Comparison of photosynthetic efficiency and growth characteristics of paprika in semi-closed vs. conventional greenhouses

This study investigated the differences in light intensity, photosynthetic efficiency, and growth characteristics of paprika plants cultivated in a semi-closed greenhouse covered with low-iron diffuse glass (SG-LDG) and a conventional greenhouse covered with low-iron regular glass (CG-LRG). There was no significant difference in light intensity between the SG-LDG and CG-LRG from the apical meristem to below 100 cm. However, below 150 cm, the SG-LDG showed higher light intensity than the CG-LRG. The light response curve and atmospheric CO₂ response(A-C_a) curve, which represent photosynthetic efficiency, were not significantly affected by crop canopy differences between the two greenhouses during the early cultivation stage. However, after 12 weeks of planting, SG-LDG showed higher photosynthetic efficiency. The J_max and V_cmax values showed no differences between the plants in the two greenhouses until 4 weeks after planting. 12 weeks after planting, plants in SG-LDG showed higher J_max and V_cmax values than those in CG-LRG. All the growth characteristics of plants cultivated in SG-LDG were superior to those of plants cultivated in CG-LRG. Therefore, the improvement in light intensity and photosynthetic efficiency at the lower positions of plants in SG-LDG is considered to have a positive impact on crop quantity and quality.