Morphological and Physiological Screening of Aerial Yam (Dioscorea bulbifera L.) for Sodium Chloride Tolerance

Abstract

Aerial yam (Dioscorea bulbifera L.) is an indigenous, edible and energy-giving crop used for herbal remedy for some common ailments like diabetes, dysentery, cholera and conjunctivitis. It is fast-growing and can adapt to different soil types and habitat conditions, therefore seen as having the potential of tolerating salt stress conditions in this area of climate change. This study, therefore, sought to determine the tolerance of D. bulbifera to salt stress conditions through morphological and physiological studies. Bulbils of D.bulbiferaof two distinguished shapes were sourced from local farmers in Abia State, AkwaIbom State and Cross River State of the Niger- Delta region of Nigeria, and established in Biological Sciences Research Farm, University of Calabar, Calabar, to have the various lines for the experiment. Randomized Complete Block Design (RCBD) with three replications was used for the study. At four weeks after sprouting, the plants were treated with 250ml of different concentrations of sodium chloride (0, 100, 200 and 300mM) twice a week for six weeks. Morphological data of leaf color, number of leaves/plant, root length, leaf length, petiole length, leaf area, vine length and number of bulbils were measured weekly during the treatment period while physiological data of Chlorophyll-a and chlorophyll- b concentrations, peroxidase and glucose-6-phosphate dehydrogenase activities were analyzed two weeks after the completion of the treatment. Results revealed that sodium chloride reduced the vine length, number of leaves, number of bulbils, chlorophyll-a and chlorophyll-b concentrations of the plant, and caused an increase in the root length, peroxidase and glucose-6- phosphate dehydrogenase activities. Although sodium chloride reduced the growth of the D.bulbifera, all the lines were able to produce bulbils at a salt concentration of 0.00mM to 200mM. Therefore, this plantcould be regarded as a moderate salt tolerant plant. Significant differences in growth and yield were found between the lines (P<0.05). Bulbils with round shape tended to show more growth than the spindle shape.