Vergara - 1976 - Physiological and morphological adaptability of ri

12 (JLLNLXTE AND rues
In saving this. I refer to controlled environments rather than to phyttotrons,
because even small installations with few conditions may help significantly‘.
However. for controlled environments to play’ their optimum role in agricultural
research they must be on a sufficient scale. in terms of the amount and variety of
conditions. so that many plants and many combinations of climatic components
can be handled simultaneously. When this is achieved we have a phytotron and,
as importantly. we may also have brought together not only the requisite range
of physical conditions. but also an interacting community’ of scientists whose
interests encompass a wide range of plants and experimental approaches. One of
the unsung virtues of phytotrons is that. in providing a focal point for work on
the responses of plants to climate. they bring together biologists from many
disciplines. from both field and laboratory in a way that fosters mutual interest
and collaborative experiments.
Research of relevance to agriculture is by no means the only role of phytotrons.
The Earhart Laboratory at Pasadena, to which the term phytotron was
first applied. encompassed a wide array of experiments on the physiology and
ecology of horticultural. agricultural, and wild plants. Research in many of the
later phjvtotrons has been concentrated on specific areas, such as environmental
control of flowering, cold hardiness, ecology of wild plants. and forestry or
horticultural problems. The phytotrons most explicitly concerned with agricultural
problems are those at Wageningen in the Netherlands; at Canberra and
Brisbane in Australia; at Raleigh. North Carolina, USA; at Palmerston North,
New Zealand". and now at Los Bafios in the Philippines. Among these, the
Brisbane phytotron has concentrated on sugar cane just as that at Los Bafios
will concentrate on riee. The problems of tobacco crops have received particular
attention in the Raleigh phytotron. A very wide range of crop plants has been
investigated at Canberra, but there has also been a great deal of work on pasture
plants and on trees with forestry potential. as there is in the Palmerston North
phytotron.
The examples given below are drawn mainly from results urith crop plants
since these are of more direct relevance to the problems facing IRRI. We begin
with a case where phytotron experiments were of crucial importance in clarifiing
the objectives of a plant breeding program. Then we consider examples of how
the effects of covary ing or interacting components ofcliinate have been analyzed,
again with a clarification of plant breeding objectives. Ways in which phfvtotrons
can be used to manipulate plant life cycles, and modify the range of adaptation
in crops are then examined, after which we consider some of the problems of
extrapolation from phytotron to field. and the need for more experiments with
plant communities under controlled conditions.
CLARIFICA TION (‘JF OBJECTIVES
Blue mold disease of tobacco. caused by the fungus Peronospora tabacma, has
long been extremely destructive to Australian tobacco crops in both seedbed and
field. In recent years it has jeopardized tobacco growing in the Mediterranean