Exogenous gibberellin can effectively and rapidly break intermediate physiological dormancy of Amsonia elliptica seeds

Abstract

Accelerated global warming is leading to the loss of plant species diversity, and ex situ preservation of seeds is becoming an increasingly important aspect of species conservation. However, information on dormancy and germination is lacking in many endangered species. Amsonia elliptica (Apocynaceae) is the only Amsonia species native to Korea, and the South Korean Ministry of Environment has designated it Class II endangered wildlife. Nevertheless, the dormancy class and the dormancy breaking method for seeds of this species for germination are not precisely known. We identified the structure of A. elliptica seeds and the causes of dormancy, which inhibits germination. In addition, we tried to develop an effective germination promotion method by testing the wet stratified condition, which breaks dormancy, and the form of gibberellin that can replace it. Fresh seeds of A. elliptica imbibe water, but the covering layers (endosperm and seed coat) inhibit germination by mechanically restricting the embryo. Initial germination tests confirmed low embryo growth potential and physiological dormancy (PD). Restriction due to the covering layer was eliminated by seed scarification, and abnormal germination was observed. After 12 weeks of cold moist stratification at 4°C, only 12% of seeds germinated. However, 68.8% of seeds subjected to 8 weeks of warm moist stratification followed by 12 weeks of cold stratification germinated, indicating that warm stratification pretreatment before cold stratification is effective in breaking dormancy. A. elliptica seeds exhibited intermediate PD. Furthermore, 61.3% of seeds soaked in 500 mg/L GA4+7 for 14 days and incubated at 25/15°C germinated. Therefore, GA4+7 rapidly broke the dormancy of A. elliptica seeds compared with warm plus cold stratification treatment, thus providing an efficient method for seedling production.

Methods for Improving the Germination of Rhodotypos scandens (Thunb.) Makino Seeds through Endocarp Removal

“…This process accelerates radicle emergence by breaking down the endosperm barriers. Numerous studies have documented that endogenous phytohormones, particularly GAs and ABA, play a regulatory role in seed dormancy and germination [ 22 , 46 , 47 , 48 ]. Furthermore, the combination of fluridone, a different class of phytohormone from the GAs used in the current study, with ER exhibited positive effects on germination characteristics, as evidenced by improvements in the MGT, TI, and GPI compared to the nontreated seeds (with endocarp) ( Figure 4 ).…”

“…Within the family Rosaceae, nondormancy and the occurrence of PD are commonly observed [ 9 , 16 ]. Various methods have been applied to overcome PD, including seed stratification [ 20 ], the use of regulatory phytohormones [ 21 , 22 ], and chemical solutions [ 23 , 24 ]. Nevertheless, within the Rosaceae family, particularly in the genera Rubus and Prunus , instances exist where a hard seed coat functions as a protective layer for the internal seed structure.…”

Dormancy-release and germination improvement of Korean bellflower (Campanula takesimana Nakai), a rare and endemic plant native to the Korean peninsula

“…GAs not only promote germination by antagonizing abscisic acid (ABA) but also release dormant seeds [ 48 ]. Several studies have reported that endogenous phytohormones, especially GAs and ABA, regulate seed dormancy and germination [ 21 , 46 , 49 – 54 ]. In this study, GA 3 pretreatment positively and effectively enhanced the germination characteristics of C .…”

Seeds of Resilience: Physiology and Mechanisms of Hardseededness

“…The increase in GA levels occurs with the release of seed dormancy, for example, during imbibition and stratification. In some dormant seeds, treatment with exogenous GA can take advantage of this opportunity to break dormancy, thereby facilitating faster seedling production [99]. Many previous studies have utilized GA to facilitate the breakage of dormancy in various plant species, including Solanum torvum [100], Chinese ryegrass (Leymus chinensis) [101], Amsonia elliptica [99], Cinnamomum migao [102], and Araticum (Annona sylvatica) [103].…”