Efecto de tratamientos pregerminativos y peso de la semilla en la germinación in vitro de Kroenleinia grusonii

Abstract

Background and Aims: Kroenleinia grusonii is endemic to Mexico and is threatened with extinction. The objective was to compare the influence of seed weight on its morphometrical variables, the effect of the interaction of pregerminative treatments and seed weight on germination and size of the seedlings, as well as present the morphological description of seedlings of K. grusonii cultured in vitro. Methods: Seeds were divided into groups: 1) ≤0.5 mg, 2) 0.6-0.9 mg and 3) ≥1.0 mg. The length, width, area and testa thickness were measured. From the embryo, the length and width were measured, and its area was calculated. Five treatments were applied: control, hydration for 24 hours, hydrochloric acid, sulfuric acid and mechanical scarification. The germination percentage and the size of the obtained seedlings were recorded after 30 days. A correlation and regression analysis was carried out to the effect of seed weight in the size variables; germination percentage was evaluated with the Mann-Whitney U test and an ANOVA with factorial arrangement was carried out for the seedling size. The morphological development of the K. grusonii seedlings was monitored for 60 days. Key results: Heavy seeds (≥1.0 mg) presented the greatest length with 1.85±0.01 mm. In the interaction of seed weight and pregerminative treatment, the most significant germination occurred in medium seeds of 0.6-0.9 mg with mechanical scarification, obtaining 66±0.47% germination. The H2 SO4 and seeds of ≥1.0 mg presented seedlings with greater stem height of 8.33±0.46 mm. Conclusions: Seed weight increases as size increases. Mechanical scarification was the best treatment for promoting seed germination. Information on seedlings’ size and morphological description can contribute to the ex situ conservation of K. grusonii. Key words: chemical scarification, mechanical scarification, seedling morphology, seedling size.