Soil application of rice husk as a natural silicon source to enhance some chemical defense responses against foliar fungal pathogens and growth performance of Bitter Gourd (<em>Momordica charantia L.</em>)

Abstract

Rice husk is a natural Silicon (Si) source. This study evaluated the effect of rice husk in two different forms; ground rice husk (GRH) and rice husk ash (RHA) on downy mildew in bitter gourd (Momordica charantia L.) leaves caused by Pseudoperonospora sp. Rice husk was added to the growing medium to achieve the final concentration of 200 mg Si /kg soil. Si accumulation in leaves, disease severity, plant growth parameters, cuticle-epidermal layer thickness, chlorophyll content, total phenolic content, peroxidase (POD) and polyphenol oxidase (PPO) activity of leaves were measured. Husk treatment lowered the downy mildew severity significantly (p < 0.05) in leaves although the difference between the effects of two husk forms was insignificant. Numbers of leaves, flowers and fruits in husk-treated plants were significantly higher (p < 0.05) than those in control plants. Cuticle-epidermal layer thickness in GRH, RHA-treated and control plants were 16.8 ± 1.21, 18.2 ± 0.98 and 13.2 ± 1.27 µm respectively. Total phenol content, POD, PPO activity and chlorophyll content in rice husk-treated plants were significantly (p < 0.05) higher than that of control plants. The enhanced disease resistance in rice husk-treated plants appears to be positively associated with the higher accumulation of silicon and Si-enhanced phenolic content and increased activity of PPO and POD enzymes in leaves.

Physiological Response of Cape Gooseberry Seedlings to Two Organic Additives and Their Mixture under Inoculation with Fusarium oxysporum f. sp. physali

“…On the other hand, it has been reported that the use of burned rice husk amendments combined with fertilizer application improves the chlorophyll content in maize plants (Saranya et al, 2018). Ratnayake et al (2018) found that foliar applications of burned rice husk favored chlorophyll content in bitter melon plants. In this study, the use of this amendment increased carotenoid content in cape gooseberry plants with and without pathogen presence.…”

“…Some of the effects of the use of burned rice husk as an amendment include an increase in dry matter content in stems and roots, LA, and relative chlorophyll content in corn plants (Saranya et al, 2018). Likewise, the application of this product favored chlorophyll synthesis in bitter melon (Momordica charantia L.) plants affected by downy mildew, and decreased the disease severity index (Ratnayake et al, 2018). In addition, it has been found that rice husk, when composted, favors the synthesis of chlorophyll, accumulation of carbohydrates, and growth of sunflower (Helianthus annuus L.) plants (Badar and Qureshi, 2014).…”

POLYMERIZED SILICON (SiO2·nH2O) IN EQUISETUM ARVENSE: POTENTIAL NANOPARTICLE IN CROPS

“…The physical, biochemical and molecular defense mechanisms in plants mediated by Si are the following: a) Si induces resistance against a wide range of diseases by acting as a physical barrier, which is based on pre-formed defense barriers before pathogen infection, b) Si-induced biochemical resistance during plant-pathogen interactions involves production, and regulating the complex network of signal pathways, c) Si may act at a molecular level to regulate the expression of genes involved in the defense response 39 . The enhanced diseases resistance in rice husk-treated plants appears to be positively associated with the higher accumulation of Si and Si-enhanced phenolic content and increase in enzymatic activity 40 .…”

Study the silica content of paddy husks from different varieties of paddy cultivated in North Western Province, Sri Lanka

“…When the burning temperature of RH is not uniform, it may yield two types of RHA. Those are Black Rice Husk Ash (BRHA), White Rice Husk Ash (WRHA) (Rathnayake, 2018). The upper layer of RH is exposed to open air and BRHA is formed in the carbonized layer.…”