Evaluation of different techniques for breaking seed dormancy of heliotropium europaeum l. (Boraginaceae)

Abstract

Prediction of germination and emergence of weeds plays a key role in weed management strategies. For this reason, the seed dormancy status of Heliotropium europaeum (Boraginaceae) was investigated in North West of Iran. The dormancy breaking treatments were after-ripening, gibberellic acid, hot water, KNO3, cold stratification, and washing. Seeds were strongly dormant at maturity and maintained high levels of dormancy for long periods of time. However, after 12 months storage at dry conditions, germination percentage increased to 37%. Washing and hot water treatments did not alter seed dormancy behavior, while the influence of gibberellic acid, KNO3 and cold stratification was significant. The highest value for germination percentage obtained by cold stratification increased the value up to 90%. Results of seedling growth showed that compared to other treatments, the seeds treated by KNO3 produced longer shoots and vigorous seedlings. The high vigor index was also recorded for cold stratification. It is concluded that the seeds of Heliotrope had a high primary dormancy and among treatments, the cold stratification was a more effective method in breaking seed dormancy .