- The term mutation was first used by Hugo de Vries (1901) who observed it in Oenothera lamarckiana.
- In 1953, S. James Watson and F.H.Crickproposed a model of double helix structure of DNA molecule for which they were awarded noble prize.
- The term gene was coined by W. Johannsen in 1909.
- In 1933, Morgan discovered hereditary functions of chromosomes.
- The term “CELL” was coined by Robert Hooke (1665).
- Schleidenand Theodor Schwann propounded the cell theory in 1839.
- Auxins were discovered by Went in 1928.
- The growth in length of plants can be measured by an instrument called Lever or Arc Auxanometer.
- The cytokinins are plant hormones which act primarily on cell division. It was first isolated by Miller and his coworkers in USA.
- The discovery of gibberellins was made by a Japanese plant pathologist Kurusowa.
- Pasteur (1860) discovered that yeast could respire in the absence of molecular oxygen.
- Dark reaction was discovered by Melvin Calvin.
- Mohl’s Half Leaf Experiment proves that carbon di oxide is essential for photosynthesis.
Symptoms of Mineral deficiency in plants:
Deficiency symptoms are external manifestations of the deficiency of mineral elements in plants. The deficiency can be related to absence of a particular nutrient in the soil or non availability of the nutrient to the plant due to various reasons. Some of the common deficiency symptoms observed in plants are:
- Chlorosis – Loss of chlorophyll leading to yellowing of leaves.
- Mottling – Appearance of patches of green and non-green areas on the leaves.
- Wilting – Drooping of the leaves due to loss of conduction of water.
- Necrosis – Death of tissues in certain parts.
- Stunted growth – Plants with shortened internodes and smaller in size.