Avaliação do efeito das concentrações de sacarose e dos estádios de desenvolvimento do fruto no cultivo in vitro de embriões de frutos de cafeeiro

Abstract

In vitro culture offers a controlled system to study the nutritional, physiologic and biochemical processes of embryos in several developmental stages. In this work, the relationship between development stage of the fruit and sucrose concentration in the culture medium for in vitro development of coffee embryos was evaluated. Embryos of Coffea arabica L. cv. Acaiá were excised and inoculated into the culture medium MS with pH adjusted to 5.8. The treatments consisted of the combination of six sucrose concentrations (0, 15, 30, 60, 90 and 120 g L-1) and six developmental stages of the fruit ('pin-head', 'lead', 'green', 'green-yellow', 'cherry' and 'overripe'). After inoculation, the embryos were incubated in growth room at 27 ± 1ºC, photoperiod of 16 hours and 35 µ mol m-2 s-1 of luminous intensity. The experimental design was entirely randomized (6 x 6 factorial), with six repetitions and the parcel constituted by four tubes each. After 60 days, the seedlings were evaluated based on shoot length, total fresh weight of shoot and root. Influences of the sucrose concentrations and the stages of fruit development were observed, and the best results were obtained with embryos excised in the stage 'green' and inoculated in the culture medium supplemented with 51 to 70 g sucrose L-1.