Redistribution of Mineral Elements During Development

摘要: In the course of a recent address on control growth and reproduc­ tion in plants, Gregory (13) drew attention to fact that over 90 per cent Of nitrogen phosphorus taken up by developing cereal plant had been accumulated when dry weight was only 25 final value. This store nutrient reserve which all later development depended, its level determined yield. The set free from senescent leaves tillers reutilized for production further which, turn, provided inflorescence. also stressed significance meristems with their potentially unlimited demand nutrients, capacity initiate "internal starvation" senes­ cence. These observations serve very well introduce review is follow for, examining evidence redistribution mineral ele­ ments during development, reviewer has attempted relate this wider problems growth. From outset it should be emphasized we are primarily concerned demonstration explanation net losses elements specific parts. To relevant, therefore, papers cover two or more parts at several stages Relatively few many composition plants fulfil these require­ ments. It seems probable some simultaneously enter leave same organ normal metabolic flux, may regarded as being redistributed organs still undergoing intake. Such phenomena not considered here, reason little reference made work radioactive tracers. A borderline case Phillis & Mason (34) who found diurnal variations content leaf cotton plant. six studied showed increases day no change decrease night. Although existence dew complicated picture, does seem likely phloem export responsible even before maximum absolute contents attained. reminder there can hard fast line between resulting activity within conditioned changes demands arise externally organ.