Effect of temperature and scarification on seed germination of Conanthera spp. (Tecophilaeaceae)

Abstract

The Chilean endemic genus Conanthera is comprised of five species of herbaceous cormous geophytes. They have ornamental value due to their bell-shaped flowers, which are blue, violet or white. Previous germination studies of Conanthera campanulata and Conanthera trimaculata were carried out at 22 °C, and manual mechanical scarification improved germination. Based on these results, it was suggested that physical dormancy is present in the non-scarified seeds. However, an improvement in germination after scarification is not enough evidence to conclude that the seed is non-permeable to water and thus has physical dormancy. The objective of the present study was to assess the testa water permeability via an imbibition test and to identify the optimum germination temperature in C. campanulata and C. trimaculata. Using 6-mo-old seeds, data from the imbibition tests showed that neither the seeds of C. campanulata nor C. trimaculata have physical dormancy. In the germination experiments, the temperature range for achieving high germination percentages was 10 to 15 °C, where germination reached 90% in less than 28 d. Temperature of 20 °C can be considered supra-optimal, while 5 and 25 °C inhibited germination. Manual mechanical scarification did not affect germination results at the range of 10 to 15 °C. However, at the supra-optimal temperature of 20 °C manual mechanical scarification increased germination, although levels were never higher than 25%.

Seeds of Resilience: Physiology and Mechanisms of Hardseededness

“…The predominant form of scarification is mechanical scarification, wherein the testa, or seed coat, undergoes physical manipulation to enable the ingress of moisture and air. Various approaches are utilized in this process, encompassing the abrasion of seed coats with tools such as metal files, sandpaper, knives for nicking, gentle hammering for cracking, or any method that weakens or opens the seed coat [34][35][36][37][38][39]. This technique finds extensive application within the realms of horticulture and agriculture, serving as a fundamental method to facilitate the germination of seeds encased in rigid or impermeable seed coats.…”