Effect of Potassium Nutrition during Bell Pepper Seed Development on Vivipary and Endogenous Levels of Abscisic Acid (ABA)

Abstract

Seeds in fruit of bell pepper (Capsicum annuum `California Wonder') plants grown in nutrient solutions deficient in potassium (<3 mmol·L-1) showed a higher incidence of sprouting (i.e., vivipary) than seeds in fruit from plants grown at adequate potassium levels (6 mmol·L-1). Tissue analysis showed a progressive drop in the leaf content of potassium with increasing plant maturation for all levels of potassium nutrition. However, potassium in fruit and seeds increased at later stages of maturity. ABA was extracted, isolated and identified from bell pepper seeds obtained from fruit grown under the potassium treatments (0.0, 0.6, 1.5, 3.0, and 6.0 mmol·L-1) at five fruit maturity stages (mature-green to overripe). At early fruit maturity stages, there were no significant differences in seed ABA content in the fruit from the different potassium treatments. However, differences in ABA content and vivipary among the potassium treatments became highly significant as the fruit matured. The concentration of ABA in seeds of potassium-deficient treatments was ≈14% of the control (0.4 versus 2.8 μg·g-1 dry mass). High concentrations of ABA in bell pepper seeds were associated with low incidence of vivipary and high potassium content in the leaves, fruit and nutrient solution.