Using Surface Response Models to Evaluate the Effects of Kinetin on Dioscorea alata Propagated in Wtro

摘要

cqvip:Kinetin is an important growth hormone used for in vitro propagation, but its dynamic and temporal effects on Dioscoreaalata have not been thoroughly evaluated. In this study, surface response models were developed to better elucidate the effects ofkinetin on D. alata propagated in vitro. Nodal segments were obtained from Akaaba, an important D. alata cultivar in Ghana, andpropagated in vitro under five kinetin rates （0, 2.5, 5, 7.5 and 10 μM）. The models were developed using segmented multipleregression with time and kinetin as the predictors. The effects on plant height, the number of leaves, shoots and roots were assessedwith three-dimensional figures for better observation of temporal trends. The model fit was very good with normalized root meansquared error （NRMSE） = 0.1, R-squared = 0.83 and adjusted R-squared = 0.82, averaged across the different growth parameters.Different kinetin levels elicited the maximum shoot, leaf and root formation, as well as the growth rates over time. Moderate kinetinlevels （2-4 μM） provided better growth at early culturing period. Higher kinetin levels （5-10 μM） suppressed the growth of theplantlets at early stages, but the plantlets recovered from the stress and resumed normal growth thereafter. After 4-5 weeks, thegrowth rates of the moderate kinetin levels （2-4 μM） declined much faster and were lower compared to the higher kinetin levels,except plant height and the number of roots which were still higher at the moderate kinetin level even after eight weeks of culturing.Thus, kinetin requirements vary depending on the growth parameters of interest.