Commercial Application of Plant growth regulators pptx

Plant biochemistry and physiology

1. Plant Growth Regulators and their use in Agriculture

2. Auxin is a major regulator of cell growth, elongation of the plant, formation of roots, and fruit and flower development. Gibberellins are capable of breaking seed dormancy, postponing senescence, promoting bolting, triggering stem elongation, and causing early seed production. Cytokinins promote cell division in the plant root and shoot system and delay the senescence of leaves. Abscisic acid inhibits plant growth and maximises its chances of surviving drought. It also signals the stomata to close, retain water, and inhibit seed germination. Ethylene is considered to be a multifunctional plant growth hormone because it regulates both growth and senescence in plants. It is also used to rapidly ripen fruits. Brassinosteroids are a class of steroidal phytohormones in plants that regulate numerous physiological processes. They control cell elongation and division, gravitropism, resistance to stress, and xylem differentiation. They inhibit root growth and leaf abscission.  PGRs involved in various growth and physiological processes

3. Increase plant growth and yield PGRs trigger the growth of plants by increasing metabolic enzyme activities and the uptake of nutrients by roots. They also enhance photosynthesis to achieve robust growth. They improve the quality and quantity of crops. Enhancing fruit quality PGRs can greatly enhance the size, colour, taste, and quality of fruit. While abscisic acid can improve the fruit's colour and flavour, gibberellins can increase its size. Farmers can use plant growth regulators to produce fruits that are not only larger and more enticing to consumers but also taste better. A sustainable agricultural alternative Plant growth regulators (PGRs) reduce the need for synthetic agrochemicals, fertilisers, pesticides, and water, allowing farmers to implement sustainable agricultural practices like precision farming. It also enables crops to grow effectively with less irrigation. General applications of PGRs in Agriculture

4. Maximise shelf life and post-harvest quality PGRs like ethylene are capable of regulating the ripening process. With the help of PGRs, farmers can delay or speed up the ripening process, allowing them to harvest crops at the perfect time and increase their shelf life. Disadvantages of PGRs PGRs have some disadvantages despite being essential to the adoption of progressive and sustainable farming practices. PGR residues have the potential to pollute the environment and cause food poisoning. To increase agricultural productivity and lessen its negative effects on the environment and human health, the use of plant growth regulators in agricultural production should be routinely monitored and regulated.

5. Auxins Auxins were the first class of growth regulators discovered. A Dutch Biologist Frits Warmolt Went first described auxins.  They are compounds that positively influence cell enlargement, bud formation, and root initiation. They also promote the production of other hormones and, in conjunction with cytokinins , control the growth of stems, roots, and fruits, and convert stems into flowers.  They affect cell elongation by altering cell wall plasticity. They stimulate cambium, a subtype of meristem cells, to divide, and in stems cause secondary xylem to differentiate.

6. Auxin Type Growth Regulators Important Role of Auxin: Induces cell division and cell growth Improves synthesis and translocation of photosynthates Induces root initiation Breaks dormancy of seeds and buds Induces flowering and fruit growth Cotton Foliar spray of 40 ppm NAA (20g/500 lit. of water/ha) at 90, 105 and 120 DAS reduces flowers, buds and squares dropping and increases yield. Pulses Foliar spraying 40 ppm NAA increases flower production, reduce flower drop and increases seed yield. Chillies Foliar spray of 100 ppm NAA at 25 DAT – to reduce the flower drop and increases fruit set and yield. Potato Foliar spray of NAA 100 ppm at 25 DAT – to increase tuber yield. Horticultur al Crops For induction of rooting in cuttings. Dip cuttings in 1000 ppm IBA and then plant.

7. Gibberellins Gibberellins (GAs) include a large range of chemicals that are produced naturally within plants and by fungi. They were first discovered when Japanese researchers, including Eiichi Kurosawa, noticed a chemical produced by a fungus called  Gibberella fujikuroi   that produced abnormal growth in rice plants.  It was later discovered that GAs are also produced by the plants themselves and control multiple aspects of development across the life cycle. The synthesis of GA is strongly upregulated in seeds at germination and its presence is required for germination to occur. In seedlings and adults, GAs strongly promote cell elongation. GAs also promote the transition between vegetative and reproductive growth and are also required for pollen function during fertilization.

