Evaluation of late leaf spot disease resistance from the parental peanut lines and f2 generations

The objective of this study was to evaluate late leaf spot (LLS) disease resistance of 64 peanut lines/varieties. There were 5 varieties, namely number of 17, 23, 24, 44 and 46 which showed infection of spots late with severe rates from 11.22 to 13.74%; disease index from 1.55 to 1.77%, respectively. Total 460 peanut samples caused by Phaeoisaraopsis personata were collected from 3 different provinces in the northern areas. The results showed that disease incidence caused loss yield in the Dien Chau - Nghe An province with prevalence from 27-32%, and in the region of Tan Yen - Bac Giang had higher rates of 12-19% in 2012. In greenhouse screening, among the parental lines, lines number TN14; TN5; TN3; TN2; CNC3, and TB25 have shown more severely infected. The proportion of infection rate was ranged from 10.13 to 16.28%; disease index from 0.93 to 2.21%, the rest of collected lines have exhibited slight influence of late spot disease with the proportion from 4.55 to 8.91%; disease index from 0.44 to 0.71%. The two varieties were A.hypoyca A.cardenasii - TN2 (No. 49) and AH 4766 - TN6 have shown most negligible infection of LLS. The individual plants of F2 population ware also evaluated LLS disease resistance. Among them, KB104, NS83, and TNKB8 were infected at the highest rate by 8.18% – 9.72%, disease index was 0.74 -1.67% respectively. The other lines number NS82; KNKB2 and NS118 displayed no infection, the other remained lines were slightly infected. The results of this study provided a useful information for future research on peanut breeding with LLS resistance in this country.