Simulation of Post-Anthesis Drought Effect On Sorghum Using Chemical Desiccants.

Drought, particularly after flowering is a major stress in sorghum production. Field evaluation for drought resistance is constrained by the fact that the screening environments often eliminate some genotypes with good agronomic characters, thereby reducing the variability in breeding population. The use of chemical desiccants allows for selection in optimal environments. This study assessed the suitability of using chemical desiccants for post anthesis stress evaluation in sorghum. Field experiments were conducted during summer 2012 at the Agronomy Center for Research and Education, Purdue University. The first factorial experiment consisted of 3 different chemicals: KI, NaClO_3nand KClO₃, each applied at 3 different rates: 0.4% WV^-1, 0.6% WV^-1 and 1% WV^-1, on 3 genotypes. A second experiment was in two sets: KI (0.6% WV^-1) stressed plots and controls, laid sided-by-side each in a randomized complete block design, replicated twice, and planted with 18 genotypes. The effect of the 3 desiccants on grain yield and 100 seed weight were significantly different. NaClO₃ was the most sever while KI had a mild effect, yet all three desiccants distinctly separated the genotypes. The choice of dosage for each desiccant was however plausible since grain yield remained the same under the different doses. Genotypic response to KI induced stress was significantly different for grain yield, 100 seed weight, stress tolerance index (STI), and stem remobilization efficiency. Grain yield under normal condition was about 2 times higher than that under KI induced stress. Genotypes with high STI had less grain yield reduction, as indicated by high negative correlation (r = -0.96) between yield reduction and STI. It is evident from here that chemical desiccants can be used for preliminary screening of large breeding populations.