Detection of durable resistant sources for sugarcane aphids, Melanaphis sacchari and their mechanisms of resistance in post rainy sorghum

Abstract

A set of 24 entries comprising B and R lines were evaluated under All India Coordinated Sorghum Improvement Project (AICSIP) at three hot spot locations, viz. Bijapur, Rahuri and Solapur during three consecutive post-rainy seasons 2008-2010 to identify durable and improved resistant sources for sugarcane aphid, M. sacchari under field conditions. Three lines (SLB 80, ICSV 93046 and SLR 31) were moderately resistant as determined by visual damage ratings and aphid population at physiological maturity. The mean aphid population was recorded as 46.9, 50.7, 51.4 aphids on SLB 80, ICSV 93046 and SLR 31 respectively, compared with 35.2 aphids/ cm2 of leaf area on TAM 428, a widely used source of resistance for M. sacchari under natural conditions. All three lines exhibited antibiosis, with an average progeny of 33.7, 39.3, 41.4 nymphs per adult on SLB 80, ICSV 93046 and SLR 31, respectively, compared to 24.4 nymphs/adult on TAM 428. Principal component analysis suggested that the genotypes with aphid resistance are quite diverse and can be introgressed into adapted local varieties. The present investigation reveals that aphid population/cm2, aphid damage rating, chlorophyll content and grain yield (g)/ plant appears to be the most reliable parameters for characterization of susceptibility or resistance to M. sacchari. The entries, SLB 80, SLR 31 and TAM 428 are resistant to aphid and could be utilized in Rabi breeding program as aphid resistant sources.