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.
Literature Cited
- Bruton, B. D. 1982. Myrothecium roridum, a probable devastating pathogen of
muskmelon in south Texas. Phytopath. 72:355 (Abstr.).
- Drake, G. N. 1980. Effect of Myrothecium roridum
on the germination of
cotton seeds. Indian Phytopath. 33:591-593.
- Harper, S. H. and J. M. Lynch. 1981. Effects of fungi on barley seed
germination. J. Gen. Microbiol. 122:55-60.
- McLean, D. M. and B. Sleeth. 1961. Myrothecium
rind rot of cantaloupes.
Plant Dis. Reptr. 45:728-729.
- Ng, T. J. and E. C. Tigchelaar. 1973. Inheritance of low temperature seed
sprouting in tomato. J. Amer. Soc. Hort. Sci. 98:314-316.
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 |
|
