Crop Physiology-3 Point Wise Notes For Competitive exam

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Abscisic acid is used as a cotton defoliant.

Cycocel is used for reducing excessive vegetative growth in cotton.

• Cycocel is used as dwarfing agent in wheat.

NAA increases number of flowers.

• Gibberellins are used for production of seedless grapes.

Gibberellins are used for increasing size of fruits.

S-shaped or sigmoid curve is typical of growth pattern of individual organs, of a whole plant and of population of plants.

• In lag period internal changes occur that are preparatory to growth. Increase in size or weight is negligible.

• In log phase or grand period of growth, growth is very fast. Logarithm of growth when plotted against time is a straight line.

Justus Von Liebig proposed law of minimum in 1862.

Blackman in 1905 propose law of optima and limiting factors.

Mitcherlich’s law of diminishing returns was proposed by Mitcherlich in 1909.

Wilcox proposed inverse yield-nitrogen law in 1929.

• According to inverse yield nitrogen law, yielding ability of any crop plant is inversely proportional to the mean nitrogen content in dry matter.

• Macy-poverty adjustment law was proposed by Macy in 1936.

• Watson developed the concept of leaf area Index (LAI).

Leaf area index = Leaf area Ground area

Yield of dry matter is a function of leaf area, net assimilation rate and duration of leaf area.

• The total drymatter produced by a crop is known as biological yield.

• Fraction of the biological yield which is useful for man is known as economic yield.

• Biological yield × K = Economic yield. K is a constant and called harvest index or coefficient of effectiveness.

Harvest index = Economic yield/Biological yield

• In many cereals, most of the drymatter in the grain is produced by photosynthesis after the ears emerge.

• Most of the dry matter of the grain is produced by the part of the shoot above the flag leaf node.

• Flag leaf contributes nearly 40% of the total dry matter in many cereals.

• In cereals, grain filling is largely dependent on photosynthesis and environmental conditions after flowering.

• In cereal, capacity for storage is determined by conditions before flowering.

• In plants where source and sink are developed simultaneously, like groundnut, redgram, cotton etc., the adjustment of two components may be more readily achieved.

• Economic yield is expressed as function of yield attributes

Y = a × b × c × d

a = final plant population at harvest

b = number of effective tillers (panicle or ear producing)

c = number of filled grains/ear

d = weight of individual grain

• Instead of individual grain weight, 100-grain weight (in case of bold grains) and 1000 grain weight (in case of small sized grains) are taken as yield attribute and this is also known as test weight.

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