Agri PDF

Plant hormones Hormones Hormones are non nutrient chemical which act as a intercellular messengers and are produce in trace amounts. Plant hormones are: Auxin Gibberellins Cytokinins Ethylene Abscisic acid Auxin Auxin term is derived from Greek word 'auxein' which means to grow. F.w.went Discovery of auxin   coined the term auxin. Isolated auxin from tips of coleoptiles of oat seedlings. Bioassay of auxin(Avena curvature test) Kogl and Haagensmit First time isolated auxin from human urine. Precursor of auxin is tryptophan. Zn is also necessary for biosynthesis of auxin. Natural auxin Indole-3-acetic acid (IAA) Indole 3butyric acid (IBA) Synthetic auxin Artificially synthesise Example:- naphthalene acetic acid (NAA) 2,4-D(2,4-Dichlorophenoxy acetic acid) IPA(indole propionic acid) Natural and synthetic auxin have been used extensively in agriculture and horticulture practice. Physiological effect and application of auxin. Apical dominance:- Higher plant growing apical bud inhib...