8. Role of Gibberellic acid as PGR Roles of Gibberellic acid Prevents genetic and physiological dwarfism Breaks seed and bud dormancy Induces flowering and seed germination Induces Parthenocarpy in fruits and vegetables Applications Rice Foliar spray of GA 3 at 100 ppm during panicle initiation stage enhances the panicle exertion and increases seed weight and yield in hybrid rice. Sunflower Foliar spray of GA 3 at 200 ppm at 45 DAS increases the seed number, seed weight and yield. Grapes Foliar spray 25-50 ppm of GA 3 in grapes just before flowering and during fruiting enhances the fruit size, sugar content and yield. Chrysanthemum Spraying GA 3 at 50-150 ppm increases the number of flowers, yield and enhances the shelf life.

9. Abscisic acid Abscisic acid (also called ABA) is one of the most important plant growth inhibitors. It was discovered and researched under two different names,  dormin  and  abscicin II , before its chemical properties were fully known. Once it was determined that the two compounds are the same, it was named abscisic acid. The name refers to the fact that it is found in high concentrations in newly  abscissed  or freshly fallen leaves.

10. Cytokinins Cytokinins  (CKs) are a group of chemicals that influence cell division and shoot formation. They also help delay senescence of tissues, are responsible for mediating auxin transport throughout the plant, and affect internodal length and leaf growth. They were called kinins in the past when they were first isolated from yeast cells. Cytokinins and auxins often work together, and the ratios of these two groups of plant hormones affect most major growth periods during a plant's lifetime. Cytokinins counter the apical dominance induced by auxins; in conjunction with ethylene, they promote abscission of leaves, flower parts, and fruits.

11. Ethylene Unlike the other major plant hormones, ethylene is a gas and a very simple organic compound, consisting of just six atoms. It forms through the breakdown of methionine, an amino acid which is in all cells. Ethylene has very limited solubility in water and therefore does not accumulate within the cell, typically diffusing out of the cell and escaping the plant. Its effectiveness as a plant hormone is dependent on its rate of production versus its rate of escaping into the atmosphere. Ethylene is produced at a faster rate in rapidly growing and dividing cells, especially in darkness. New growth and newly germinated seedlings produce more ethylene than can escape the plant, which leads to elevated amounts of ethylene, inhibiting leaf expansion (see hyponastic response).

12. Ethrel – Plant Growth Regulator Physiological roles Induces auxin production Induces flowering Activates enzymes in respiration Induces resistance to frost and diseases Accelerates seed germination and lates flow Induces branching Crops Doses Time of Application Uses Grapes 80 ppm Tenth day after flowering Seedless fruits, increases fruit weight, size and colour Cucumber Snake gourd Bitter gourd Ribbed gourd Pumpkin 300 ppm At peak vegetative stage Increases male and female flowers Banana 40 ppm At peak vegetative stage Induces flowering Mango 1000 ppm At the time of fruit maturity Induces ripening Jatropha 100 ppm (2 times) At flower initiation stage and pod filling stage Induces ripening Induces flowering, pod setting and seed yield

13. Brassinosteroids Brassinosteroids  (BRs) are a class of polyhydroxysteroids , the only example of steroid-based hormones in plants. Brassinolide  was the first brassinosteroid to be identified and was isolated from extracts of rapeseed ( Brassica napus ) pollen in 1979.  This plant hormone was identified by Mitchell et al , who extracted ingredients from Brassica pollens only to find that in the extracted ‘ingredients’ main active component was  Brassinolide . This finding meant the discovery of a new class of plant hormones called Brassinosteroids . These hormones act very similarly to animal steroidal hormones by promoting growth and development.

