Propagação de Dioscorea trifida l.f. a partir de minitubérculo, estaquia e cultivo in vitro

Abstract

The caras (Dioscorea spp.) are monocotyledonous belonging to the Dioscoreaceae family, being popularly known as yam, ñame, or igname. The most cultivated species are those that serve for food, as Dioscorea trifida. They have excellent nutritional and energetic properties when compared with other tubers, besides being a rustic vegetable crop that little demanding when it comes to soil, fertilization and the use of pesticides. Despite the advantages, the crop still presents low productivity, mainly due to the low supply of quality propagation material and its high acquisition cost. So, the objective of this work was to evaluate the propagation of D. trifida through miniseed tubers, cuttings and in vitro culture. Mini tubers from plants at eight months of age were divided into five classes according to their mass and evaluated in a completely randomized design (CRD) experiment with five treatments and four replications. The sprouting, sprout velocity index, shoot sprouting time, number of shoots tubers-1 , percentage of tubers with apical dominance, number of leaves, shoot length and percentage of tuberization were evaluated. Mini tubers with mass above 18.45 g were promising as propagating material of D. trifida. With the cutting technique, the production of seedlings with only one nodal segment, without the use of growth regulators, was evaluated through a CRD experiment with six varieties / crosses. The percentages of survival, sprouting, rooting and tuberization were evaluated , besides the rate of sprouting speed and number of shoots and stalk roots -1 . Cuttings of all varieties / crosses with only one nodal segment and without the use of exogenous auxin showed viability in the production of seedlings. In the experiment with in vitro culture, the influence of benzylaminopurine (BAP) on the induction of in vitro budding of nodal segments of D. trifida was evaluated by means of a CRD experiment with four concentrations of the growth regulator, and the plant height, number of leaves, roots and shoots, percentage of survival and callus formation. There wasn’t statistically significant difference for the percentage of bud explants and number of shoots, demonstrating the possibility of multiplication of D. trifida without addition of BAP. The three methods were promising for propagation of the species and should be attentive to some characteristics such as: mini tubers with mass above 18.45 g; cutings and explants for micropopagation must contain a nodal segment and don’t require addition of growth regulator.