Role of ethylene in germination and seedling growth of littleseed canarygrass (Phalaris minor Retz.)

Abstract

Littleseed canarygrass is a major weed of wheat in rice–wheat cropping system of North-West India. The present study was conducted to study the role of ethylene in germination ecology and seedling growth of littleseed canarygrass and wheat using cobalt chloride (inhibitor of ethylene synthesis) and ethephon (ethylene source). Cobalt chloride at concentrations ≥0.1 mM caused significant reduction in germination (%), germination index and increased the mean germination time of littleseed canarygrass, whereas wheat seeds exhibited significant decrease in germination (%) at cobalt chloride concentrations ≥0.5 mM. Cobalt chloride at higher concentrations significantly reduced the seedling growth of littleseed canarygrass and wheat with more pronounced effect on root length as compared to shoot length. It also significantly increased the membrane leakage and soluble sugar content of seedlings of both species with concomitant decrease in chlorophyll and protein content. Ethephon at 0.1 and 1 mM concentrations significantly increased the germination (%), speed of germination with concomitant decrease in mean germination time as compared to control. Ethephon concentrations 0.1 and 1 mM had no effect on membrane leakage, total soluble sugars and protein content but increased the chlorophyll content in seedlings of both species. Seed dormancy of littleseed canarygrass induced by higher concentrations of cobalt chloride, i.e., 2.5 and 5 mM could also be overcome by treatment with 1 mM ethephon, confirming the role of ethylene in germination of this weed.