Submitted to: In Vitro Cellular and Developmental Biology
Publication Type: Abstract Only
Publication Acceptance Date: 6/14/2008
Publication Date: 6/14/2008
Citation: Niedz, R.P., Evens, T.J. 2008. Regulating NH4+, N0-, and K+ concentration and proportions improves in vitro tissue growth. In Vitro Cellular and Developmental Biology. 44:S72
Technical Abstract: A mixture-amount experiment that simultaneously varied both the ratios and total ionic concentration (from 20-100 mM) of NH4+, NO3+, and K+ was used to maximize sweet orange callus growth cv. ‘Hamlin.’ These experiments were free of ion confounding effects, i.e. ions added via pH adjustments and salt-derived counter-ions that are typically unaccounted for in experimental designs and analyses, and were used to quantify the effects and interactions of these nutrients on in vitro growth. The primary result was the identification of a region within the design space where callus fresh weight was ca. 175% greater than an MS control (the standard mineral nutrient formulation used for this cell line). Media recipes selected from this region specified 37.5 mM total nitrogen with a 0.25:0.75 NH4+:NO3+ ratio as compared to MS with 60 mM total nitrogen with a 1:1 NH4+:NO3+ ratio. Using a multivariate, mixture-amount approach it was possible to efficiently identify media compositions that provided the “best” growth and simultaneously quantify the main and interaction/blending effects, thus providing an empirical understanding of the “why” and “how” of ion-specific effects. These results illustrate the importance of designing experiments free of ion confounding when defining mineral nutrient formulations.