The effect of micronutrients and gibberellic acid on the germination and metabolism of seedlings ofthemeda triandraforsk

Dormancy of the caryopsis of Themeda triandra Forsk was shown to be broken by the addition oí boron to the germination media. This effect was specific to boron, as no response was observed with zinc, copper, manganese, iron, cobalt and molybdenum in the germinating media. Evidence is put forward suggesting that dormancy is regulated by the stale of the endogenous boron in the caryopsis. It was found to stimulate the synthesis of RNA in the embryo and endosperm tissue, and also α‐amylase activity in both tissues, particularly the endosperm. The transiocation of the sugars from the endosperm to the embryo appears also to be regulated by boron. Gibberellic acid was also found to break dormancy, and to stimulate RNA synthesis and α‐amylase activity in the caryopsis.