Silicon Enhances Resistance to Red Crown Rot Caused by Calonectria ilicicola in Soybean

Khin Thuzar Win,Satoru Maeda,Michie Kobayashi,Chang-Jie Jiang

doi:10.3390/agronomy11050899

Abstract

Silicon (Si) application is known to enhance plant resistance to diverse pathogens. Therefore, a greenhouse study was conducted to determine whether Si reduces red crown rot (RCR) of soybean caused by the soil-borne fungal pathogen Calonectria ilicicola. The soybean cultivar Enrei was grown in soil mixed with different concentrations of sodium silicate (Na2SiO3) and inoculated with C. ilicicola (1% w/v). Si application significantly reduced RCR severity and relative fungal growth in the roots, as per qPCR, at both sampling time points. Notably, the shoot Si content correlated significantly with RCR severity in the roots. In addition, Si application reduced the accumulation of malondialdehyde, indicating that the maintenance of cellular membrane integrity is an important mechanism underlying Si-mediated protection of soybean plants from RCR. Furthermore, Si-treated plants exhibited improved water and nitrogen uptake and root and shoot growth. Aboveground biomass and seed yield at harvest increased with increasing Si concentration (0.0–3.0 g Na2SiO3 kg−1 soil). However, further increase in Si concentration (6.0 g Na2SiO3 kg−1 soil) reduced seed yield. Therefore, Si treatment can be used as an effective strategy to control RCR in soybean.

Highlights

Soybean (Glycine max (L.) Merr.) is one of the most economically important agricultural crops in the world, providing abundant vegetable protein and edible oil for human consumption and animal feed
We found that C. ilicicola infection increased MDA accumulation at the early stages (1–3 days post-inoculation (DPI)), which was significantly suppressed by Si treatment (3.0 g L−1)
Effect of Si Application on Seed Yield Infection with red crown rot (RCR) significantly reduced the aboveground dry weights (DWs) by 64% and seed yield by 79% in the inoculated control compared to the un-inoculated contr9oolf(1F2igure 5) The reduction in aboveground DW and seed yield were markedly alleviated by Si appli cation to 20–41% and 17–73%, respectively

Summary

Introduction

Soybean (Glycine max (L.) Merr.) is one of the most economically important agricultural crops in the world, providing abundant vegetable protein and edible oil for human consumption and animal feed. It has recently been estimated that as much as 11–32% of the global soybean yield is lost annually owing to diseases caused by diverse pathogens and pests. The soil-borne fungal pathogen Calonectria ilicicola Boedijin and Reitsma (anamorph Cylindrocladium parasiticum Crous, Wingfield, and Alfennas) causes red crown rot (RCR) [1,2,3]. RCR is one of the most severe diseases affecting soybean in Japan, because more than 80% of the soybean crops are cultivated in paddy-converted fields [8]. It has been estimated that soybean yield losses from C. ilicicola range from 25 to 30% [10,11] to as high as 50%, especially in a susceptible cultivar, depending on the occurrence of the environmental conditions that favor fungal colonization [3]

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