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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). Related to the phyllochron is the 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 ..., which is the rate of leaf primordia initiation. Since many more leaf primordia are initiated than leaves develop, the plastochron develops at a much faster rate (sometimes as much as twice as quickly) as the phyllochron. Initially, a young plant will only produce phytomers at its apical meristems but later in development, secondary meristems will begin to form and phytomers will be formed on this lateral plant growth. Notes References * Ho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyllochron
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. The interval between leaf appearances can be recorded in both standard measurements of time 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 fashion. In all cultivars of cereals, fluctuations in temperature 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 variati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meristem
The meristem is a type of tissue found in plants. It consists of undifferentiated cells (meristematic cells) capable of cell division. Cells in the meristem can develop into all the other tissues and organs that occur in plants. These cells continue to divide until a time when they get differentiated and then lose the ability to divide. Differentiated plant cells generally cannot divide or produce cells of a different type. Meristematic cells are undifferentiated or incompletely differentiated. They are totipotent and capable of continued cell division. Division of meristematic cells provides new cells for expansion and differentiation of tissues and the initiation of new organs, providing the basic structure of the plant body. The cells are small, with no or small vacuoles and protoplasm fills the cell completely. The plastids (chloroplasts or chromoplasts), are undifferentiated, but are present in rudimentary form (proplastids). Meristematic cells are packed closely together ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 measuring the age of a plant dependent on morphological traits rather than on chronological age. Use of these indices removes differences caused by germination, developmental differences and exponential growth. Definitions The spatial pattern of the arrangement of leaves is called phyllotaxy whereas the time between successive leaf initiation events is called the plastochron and the rate of emergence from the apical bud is the phyllochron. Plastochron ratio In 1951, F. J. Richards introduced the idea of the plastochron ratio and developed a system of equations to describe mathematically a centric representation using three parameters: plastochron ratio, divergence angle, and the angle of the cone tangential to the apex in the area being ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
