Pk. Jensen, EFFECT OF LIGHT ENVIRONMENT DURING SOIL DISTURBANCE ON GERMINATION AND EMERGENCE PATTERN OF WEEDS, Annals of Applied Biology, 127(3), 1995, pp. 561-571
This paper describes results from experiments which investigated the e
ffects of light intensity during soil disturbance on germination and e
mergence pattern of weeds. Different emergence patterns were demonstra
ted for seeds which are instantly flash induced compared to seeds whic
h are induced to germinate by integrating a weak light signal over a p
eriod of time. A reduced and delayed emergence is achieved after a dis
turbance in darkness compared to a soil disturbance in daylight. The i
ncreased emergence after soil disturbance in daylight is due to additi
onal plants originating from seeds placed at a soil depth in the pots
where daylight cannot penetrate and induce seeds to germinate, but whi
ch are induced during the short exposure period. A close relationship
between soil disturbance intensity and number of weed plants emerging
was found in field experiments with shallow harrowings. it was also sh
own that a portion of the increased number of seedlings arising when s
oil disturbance is carried out in daylight, compared to soil cultivati
on in darkness, originates from seeds germinating from deeper soil lay
ers, resulting in a deeper average germination depth.