Effect of mechanical and chemical scarifications of date palm seeds (Phoenix dactylifera L.) on in vitro germination

Omar M. Al Zoubi

Abstract: Hard seed coat structure is the main reason for dormancy of Date Palm seed (Phoenix dactylifera L.), making it hard to absorb water during germination. Physical, mechanical, or chemical scarification treatments are useful in resolving dormancy conditions in seeds. In the present study, the effect of mechanical (braking and dividing into six groups) and chemical (sulfuric acid (H2SO4), potassium nitrate (KNO3), sodium hydroxide (NaOH) treatments on the germination of date palm seeds was performed for different treatment period (0, 10, 20, 30, 40, 50 min). Among mechanical treatments, intact operculum with scarification showed the highest germination percentage (GP) (86.70%) of the seed in vitro germinated. Regarding the chemical treatments, each treatment period had an effect on the seeds, GP of 86.70%, and 80.0% was exhibited for 30 min with NaOH and KNO3, respectively. Moreover, soaking of date palm seed in H2SO4 for 30 min resulted in the highest GP of 96.7%, on 12th day of culture and number of days lapsed to reach 50% of GP (GT50) of 5.12 days, the germination speed GRI and CGRI of seeds were no significant different in the treatments of H2SO4 for 20 or 30 min of the seed in vitro germinated. For all treated time, the seeds that pre-germinated in vitro shortened the days for germination and resulted in a significant increase in germination percentage compared with soil tested. The results presented herein suggest that date palm seed demonstrated
exogenous dormancy that is completely imposed by the hard seed coat. That can be effectively overcome by both mechanical and chemical scarification.

Keywords: date palm; germination percentage; in vitro germination; mechanical and chemical; scarifications; seeds

Date published: 2020-02-26