Glycine betaine and shikimic acid: Induced modification in growth criteria, water relation and productivity of droughted Sorghum bicolor plants

To evaluate the beneficial role of glycine betaine and shikimic acid and their combination on Sorghum bicolor plants under water deficit conditions, the plants were grown under greenhouse conditions and subjected to withholding water at days 40 from sowing. Analysis of growth, photosynthetic pigments, some solutes concentration, water relations and yield were carried out. Water stress markedly reduced S. bicolor growth, chl a, chl b, carotenoids concentrations, RWC, transpiration rate and total leaf conductance at both lower and upper leaf side as well as yield components. On the other hand, total soluble sugars increased and proline accumulated in S. bicolor plants grown under drought conditions. The applied chemicals mitigated the effect of water stress on S. bicolor growth and yield. The effect was more pronounced with glycine betaine + shikimic acid treatment. Used chemicals increased the formation of photosynthetic pigments as well as soluble sugars concentrations, and lowered proline concentration and transpiration rate of S. bicolor plants under the stress conditions as compared with untreated droughted plants. The economic yield (grain yield) was found to be strongly positively correlated with shoot fresh and dry weights, leaf area, chlorophyll a concentration, transpiration rate, RWC and the biomass of developing grains. On the other hand, the economic yield was strongly negatively correlated with proline concentration of S. bicolor leaves.