Abstract:Under the conditions of ample water and nutrients, production of an excess root system may reduce the growth of shoots because of the competition of carbohydrates between roots and shoots. Roots are the major sink for assimilates, requiring twice as much assimilate to produce per unit dry matter as the shoots. Passioura( 1983) doubted that the root system of many crop plants may be excessive; and suggested that smaller root system may be beneficial for assimilate to be transferred to shoots. Based on the a...