Influence of silicon on some components of resistance to anthracnose in susceptible and resistant sorghum lines

Abstract

This study aimed to evaluate the effect of silicon (Si) rates on some components of sorghum resistance to anthracnose. Two 2×5 factorial experiments, consisting of two sorghum lines (BR005 and BR009, resistant and susceptible, respectively) and five Si application rates (0, 0.06, 0.12, 0.24 and 0.30 g Si kg −1 of soil) were arranged in a completely randomised design with three replications. Plants from both lines were inoculated with a conidial suspension of Colletotrichum sublineolum (1×10 6 conidia ml −1 ) 30 days after emergence. The incubation period (IP), latent period (LP 60 ), area under relative infection efficiency progress curve (AURIEPC), area under anthracnose index progress curve (AUAIPC), final disease severity (FDS), percentage of pigmented leaf area (PLA), and percentage of necrotic leaf area (NLA) were evaluated. Silicon and calcium (Ca) content in leaf tissue of both lines was also determined. The content of Si in leaf tissue increased relative to the control by 55 and 58%, respectively, for the susceptible and resistant lines. There was no significant change in Ca content in leaf tissue for either of the lines; therefore the variations in Si accounted for differences in the level of disease response. The IP for the resistant line was not affected by Si application rates. The LP 60 was not evaluated in the resistant line due to the absence of acervuli. For the resistant line, Si application rates had no significant effect on AUAIPC, FDS, percentage of PLA, and percentage of NLA. On the susceptible line, a quadratic regression model best described the effect of Si application rates on IP, LP 60 , AURIEPC, AUAIPC, FDS, percentage of PLA, and percentage of NLA. The correlation between Si content in leaf tissue of the susceptible line and the AURIEPC, AUAIPC, FDS, PLA, and NLA was negatively significant (r = −0.57, −0.37, −0.40, −0.67, and −0.77, respectively). There was no correlation between Si content and IP or LP 60 . The correlation between the percentage of PLA with the percentage of NLA was negatively significant (r = −0.74). In conclusion, the results from this study underscore the importance of Si in sorghum resistance to anthracnose particularly for the susceptible line.

Efeito da aplicação foliar de silicato de potássio e de fungicida na severidade da ferrugem da folha e da mancha amarela do trigo

“…Em cafeeiro, a aplicação foliar de SP também não foi eficiente no controle da ferrugem, mesmo em curto intervalo de aplicação (15 dias) (Neto et al, 2007). Esses resultados diferem dos obtidos por Datnoff et al (2007), Resende et al (2009) e Domiciano et al (2010, os quais reportaram o potencial do Si, fornecido por via do solo ou por solução nutritiva, em reduzir a severidade de algumas doenças economicamente importantes, em culturas como o arroz, cevada, milho, sorgo e trigo. Esse resultado positivo deve-se, principalmente, ao fato de as monocotiledôneas acumularem mais Si na parte aérea e por ter sido o Si fornecido por solução nutritiva, ou aplicado no solo, em comparação com os da aplicação foliar.…”

Inducers of resistance and silicon on the activity of defense enzymes in the soybean-Phakopsora pachyrhizi interaction

“…It is believed that Si acts as a physical barrier after being deposited under the cuticle, resulting in a cuticle-Si double layer (Yoshida et al, 1962) that can prevent or delay pathogen penetration, thereby prolonging the incubation period and even the latent period (Datnoff et al, 2007;Resende et al, 2009). Moreover, in the presence of Si, plants infected by pathogens generally exhibit increased production of phenolics and phytoalexins, increased activity of chitinases, peroxidases and polyphenoloxidases and the transcription of genes encoding for β-1,3-glucanases, peroxidases and PR-1 (Datnoff et al, 2007) besides increased formation of papillae and callose and hydrogen peroxide deposition in the infected cells (Shetty et al, 2012).…”

Effect of silicon application on Sorghum bicolor exposed to toxic concentration of zinc

“…Although Si has not been considered as an essential element for higher plants, it has been proved to be beneficial for optimal growth and development of many plant species, especially in stressful conditions induced by biotic or abiotoc stress factors (Ma 2004;Liang et al 2007). For example, Si plays an important role in increasing the resistance of plants to pathogenic fungi (Fauteux et al 2005;Resende et al 2009). Silicon also mitigates cadmium inhibitory effects in rice and maize plants (Nwugo & Huerta 2008;Vaculík et al 2009).…”