Species belonging to the genus Trichoderma are considered as one of the most potential biocontrol agents which can be readily collected from soil and found effective against various fungal and bacterial diseases. In rice-growing areas, the major fungal pathogens affecting rice production include Rhizoctonia solani causing sheath blight and Sclerotium oryzae causing stem rot disease of rice. Due to the lack of resistant varieties and detrimental effects of chemicals, biocontrol gives a good opportunity to manage the diseases efficiently in a sustainable manner. Trichoderma spp. from native rice rhizosphere soil were examined for their antagonistic efficiency to supress the two soil-borne rice pathogens, viz., R. solani and S. oryzae. Morphological, biochemical and molecular characterisation of the isolates led to the identification of species as T. asperellum. The isolates of Trichoderma spp. were found to be positive to IAA release and phosphate solubilisation and were screened against R. solani and S. oryzae in vitro and in vivo in pots under glass house conditions. Regression analysis indicated a positive correlation between the amount of chlamydospores produced by T. asperellum and their antagonistic potential against the two pathogens. Exposure to external stimuli, viz., light, injury and nitrogen sources in culture media triggered increased conidiation in Trichoderma isolates. Among the four isolates studied, Trichoderma asperellum IIRRCK1 (TAIK-1) was found to be the most effective in improving plant growth in rice and highly antagonistic against R. solani and S. oryzae. Sorghum grain was found to be the most suitable among different organic substrates studied to provide better growth and viability of TAIK-1 and improved the efficiency of the seed treatment and soil application. External stimuli in the form of near UV blue light, mechanical injury to the colonies and nitrogen source added to the culture media help in faster conidiation of Trichoderma. Strain TAIK-1 showed strong competitive and antagonistic activities against fungal soil-borne pathogens, in addition with promoting healthy growth and development of rice plants. This can be a suitable and safe alternative to chemical management in the rice fields for long-term scenario.

中文翻译：

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木霉天然分离物作为水稻鞘枯病和茎腐病病原菌的生物抑制剂

属于木霉属的物种被认为是最有潜力的生物防治剂之一，可以很容易地从土壤中收集它们并发现其对各种真菌和细菌性疾病有效。在水稻种植地区，影响水稻生产的主要真菌病原体包括引起鞘枯萎病的茄根丝枯病和引起水稻茎腐病的米糠菌。由于缺乏抗药性品种和化学药品的有害作用，生物防治提供了以可持续方式有效管理疾病的良好机会。木霉属。研究了来自天然水稻根际土壤中的稻草对两种土壤传播的水稻病原菌（即R. solani和S. oryzae）的拮抗作用。分离物的形态，生化和分子表征导致将物种鉴定为T. 曲霉。木霉菌的分离株。被发现对IAA释放和磷酸盐增溶呈阳性，并在温室条件下在罐中体外和体内筛选了R. solani和S. oryzae。回归分析表明，曲霉产的衣原体孢子数量与其对两种病原体的拮抗潜力呈正相关。暴露于培养基中的外部刺激（即光，损伤和氮源）会导致木霉菌分离物中的绝种增加。在研究的四个分离株中，曲霉木霉IIRRCK1（TAIK-1）被发现对改善水稻中的植物生长最有效，并且对茄形假单胞菌和米曲霉具有高度拮抗作用。发现高粱谷物最适合研究的各种有机底物，以提供更好的TAIK-1生长和活力，并提高种子处理和土壤施用的效率。接近紫外线的蓝光形式的外部刺激，对菌落的机械损伤以及向培养基中添加的氮源有助于更快地分生木霉。TAIK-1菌株除了能促进水稻植物的健康生长和发育外，还对真菌性土壤传播的病原体表现出强大的竞争和拮抗作用。从长远来看，这可能是稻田化学管理的合适且安全的替代方法。对菌落的机械损伤和添加到培养基中的氮源有助于更快地分生木霉。TAIK-1菌株除了能促进水稻植物的健康生长和发育外，还对真菌性土壤传播的病原体表现出强大的竞争和拮抗作用。从长远来看，这可能是稻田化学管理的合适且安全的替代方法。对菌落的机械损伤和添加到培养基中的氮源有助于更快地分生木霉。TAIK-1菌株除了能促进水稻植物的健康生长和发育外，还对真菌性土壤传播的病原体表现出强大的竞争和拮抗作用。从长远来看，这可能是稻田化学管理的合适且安全的替代方法。