The phyllochron is the intervening period between the sequential emergence of
leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
on the main
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
of a
plant
Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...
, also rendered as ''leaf appearance
−1''. This measurement is used by
botanists
This is a list of botanists who have Wikipedia articles, in alphabetical order by surname. The List of botanists by author abbreviation is mostly a list of plant taxonomists because an author receives a standard abbreviation only when that auth ...
and
agronomists
An agriculturist, agriculturalist, agrologist, or agronomist (abbreviated as agr.), is a professional in the science, practice, and management of agriculture and agribusiness. It is a regulated profession in Canada, India, the Philippines, the U ...
to describe the growth and
development of plants, especially
cereals
A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food en ...
. The term phyllochron was first described in 1966.
The interval between leaf appearances can be recorded in both standard measurements of
time
Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to ...
as well as thermal time (e.g.
growing degree units).
One
phytomer unit is added over the course of one phyllochron. No significantly robust equation to predict phyllochrons has been developed.
Variation
Increases in phyllochron in cereals correlates with growing degree units in a slightly
curvilinear
In geometry, curvilinear coordinates are a coordinate system for Euclidean space in which the coordinate lines may be curved. These coordinates may be derived from a set of Cartesian coordinates by using a transformation that is invertible, l ...
fashion.
In all cultivars of cereals, fluctuations in
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
are the primary factor that affects the length of the phyllochron.
Less important secondary factors emerge in a number of different and sometimes contradictory studies on phyllochron response to variation in
light
Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...
,
CO2 level,
irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
,
nitrogen
Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...
availability,
salinity
Salinity () is the saltiness or amount of salt dissolved in a body of water, called saline water (see also soil salinity). It is usually measured in g/L or g/kg (grams of salt per liter/kilogram of water; the latter is dimensionless and equal ...
,
soil properties, planting depth, planting time, and
genotype
The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...
.
In
cereals
A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food en ...
, the phyllochron may vary in speed between the main stem and the
tillers.
The phyllochron may or may not be equal to the length of time taken for one leaf to grow.
It is more accurate to determine the value in a laboratory study than in the field,
[ as field studies have not always noted the non-linear relationship of temperature and leaf appearance.]
See also
*Phenology
Phenology is the study of periodic events in biological life cycles and how these are influenced by seasonality, seasonal and interannual variations in climate, as well as environmental factor, habitat factors (such as elevation).
Examples includ ...
*Phytomer Phytomers are functional units of a plant, continually produced by root and shoot meristems throughout a plant's vegetative life-cycle.. Increases in a phytomer can be measured using the rate of phyllochron (rate of appearance of leaves on a shoot) ...
*Plant development Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant a ...
*Plastochron As the tip of a plant shoot grows, new leaves are produced at regular time intervals if temperature is held constant. This time interval is termed the plastochron (or plastochrone). The plastochrone index and the leaf plastochron index are ways of ...
References
{{Reflist, 2, refs=
[{{cite journal, last=Wilhelm, first=W. W., author2=McMaster, Gregory S., title=Importance of the Phyllochron in Studying Development and Growth in Grasses, journal=Crop Science, date=Jan–Feb 1995, volume=35, issue=1, doi=10.2135/cropsci1995.0011183x003500010001x]
[{{cite book, editor-last=Singh, editor-first=Guriqbal, title=The Soybean: Botany, Production and Uses, year=2010, publisher=CABI, location=Wallingford, UK, isbn=978-1-84593-644-0]
[{{cite book, last=McMaster, first=Gregory S., title=Advances in Agronomy Vol. 59, year=1997, publisher=Academic Press, location=London, isbn=978-0-12-000759-2, pages=63–102, authorlink=Phenology, Development, and Growth of the Wheat (Triticum aestivum) Shoot Apex: A Review, editor=Sparks, Donald L.]
[{{cite journal, last=McMaster, first=G S., title=Phytomers, phyllochrons, phenology and temperate cereal development, journal=The Journal of Agricultural Science, date=20 July 2005, volume=143, issue=2–3, pages=137, doi=10.1017/S0021859605005083]
[{{cite book, title=The growth of cereals and grasses: proceedings of the Twelfth Easter School in Agricultural Science, University of Nottingham, year=1965, publisher=Butterworths, location=London, pages=20–38, author=Bunting, A. H., authorlink=Some aspects of the morphology and physiology of cereal in the vegetative phase, author2=Drennan, D. S. H., editor=Milthorpe, F. L. , editor2=Ivins, J. D.]
Plant anatomy
Plant morphology