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Cucurbit Genetics Cooperative Report 8:44-45 (Article 17) 1985

Effect of Inoculation with Myrothecium roridum Tode ex Fries on Seed Germination and Early Seedling Growth of 12 Cultivars of Muskmelon (Cucumis melo)

Kuti, J., T. J. Ng, and G. A. Bean

University of Maryland, College Park, MD 20742 U.S.A.

Myrothecium roridum Tode ex Fries, a common soil fungus that produces mycotoxins, has been reported to be pathogenic to several plant species. McLean and Sleeth (4) reported that symptoms of pathogenicity of M. roridum on muskmelon included leaf spots, stem decline and postharvest rind decay of fruits. Recently Bruton (1) reported the devastating economic effect of the pathogen in Texas, where fruit losses occurred up to 30%. As soilborne pathogens are also known-to affect seed germination (2,3), this study was initiated to ascertain the influence of the pathogen on seed germination and seedling growth of muskmelon.

Myrothecium roridum (ATCC#52485) was isolated from a diseased melon fruit in Texas and maintained on potato dextrose agar (PDA). Twelve muskmelon cultivars were used: 'Amarelo' (AMR), 'Big Daddy' (BDY), 'Don Juan' (DJN), 'Early Dawn' (EDN), 'Hale's Best' (HBT), 'Harmony' (HAR), 'Hearts of Gold' (HOG), 'Iroquois' (IRQ), 'Jumbo Hale's Best' (JHB), "PMR 45' (PMR), 'Schoon's Hardshell' (SHS), and 'Summet' (SUM).

Seed Treatment: A 14-day culture of M. roridum on a PDA slant was washed twice in sterile water and a spore suspension containing 106 spores/ml prepared. Seeds were soaked for 8 hrs in either the spore suspension or sterile water.

Soil Treatment: 125 gm of sterilized oat grains were inoculated with 10 ml of a 106 spores/ml solution of M. roridum in 250 ml flasks. The cultures were grown for 25-30 days with daily agitation of the flasks for uniform fungal growth. The oat grain mixture containing the spores was then mixed with sterile sand at a ratio of 1:10 (oats/sand, w/w) in a cement mixer for 30 min.

Each treatment was sown in a randomized complete block design with 4 replications of 10 seeds each. Seeds were considered germinated when cotyledons were visible. A germination index (5) was calculated for each experiment, and seedling growth was evaluated by recording shoot dry weight after 8 weeks of growth in the greenhouse.

Analyses of variance of the results revealed significant differences among cultivars for both germination and seedling growth (Table 1). The pathogen effect was more pronounced in the seed treatment study, and cultivar responses were similar to our results with leaf tissue inoculation using M. roridum.

Table 1. Effect of Myrothecium roridum on seed germination and seedling growth of muskmelon after seed and soil treatment.

zMean separation in columns by Duncan's Multiple Range Test, 5% level.

 

 

Germination Index


Shoot Dry Weight (g)


Treatment

Cv.

Treatment

Control

% of
Control

Treatment

Control

% of
Control


Soil

AMR

11.2z

14.Oa

80.0

0.308c

0.352c

87.5

 

BDY

10.4b

13.4b

77.6

0.215h

0.289f

74.4

 

DJN

10.0bc

11.3de

88.5

0.212h

0.233h

91.0

 

EDN

11.5a

11.8d

97.5

0.386a

0.398a

97.0

 

HBT

10.3b

11.7d

88.0

0.234g

0.242g

96.7

 

HAR

11.6a

13.7ab

84.7

0.187i

0.233h

80.3

 

HOG

6.6e

9.7g

68.0

0.278d

0.337d

82.5

 

IRQ

9.5c

11.7d

81.2

0.246fg

0.311e

79.1

 

JHB

8.3t

10.1f

82.2

0.366b

0.382b

95.8

 

PMR

10.5b

11.1e

94.6

0.370b

0.389b

95.1

 

SHS

4.1f

7.4h

55.4

0.105j

0.194i

54.1

 

SUM

6.5e

12.5e

52.0

0.261e

0.337d

90.0

Seed

AMR

7.5d

14.7a

51.0

0.283b

0.383a

73.9

 

BDY

6.1e

10.8e

56.5

0.240f

0.367c

65.4

 

DJN

7.9d

13.2bc

59.8

0.269cd

0.337e

79.8

 

EDN

11.4a

12.6c

90.5

0.343a

0.368bc

93.2

 

HBT

8.6c

12.7c

67.7

0.258d

0.295h

87.5

 

HAR

3.8g

13.9b

27.3

0.159h

0.257i

61.9

 

HOG

7.3d

10.4e

70.2

0.255d

0.362cd

70.4

 

IRQ

5.8ef

11.6t

50.0

0.246ef

0.358d

68.7

 

JHB

8.6c

13.8b

62.3

0.269c

0.331f

81.3

 

PMR

10.6b

11.6d

91.4

0.345a

0.380ab

90.8

 

SHS

3.2g

7.4f

43.2

0.121i

0.219j

55.3

 

SUM

5.3f

14.3a

37.1

0.192g

0.319g

60.2


Literature Cited

  1. Bruton, B. D. 1982. Myrothecium roridum, a probable devastating pathogen of
    muskmelon in south Texas. Phytopath. 72:355 (Abstr.).
  2. Drake, G. N. 1980. Effect of Myrothecium roridum on the germination of cotton seeds. Indian Phytopath. 33:591-593.
  3. Harper, S. H. and J. M. Lynch. 1981. Effects of fungi on barley seed germination. J. Gen. Microbiol. 122:55-60.
  4. McLean, D. M. and B. Sleeth. 1961. Myrothecium rind rot of cantaloupes. Plant Dis. Reptr. 45:728-729.
  5. Ng, T. J. and E. C. Tigchelaar. 1973. Inheritance of low temperature seed sprouting in tomato. J. Amer. Soc. Hort. Sci. 98:314-316.
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Page citation: Wehner, T.C., Cucurbit Genetics Cooperative;
Created by T.C. Wehner and T. Ng, 1 June 2005; design by C.T. Glenn;
send questions to T.C. Wehner; last revised on 11 December, 2009