CTAHR Masters Theses
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ItemThe effects of age, temperature and duration of exposure to temperature on susceptibility of pineapple to floral induction with ethephon( 1977-12)In pineapple (Ananas cornosus (L.) Merr.), the natural transition from the vegetative apex (or from vegetative development) to the initiation of reproductive structures occurs under a variety of climactic, physiological and cultural conditions. Many years ago it was shown that pineapple could be induced to initiate reproductive development by the application of acetylene, ethylene or napthalene acetic acid. However, numerous reports in the literature and local experience showed that the susceptibility of the pineapple to chemical induction of flowering was affected by many factors. These factors include cultivar, size and/or age, temperature, water and nutrient stress, light reception and a reduction in growth rate. In areas where warm summers and frequent rains often produce rapid vegetative growth, certain chemicals are known to be ineffective as forcing agents. Variation in the susceptibility of certain cultivars has also been observed and there are differences between treatments and time of year application is made. Such variations result in inefficient use of the labor force in the field and in the cannery. In addition, it is often advisable to avoid forcing plants at certain times of the year when fruit quality, size and shape are known to be affected. For example, forcing with SNA during the summer will not only result in delayed development of the inflorescence but elongated fruits low in Brix and high in acid content. Ethylene, on the other hand, may be used equally well throughout the year (W. G. Sanford, personal connnunication). Because of frequent failures in attaining high floral induction percentages in the tropics, there is a need for studies using controlled temperature to elucidate the relationship between climactic factors and susceptibility to forcing. Little or no published information was found on the relationship between the efficacy of a forcing agent and plant age and temperature. A knowledge of how to grow a pineapple plant which is or is not susceptible to floral induction could furnish a good foundation on which to develop chemicals for the inhibition of natural flowering. Such tests could also provide material for the study of the physiology and biochemistry of the flowering process. The main objective of this study was to evaluate the effects of temperature and age on susceptibility of pineapple to flower induction with ethephon. The diurnal variation in leaf resistances at varying temperatures and growth stages and data on the effects of temperature and age on titratable acids and leaf starch and nitrogen were collected to provide basic information on plant response to treatment.
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