Factors controlling seed dormancy and germination response of Brachypodium hybridum growing in the hot arid mountains of the Arabian Desert

Seed dormancy and germination have been studied in the genetic model Brachypodium species complex in cooler, moist higher latitudes. Studying environmental factors in arid mountains affecting dormancy and germination in Brachypodium complex could determine the factors controlling these processes. This study assesses the impacts of temperature during seed maturation, seed after-ripening, drought, photoperiod, and thermoperiod on final germination and germination rate index of B. hybridum in the Arabian Desert. Seeds were germinated in dark and light and under different ratios of red:far red lights at three diurnal thermoperiods. The final germination percentage was significantly greater at 15/25 °C and 20/30 °C than at 25/35 °C and in light rather than in darkness. Seeds that reached maturity at 15/25 °C attained greater and faster germination than those that reached maturity at 20/30 °C. One-year after-ripening enhanced the final germination percentage and reduced photoperiod requirement. Light quality di...