14. Brassinolides (BR) Plant Growth Regulators Roles of BR Increases growth and uptake of nutrients Imparts resistance to drought, salinity and heat Increases flowering, fruit set and yield Application in crops Rice Foliar spray of 0.3 ppm BR at panicle initiation and flowering stages increase grain yield. Groundnut Foliar spray of 0.5 ppm BR on 40 DAS increases pod yield. Cotton Foliar spray of 0.5 ppm BR at flowering stage increases cotton ‘ kapas ’ yield.

15. Jasmonates Jasmonates  (JAs) are lipid-based hormones that were originally isolated from jasmine oil.  JAs are especially important in the plant response to attack from herbivores and necrotrophic pathogens.  The most active JA in plants is  jasmonic acid. Jasmonic acid can be further metabolized into methyl jasmonate  ( MeJA ), which is a volatile organic compound. This unusual property means that MeJA can act as an airborne signal to communicate herbivore attack to other distant leaves within one plant and even as a signal to neighboring plants.  In addition to their role in defense, JAs are also believed to play roles in seed germination, the storage of protein in seeds, and root growth.

16. Salicylic acid Salicylic acid (SA) is a hormone with a structure related to benzoic acid and phenol. It was originally isolated from an extract of white willow bark ( Salix alba ) and is of great interest to human medicine, as it is the precursor of the painkiller aspirin. In plants, SA plays a critical role in the defense against biotrophic pathogens. In a similar manner to JA, SA can also become methylated. Like MeJA , methyl salicylate is volatile and can act as a long-distance signal to neighboring plants to warn of pathogen attack. In addition to its role in defense, SA is also involved in the response of plants to abiotic stress, particularly from drought, extreme temperatures, heavy metals, and osmotic stress.

17. Salicylic acid can increase yield in pulses and oilseeds Physiological Role of Salicylic Acid Acts as a growth hormone Maintains water balance Acts as a chelate for Phosphorus uptake Improves flowering and pod yield Induces resistance to pest and disease Commercial Application Foliar spray of 100 ppm salicylic acid (50g/500 lit. water/ha) for Greengram , Blackgram , Sesamum, Castor and Groundnut. Time of spray At flowering stage At 15 days after first spray

18. Strigolactones  (SLs) were originally discovered through studies of the germination of the parasitic weed  Striga lutea . It was found that the germination of  Striga  species was stimulated by the presence of a compound exuded by the roots of its host plant.  It was later shown that SLs that are exuded into the soil also promote the growth of symbiotic arbuscular mycorrhizal (AM) fungi.  More recently, another role of SLs was identified in the inhibition of shoot branching.  This discovery of the role of SLs in shoot branching led to a dramatic increase in the interest in these hormones, and it has since been shown that SLs play important roles in leaf senescence, phosphate starvation response, salt tolerance, and light signalling . Strigolactones

19. Growth regulators for agricultural crops Crop Chemical/Dosage Response Rice Kinetin, GA3 and Triacontranol (1000 ppm) Grain filling and partitioning Delayed senescence Cotton IAA, NAA (30 ppm), CCC ( cycocel ) Increase grain yield Decrease boll shedding Increase photosynthetic rate and yield Increase number of bolls, boll weight and lint yield Sunflower Benzyl adenine (BA) (250 ppm) GA+BA (150 ppm) Increase yield and Achenes weight and number Groundnut Mepiquat chloride (125 ppm) (2,3,4-Dchlorophynoxy triethyl amine) Increased grain yield and chlorophyll synthesis and decrease chlorophyllase activity . Stimulation of assimilate transport in germination Sugarcane Ethephon Glyphosine Reduced growth rate and regulate ripening Tapioca Ethrel (250 ppm) CCC (1000 ppm) Early tuberization Increase the weight of storage roots Pigeonpea Ethrel (40 ppm) and GA3 (20 ppm) CCC (0.64 mM) Increase grain yield Respond well for RWC, chlorophyll and stomatal conductance Carrot and Potato GA3 (50 ppm) Induction of flowering in long day and seed setting

