Agro-morphological characterization of diverse sorghum lines for pre-and post-flowering drought tolerance

Abstract

The impact of drought stress on sorghum yield does not only depend on the intensity and timing of drought, but as well on the developmental stage of the crop. One of the limitations in breeding for pre-and/or postflowering drought stress resistance in sorghum is the less availability of diverse genetic sources possessing drought tolerant agro-morphological or physiological traits that could be introgressed into elite sorghum lines. This research evaluate a diverse group of 54 introgressed, converted, and commonly used sorghum breeding lines for their tolerance to field drought stress imposed at the pre-flowering and post-anthesis developmental stages in 2015 and 2016 growing seasons. Agro-morphological characteristics such as panicle area, panicle width, and percent green leaf and yield-related characteristics such as total above ground dry biomass and dry panicle weight were identified as significant predictors of grain yield under water stress. The current research identifies other sources that could be use by breeding programs as donor lines for traits related to pre-and postflowering drought tolerance in sorghum. Following statistical distribution and Tukey-Krammer HSD connecting letter tests, lines JB39, SC191, and SC270 and RIL R.11269 were identified as plausible sources for pre-flowering drought tolerance, and JB14, JB15, JB19, JB22, JB24, JB25, JB26, and JB33 as sources for the staygreen trait. While the staygreen is a good selection tool for postflowering drought tolerance, identifying staygreen lines with minimal reductions in grain yield and with earlier flowering dates (JB14, JB22, JB24 and JB25 in this study) than most commonly used staygreen donor lines, will ensure that grain yield is not over sacrificed by the ability of the crop to staygreen under terminal drought conditions.