Germination of Pulsatilla seeds as influenced by seed morphology, moinst 5 degrees C and gibberellin treatment, and detection of nickle in seeds

Authors: YUAN, TAO - Beijing Forestry University; WEI, QIUYING - Beijing Forestry University; Bauchan, Gary

Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/7/2019
Publication Date: 11/1/2019
Citation: Yuan, T., Wei, Q., Bauchan, G.R. 2019. Germination of Pulsatilla seeds as influenced by seed morphology, moinst 5 degrees C and gibberellin treatment, and detection of nickle in seeds. HortScience. 54(11):2015-2023. https://doi.org/10.21273/HORTSCI14056-19.
DOI: https://doi.org/10.21273/HORTSCI14056-19

Interpretive Summary: Alpine pasque flowers are a favored early spring-time flower for gardeners. There is a shortage of seeds of these plants due to poor germination rates. An investigation was begun to determine what the reasons are for the poor germination and how to increase germination of the seeds. Light microscopy and scanning electron microscopy (SEM) studies were used to observe developed seeds and germination. Various seed treatments were tested with seeds soaked in water at 5 degrees celcius for 12-17 days with the addition of 50 parts per million gibberellic acid, a plant hormone, used to break dormancy. This treatment was found to increase germination rates by 64%. In addition, nickel, a toxic heavy metal, was discovered in germinating seeds. This could be a cause of poor seed germination. This research will be used by scientists, horticulturists, seed producers, botanic gardens, and gardeners as a means to increase seed germination and the availability of this favored flower.

Technical Abstract: Seeds of Pulsatilla turczaninovii were categorized to full and empty seeds based on observations under a light microscope and on X-ray images. Germination test for full or empty seeds was evaluated as affected by the duration of gibberellin GA3 and the moist 5ºC (cold stratification; CS) treatment. The morphological and elemental components of P. turczaninovii and P. cernua var. koreana seeds were analyzed using low-temperature scanning electron microscopy (LT-SEM) and energy dispersive X-ray diffraction analysis. The results showed that 64% of full and semi-full P. turczaninovii seeds 10 w after harvesting germinated in 17–19 d; however, the germination rate, including empty and semi-empty seeds was lower (52.6%). Full seeds with damaged or dried vegetative organs (embryo or endosperm) and semi-full seeds with severely damaged vegetative organs were observed and this could be related to low germination rates. Germination patterns of seeds stored dry at 5ºC for 44 w that showed a sigmoid pattern were increased by immersing seeds in GA3 solution for 8 h and treating seeds with 16 or 32 d of CS. More seeds germinated between 12–17 d as compared with 17–29 d, especially when they were treated with GA3 and received 32 d of CS. Comparison of germination rates of visually full seeds upon harvest (52.6%) with those that had been stored dry for 44 w (26.3–29.7%) suggested that the viability of seeds may have decreased. Dormancy could be a factor that decreased germination, and can be removed by low temperature and GA3 treatment. LT-SEM revealed a valley-like, sunken streak in empty seeds of P. cernua var. koreana. The nickel content in the trichome and seed coat of full and empty seeds of both taxa ranged from 2.98 to 4.62 (weight %), as determined on X-ray images. Our study suggested that the low germination rate was due to either the presence of dormancy, damage to either embryo or endosperm, a loss in viability, or the presence of nickel in the seeds.