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

Abstract

Abstract:Kinetin is an important growth hormone used for in vitro propagation, but its dynamic and temporal effects on Dioscorea alata have not been thoroughly evaluated. In this study, surface response models were developed to better elucidate the effects of kinetin on D. alata propagated in vitro. Nodal segments were obtained from Akaaba, an important D. alata cultivar in Ghana, and propagated in vitro under five kinetin rates (0, 2.5, 5, 7.5 and 10 µM). The models were developed using segmented multiple regression with time and kinetin as the predictors. The effects on plant height, the number of leaves, shoots and roots were assessed with three-dimensional figures for better observation of temporal trends. The model fit was very good with normalized root mean squared 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 kinetin levels (2-4 µM) provided better growth at early culturing period. Higher kinetin levels (5-10 µM) suppressed the growth of the plantlets at early stages, but the plantlets recovered from the stress and resumed normal growth thereafter. After 4-5 weeks, the growth 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.

Effects of Low-Dose Kinetin, 2,4-D and Monochromatic Light Conditions on Flavonoid Content in Callus Culture of Dioscorea esculenta

“…Several studies have also investigated the effects of kinetin, 2,4-D, and lighting conditions on the callus growth of some Dioscorea species. Kinetin significantly increased the growth and differentiation of callus D. alata propagated in vitro with an optimal concentration of 2.5 mg/L [19]. Furthermore, 2,4-D acts like auxin, significantly affecting plant calluses' growth, such as Stelechocarpus burahol [20] and Elaeocarpus grandiflorus [21].…”