A manual of rice seed health testing - IRRI books - International Rice ...

More documents

Recommendations

Info

Table 6.3 percent incidence of different seedborne pathogens on treated incoming seed lots received for postentry clearance by the IRRl Seed Health Unit, 1987-1990. a Pathogen Affected seed lots 1987 1988 Detection levels Mean value Affected seed lots Detection levels Mean value Alternaria padwickii Curvularia spp. Sarocladium oryzae Microdochium oryzae Fusarium moniliforme Drechslera oryzae Pyricularia oryzae Tilletia barclayana Aphelenchoides besseyi b 33.3 44.4 10.2 9.3 1.8 36.0 0.0 46.2 44.0 1 - 44 1-15 1-27 1-14 1 1-62 0 1-52 1-797 10.5 3.1 6.3 5.0 1.0 8.4 10.6 67.0 17.5 24.9 4.6 0.9 1.4 18.9 0.0 37.3 25.8 1- 40 1- 41 1-11 1-3 1 1-44 0 1-75 1-344 8.0 5.4 2.1 2.0 1.0 6.2 11.4 26.5 Pathogen Affected seed lots 1989 Detection levels Mean value Affected seed lots 1990 Detection levels Mean value Alternaria padwickii 4.1 Curvularia spp. 30.3 Sarocladium oryzae 7.4 Microdochium oryzae 1.6 Fusarium moniliforme 0.0 Drechslera oryzae 14.8 Pyricularia oryzae 12.3 Tilletia barclayana 98.4 Aphelenchoides besseyi b 27.0 1-49 1-10 1-4 1-3 0 1-12 1-17 1-89 1-84 11.4 1.6 1.6 2.0 1.9 5.5 24.4 15.8 24.2 44.7 0.8 2.3 1.5 35.6 0.0 41.7 31.1 1-21 1-66 1 1 1 1-31 0 1-83 1-54 3.1 10.8 1.0 1.0 1.0 2.5 18.0 10.9 a Based on 200 seeds per seed lot. No. of seed lots examined: 225 (1987), 217 (1988), 122 (1989), 132 (1990). b Actual nematode count. 6.2 The blotter method. a. Moistening blotters. b. Placing 25 seeds on blotters. c. Incubating seeds. Agar plate method General: Detects and identifies seedborne fungi through colony characteristics which they exhibit when grown on nutrient agar. Although data are not statistically conclusive, our experience indicates that common pathogens (including Alternaria padwickii, Bipolaris oryzae, Sarocladium oryzae, and Microdochium oryzae ) are detected more easily using natural agar media than using synthetic ones. (See Appendix 2 for recipes.) We have worked with water agar, potato dextrose agar, potato sucrose agar, Czapek-Dox agar, guicol agar, polished rice agar, rice hull decoction agar, rice straw decoction agar, rice bran agar, and malt extract agar. Germination inhibitors such as 2,4 dichlorophenoxyacetic acid (an herbicide) can be used but IRRl achieved satisfactory results without the inhibitor. Plant debris and other inert matter can be similarly plated. Procedure: 1.Take 400 seeds as working sample. Pretreat seeds with 1% sodium hypochlorite for 10 min. 2. Drain off excess liquid. Place seeds (10 seeds per agar plate) (Fig. 6.3) on either malt extract agar or potato dextrose agar in 9.5-cm petri dishes. 3. Incubate at 22 °C for 5-8 d, either under alternate cycles of NUV light and darkness, or in darkness. Fungi 27
Results: Examine plates for charac- teristic pathogen colonies, beginning on the third day and continuing through the eighth day of incubation. Also examine seeds under a stereobinocular microscope. View spores and other fungal structures under a compound microscope to distinguish the fungal forms. Express results as a percentage of seeds infected. Washing test General: Detects identifiable spores on seed surfaces. Procedure: 1. In a convenient vessel (beaker or flask), place the working sample and add water, with or without a wet ting agent, or alcohol. Shake vigorously to remove organisms adhering to the seed surface. 2. Transfer washings into centrifuge tubes and centrifuge for about 5 min at low speed (3000-5000 rpm). 3. Decant excess liquid from each centrifuge tube and examine extracted material under a compound microscope for fungal spores, hyphae, and nematodes. 4. Stain with lactophenol blue to color spores and hyphae and thus detect fungi more easily. Results: Use a haemocytometer to count the number of spores. 