Plant Growth Regulators (PGR) Economic Implications Lecture 14 PDF

HRT 4300 LECTURE 14  PGR & ECONOMC IMPLICATIONS Intro living organism – complex structural & biochemical entities growth & dev. – result of complex physiological & biochemical, genetic, environmental effects PGRs – endogenous & exogenous : affect plant growth & dev. in ma...

HRT 4300 LECTURE 14  PGR & ECONOMC IMPLICATIONS Intro living organism – complex structural & biochemical entities growth & dev. – result of complex physiological & biochemical, genetic, environmental effects PGRs – endogenous & exogenous : affect plant growth & dev. in many ways direct economic implications PGR as a New Source of Productivity Growth rising global demand for food prod. & need for improvement in agric. productivity using chemicals to improve the growth & dev of crop plants – not new use rose in 1930 with the discovery of auxins range of product uses exemplify the categories of economic benefit :  Categories of economic benefit : - uses to increase output : increasing yield improving quality increasing value extending season & increasing continuity of supply - cost saving uses : direct labour replacement facilitating mechanization simplifying plant breeding extending season & increasing the continuity of supply Uses to Increase Output i. Increasing Yield chlormequat chloride to shorten & stiffen wheat straw, allowing increased use of nitrogen fertilizers GA to increase fruit set of mandarin, clementines, tangerines benefit/cost ratio 9:1  GA to overcome losses of apple yield due to frost damage  GA to increase berry size of seedless grapes benefit/cost ratio 40:1  GA to overcome low temp. constrains to sugarcane growth Ethapon to stimulate latex flow in rubber Glyphosine to ripen sugarcane 10-15% increase in sucrose ii. Improving Quality GA + mechanical thinning to increase berry size of seedless grapes Ethylene to de-green citrus fruit  Daminozide or chlorphonium chloride to dwarf pot-plants to make them more acceptable to consumer market Gibberellins to delay ripening & improve storage life of bananas iii. Increasing Value GA to advance or retard maturity of artichoke in order to capture higher prices  GA to retard ripening of grapefruit to spread harvesting & to capture higher prices iv. Extending Season & Increasing Continuity of Supply Maleic hydrazide & other sprouting inhibitors to extend storage of bulbs & root crops  GA to force rhubarb for early production Cost Saving Uses i. Direct Labour Replacement Maleic hydrazide & fatty alcohol contact bud killers to control growth of suckers in tobacco NAA to thin overset fruit Dikegulac-sodium to control growth of hedges ii. Facilitating Mechanisation fruit looseners (e.g. Ethapon) to aid synchronised ripening & loosening of fruit for mechanical harvesting retardants (e.g. daminoxide) to reduce length of peanut runners & facilitate harvesting defoliants to remove excessive vegetation on crops iii. Simplifying Plant Breeding sex change in Cucurbits : a mixture of Gibberellins A4 & A7 to increase staminate flowers iv. Extending Season & Increasing the Continuity of Supply Maleic hydrazide to extend storage of bulbs and root crops Conclusion success on use of PGR depends on : - clear understanding of the need of agriculture - scope for growth modifications - various plant physiological processes The End