Seed Health Management for Better Productivity - Govind Ballabh ...

More documents

Recommendations

Info

(Seed Health Management for Better Productivity)Historical development of Seed Health TestingThe first seed testing station was established by Nobbe in Saxony in1869. Nobbe in his1876 publication Samenkunde mentions smut balls and sclerotia but does not describe anymethod for their detection except visual examination of the seed.The first seed health test toappear was developed by Hiltner working in Germany in 1917.The most notable of the earlypioneer in seed health testing was with out doubt Dr. L.C .Doyer .The most notable of the earlypioneer in seed health testing was with out doubt Dr. L.C .Doyer and Paul Neergarad, also knownas father of seed pathology, who coined the tem seed pathology as an important discipline in PlantPathology .In 1918, first seed health testing laboratory was established at the Government Seedtesting laboratory in Wageningen, The Netherlands. Doyer was the first official Seed pathologist .She was the first chairperson of the ISTA Plant Disease Committee, a position she held until herdeath in 1949.At sixth ISTA congress, at Wageningen, she presented her proposal for recordingSanitary conditions of Seed on the International rules of Seed Testing. Later Dorph-Petersen, thefirst ISTA president, presented a report in International Seed Testing Conference held in 1921 inCopenhagen, on Remarks on the Investigations of the Purity of Strain and Freedom fromDisease.At the 1924 congress held in Cambridge, Genter spoke on the subject Determination ofplant diseases transmitted by seed.The first International Rules for Seed Testing were published by ISTA in 1928. Thisdocument contained a special section on Sanitary Condition in which special attention wasrecommended for Claviceps purpurea, Fusarium, Tilletia, and Ustilago hordei on cereals;Ascochyta pisi on peas, Colletotrichum lindemuthianum on beans and Botrytis, Colletotrichumlinicola, and Aureobasidium lini on flax.Seed Health testingMethods for seed health testing such as, incubation methods, grow out test and otherconventional methods often vary from one laboratory to another which is inadequate forcomparative seed health testing.In 1957, the Plant Disease Committee established a comparative seed health testingprogramme aimed at standardizing techniques for the detection of seedborne pathogens.Subsequent symposia have focused on Seed Health Testing - Progress towards the 21stCentury (Cambridge, UK 1996) and most recently in August 2003, Disease thresholds and theirimplication in seed health testing (Ames, Iowa).Recent Advances in Seed Health Testing proceduresToday, seed health testing is routinely carried out in most countries for domestic seedcertification, quality assessment and plant quarantine. The first PDC Seed Health Symposium washeld in Ottawa, Canada in 1993 and focused on quality assurance in seed health testing. Thedemand for better seed quality of conventional varieties and transgenics, greater sensitivity in- 34 -
(Seed Health Management for Better Productivity)detecting seedborne pathogens and shorter turn around times for seed testing is forcing seedhealth testing laboratories to incorporate new technologies to meet this challenge globally.Technological improvements have increased test sensitivity permitting detection of very lowlevels of inoculum using rapid indirect tests on bulked samples of 1000 -10,000 seeds.Seed healthtesting has undergone significant changes. Seed health testing was primarily directed towardsfungi and relied on incubation and identification, or grow out tests for detection of these pathogenson seed. Such tests are labour intensive and in some cases require high levels of infection beforethey can be detected. Sousa Santos et al. (1997) used PCR to detect the presence of Clavibactermichiganensis pv michiganensis in infested tomato seed lots.Detection technology for seed borne bacteria and virusesSerological-based seed assays, such as the enzyme -linked immunosorbent assay(ELISA), continue to be used with some success for fungi and bacteria.However, they lack the specificity and sensitivity needed to detect many seedborne viruses(McGee, 1995).About 20% of the known plant viruses are transmitted through seeds of infected plants andin many cases the rate of transmission is very low. Seed transmission rate of maize chloroticmottle spot virus was 17 in a total of 42,000 plants or 0.04%( Jensen et al. (1991).The seedtransmission rate of maize dwarf mosaic was one seed in 22,189 (Mikel et al.,1984).The incredibly low rate of seed transmission of these pathogens, and the fact that plantviruses are strict obligate parasites, most conventional types of seed assays used to detect fungiand bacteria are useless.Kohnen et al. (1992) employed molecular technology to detect pea (Pisumseedborne mosaic virus.sativum)With the introduction of DNA-based assays and polymerase chain reaction (PCR)-basedassays, researchers have the ability to detect very minute amounts of a specific DNA sequence onthe surface of or internal to a seed.Specificity has also improved through the use of antibiotics and other agents in selectivemedia for recovery of pathogens from seed. Biological reagents such as antibodies and DNAmarkers also contribute to improve seed health assays.DNA-based polymerase chain reaction (PCR) method has been developed as analternative to grow- out -test. This test holds great promise for the future of seed health testing.Still very much in the development stage, PCR assays have high sensitivity and specificityand often require as little as 24 or 48 hours to complete. They are applicable to a wide range ofpathogens and can be used to separate closely related species.Challenges Ahead- 35 -
Page 13 and 14: (Seed Health Management for Better
Page 33: (Seed Health Management for Better
Page 85 and 86:
(Seed Health Management for Better
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Page 149 and 150:
Page 151 and 152:
Page 153 and 154:
Page 155 and 156:
Page 157 and 158:
Page 159 and 160:
Page 161 and 162:
Page 163 and 164:
Page 165 and 166:
Page 167 and 168:
Page 169 and 170:
Page 171 and 172:
Page 173 and 174:
Page 175 and 176:
Page 177 and 178:
Page 179 and 180:
Page 181 and 182:
Page 183 and 184:
Page 185 and 186:
Page 187 and 188:
Page 189 and 190:
Page 191 and 192:
Page 193 and 194:
Page 195 and 196:
Page 197 and 198:
Page 199 and 200:
Page 201 and 202:
Page 203 and 204:
Page 205 and 206:
Page 207 and 208:
Page 209 and 210:
Page 211 and 212:
Page 213 and 214:
Page 215 and 216:
Page 217 and 218:
Page 219 and 220:
potential. An improvement in qualit
Page 221 and 222:
9. Session Arrangement CommitteeDr.
Page 223 and 224:
9. Dr. Pradip Kumar BorahSr. Scient
Page 225 and 226:
TRAININGONANNEXURE-IIISEED HEALTH M
Page 227 and 228:
ANNEXURE-IVCENTRE OF ADVANCED STUDI
Page 229 and 230:
SundayApril 6MondayApril 7TuesdayAp
Page 231:
TuesdayApril 15WednesdayApril 16Thu
show all

Seed Health Management for Better Productivity - Govind Ballabh ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?