In vitro shoot growth of Brugmansia × candida Pers

Abstract

The objective of this study was to improve the growth of in vitro shoot cultures of Brugmansia × candida ‘Creamsickle’. Several mineral nutrient experiments were conducted to determine the effect of NH ⁺₄ , NO ⁻₃ , K⁺, FeSO₄/EDTA, ZnSO₄, MnSO₄, and CuSO₄ on quality, leaf width and length, size and weight of shoot mass, and shoot number. The experiment to determine the levels of NH ⁺₄ , NO ⁻₃ , and K⁺, was conducted as a 2-component NH ⁺₄ : K⁺ mixture crossed by [NO ⁻₃ ] and resulted in an experimental design free of ion confounding and capable of separating the effects of proportion and concentration. The results of the NH ⁺₄ -K⁺-NO ⁻₃ experiment revealed a region in the design space where growth was significantly improved; the region generally had lower total nitrogen and lower NH ⁺₄ :K⁺ ratios than MS medium. The experiments to determine the appropriate levels of Fe, Zn, Mn, and Cu were conducted at six log levels ranging from 0 to 1 mM. Of the four metal salts tested, MnSO₄ had the least effect on in vitro shoot growth and its concentration was reduced from 0.1 mM (MS level) to 0.001 mM. CuSO₄ had large effects on in vitro shoot growth and was increased from 0.0001 mM to 0.001 mM. A 2-level factorial of NH ⁺₄ -K⁺-NO ⁻₃ , FeSO₄/EDTA, and ZnSO₄ was conducted and several formulations identified for their improvements of quality and growth. In addition to the changes to MnSO₄ and CuSO₄, these formulations were characterized by lower levels of NH ⁺₄ , K⁺, NO ⁻₃ and Zn, and higher levels of FeSO₄/EDTA. Overall, several nutrient formulations were identified as superior to MS medium for growth of in vitro shoot cultures of B. ‘Creamsickle’.