Effect of the burial depth and environmental factors on the seasonal germination of bearded sprangletop (Leptochloa fusca [L.] Kunth ssp fascicularis [Lam.] N. Snow)

Abstract

Bearded sprangletop recently was introduced to Turkey, where it has adapted to rice cultivation and become an important weed in many regions of the country. Experiments were conducted to determine the effects of light, temperature, osmotic stress, salt stress, pH and flooding on bearded sprangletop germination and emergence. Mature bearded sprangletop seeds were collected from rice fields in August 2008. Approximately 1250 seeds were wrapped in plastic fabric and buried at 2 or 10cm in pots in flooded or non-flooded conditions. In this experiment, seed germination in the light from the flooded and non-flooded treatments began in the spring, peaked in summer and decreased in the fall. This pattern was repeated the following year after exposing the seeds to natural seasonal temperature changes. As either the level of water stress or NaCl concentration increased, cumulative seed germination decreased. No seed germinated when the NaCl concentration exceeded 400mole. The level of seedling emergence decreased with an increasing burial depth. Under the flooded conditions, emergence began in late April and continued until early July, with peak emergence in the first week of June. Under the non-flooded conditions, bearded sprangletop emerged later than under the flooded conditions and the overall level of emergence was lower. The depth of burial and water stress appear to be the most important factors that limit seed germination. Germination was stimulated by light, suggesting that the seeds are positively photoblastic.