ABSTRACT
This chapter provides a discussion of the regulation of shoot/root relationships. When considering shoot/root relationships, one should realize that plants have evolved over many years and that each plant is genetically programmed for a number of alternative developmental patterns. New shoots develop rapidly from the crown buds during the following spring, at the expense of the stored reserves in the large tap roots. Spectral composition of light can alter the shoot/root ratios of developing plants. Knowledge of photoperiodic regulation of shoot/root relationships is important in management of root crops. An important point is that even though the shoots of biennial legume plants seem to stop growth late in the season, root enlargement continues with the decreasing day lengths, until the shoots freeze. The plants grown on nine-hour photoperiods developed only low-growing shoots and large, fleshy tap roots.
