Effects of super-absorbent polymers with different granularities on the physicochemical properties of substrate and the growth of lettuce seedlings

摘要

The suitable granularities of super-absorbent polymers (SAP) in substrate for the growth of lettuce seedlings was studied. An experiment was conducted on two different granularities 40 mesh (Tl) and 20 mesh (T2) SAP in substrate and substrate withoutSAP as control. The effects of different granularities SAP on the physicochemical properties of the substrate, morphological indexes and the physiological indexes of lettuce seedlings were investigated. The results showed that the electrical conductivity(EC) value of Tl and T2 respectively increased by 5.53 and 4.63% compared with the control, and the pH of Tl and T2 respectively increased by 13.23 and 11.76% compared with the control. The saturated water absorption of T2 increased by 9.62% compared with the control; the saturated water absorption capacity of Tl and T2 increased significantly by 6.95 and 5.85%. The fresh weight, dry weight, root shoot ratio, and seedling index of Tl and T2 were increased significantly. The biomass of Tl was significant increased. The chlorophyll a, chlorophyll b and total chlorophyll content of Tl were significantly increased. The net photosynthetic rate and transpiration rate of the lettuce seedlings were significantly increased in Tl and T2. The net photosyntheticrate of Tl was increased by 14.82% compared to T2. The results showed that 40 mesh and 20 mesh SAP in substrate can significantly promote the growth of lettuce seedlings, with 40 mesh SAP in substrate for lettuce seedling recommended.