6.3 Agar plate showing ten evenly spaced rice seeds. Growing-on test General: Detects seedborne fungal, viral, and bacterial pathogens which are readily transmittable. Procedure: Sow seeds on a suitable medium (sterilized soil, sand, or water agar) under optimal conditions for germination in order to detect symptoms of infection that are not normally detected by other methods. Isolation Seedborne fungi can be conveniently isolated using standard mycological techniques. Procedure: 1.Pick up actively growing mycelia or spores with a sterile needle under aseptic conditions. 2. Inoculate mycelia or spores on petri plates or slants containing the appropriate agar medium. 3. Incubate at 28 °C. Identification Identify fungi after viewing them under a stereobinocular microscope at different magnifications. Procedure: 1. Prepare slide mounts of spores or other bodies in a drop of water or lactophenol blue and examine under a compound microscope for shape, size, and color. 2. Compare findings with those on pp. 75-89 and with literature available on fungal taxonomy (Booth 1977; Ellis 1971, 1976; Ou 1985; Raper and Fennell 1977; Raper and Thom 1984; Sutton 1980). 28 Rice seed health testing manual
Page 2 and 3: A Manual of Rice Seed Health Testin
Page 4 and 5: Contents Foreword v Preface vi Part
Page 6 and 7: Foreword Intensive collaboration ch
Page 8: Part 1 Introduction CHAPTER 1 Rice
Page 11 and 12: tional levels (Kahn 1988). Quaranti
Page 13 and 14: Morphology of the mature plant Matu
Page 15 and 16: two-celled, besifixed, deeply sagit
Page 18 and 19: Part 2 Procedures for seed health e
Page 20 and 21: CHAPTER 3 Equipment J.K. Misra, T.W
Page 22: 3.2 Dry seed inspection using a mag
Page 25 and 26: Example. In a two-stage random samp
Page 27 and 28: solid pointed end. The tube and sle
Page 30: CHAPTER 5 Dry seed inspection J.K.
Page 33: Detection Blotter and agar plate me
Page 37 and 38: Extraction and isolation It is esse
Page 39 and 40: GRINDING METHOD (FOR SMALL-SCALE SE
Page 41 and 42: flagellum. Cells occur singly, in p
Page 43 and 44: 7.6 Oxidase test reaction. L = colo
Page 45 and 46: 7.9 Production of 2-ketogluconate.
Page 47 and 48: 1. Grow pathogen-free plants under
Page 49 and 50: 7.12 a. P. glumae type A colony on
Page 51 and 52: A1. Macerate 100 seeds in 10 ml of
Page 53 and 54: Results: 7.Streak the bacteria onto
Page 55 and 56: Sieve method (Fig. 8.1) Procedure:
Page 58 and 59: CHAPTER 10 Field inspection J.K. Mi
Page 60 and 61: Table 10.2. continued Disease Fungi
Page 62 and 63: Table 10.2. continued Disease Growt
Page 64: additional precaution, the multipli
Page 67 and 68: terracoat (5-ethoxy-3- trichloromet
Page 70: Part 3 Pests and pathogens CHAPTER
Page 73 and 74: elevant tests for determining the i
Page 75 and 76: Table 12.1 continued Family and spe
Page 77 and 78: Cryptolestes pusillus Schonherr The
Page 79 and 80: Rice weeviI Scientific name: Sitoph
Page 82 and 83: CHAPTER 14 Fungal pathogens J.K. Mi
Page 84 and 85:
THE DISEASE—BROWN SPOT Sir John W
Page 86 and 87:
Symptoms Glumes are discolored, and
Page 88 and 89:
y low relative humidity. Released a
Page 90 and 91:
THE DISEASE—STEM ROT Stem rot was
Page 92 and 93:
THE DISEASE—SHEATH BLIGHT Sheath
Page 94 and 95:
Sarocladium oryzae is seedborne. Th
Page 96:
Although not currently considered a
Page 99 and 100:
Pseudomonas fuscovaginae Pathogen:
Page 101 and 102:
See Chapter 7 and Figure 15.4a for
Page 103 and 104:
Infected seeds and contaminated wat
Page 105 and 106:
For further details, see the Common
Page 107 and 108:
nonfluorescent) and Erwinia herbico
Page 109 and 110:
Franklin M T, Siddiqi M R (1972) Ap
Page 111 and 112:
Tai F L, Siang W N (1948) 'I-chu-hs
Page 113 and 114:
106 Rice seed health testing manual
Page 115 and 116:
108 Rice seed health testing manual
Page 117 and 118:
After autoclaving the medium, add t
Page 119 and 120:
smoniloid = having swellings at reg
show all

A manual of rice seed health testing - IRRI books - International Rice ...

Create successful ePaper yourself

Delete template?

Save as template?