Determination of pineapple (Ananas comosus, MD-2 hybrid cultivar) plant maturity,the efficiency of flowering induction agents and the use of activated carbon

Natural flowering is one of the major agronomic problems in pineapple (Ananas comosus) cultivation. It causes heterogeneous flowering and fruit development with multiple harvest passes of the same field as an inevitable consequence. To avoid natural flowering, pineapple plants are induced to synchronize flowering by external ethylene treatments. In this research it is shown that pineapple plants (MD-2 hybrid cultivar) are already sensitive to external ethylene treatments at an early developmental stage, i.e. 3 months after planting, although no natural flowering occurs during this early stage of plant development. These results indicate that young pineapple plants already posses all the necessary factors to induce flowering in response to ethylene treatments. Additionally the efficiencies of flowering induction of different external ethylene treatments, including a novel agent developed at our lab, called ‘zeothene’, were evaluated. Zeothene (=zeolite containing ethylene gas) and ethylene dissolved in water (both applied in the central cup of the plant) were proved to be very efficient flowering induction agents. The commercial cultivation practice, in which ethylene gas is sprayed with water over whole plants, was found less efficient confirming that central cup applications are more efficient than whole plant spraying. Cup applications allow the active ingredient (ethylene or ethephon) to be taken up immediately by the apical meristem resulting in an efficient flowering induction signal. The addition of activated carbon to enhance the flowering induction treatment was found to be useful only with a very high dose of activated carbon (5%) and a long interaction time (at least 5–30 min) between the activated carbon and the flowering induction solution.