Bio-efficacy of Nanosilicon in Regulating Oxidative Activity to Control Rice Seedlings Rot Disease Caused by Burkholderia glumae

Abstract

Bacterial panicle blight and seedling rot diseases in rice plants (Oryza sativa L.) are caused by the pathogenic bacterial Burkholderia glumae. The nanosilicon treatment is gaining attraction but its effectiveness towards B. glumae infection in rice seedlings through regulating enzymatic activities remains largely unexplored. This study aimed to evaluate the bio-efficacy of nanosilicon in controlling seedling rot disease through regulation of peroxidase and polyphenol oxidase enzymes after challenge infected with B. glumae in rice variety MR297 and PadiU Putra. Nanosilicon was applied as seed priming in germination testing at 0, 300, 600, and 900 ppm on both rice varieties before B. glumae inoculation. Both rice seed varieties primed with nanosilicon at 600 ppm exhibited a significant increase in seedling germination performances over control. The rice seedling of MR297 was more responsive to nanosilicon at 600 ppm with only 17.78% of disease severity index over 26.67% in PadiU Putra and was therefore selected for the enzymatic activity screening. The results showed that the foliar spray of nanosilicon rice plants (MR297) significantly increased both peroxidase (POX) at 24 h and polyphenol oxidase (PPO) at 48 h after B. glumae inoculation with 20.44/min/g and 7.46/g activities, respectively. In addition, the plant growth performances were significantly increased compared with control under the same treatment. This demonstrates nanosilicon's potential to control rice seedling rot disease by regulating POX and PPO activities and hence promote plant growth. The application of nanosilicon is an environmentally friendly approach for controlling B. glumae infection at the early rice growing stage.

Keywords: Burkholderia glumae; enzymatic activity; nanosilicon.

Fig. 1

Disease severity of Burkholderia glumae inoculated MR297 seedlings (A) and PadiU Putra (B) seedlings at 14 DAG with nanosilicon priming: 0 ppm (a), 300 ppm (b), 600 ppm (c), and 900 ppm (d), respectively. Rice seedlings with severe browning shoot and maceration roots were observed in control, without nanosilicon seed priming (a). While, in nanosilicon priming rice seedlings (b), (c), and (d) indicated different severity levels responding to the nanosilicon concentrations.

Fig. 2

Peroxidase (POX) enzyme activity of nanosilicon-foliar sprayed rice plants (MR297) after Burkholderia glumae inoculation at 28 days after transplant. Vertical bars indicate standard errors.

Fig. 3

Polyphenol oxidase (PPO) enzyme activity of nanosilicon-foliar sprayed rice plants (MR297) after Burkholderia glumae inoculation at 28 days after transplant. Vertical bars indicate standard errors.

Fig. 4

The bio-efficacy of nanosilicon as a foliar spray in growth promotion of rice plant variety MR297 at 45 days after transplanting. Rice plants (MR297) foliar sprayed with nanosilicon at 0 ppm (control) (a), 300 ppm (b), 600 ppm (c), and 900 ppm (d).