Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia

Abstract

Abstract. Mau YS. 2018. Resistance response of fifteen sweet potato genotypes to scab disease (Sphaceloma batatas) in two growing sites in East Nusa Tenggara, Indonesia. Trop Drylands 2: 5-11. Scab disease is one of most prevalent problems of agricultural crops, including sweet potato, in tropical and sub-tropical regions. This study aimed to evaluate and determine the scab resistance levels of local sweet potato genotypes from Nusa Tenggara Timur (NTT) Province, Indonesia, and to identify sweet potato genotypes with good resistance levels to scab disease. Field experiments were carried out in two growing locations involving potential sweet potato clones from NTT Province. The experiment was carried out in the fields employing a Randomized Block Design with a mono-factorial treatment design in each location. The treatment assigned was sweet potato genotype, each consisting of two replicates. The variables observed were disease severity that was assessed at 2, 4, 6, and 8 weeks after inoculation (WAI), which then was used to calculate the Area Under the Disease Progress Curve (AUDPC) of the disease severity. The ANOVA of AUDPC was used to determine the treatment effect, and the disease severity at 8 WAI was used to assess scab resistance level of the sweet potato genotypes tested. The study results showed highly significant differences in disease severities among the tested sweet potato genotypes within each trial location. The majority of the genotypes tested were classified Resistant or Moderately Resistant to scab disease, except the check clone SLM-01 and KRA-01 that were, respectively, Susceptible and Moderately Susceptible to scab disease. The majority of sweet potato genotypes evaluated were consistent in their resistance performance in the two trial locations.