Relation between pattern of development of wheat seedlings and growth rate of leaves, tillers and roots

Relation between pattern of development of wheat seedlings (Triticum aestivum L. Fiori et Paol.) and growth rate of leaves, tillers and roots. In two glasshouse and two phytotron experiments, the early growth and development of spring wheat and unvernalized autumn wheat in long and short days was observed by frequent assessments of dry weight of shoots and roots and by daily measurements of length and dry weight of individual leaves. In an additional experiment, the pattern of dry matter distribution during germination was studied. The rate of leaf emergence and appearance was decelerated by short days in spring wheat and by long days in unvernalized autumn wheat. The growth rate of individual leaves showed a pattern of successive reductions and accelerations, being highly synchronized between leaves and clearly related to the succession in emergence of leaves and tillers. Growth rates of main shoot and tillers were apparently synchronized, while those of the seminal root system appeared to show an oppositional pattern as compared to the shoot. It is suggested that variation in the growth rare of existing organs is based on hormone controlled variation in meristematic activity, which is influenced by day length and the state of vernalization of the plant.