A photoelectric sensor for distinguishing between plant material and soil
1976; Elsevier BV; Volume: 21; Issue: 2 Linguagem: Inglês
10.1016/0021-8634(76)90069-x
ISSN1095-9246
AutoresA.W. Hooper, G.O. Harries, B. Ambler,
Tópico(s)Light effects on plants
ResumoA sensor has been designed which detects the presence of a seedling in a tungsten-halogen light beam scanning over soil. Its operation depends on measuring the ratio of visible to near-infrared reflected radiation, which is less for leaves than for soil, due to absorption of visible red radiation by chlorophyll. Diffuse reflection spectra have been measured for various leaves and soils. These are used to predict and explain the behaviour of the sensor. The effect of varying illumination, particularly due to sunlight, is considered. The sensor may find application as a plant detector for selective thinning machines for row-crops. Trials with sensors fitted to a five-row thinning machine have been carried out in sugar beet, lettuce and cabbage.
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