Morphometry, in vitro-ex vitro germination and tetrazolium testing of stinking passionflower [Passiflora foetida var. glaziovii Killip] (Passifloraceae) seeds

Abstract

Passiflora foetida L. has broad utility as a medicinal and ornamental plant; however, information regarding varieties and the physiological potential of their seeds are scarce. Here, we aim to evaluate in vitro and ex vitro germination behaviour and to adapt tetrazolium methodology for P. foetida var. glaziovii Killip. The botanical identification and characterisation were performed through the observation of morphological characters and consultation of the relevant literature. Ex vitro germination was performed on rolled and flat Germitest paper at continuous (25 °C) and alternating (20 and 30 °C; night and day, respectively) temperatures. Seeds with the completely removed integument were used for in vitro germination and tetrazolium tests. The in vitro germination test was performed with MS medium using seeds conditioned under different light qualities (white, red, far-red or darkness) and at two temperature regimes (25 °C; 20 and 30 °C alternating temperature). For the tetrazolium test, seeds were soaked in different concentrations of tetrazolium salt (2.5, 5.0, 7.5 or 10 g L -1 ) at different temperatures (30, 35, 40 or 45 °C) for two hours in the dark. This is the first record of P. foetida var. glaziovii, a wild herbaceous vine with glandular trichomes on its leaves, bracts and stipules; fruit bacoid, elliptic, glabrous, in Espírito Santo State, Brazil. The seeds are small (approximately 4.87 mm long and 2.15 mm wide) and non-photoblastic, and in vitro germination must be performed using an alternating temperature (20 and 30 °C) regime. The best result of germination was achieved using a concentration-temperature combination of 10 g L -1 tetrazolium and 30 °C.