Aclimatização de Dendrobium phalaenopsis Deang Suree

Abstract

The experiment was conducted at the Laboratory of in vitro and in Jardinocultura area of the Faculdade de Ciências Agrárias (FCA) - Universidade Federal da Grande Dourados (UFGD) to assess luminosity conditions and their joint effect of immersion time in distilled water on plants of Dendrobium phalaenopsis Deang Suree. Were used as study material, plants with 180 days originating from in vitro sowing, standardized in size and characterized to fresh weight, number of leaves, pseudobulb length, diameter of the largest pseudobulb, number of pseudobulbs and length of root. Two experiments were conducted. In the first experiment a set of 40 plants was placed directly in the greenhouse covered by two 50 % shade screens (162,0 mol m-2 s-1) and three sets of 40 plants each were transferred to growth room with controlled temperature and photoperiod (12 h, 25 ± 2 °C) and submitted to intermediate acclimatization for 30 days under the following luminosity conditions: 1 - white fluorescent light (18,9 μmol m-2 s- 1) 2 - white fluorescent light + red fluorescent light (14,85 μmol m-2 s-1) and 3 - red fluorescent light (9,45 μmol m-2 s-1). After to intermediate acclimatization period, the plants were characterized anatomically and transferred to the greenhouse containing control. In the second experiment, a set, regarded as control, was not submitted to immersion and the other plants were immersed in distilled water for 12; 24; 36; 48; 60; 72 or 84 hours. After each immersion period the plants were transferred to polypropylene container containing as substrate a mixture of sphagnum and coconut fiber (1:1 v v-1). The plants were allocated in growth room with controlled temperature and photoperiod (12 h, 25 ± 2 °C) during 30 days for intermediate acclimatization being submitted to two luminosity conditions (14,85 or 18,9 μmol m-2 s-1). After a period of acclimatization intermediate, the plants were transferred to greenhouse. Being subsequently evaluated for the same characteristics of the first experiment, are calculated the percentages of increments of their initial values. For experiment 1, only plants submitted to intermediate acclimatization, with red light, were statistically better to the control in relation to the survival percentage and increase in fresh weight. For experiment 2, with the increase of immersion time was decreased in increments of fresh weight and number of pseudobulbs as well as the number of roots of plants grown under white light + red light. The immersion default in distilled water independently of the luminosity condition is beneficial to plants of D. phalaenopsis Deang Suree.