Dormancy and viability ofPhalaris minorseed in a rice–wheat cropping system.

OmH, KumarS&DhimanSD (2005) Dormancy and viability ofPhalaris minorseed in a rice–wheat cropping system.Weed Research45, 140–148.Seed placement, soil temperature and soil moisture content influenced the process of after-ripening inPhalaris minorseeds. Seeds ofP. minorcollected from the soil just after wheat harvesting exhibited higher germination than seeds fromP. minorthreshed directly. There was a pronounced impact of periodic inhabitation of seed into the soil on germination after its dispersal. Germination was strongly inhibited when the seed was kept in soil at more than field capacity (FC) or in water. Maximum germination of seed incubated in soil at FC occurred at 30°C while a temperature of 40°C favoured after-ripening of seed when mixed with dry soil or kept dry without any medium. Release from conditional dormancy was quicker in the seed retrieved from the soil kept at 20°C than at 10°C. Seed release from conditional dormancy and germination increased with a rise in temperature from 30 to 40°C when the seed was retrieved from incubation in soil at FC for 70 days. The seed kept immersed in water was least responsive to a rise in temperature. Seed recovered from dry soil, or kept without any medium, responded quickly at both temperatures. Light enhanced the germination ofPhalaris minorseed. The seedbank subjected to rice (Oryza sativa) field management conditions lost vigour in comparison with the seed stored in laboratory. There was significant variability in seed viability when exposed to differential water management conditions in rice. [ABSTRACT FROM AUTHOR]