Differential responses of sorghum genotypes for tolerance to aluminum in nutrient solutions

Abstract

A nutrient solution technique was used to screen 391 sorghum genotypes (181 from BAG-sorghum, 71 from CNPMS, 17 SEPON from ICRISAT and 122 from sweet sorghum collection) for Al tolerance. The differential behavior was based on the root growth of young sorghum plant grown in nutrient solutions with varied Al (0.0, 2.25 and 4.5 mg of Al/l for grain sorghum and 0.0, 2.5 and 5.0 mg of Al/l for sweet sorghum). For comparison purposes, the relative seminal root length (SRRL = SRL_+Al/SRL_-Al, where SRL = Seminal Root Rength and SRRL = Seminal Root Relative Length) was estimated. Based upon the percentual frequency distribution of SRRL values obtained for the different genotypes tested and based upon the SRRL values of SC 208 (Al susceptible) and SC 283 (Al-tolerant) three classes of differential responses to Al were identified: Susceptible (SRRL <0.50). Intermediate (0.50 < SRRL <0.71) and Tolerant (SRRL > 0.70). Among the materials tested, the following were classified as being tolerant to Al: IS 3625,IS 7173 C (SC 283) IS 12666, 5DX61/6/2, 3DX57/1/1/91O, 156-P-5-Serere-1, 9DX9/11, Brandes, MN 4004 and MN 1204. The technique proved to be effective to screen large number of line for Al tolerance and should be used as a tool in a breeding program.