Fifty-three potato varieties developed by the breeding program of the International Potato Center and released in different countries around the world were evaluated for their resistance to late blight in two locations in Peru.
The experimental design was a randomized complete block design with 3 replications of 15 apical stem cuttings in Oxapampa and 10 tubers in Mariscal Castilla. Plots were 11.9 x 18.5 m in size with 30 cm in-row and 0.9 m between-row spacings. Spreader rows around plots were used at each site. Mancozeb was applied weekly until 30 days after transplanting or planting, after which the plants were left to natural infection. Due to climatic conditions not conductive to the disease in Oxapampa, inoculum was enhanced with local isolate (POX 067, with virulence R1, 2, 3, 4, 5, 6, 7, 10, 11) at a concentration of 5000-sporangia/ ml at 49 days after planting. Percentage of foliar infection was estimated visually every 3 days for 8 times in Oxapampa and every 7 days for 12 times in Comas, then values were converted to the relative area under the diseases progress curve (rAUPDC). rAUDPC rankings were analyzed for phenotypic stability with nonparametric measures.
data(ComasOxapampa)
A data frame with 168 observations on the following 4 variables.
Experimental field, 2002. Data Kindly provided by Wilmer Perez.
cultivar cultivar
replication replication
comas comas
oxapampa oxapampa
International Potato Center. CIP - Lima Peru.
library(agricolae) data(ComasOxapampa) # Oxapampa (10 35 31 S latitude, 75 23 0 E longitude, 1813 m.a.s.l ) # Comas, Mariscal Castilla (11 42 54 S latitude, 75 04 45 E longitude, 2800 m.a.s.l,) # cultivars LBr-40 (resistant), Cruza 148 (moderately resistant) and Pimpernell (susceptible) str(ComasOxapampa)#> 'data.frame': 168 obs. of 4 variables: #> $ cultivar : Factor w/ 56 levels "Amarilis-INIA",..: 1 2 3 4 5 6 7 8 9 10 ... #> $ replication: Factor w/ 3 levels "I","II","III": 1 1 1 1 1 1 1 1 1 1 ... #> $ comas : num 0.57 0.319 0.5 0.423 0.555 0.305 0.707 0.602 0.655 0.471 ... #> $ oxapampa : num 0.6 0.661 0.627 0.511 0.683 0.397 0.68 0.618 0.723 0.625 ...means <- tapply.stat(ComasOxapampa[,3:4],ComasOxapampa$cultivar,mean) correlation(means$comas,means$oxapampa, method="kendall")#> #> Kendall's rank correlation tau #> #> data: means$comas and means$oxapampa #> z-norm = 4.155918 p-value = 3.239838e-05 #> alternative hypothesis: true rho is not equal to 0 #> sample estimates: #> tau #> 0.3820664