K-Nutrition, Growth Bud Formation, and Amine and Hydroxycinnamic Acid Amide Contents in Leaf Explants of Nicotiana tabacum Variety Xanthi n.c. Cultivated in Vitro

The effects of K-nutrition on growth (increase of fresh weight), bud formation (time of emergence, number of buds), and amine and hydroxycinnamic acid amide contents in foliar explants of Nicotiana tabacum cv Xanthi n.c. cultivated in vitro were examined. In K-deficient medium and in high K medium growth and bud formation were markedly inhibited. Marked changes of amine content (a diamine, putrescine; a phenolic amine, phenethylamine) were observed after a few days of culture. No apparent relationship was found between these amines and growth or bud differentiation. In contrast, changes in hydroxycinnamic acid levels were shown to correlate well with growth and bud formation. The greatest stimulation of budding and growth was correlated with the greatest accumulation of these amides. The highest contents of hydroxycinnamic acid amides were found during the first 15 days in culture when intensive cell division took place. Then they declined sharply after 26 days in culture as the rate of cell division decreased and differentiation occurred.