Effect of Ethylene-Chlormequat-Potassium on root morphological structure and grain yield in sorghum

Shaping good root structure is the key problem to play the high yield potential of sorghum and increase the yield of grain sorghum. To investigate the effect of Ethylene-Chlormequat-Potassium (ECK) on sorghum root morphology and yield, field trials were conducted in 2020 and 2021 using the medium to tall sorghum variety Liaoza 19 (LZ19) and the dwarf variety Liaoza 37 (LZ37). A randomized zonal experimental design was used to set up the ECK treatment with a foliar spray of 0.75 L hm2 at the five-leaf stage of sorghum and a control spray with an equal amount of clean water (CK). The results showed that compared with CK, sorghum root dry weight showed a gradual decrease from the flowering stage. ECK significantly increased root dry weight of LZ19 and LZ37 at filling and maturity stages by 11.4% and 19.7%, 10.6% and 9.9%, respectively. ECK increased root length and root surface area of fine and medium roots (root system diameter < 4 mm) of LZ19 and root length, root surface area, and root volume of LZ37 at different diameters at grain filling stage. At maturity stage, ECK increased root length, root surface area, root volume, and root mean diameter of LZ19 and that of LZ37, and the increase of system morphological indexes was the largest in the two varieties. ECK treatment increased the yield of LZ19 by 3.3% and 13.4%, and LZ37 by 11.4% and 9.8% in 2020 and 2021, respectively, compared with CK. In conclusion, ECK treatment promoted sorghum root development and significantly increased sorghum yields, which can be used as an important cultivation measure for sorghum root promotion and yield increase in summer sown areas