20. Plant growth regulators and horticultural crops Crop Chemical/Dose Response Mango Ethephon (1000 ppm) Accelerated fruit ripening and improves surface color Citrus Ethrel (1000 ppm) Induce yellow color with in seven days Banana Ethrel (1000 ppm) Accelerated ripening by two days Papaya Ethephon + NaOH (2000 ppm) Ripening within 24 hours Sapota Ethephon + NaOH (500 ppm) Ripening within two days

21. PGRs application in flowering and fruit set Crop Chemical Dose Time of spray and number of spray Response Coconut 2,4-D 30 ppm One month after opening of spathe, through micro sprayer Fruit setting percentage increased to 32.5% against 23% in control Banana 2,4-D 25 ppm Within a week after opening of last bud Prevents seediness in poovan Mandarin orange 2,4-D or NAA 20 ppm, 100 ppm Spray at flowering Increase fruit set Thompson seedless GA3 25 ppm Dip cluster at calyptra falling stage Increase fruit set Pine-apple Planofix 10 ppm +2% urea 0.04% sodium carbonate +20 ppm ethrel 50 ml/plant applied in to the crown 200 to 300 ppm At 35-40 leaf stage Sprayed during fruiting Induced uniform flowering to increase the fruit size Snake gourd Bitter gourd Bottle gourd Ethrel 100 ppm 4 times 10-15 days after sowing at weekly intervals Increase in yield Ribbed gourd Pumpkin Ethrel 250 ppm 4 times 10-15 days after sowing at weekly intervals Increase in yield Sweet potato Ethrel 250 ppm At fortnight interval from 15 days after planting Increased tuber yield

22. Commercially available PGRs with active ingredient/s Active ingredient/formulation/concentrate Product name Company name Crops AUXINS 2-(1-naphthyl)acetic acid SL 45 g/l Planofix Bayer Apple Pear Pineapple 4-indol-3-ylbutyric acid DP 1 g/kg Seradix B No. 1 Bayer Ornamentals 4-indol-3-ylbutyric acid DP 3 g/kg Seradix B No. 2 Bayer Ornamentals 4-indol-3-ylbutyric acid SL 8 g/kg Seradix B No. 3 Bayer Ornamentals GIBBERELLINS Gibberellins SL 32 g/l ProGibb 4% Valent BioSciences Grape, Pear, Citrus, Potato, Mango, Hops, Grape-seedless CYTOKININS 6-benzyl adenine/gibberellins SL 19/19 g/l Promalin Valent BioSciences Apple, Plum, Flowers, Ornamentals ETHYLENE Ethephon SL 480 g/l Ethrel Bayer Apple, Cherry, Citrus, Cotton, Grape, Maize, Peach, Pineapple, Plum, Prune and Sugarcane, Tobacco GROWTH RETARDANTS Paclobutrazol SC 250 g/l Cultar Syngenta Litchi, Mango, Peach, Plum Daminozide SP 850 g/kg B-Nine SP Crompton Chemical Flowers, Ornamentals Glyphosate- isopropylamine SL 360 g/l Glyphosate 360 Acid Monsanto Sugarcane and Grasses (chemical mowing) Glyphosate- isopropylamine SL 360 g/l Mamba 360 SL Dow AgroSciences Sugarcane and Grasses (chemical mowing) Glyphosate- isopropylamine SL 360 g/l Roundup Monsanto Sugarcane and Grasses (chemical mowing) Glyphosate- isopropylamine SL 360 g/l Roundup Ultra Monsanto Sugarcane and Grasses (chemical mowing) GROWTH INHIBITORS Mepiquat chloride SL 50 g/l Pix BASF Cotton Chlormequat chloride SL 750 g/l CeCeCe 750 BASF Pear, Wheat Chlormequat chloride/ethephon SL 300/150 g/l Uprite Bayer Wheat DEFOLIANTS Thidiazuron /diuron SC 120/60 g/l Droppa Ultra Bayer Cotton GROWTH STIMULATORS Brassinolide SL 0.1% Double Godrej Agril and Hortil crops SL - Liquid Suspension; WP- Wettable Powder; EC – Emulsifiable Concentrate; DP – Powder Dust