Substrate, moisture, temperature and seed germination of the threatened endemic tree Eriotheca vargasii (Malvaceae)

Abstract

We studied the germination of Eriotheca vargasii (Malvaceae), a poorly known endemic Peruvian Andean tree species characteristic of the dry forests of the Torobamba river valley. We determined seed characteristics, embryo morphology, viability, and assessed the influence of substrate (natural soil and commercially prepared media), temperature (controlled at 25 ºC and at ambient temperature between 18-22 ºC), and moisture (25 % and 50 % field capacity) on seed germination. Although most seeds were ovoid in shape and contained well-developed embryos, only 46% of them were viable. Substrate moisture levels had no influence on germination capacity or rate. In contrast, temperature and substrate type showed strong effects on germination. We observed the highest proportion of germinated seeds in prepared media at both temperatures tested (> 61 %). Furthermore, substrate types also influenced germination rates, with lower values in natural soil. The strongest effect on germination rates was by temperature, enhancing the difference in responses in substrate types. The low proportion of germinated seeds in soil (< 39 %), together with external local stress factors (e.g. grazing impact by herbivores), may be the critical factors contributing to the nearly total absence of seedlings and saplings of E. vargasii in the study area despite abundant seed production.

The Imbibition, Viability, and Germination of Caper Seeds (Capparisspinosa L.) in the First Year of Storage

“…There were no differences (p ≤ 0.05; Table 1) in the statistical analysis performed at 96 h, in which the moisture content of the three states seeds was about 32%. According to Juan [14], the initial moisture of DS and SS was adequate for its conservation, while the moisture reached in the three seed states was sufficient for efficient germination, which generally ranges between 25 and 50% depending on the species [34][35][36], and particularly for caper seeds as [14,18] stated. The evolution of the imbibition is shown in Figure 1b.…”

Germination Data Analysis by Time-to-Event Approaches

“…McNair et al [17] reviewed exhaustively non-parametric and semi-parametric models applied to germination data, whereas Onofri et al [18] considered a range of AFT models to describe germination responses for different weed species. Other authors applied these methods to their research, more precisely non-parametric and semi-parametric models [19][20][21][22][23][24][25][26][27] and AFT model [28,29].…”