CONSTRAINTS ON PLANTS IMPOSED BY CLIM, CONDITIONS
We have to take account of the needs of each species and to recognise a certain balance between temperature and light: a night temperature lower than the day temperature is favourable to growth. A temporary water deficiency can sometimes be favourable to the normal development of a crop.
Also, there always exists a limiting factor which can be difficult to detect. For example, during a period of high photosynthetic activity, carbon dioxide is usually limiting.
For these reasons, we do not know sufficient to be able, in each particular situation, to define precisely what are the ideal conditions. The aim of greenhouses and shelters is to change the climatic conditions in a favourable direction, but the control of growing crops under these conditions remains a delicate affair requiring much study to bring about an improvement.