Germination and decreased growth of Kochia scoparia in relation to its autoallelopathy

Abstract

The autotoxic properties of Kochia scoparia phytotoxins on its germination and on radicle and seedling growth were studied. Inhibition of seed germination, a commonly known allelopathic phenomenon, did not occur and seeds reached close to 100% germination within 24 h when tested against different phytotoxins isolated from Kochia leaves regardless of the concentrations applied. Similarly, the radicle length of Kochia seeds measured was not significantly affected. However, when radicles were allowed to grow for an extended period of time in various concentrations of isolated phytotoxins, their length was significantly reduced in almost all cases. Such autotoxic growth retardation patterns were more pronounced in 10-day-old seedlings. It appears that Kochia phytotoxins do not inhibit germination but retard growth later, which also supports the high density but drastically reduced growth of Kochia in its 2nd year of revegetation in the field. The autotoxins isolated and identified from Kochia leaves were phenolics and flavanoids.