Seed germination of Paederotella pontica (Rupr. ex Boiss.) Kem-Nath.- rare endemic species of the Caucasus

Institute of Botany, Ilia State University, Georgia

^* Corresponding author: nana.shakarishvili.1@iliauni.edu.ge

Abstract

Paederotella pontica is a Colchis tertiary relict species, regional narrow endemic to the Caucasus, representative of an oligotypic genus. The aim of this study was to determine dormancy-breaking requirements and develop seed germination protocol for P. pontica. Freshly matured seeds of P. pontica are morphophysiologically dormant (MPD). Mean length of seed is 820 μm, linear embryo is fully differentiated, on average 625 μm long. Penetration of tetrazolium salt indicates the permeability of seed coat and high percentage of vital seeds in capsules. Prior to root emergence, the E:S ratio increased from 0.76 to 0.9. Effects of warm and cold stratification and gibberellic acid (GA₃) on embryo growth and seed germination were studied under laboratory conditions. Since cold stratification is the only requirement for the loss of MPD, the longest embryo growth occurred during this treatment and GA₃ promoted MPD loss, we concluded that P. pontica seeds have intermediate complex MPD. Based on the treatment results a germination protocol is proposed: 1. Dry storage at 20°C, 2 months; 2. Cold-wet stratification at 3°C, 3 months; 3. Germination at 20/15°C day/night. Under developed conditions germination is fast, synchronous and yields to 80%.