Potato genotypes reaction to early blight and late blight in organic cultivation

Disease management in conventional potato crops requires the use of larger amounts of phytosanitary products and increased toxicity with regard to organic cultivation which may pose a risk to human health and have a negative impact on the environment as well. The present study aimed to evaluate the yield and the reaction of potato genotypes to both late blight and to early blight under an organic system of cultivation. Eperiments were conducted in the field in the municipalities of Lages, SC and Quilombo, SC, south Brazil, during the crops of 2012/2013 and 2013/2014. The experimental design consisted of a randomized complete block design with 4 replications; The following eight local clones from the Santa Catarina mountain range (serra) were evaluated: SJ01273-1; SJ01251-1; SJ01213-1; SMSJ07344-54; SJ04510-1; SJ05621-11; SJ02411-5; and SJ04521-3; and 8 commercial cultivars were assessed as follows: Agate, Asterix, and Monalisa of Dutch origin; Panda of German origin; and BRS Ana, BRS Eliza, Cota, and Catucha of Brazilian origin. Incidence and severity of late blight and early bright and the weight and number of tubers produced were evaluated. Potato genotypes showed variability in terms of tuber production and disease resistance. The regional clone 15 and cultivars BRS Ana and Cota presented resistance to early blight and to late blight in both cultivated sites. Genotype 35 and cvs. Asterix and BRS Ana were the ones that had the largest productions. Genotype 35 was the most productive one among all genotypes/clones evaluated (16,926.81kg ha-1). There was variability between different local potato genotypes in terms of productivity potential and resistance to diseases under the organic system of cultivation. These findings showed that there is a source of resistance to genetic improvement programs. RESUMO: O manejo de doenças nos cultivos convencionais de batata requer emprego de maior quantidade de produtos fitossanitários e de maior toxicidade em relação ao cultivo orgânico, que pode acarretar riscos a saúde humana e impacto ambiental. Este trabalho teve como objetivo avaliar o rendimento e a reação de genótipos de batata à requeima e à pinta preta sob sistema orgânico de cultivo. Os experimentos foram conduzidos a campo nas safras 2012/2013 e 2013/2014 em Lages/SC e em Quilombo/SC. O delineamento experimental foi de blocos ao acaso com quatro repetições. Avaliou-se oito clones locais oriundas da serra catarinense: SJ01273-1; SJ01251-1; SJ01213-1; SMSJ073