Improvement of Growth, Photosynthesis and Antioxidant Defense in Rice (Oryza sativa L.) Grown in Fly Ash-Amended Soil

Abstract

Due to the hostile conditions created by fly ash, its utilization in vegetation is restricted. Therefore, fly ash with soil amendment may offer a suitable combination to support plant growth, with reduced risk of metal toxicity. The present study evaluated different concentrations of fly ash with soil amendments on growth, photosynthesis, photosystem (PS) II activity and antioxidant defense in rice (Oryza sativa L.) seedlings to find out the optimum use of fly ash in rice cultivation. Low levels of fly ash (25%) amended soil improve the seedling growth parameters, CO2 photosynthetic rate and stomatal conductance in rice seedlings. Whereas leaf pigments and PS II activity remain unchanged under 25% fly ash treatment as compared to the plants grown in garden soil; however, these parameters declined under the treatments with higher levels of fly ash. Furthermore, the activities of some antioxidant enzymes and protein increased over control under low level of fly ash. The results showed maintenance of photosynthesis and PS II activity of rice seedlings under low levels of fly ash amendment, due to better antioxidative protection from oxidative damage. Taken together, soil amended at 25% fly ash improved the growth of rice seedlings; making fly ash a suitable component of plant growth substance. It can be concluded that a low level of fly ash can be used in amending rice soil for a short period of time but continuous use of fly ash can cause permanent soil contamination by increasing the load of toxic metals.