Role of Plant Growth Regulators for Increasing the Vase Life of Cut Fl

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Plant growth regulators and cut flowers

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WELCOME

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Role of Plant Growth Regulators for Increasing the Vase Life of Cut Flowers Speaker: Arvind Kumar Verma Ph.D. Scholar, IARI, New Delhi Chairperson: Dr. S.S. Sindhu (Principal Scientist)

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Commercial floriculture is one of the most profitable agro-industries in the world Global trade of flowers estimated about $40 billion (60% cut flowers) Floriculture industry is growing @ 10-15% and growth potential 25-30% per annum A short post-harvest longevity remains as a major limiting factor for cut flower Attempts have been made to retard the post-harvest processes by applying plant growth regulators that inhibits ethylene biosynthesis Cut flowers are highly perishable, hence any effort to improve their vase life by regulating senescence, either through chemical or genetic means, will reduce the post harvest losses Senescence of cut flowers is under hormonal control Long vase life of flowers with PGRs based on SAG that either suppresses ethylene synthesis or reduce the sensitivity to ethylene Chemicals have the heavy metals may become potent environmental pollutants Introduction

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What is Vase Life ? Period for which flowers remain in presentable form without loosing its grade and quality Why to increase the vase life ? Improve the opening, size, colour and longevity Reduction in sensitivity of flowers to dramatic climatic conditions Reduction in sensitivity to ethylene during handling and shipment Minimize the hazard of damage by adverse climate and insect-pests To trap the long distance markets and consumer’s satisfaction

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Plant Growth Regulators Plant growth regulators are organic compound other than nutrients that alter the growth and development of plants at very low concentrations. Classification of plant growth regulators Auxins Gibberellins Cytokinins Ethylene Abscisic acid Polyamines

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Reducing ion leakage Improve water uptake Maintain petal turgidity Reduce water stress damage Improving membrane stability Delaying peroxidation of membrane lipids Inhibit ethylene production and reduce sensitivity to ethylene How do PGRs work?

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Decrease in water uptake Degradation of macromolecules Loss of membrane integrity and cellular compartmentation Decrease in fresh weight Decrease in water content Increased respiratory activity Increase in hydrolytic enzyme activity Increase in evapotranspiration Increase in bacterial contamination Pollination Causes of flower senescence

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Changes during senescence Morphological Loss in weight Loss in moisture Changes in colour Physio-biochemical Increase in respiration Decrease in chlorophyll Increase in protease activity Increase in cell permeability Increase in hydrolytic enzymes Degradation of macro molecules Production of reactive oxygen species Increase in ethylene and decrease in cytokinins level

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Determinants of flower senescence Developmental stage of flower at harvest Pro-senescence signals from specific tissues (e.g. Pollination) Stress related metabolism (Temp., wounding, nutrient deficiency etc.) Patterns of flower senescence Monocarpic plants completion of reproductive development culminates in death Polycarpic plants - two patterns based on ethylene sensitivity ethylene-dependent ethylene-independent

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Teixeira, 2003 Growth and respiration in climateric and non-climateric species

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Ethylene It is a gaseous, colourless unsaturated hydrocarbon plant hormone It play a crucial role in the senescence of flower ACC= 1-aminocyclopropane-1-carboxylic acid; SAM= S-adenosylmethionine http://plantandsoil.unl.edu ACC oxidase

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End of flower opening or cutting of flower Increased generation of superoxide radicals (O-2) Increase in oxidative stress Decrease polar lipid content Peroxidation of lipid Loss in membrane integrity High rate of respiration Vascular occlusion Water stress ABA production Flower Senescence Arora , 2005 Flower senescence

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Strategies of extending flower longevity countering senescence/PCD

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Auxin=10-3M

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5µM NAA 1mM AVG

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Effect of pulsing treatment with NAA and AVG and their combination on vase life of inflorescence and opened flowers of Eustoma 5µM NAA, 1µM AVG Yumoto and Ichimura, 2010

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Role of cytokinins on flower senescence Cytokinin known to counteract ethylene action Cytokinin applications to flowers Delay senescence Increases vase solution uptake Reducing ion leakage Maintaining cellular integrity and proteins Reduce ethylene biosynthesis Inhibits activity of ACC synthase and oxidase Cytokinins (CKs)

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Effect of concentration of cytokinins on longevity and flower diameter of carnation cv.‘Charlotte’ Anna and Danuta, 2003

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Effect of pulse treatment with KIN on ethylene production and activity of ACC oxidase in carnation flower

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Effect of pulse treatment with BA on vase life carnation flower Effect of pulse treatment with KIN on vase life carnation flower Effect of pulse treatment with cytokinins on vase life of carnation flower Contd…….

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0.5mM TDZ, 0.22mM BA and/or 1mM GA3

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Contd….. S-1 S-2 S-3

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Gibberellins Effect of GA3 on post harvest quality and vase life of gerbera cut flower Effect of GA3 on bent neck, dry matter and water content of gerbera cut flower

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Effect of PGRs with sucrose on FW and DW of cut spike 3 DAT, maximum number of open flowers at any one time per spike and total solution uptake

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Contd… Effect of PGRs with sucrose in the vase solutions on membrane stability index (MSI) and vase life of gladiolus

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Pandey et al., 2000 PAs biosynthetic pathways SAM= S-adenosylmethionine MGBG= methylglyoxal-bis-(guanylhydrazone) Polyamines (PAs) PAs are a effective anti-senescence agents and found to retard chlorophyll loss, membrane deterioration and increases in RNase and protease activities, It play a crucial role in suppressing the onset of senescence Endogenous polyamines (spermine and spermidine) suppress ethylene production

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“tug of war” between polyamines and ethylene Pandey et al., 2000

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Changes in the levels of polyamines in the petals of rose during different postharvest periods Sood and Nagar, 2008

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Studies on the effect of foliar application of putrescine on fresh wt. and dry wt. of gladiolus flower Nahed et al., 2009

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It is generally known as a strong growth inhibitor and a senescence stimulating factor but it also control stomata closure in plants Under water stress condition, turgor pressure declines and it results in an increase in cytosolic and apoplanstic ABA levels Abscisic acid (ABA)

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S1= closed bud; S2= closed and heavily pigmented bud; S3= commercial stage; S4= sepals completely opened, S5= petals completely unfolded; S6,= flower completely senesced with petal bluing

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ABA conc. and rate of ethylene evolution in rose petals at different stages of senescence Condt….. Abscisic acid concentration (ng g-1 Fw) Rate of ethylene evolution (nl g-1 Fw h-1)

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Effectiveness of PGRs depend upon the developmental stages of flowers Auxin alone did not increase vase life of flower but extended the vase life with combination of other PGRs CKs and GA are the most potent PGRs for increasing the vase life Combinations of CKs and GA3 with sucrose enhanced the vase life PGRs decreased the production of ROS PAs are a effective anti-senescence agents which help in slow down the senescence process ABA and ethylene both stimulate senescence and suggested ethylene production linked with ABA concentration Cultivar may also be a factor affecting the efficiency of PGRs in delaying flower senescence Higher conc. of PGRs may promote the flower senescence Conclusion