Biology -Important Concepts/Points
Important Points On Plant Hormones
1. The first idea of plant hormones was given by Von Sachs ‘organ forming substance.’
2. Auxin was the first Plant hormone discovered by F.W. Went.
Auxin is important in Tissue culture & Grafting.
It stimulates division of intrafascicular cambium. Also in healing of wounds.
Auxin spray prevents lodging of crops, immature leaves & fruits.
Auxin is inhibitor of flowering but it promotes uniform flowering in Pine apple & Litchi plants.
3- The term hormone was given by Starling & Phytohormone by Thieman.
4- Chemicals which act as natural Phytohormones are called as synthetic growth hormones or Synthetic Auxins
Examples are NAA, 2, 4-D, 2, 4, 5-T, IPA PAA, IBA Maleic hydrazide (MH).
Full Forms –
NAA-Napthalene acetic acid
2-4-D – 2, 4-Dichlorophenoxy acetic acid.
2, 4, 5- T – Trichloro phenoxy acetic add.
IPA – Indole propeonil pyruvic acid
PAA – Phenyl/phenoxy acetic acid·
Important Points-
1-Charles Darwin & F. Darwin (1880) was the first one to study phototropism.
2-F.W. Went (1928): Went isolated the growing tip of Avena sativa on agar plate & perform Agar-block experiment.
It is Went , who has given name ‘auxin’ to growth substance, thus credit of Auxin discovery goes to F.W. Went.
3-The phenomenon in which apical bud dominates over the growth of lateral buds is called Apical Dominance.