Influence of Organic Acids on Growth and Phenological Responses of Rice (Oryza sativa L.) under Rhizoctonia solani Infection
Akshita Maheshwari *
Department of Crop Physiology, College of Agriculture, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India and Division of Microbial Technology, CSIR National Botanical Research Institute, Lucknow, Uttar Pradesh, India.
Suchi Srivastava *
Division of Microbial Technology, CSIR National Botanical Research Institute, Lucknow, Uttar Pradesh, India.
Rajeev Kumar
Department of Crop Physiology, College of Agriculture, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
Ananya Dwivedi
Division of Microbial Technology, CSIR National Botanical Research Institute, Lucknow, Uttar Pradesh, India and School of Life Sciences and Biotechnology, Chhatrapati Shahu Ji Maharaj University, Kanpur, Uttar Pradesh, India.
Prabhakar Kumar Singh
Department of Genetics and Plant Breeding, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
M. Z. Siddiqui
Department of Agronomy, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
Ashwani Kumar
Department of Crop Physiology, College of Agriculture, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
Rakesh Yadav
Department of Crop Physiology, College of Agriculture, C.S.A. University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
*Author to whom correspondence should be addressed.
Abstract
Rhizoctonia solani Kühn (RS), which causes sheath blight in rice, is a soil-borne fungal pathogen that adversely affects plant growth and productivity. It causes characteristic sheath lesions and can also interfere with vegetative development and reproductive transition. The present study evaluated the potential of two organic acids, benzoic acid (OA1) and oxalic acid (OA2), to modify growth and phenological responses of rice under R. solani stress. Eight treatments were evaluated: untreated control, pathogen infected control (RS), benzoic acid (OA1), oxalic acid (OA2), benzoic acid with oxalic acid (OA1OA2), benzoic acid with pathogen (OA1RS), oxalic acid with pathogen (OA2RS), and benzoic acid with oxalic acid with pathogen (OA1OA2RS). Studies on the effects of organic acids on rice growth and phenology under pathogen stress are limited. Therefore, treatment effects were assessed using growth parameters, including relative growth rate, total dry matter, flag leaf number and flag leaf weight and phenological parameters, including days to flowering and days to maturity. Fungal infection adversely affected plant growth and development compared with the healthy control, with reductions of approximately 25% in RGR and TDM. Organic acid application moderated these effects, with OA1 and the combined organic acid (OA1OA2) treatment showing the most favourable overall performance. The superior performance of benzoic acid-based treatments was reflected in improved relative growth (OA1 by 27%; OA1RS by 13%) and the maintenance of flag leaf development (OA1 by 12%) and biomass compared with Rsolani-infected plants, together with comparatively favourable flowering and maturity responses. The results suggest that exogenous organic acids may improve rice performance under R. solani stress. Information about the mechanisms involving defence activation, stress regulation and the maintenance of functional tissues remains limited. The present findings also indicate that benzoic acid, alone or in combination with oxalic acid, warrants further investigation as a potential component of integrated sheath blight management.
Keywords: Oryza sativa, Rhizoctonia solani, sheath blight, organic acid, relative growth rate, flag leaf, flowering, maturity