Effects of elevated ozone levels on photosynthesis and physiological response in rice (Oryza sativa L.)

บทคัดย่อ

Elevated tropospheric ozone (O3) has become a major threat to agriculture and crop production in several countries. This research was to investigate the effects of elevated ozone on photosynthesis, stomatal conductance, chlorophyll and the dry weight of Thai rice RD47. Rice samples were fumigated by ozone concentrations at 40 (EO340) and 70 nmol/mol (EO370). Plants were kept in climate control chambers for 28 days. Elevated ozone was given according to the different treatments as experimentally designed. From the results, elevated ozone 70 nmol/mol significantly caused severe damage to rice RD47 by photosynthesis, stomatal conductance, chlorophyll, shoot, root and total dry weight decreased to 44.42, 28.47, 16.17, 19.41, 49.53 and 37.05% as compared to the control group (p < 0.05), respectively. The higher ozone concentration at 70 nmol/mol obviously caused more effects than the ozone concentration at 40 nmol/mol. Finally, the intrinsic physiological response by interfering with the stomata aperture was determined to be one of the key effects of ozone. Photosynthesis mechanisms were severely disrupted, resulting in a reduction in carbon assimilation through dry weight loss.