How to calculate leaf plastochron index?
P. I. = Plastochron Index; n = it is the serial number of that leaf, which is 10 mm or just exceeds 10 mm length (counted from the base of the shoot); n + 1 = it is the succeeding leaf with a length that is less than 10 mm; Ln = length of n leaf; log 10 = it is the predetermined reference value of leaf length.
How do you determine a leaf’s age?
We propose a new method, the leaf measuring-interval index (LMI), to estimate leaf age in morphological and physiological studies of leaves. When the plastochron, the interval between the initiation of successive leaves, is constant, the well-known leaf plastochron index (LPI) provides a robust measure of leaf age.
What is plastochron botany?
A plastochron is defined as the time interval between two successive recurring events during the growth of plant shoots, such as leaf initiation.
Why are stomata located under the leaf?
The stomata must be open during the daylight hours to let oxygen and carbon dioxide pass through. While they are open, water vapor escapes into the atmosphere (transpiration). Transpiration is the loss of water through stomata, so, more stomata are found on the lower surface to prevent excessive loss of water.
What are leaf primordia?
Leaf primordia are groups of cells that will form into new leaves. These new leaves form near the top of the shoot and resemble knobby outgrowths or inverted cones.
What is a leaf edge?
The edge of the leaf is called the margin. Parts of a leaf: A leaf may seem simple in appearance, but it is a highly-efficient structure. Petioles, stipules, veins, and a midrib are all essential structures of a leaf. Within each leaf, the vascular tissue forms veins.
Who introduced the idea of plastochron ratio?
F. J. Richards
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 considered.
What is plastochron periodicity?
The periodic initiation of lateral organs by the SAM defines a developmental unit known as a plastochron, which gives the shoot time to extend before the next organ is initiated. Shoots are thus composed of nodes and internodes, the nodes bearing the lateral organs (usually leaves).
Why are guard cells on the bottom of leaves?
Stomata are typically found in plant leaves but can also be found in some stems. Specialized cells known as guard cells surround stomata and function to open and close stomatal pores. The majority of stomata are located on the underside of plant leaves reducing their exposure to heat and air current.
On which surface of leaves are stomata present?
epidermis
Stomata are cell structures in the epidermis of tree leaves and needles that are involved in the exchange of carbon dioxide and water between plants and the atmosphere.
What do bud primordia become?
Primordium Initiation Primordia initiation is the precursor for the start of a primordium, and typically confers new growth (either flowers or leaves) in plants once fully mature. In pines, the leaf primordia develop into buds, which eventually elongate into shoots, then stems, then branches.
How to determine the plastochron index of a plant?
The developmental index is the plastochron age of a shoot. Plastochron Index (P. I.) can also be defined as a measure of plant growth and is used to determine the rate of growth based upon the initiation of successive leaf primordia.
Why was the plastochron index introduced in 1957?
The plastochron index (PI) introduced by Erickson and Michelini in 1957 provides a solution to a long-standing problem, of how to measure time in growing plant populations, such that the occurrence of critical developmental events can be more readily detected, compared, and analyzed, than if chronologic time is used.
How to calculate viscosity index from 40 to 100°C?
ASTM D2270 / Viscosity Index (VI) from 40°C and 100°C Standard practice for calculating viscosity index from kinematic viscosity at 40 and 100°C Calculator for viscosity index (VI) according to ASTM D2270 and ISO 2909.
Who was the first person to use the term plastochron?
Askenasy coined the term plastochron to refer to the time that elapsed between initiation of two successive internode cells of Nitella.
