Germination Ecology of Lathyrus aphaca, a Problematic Weed of Wheat Crop under Semi-Arid Conditions of Pakistan

Abstract

ABSTRACT: Lathyrus aphaca is an aggressive dicotyledonous weed. The effect of different agroecological components/factors on the germination ecology of this weed was explored under a glasshouse and laboratory condition in 2014. The germination response of L. aphaca was lower at high temperature while maximum seed germination was found at 15/12 oC (day/night). Light significantly stimulated L. aphaca germination; nevertheless, substantial germination occurred under dark conditions. More than 86-90% of L. aphaca seeds germinated at pH level of 6.2-7.5. A significant quantity of seed germinated at 250 mM NaCl. There was no germination at -1 MPa. When the temperature was lower than 20/15 oC (day/night) initiation time of germination and germination index (GI) decreased but time to 50% germination (T50) and mean germination time (MGT) increased. Darkness resulted in increased time to start germination, T50, MGT and decreased GI in L. aphaca when compared with the 10 and 12 h photoperiods. The pH of 6 and above 7 enhanced germination time, T50, MGT but decreased GI. Salt stress above 100 mM increased time to germination, T50, MGT but reduced GI. Osmotic potential above -0.4 MPa increased initial germination time, T50 and MGT as well as decreased germination index (GI) of L. aphaca. Increased seed depth in soil lowered germination percentage and GI but enhanced initial germination time, T50, MGT. It was concluded that L. aphaca can grow over a wide range of agroecological/environmental conditions. These results may aid the development of agronomic tools and strategies for weed management in arable crops for yield enhancement.