Citrullus lanatus (Thunb.) Matsum. & Nakai - Cucurbit Breeding ...

Table 1. Continued. z
Generation Total Susceptible y Resistant x Expected w χ 2 df P-value
PI 526233 × 'Allsweet'
Field test
P aS 1 v 4 1 3
P bS 1 u 1 1 0
F 1 2 2 0
F 2 75 72 3 3:1 17.64 1 0.00
BC 1P a 19 19 0 1:1 19.00 1 0.00
BC 1P b 11 11 0
Greenhouse test
P aS 1 v 3 0 3
P bS 1 u 3 3 0
F 1 6 5 1
F 2 75 31 44 3:1 45.34 1 0.00
BC 1P a 21 15 6 1:1 3.86 1 0.05
BC 1P b 12 12 0
z Data are ratings from four families of resistant PI accessions by susceptible cultivars of Citrullus lanatus
var. lanatus and citroides. Disease assessment scale adopted for evaluating watermelon for resistance to
gummy stem blight: 0 = no disease; 1 = yellowing on leaves (suspect of disease only); 2 to 4 = symptoms
on leaves only; 5 = some leaves dead, no symptoms on stem,; 6 to 8 = symptoms on leaves and stems; 9 =
plant dead
y Susceptible plants had a disease rating > 4.5
x Resistant plants had a disease rating < 4.5
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