Studies On Sorghum [Sorghum Bicolor (L.) Moench] Minicore Germplasm and Breeding Lines to Identify Potential Sources for Abiotic and Biotic Stressors.

Increased water scarcity and climate change coupled with increased food and energy demands necessitates identifying potential sources to develop high yielding sorghum hybrids under abiotic and biotic stress conditions. Field studies under irrigated and rainfed conditions were conducted in 2011 at Hays, Kansas with a total of 140 sorghum genotypes (84 photo-insensitive minicore germplasm (ICRISAT, India), 50 promising breeding lines and 6 checks, TX7000R, TX7078R, TX3042B, SC399R, SC599R, B35) to identify potential sources for drought tolerance and stalk rot and charcoal rot disease resistance, which are highly related to post-flowering drought tolerance. Three drought-related traits, including leaf canopy temperature, chlorophyll content and photosynthetic efficiency (Fv/Fm), were measured on three consecutive dates at an interval of 10 days starting from anthesis. Genotypes IS28451, IS19445, IS19262, IS22616, PI26737R, Tx7000R, B35, PI533946R, PI576380R and SC599R were identified with high photosynthetic efficiency and PI533946R and PI576380R showed both high photosynthetic efficiency and harvest index in both environments. For stalk rot (Fusarium thapsinum) and charcoal rot (Macrophomina phaseolina), plants were inoculated following previously published procedures. Lesion length, plant height and grain yield were measured. Average lesion length across genotypes between irrigated and rainfed experiments respectively recorded 13.1 and 9.3 cm for charcoal rot and 10.4 and 8.4 cm for stalk rot indicated that disease development for both pathogens was higher under irrigated conditions. In this study, genotypes IS29233, IS2864, PI565174R and SC599R were identified as resistance sources to both stalk and charcoal rot. SC599R showed high photosynthetic efficiency as well as stalk rot and charcoal rot resistance in both environments.