Roger G.S. (Tony) Bidwell, Ph.D

Tony joins us from Nova Scotia. He obtained his B.Sc. at Dalhousie University and his Masters and Ph.D. at Queens University where he is currently a Professor Emeritus. Tony spent many years in the academic field before joining the Atlantic Institute of Biotechnology as Executive Director. Until his retirement, Tony was the Director and Senior Partner with Atlantic Research Associates.

Tony was elected Fellow of the Royal Society of Canada, 1973, and Fellow of the American Association for the Advancement of Science, 1987. In 1977, he was awarded the Queen Elizabeth II Silver Jubilee Medal and received the Gold Medal of the Canadian Society of Plant Physiologists in 1979. Tony has attended numerous guest lectureships, scientific visits, visiting professorships, and has written over 140 scientific papers and six books, including Plant Physiology and three volumes of a Treatise on Plant Physiology. Tony’s research included plant metabolism, biochemistry, photosynthesis, nitrogen biochemistry, ecophysiology, and reaction of plants to environmental stress.

Tony is now retired and living on an old farm, growing apples (cider!) and new and unusual varieties of food plants (practical plant physiology). His hobbies include bicycling, camping, skiing, music and traveling.

Scotobiology of Plants

Plants do not normally react strongly to the simple experience of darkness. However, autotrophic plants depend on light for their food, so darkness (the absence of light) influences their growth, and prolonged darkness is deadly. Certain unicellular algae (both marine and soil) avoid this problem in an interesting way. In light, they photosynthesize normally and make all the carbon compounds they need. But in darkness, they rapidly develop a powerful transport system that pumps external organic carbon compounds (particularly sugars) into their cells, providing an alternative source of energy and metabolites. The transport system is lost and photosynthesis begins when the light is turned on, and the rate of photosynthesis and transport may vary inversely with the light intensity. This mechanism provides a strong competitive advantage for these organisms.

The periodicity and duration of light and darkness is powerfully important in the development of many plants. The measurement by plants of light/dark periodicity enables them to fit their growth patterns to the seasons, and the duration of periodic darkness is critical for the onset of flowering in many higher plants. Thus, relatively strong light pollution during the night (as from street or flood lights) may seriously disturb the normal growth, development, flowering and senescence patterns of sensitive plants.

Darkness is properly described as the absence (or near absence) of light. The absolute level of darkness (really the absolute level of dim light) may be important in the behaviour of plants. The moon’s effect on plant growth and development is the subject of much popular speculation, and there is some suggestion that moonlight may affect the development and nutritional status of certain plants. This type of response would require appropriate pigments as well as signaling systems to couple them to response mechanisms, and these might be affected by light pollution of the night. But the effects, whether beneficial or damaging, are probably quite small.

There is evidence that certain plants are specifically capable of detecting dark objects or places (i.e. areas or locations of low or reduced light) and reacting to them. Scototropic behaviour of a tropical vine has been reported, in which the seedling vines grow toward dark objects. This is an adaptive characteristic that enables young vines to grow towards the trunk of a large tree, which is darker than the surrounding terrain. When the vine reaches the tree trunk, it looses its sco-totropism and becomes phototropic, growing (usually upward) towards the light like other plants. However, this behaviour, though interesting, would not be affected by light pollution.

It is frequently stated that the shoots of young seedlings, after germination in the soil, grow upwards in order to reach the light, and the roots grow downwards to stay in darkness. This is wholly incorrect; shoots grow upwards because they are negatively geotropic, an adaptive char-acteristic that does indeed ensure that they will reach the light, and roots are positively geotropic and grow down, with the result that they stay in the ground. Shoots do not seek light, and roots do not seek dark or avoid light. This aspect of plant behaviour is unrelated to light or its absence.

In general, plants are not usually much affected by the absence of absolute darkness at night, that is, by light pollution. Bright illumination at night may affect the flowering of sensitive plants, and other aspects of growth and development behaviour, including maturation and senility, may be affected. But lower levels of light pollution, which might affect animal behaviour or astronomical observation, seldom affect plants in any significant way. Plants cannot be likened to the canaries in coal mines as indicators of excessive levels of pollution.

Scotobiology Of Plants (pdf) - Tony Bidwell
 

SPEAKERS

Bidwell, Tony
Buchanan, Bryant
Crawford, Dr. David L.
Dick, Robert Stephen
Dickinson, Terence
French, Randy P.
Hill, Tom
Hills, Reverend Johanne
Hollan, Jenik
Hummel, Monte
Lickers, F. Henry
Lockley, Steven W.
Mesure, Michael
Moore, Chad A.
Reid, Ron
Riley, John L.
Roberts, Dr. Joan
Rutenberg, Tony
Shaver, Dorothy
Welch, David
Whitehead, Brian
Wise, Sharon