Leaf leachate of Anthemis cotula inhibits seed germination of the commonly cultivated field crops in Kashmir valley. Among the four indices of germination (G T , S, AS, CRG), S (speed of germination) and AS (speed of accumulated germination) are sensitive enough to establish the allelopathic activity of the leaf leachate. Inhibition of seed/grain germination of the field crops showed a species-specific and dose-dependent response with highest inhibition occurring at 5000 ppm concentration. Brassica campestris seeds are most sensitive, whereas those of Vigna radiata are least sensitive. Interestingly, achene germination of A. cotula is promoted by its own leachate at low concentrations and inhibited at high concentrations.

Anthemis cotula is a widespread invasive alien species in Kashmir Himalaya. Being a winter annual, the species reproduces entirely by achenes and synchrony between germination requirements of the species and the habitat conditions must be of critical importance in its invasiveness. To examine how the achenes of different ages respond to different environmental cues, two laboratory experiments were performed wherein effects of different nitrogen applications and growth hormones under continuous light and dark conditions were explored. Results show that the achenes are positively photoblastic and have requirement for after-ripening. Nitrogen applied either as potassium nitrate NO À 3 or as thiourea NH þ 4 significantly improved achene germination both under continuous light and dark conditions. Although kinetin (6-furfurylaminopurine) did not influence achene germination, gibberellic acid (GA 3 ) applied at 1.0 mM concentration had the most significant effect on the final percentage germination under both light and dark conditions. These results suggest that the achenes have an elaborate mechanism of sensing the habitat conditions that helps them to synchronise their germination with favourable environmental conditions -a strategy that aids the species in ensuring recruitment, survival and its spread in Kashmir Himalaya.

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