Low temperature and the growth of plants

The growth responses of plants at low temperature are discussed, with particular reference to the reversible effects of low positive temperatures upon the growth of obligately chilling-resistant species. Techniques for the measurement of growth and the control of meristem temperature are described, and evidence concerning the sites of temperature perception and transduction in the developing monocot leaf is reviewed. The rapidity and reversibility of such responses, and their apparent independence of changes in carbon supply or meristem cell turgor are held to support the hypothesis that chilling alters the physical properties of the walls of extending cells within the meristematic zone. The existence of marked genetic variability in these responses facilitates agricultural exploitation of low-temperature growth. The effects of longer-term chilling upon growth, cell extension and cell division are described, with particular reference to interactions with other environmental variables and with developmental factors which can alter the nature of the temperature response. The relationship between growth reduction and the development of freezing tolerance during chilling is discussed in relation to programmes of crop improvement which will maximize productivity at low temperatures without adversely affecting survival.