2.1 │ Plant material
Two cucumber genotypes to damping-off (Soheil and Ramezz), one moderately resistant genotype (Baby) and three susceptible genotypes (Extrem, Mini 6-23 and Yalda) were selected among a collection of thirty-eight commercial genotypes of domestic and exotic hybrids, and inbred lines from different seed companies, we recently investigated and were screened in another study to identify resistant and susceptible genotypes (Hashemi et al., 2019, Nasr Esfahani 2019). The six genotypes are listed from least to most susceptible according to the disease severity index in greenhouse investigations in Table 1. A number of 100 seeds per genotypes were grown in seedling nursery trays filled with forced-air oven sterilized mix of sand-peat moss in equal parts at 200°F for 30 minutes. Cucumber seedlings were grown in a greenhouse condition (26±2°C), provided with 16 h photoperiod and 65% relative humidity. The experiment was arranged in a completely randomized factorial design with three replications (Nasr Esfahani 2012, 2014).