Inheritance of deep seed dormancy and stratification-mediated dormancy alleviation in Amaranthus tuberculatus

Amaranthus tuberculatus is a weed species that has shifted emergence patterns over the past few years, presumably due to changes in seed dormancy in response to selection in agricultural fields. Although it is recognized that the seed dormancy phenotype is greatly affected by the environment, it is also acknowledged that the genotype plays a significant role. However, the importance of the genotype in determining intra-population seed dormancy variability, and the effect on emergence patterns, is not well understood. The objective of the present study was to determine the importance of the genotype on deep dormancy and the stratification-mediated dormancy alleviation in A. tuberculatus . Wild populations differing in seed dormancy were crossed and F 2 families were generated. These families were used to determine narrow sense heritability of dormancy and stratification-mediated dormancy alleviation at the individual ( h i 2 ) and family ( h f 2 ) levels. h i 2 ranged from 0.13 to 0.4 and 0.04 to 0.06 for the dormancy and stratification response, respectively. In the case of h f 2 , the values ranged from 0.76 to 0.91 for deep dormancy and from 0.33 to 0.58 for the stratification response. The genetic correlation between these two traits was below 0.075, indicating that different genes control them. High temperature strengthened the dormancy of deeply dormant seeds, making them less sensitive to stratification. However, high temperature promoted the germination of non-deeply dormant seeds. It is proposed that delayed weed emergence can be generated by selecting genes that control stratification response, and not necessarily only the genes that are directly responsible for deep dormancy.