Biochemical Defenses Induced by Natural Silicon in the Management of Rice Yellow Stem Borer, Scirpophaga incertulas (Walker)

Abstract

Rice (Oryza sativa L.) one of the primary and staple food crops consumed throughout Asia belongs to Poaceae family. Yellow stem borer, Scirpophaga incertulas W. is a predominant insect pest infesting rice in India which damages the crop throughout the cropping season. Aim: Present investigation was carried out to study the efficacy of foliar sprayed natural silicon in inducing biochemical defenses and reducing the damage caused by yellow stem borer in rice. Study Design: Field experiment was laid out by using Randomized Block Design consisting of three different treatments replicated seven times. Place and Duration of Study: The experiment was carried out at Paddy Breeding Station, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India during the year 2022. Methodology: Field experiment was carried out to study the effect of natural silicon on per cent damage caused by rice yellow stem borer. In addition, enzyme studies were carried out to find the biochemical changes occurred in the plants due to different treatments. Treatments comprised of foliar spray of 2% natural silicon (100% SiO2) at 15, 30 and 45 days after transplanting (DAT) (T1), TNAU organic package of practices for rice (T2) and untreated control (T3). Results: Foliar spray of 100% pure natural silicon along with stem borer feeding resulted in significant increase in the activities of defense associated enzymes namely, peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL). In addition to defensive enzymes, total phenol content was found to be significantly higher in silicon treated plants when compared to other two treatments. Such increase in biochemical parameters viz., the defensive enzymes and phenols resulted in significant reduction in the damage caused by stem borer with the lowest mean of 2.78 %, followed by 6.32 % in organic practice as against 9.34 % in untreated control. Conclusion: Silicon obtained from natural sources can be employed as a safe and promising organic amendment in the management of yellow stem borer infesting rice by inducing resistance in plants.