Rice is a major food source for more than half of the world population. It is the only crop whose cultivation utilizes large area of land for food production. Recent surveys on rice production revealed that its potential yield has drastically reduced and its demand has exceeded over its production. In this context, the present study focuses on the biocontrol ability of chitosan nanoparticles (ChNP) against rice sheath blight pathogen (ShB) Rhizoctonia solani. To determine the percent disease suppression, detached leaf assay followed by greenhouse experiments were performed. The defence enzyme levels as well as the total phenol content were analysed to understand the mechanism of action of ChNP against ShB. This study recommends ChNP as a cost-effective alternative for chemical fungicides with potential biocontrol efficacy. ChNP was found to suppress 90% disease in detached leaf assay and 75% under greenhouse conditions. The enzyme specific activity of all the defence enzymes were significantly higher than the chemical control. The peroxidase, phenylalanine ammonia-lyase and chitinase enzymes were found to be the most active defence enzymes with 0.19,7.28 and 118.16 U/min/ml/mg protein compared to 0.01, 4.99 and 62.22 U/min/ml/mg protein for control. Hence, the current study suggest that ChNP, a non-toxic biodegradable biopolymer, can be an effective biocontrol agent against ShB caused by R.solani. It is a potent plant immunity booster that can be used as a suitable alternative to commercially available chemical fungicides. Further field trials in this respect are needed to determine the dosage for their application in rice fields.

大米是世界一半以上人口的主要食物来源。它是唯一种植大面积土地用于粮食生产的作物。最近对稻米生产的调查表明，稻米的潜在产量已大大降低，其需求超过了其产量。在这方面，目前的研究集中在壳聚糖纳米颗粒的能力生物防治（ChNP）对水稻纹枯病菌病原体（纹枯病）纹枯病。为了确定疾病抑制百分比，进行了离体叶片测定，然后进行了温室实验。分析防御酶水平以及总酚含量，以了解ChNP对抗ShB的作用机理。这项研究建议使用ChNP作为具有潜在生物防治功效的化学杀菌剂的经济有效替代品。在脱叶试验中发现ChNP可抑制90％的疾病，而在温室条件下可抑制75％的疾病。所有防御酶的酶比活性均显着高于化学对照。发现过氧化物酶，苯丙氨酸氨裂合酶和几丁质酶是最活跃的防御酶，蛋白质为0.19、7.28和118.16 U / min / ml / mg，而对照蛋白质为0.01、4.99和62.22 U / min / ml / mg。 。因此，目前的研究表明ChNP，R.solani。它是一种有效的植物免疫增强剂，可用作市售化学杀菌剂的合适替代品。需要在这方面进行进一步的田间试验以确定它们在稻田中的剂量。