Dormancy of weed seeds is a significant feature contributing to their survival rate since it helps the weeds to avoid
herbicides and other weeding practices along with unfavorable environmental conditions. We investigated the effects of
different dormancy breaking treatments on the germination of
Rhynchosia capitata
, a common summer annual weed, which
is emerging as a weed threat in Pakistan. Seeds were soaked in thiourea, KNO
3, HCl, HNO
3, and H
2SO
4, and they were
also mechanically scarified (sandpaper). Results indicated that
R. capitata seeds show signs of physical dormancy that is
mainly due to the impermeability of their coat. Mechanical scarification and acid scarification (soaking of seeds in H
2SO
4
for 60 and 80 min and in HCl for 12 and 15 h) were very efficient in breaking dormancy and promoting germination. Seed
soaking in HNO
3 for 1 to 5 d showed little effect whereas various concentrations of thiourea and KNO
3 were ineffective in
breaking
R. capitata seed dormancy.