Dormancy and viability of Phalaris minor seed in a rice–wheat cropping system

Abstract

Summary Seed placement, soil temperature and soil moisture content influenced the process of after‐ripening in Phalaris minor seeds. Seeds of P. minor collected from the soil just after wheat harvesting exhibited higher germination than seeds from P. minor threshed 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 of Phalaris minor seed. 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.

Phalaris minor seedbank studies: longevity, seedling emergence and seed production as affected by tillage regime

“…Therefore, factors other than relative moisture distribution, such as soil physicochemical properties, soil temperature and mechanical or light stimulation breaking seed dormancy during ploughing, may have been involved. Om et al. (2005) and Jimenez‐Hidalgo et al.…”

“…These conditions are considered optimal for P. minor germination (Bhan & Choudary, 1976; Singh & Dhawan, 1976; Okereke et al. , 1981; Mehra & Gill, 1988; Om et al. , 2005).…”

Effect of herbicide resistance on seed physiology of Phalaris minor (littleseed canarygrass)

“…Species of the genus Phalaris require periods of low temperature to break seed dormancy (Om et al, 2005). To determine whether each accession requires different conditions to break dormancy, batches of 100 seeds were stratifi ed at 5 °C for 10, 20, and 30 days.…”

“…two years under fi eld conditions and require a period of cold to break dormancy. Under natural conditions, the seeds reach their highest germination percentage at 70 days after dispersal (Om et al, 2005). However, excess of soil humidity decreases their vigor and longevity, depending on their depth in the soil (Franke et al, 2007).…”

Effects of temperature and pre-germinative treatments on seed germination of Talinum triangulare (Jacq. ) willd (Portulacaceae)

“…Various factors affect the seed dormancy level of wild species. These types of study have been done principally with temperate climate species and have shown that the main stimulants are: light (Om et al, 2003), alternate temperatures (Ikeda et al, 2008;Ferreira e Rosa, 2009) and potassium nitrate (Chauhan et al, 2006).…”