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The phyllochron is the intervening period between the sequential emergence of leaves on the main stem of a plant, also rendered as leaf appearance−1. This measurement is used by botanists and agronomists to describe the growth and development of plants, especially cereals. The term phyllochron was first described in 1966.[1] The interval between leaf appearances can be recorded in both standard measurements of time as well as thermal time (e.g. growing degree units).[2] One phytomer unit is added over the course of one phyllochron. No significantly robust equation to predict phyllochrons has been developed.[3]


Increases in phyllochron in cereals correlates with growing degree units in a slightly curvilinear fashion.[4] In all cultivars of cereals, fluctuations in temperature are the primary factor that affects the length of the phyllochron.[3] Less important secondary factors emerge in a number of different and sometimes contradictory studies on phyllochron response to variation in light, CO2 level, irrigation, nitrogen availability, salinity, soil properties, planting depth, planting time, and genotype.[3][4] In cereals, the phyllochron may vary in speed between the main stem and the tillers.[4] The phyllochron may or may not be equal to the length of time taken for one leaf to grow.[2] It is more accurate to determine the value in a laboratory study than in the field,[5] as field studies have not always noted the non-linear relationship of temperature and leaf appearance.[3]

See also[edit]


  1. ^ Bunting, A. H.; Drennan, D. S. H. (1965). Milthorpe, F. L.; Ivins, J. D., eds. The growth of cereals and grasses: proceedings of the Twelfth Easter School in Agricultural Science, University of Nottingham. London: Butterworths. pp. 20–38. 
  2. ^ a b Wilhelm, W. W.; McMaster, Gregory S. (Jan–Feb 1995). "Importance of the Phyllochron in Studying Development and Growth in Grasses". Crop Science. 35 (1). 
  3. ^ a b c d McMaster, G S. (20 July 2005). "Phytomers, phyllochrons, phenology and temperate cereal development". The Journal of Agricultural Science. 143 (2–3): 137. doi:10.1017/S0021859605005083. 
  4. ^ a b c McMaster, Gregory S. (1997). Sparks, Donald L., ed. Advances in Agronomy Vol. 59. London: Academic Press. pp. 63–102. ISBN 978-0-12-000759-2. 
  5. ^ Singh, edited by Guriqbal (2010). The Soybean: Botany, Production and Uses. Wallingford, UK: CABI. ISBN 978-1-84593-644-0.