pseudomonas putida, Pseudomonas fluorescence and Xanthomonas campestris. However, the extent of antibacterial activity varied among different bacterial species. The antibacterial activity against S. aureus, B. bronchiseptica, and B. subtilis was bactericidal in nature, whereas, against other tested bacterial species was bacteriostatic. Efficacy of the antibacterial activity of these alkaloids was evaluated by comparing with that of standard antibiotics. Differential localization of the antibacterial principle was observed among the Aconitum species studied.

Influence of storage time on earliness of sprouting and tubering in Dioscorea rotundata yams

SUMMARYTubers of Dioscorea rotundata yam obtained from the same harvest were stored at room temperature (25–30 °C). After storage for various durations, tuber samples were taken and used as planting material. The number of days to sprouting, for head pieces and non-head pieces alike, decreased with increasing storage time up to 159 days. Heads sprouted earlier than non-heads. The number of days to formation of new tubers also decreased with increasing storage age of the parent tuber up to 226 days. The interval from sprouting to tubering was constant up to 106 days of storage, decreased rapidly between 106 and 226 days, and thereafter remained constant. The implications of these results for off-season yam production are discussed.