youtor.org
Plant Hormone class 10 plant hormone in bengalipgr life sciencewbcsauxingibberellinscytokinin
#############################
Video Source: www.youtube.com/watch?v=BsEY94TRgBk
Plant Hormone class 10. plant hormone in bengali/pgr/ life science/wbcs/auxin/gibberellins/cytokinin .It is for the student of west bengal reading in class 10. #lifescience #wbbselifescience #wbbselifescienceclass10chapter 3 • #class10lifescience #malda biology #wbbselifesciencechapter3 #lifescienceinbdngali #wbbsescienceforclass10#1st chapter 3lifescienceclass10 . • উদ্ভিদের বিভিন্ন হরমোন তার প্রকৃতি তার কাজ এবং কৃষি ক্ষেত্রে হরমোন গুলির ভূমিকা এখানে আলোচনা করা হলো I • Charles Darwin and his son Francis Darwin when they observed that the coleoptiles of canary grass responded to unilateral illumination by growing towards the light source (phototropism). Aftera series of experiments, it was concluded that the tip of coleoptile was the site of transmittable influence that caused the bending of the entire coleoptile (Figure 15.10). Auxin was isolated by F.W. Went from tips of coleoptiles of oat • seedlings. Auxins (from Greek ‘auxein’ : to grow) was first isolated from human urine. • The term ‘auxin’ is applied to the indole-3-acetic acid (IAA), and to other • natural and synthetic compounds having certain growth regulating • properties. They are generally produced by the growing apices of the stems • and roots, from where they migrate to the regions of their action. Auxins • like IAA and indole butyric acid (IBA) have been isolated from plants. • NAA (naphthalene acetic acid) and 2, 4-D (2, 4-dichlorophenoxyacetic) • are synthetic auxins. All these auxins have been used extensively in • agricultural and horticultural practices. • They help to initiate rooting in stem cuttings, an application widely • used for plant propagation. Auxins promote flowering e.g. in pineapples. • They help to prevent fruit and leaf drop at early stages but promote the • abscission of older mature leaves and fruits. • In most higher plants, the growing apical bud inhibits the growth of • the lateral (axillary) buds, a phenomenon called apical dominance. • Removal of shoot tips (decapitation) usually results in the growth of lateral • buds Auxins also induce parthenocarpy, e.g., in tomatoes. They are widely used as herbicides. 2, 4-D, widely used to kill dicotyledonous • weeds, does not affect mature monocotyledonous plants. It is used to prepare • weed-free lawns by gardeners. Auxin also controls xylem differentiation and helps in cell division. • The ‘bakane’ (foolish seedling) disease of rice seedlings, was caused • by a fungal pathogen Gibberella fujikuroi. E. Kurosawa reported the • appearance of symptoms of the disease in uninfected rice seedlings when • they were treated with sterile filtrates of the fungus. The active substances • were later identified as gibberellic acid. • Gibberellins are another kind of promotery PGR. There are more than 100 gibberellins reported from widely different organisms such as fungi and higher plants. They are denoted as GA1 GA2 GA3 and so on. However Gibberellic acid (GA3 ) was one of the first gibberellins to be discovered and remains the most intensively studied form. All GAs are acidic. They produce a wide range of • physiological responses in the plants. Their ability to cause an increase • in length of axis is used to increase the length of grapes stalks. Gibberellins, • cause fruits like apple to elongate and improve its shape. They also delay • senescence. Thus, the fruits can be left on the tree longer so as to extend • the market period. GA3 is used to speed up the malting process in brewing • industry. • csugarcanet ores carbohydrate as sugar in their stems. Spraying • sugarcane crop with gibberellins increases the length of the stem, thus • increasing the yield by as much as 20 tonnes per acre. • Spraying juvenile conifers with GAs hastens the maturity period, thus • leading to early seed production. Gibberellins also promotes bolting • (internode elongation just prior to flowering) in beet, cabbages and many • plants with rosette habit.
#############################
