Effect of a super absorbent polymer on germination, morphology, and drought resistance of Cynodon dactylon

This study was conducted to determine the effect of a super absorbent polymer on stolon germination and seedling morphological characteristics of Cynodon dactylon and optimum polymer quantity. We used an indoor pot experiment with 5 gradients of super absorbent polymer concentration 0(CK), 0.10%, 0.20%, 0.30%, and 0.40% under two moisture conditions (adequate water supply and limited water supply) to conduct a comprehensive analysis, as well as an evaluation of drought-resistance of C. dactylon. The results showed that: 1) A suitable concentration of super absorbent polymer can improve germination rate, germination potential, and the germination index of C. dactylon stolons, and the optimal super absorbent polymer concentration under sufficient water supply conditions was 0.30%, 0.20%, and 0.10%, respectively. These values increased by 13.24%, 10.11%, and 20.14% compared with that of the CK, respectively. Optimal super absorbent polymer was 0.30% under limited water supply conditions, and the values increased by 12.67%, 14.87%, and 8.71% compared with that of the CK, respectively; 2) The application of super absorbent polymer improved the biomass and root-shoot ratio of C. dactylon seedlings, whereas when the concentration was 0.20% to 0.30%, the C. dactylon root-shoot ratio was lower than that of the CK. Under sufficient water supply conditions, root-shoot ratio reached the maximum (0.019) at 0.10%, and at 0.40% (0.013) under the limited water condition, the root-shoot ratio was higher than that of the CK; 3) The application of super absorbent polymer could increase the plant height and root length; plant height increased first and then decreased with the increase of super absorbent polymer concentration under the two water conditions. Root length increased with the increase of super absorbent polymer concentration under both conditions and reached the maximum in the 0.40% treatment; 4) Based on membership function analysis, adding a suitable concentration of super absorbent polymer can improve the drought-resistance of C. dactylon seedlings. The order of concentrations for drought resistance of C. dactylon seedlings was 0.20% > 0.30% > 0.40% > 0.10% > 0 under sufficient water supply conditions and was 0.30% > 0.40% > 0.20% > 0.10% > 0 under limited water conditions. Therefore, we suggest the addition of super absorbent polymer at a concentration of 0.20%～0.30% when using C. dactylon for lawn laying and ecological afforestation, which is beneficial to greenland construction and prolongation of lawn irrigation time.