TITLE:
Effect of Various Soil Media on Disease Severity of Fusarium Wilt in Watermelon
AUTHORS:
Geoffrey Meru, Cecilia McGregor
KEYWORDS:
Breeding, Citrullus lanatus, Pathogen, Fusarium oxysporum, Race 1, Soil-Type, AUDPC
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.11 No.12,
December
9,
2020
ABSTRACT: Fusarium wilt is a major disease of watermelon (Citrullus lanatus) caused by Fusarium oxysporum f. sp. niveum (Fon). Use of host resistance is the most effective management strategy for the disease, and a major objective for
breeding programs. Screening assays rely on the ability to discriminate
resistant and susceptible genotypes in segregating populations. However, complex interactions between Fon and the soil
environment can influence symptom development and disease severity rating. In
the current study, severity of Fusarium wilt (race 1) in sand-peat (1:1 v/v),
sand-perlite (1:1), sand-peat-vermiculite (4:1:1), peat-perlite (1:1)
and Fafard 3B potting media was compared among five watermelon cultivars:
Calhoun Gray (resistant), SunSugar
(resistant), Allsweet (moderately resistant), Sugar Baby (susceptible) and
Charleston Gray (susceptible). Plant biomass (average dry weight/plant) was
lowest in peat-perlite (1.67 g) and
sand-peat (2.16 g), and was significantly different (α = 0.05) from that of sand-perlite (3.48 g), sand-peat-vermiculite
(4.94 g) and Fafard 3B (6.90 g). Conversely, disease severity [area under disease
progress curve (AUDPC)] across cultivars was significantly higher in
peat-perlite (AUDPC = 62.96) and sand-peat (AUDPC = 40.87), than in
sand-perlite (AUDPC = 11.55), sand-peat-vermiculite (AUDPC = 10.67) and Fafard
3B (AUDPC = 9.29). Consistent discrimination (α = 0.05) of resistant and susceptible cultivars was realized in
sand-peat-vermiculite and Fafard 3B, but was not possible in peat-perlite,
sand-peat and sand-perlite. Collectively, these findings support suitability of
sand-peat-vermiculite and Fafard 3B for routine screening of Fusarium wilt
resistance in watermelon.