Bacterial blight (BB), caused by Xanthomonas oryzae pv. oryzae (Xoo) is a major threat to rice production as it accounts for loss up to 50% of annual rice grain yield. Xoo causes leaf tissue necrosis and as a result there is downregulation of the photosynthetic mechanisms of plant. Measurement of chl a fluorescence is an easy, fast, non-invasive and highly sensitive technique that can be used to understand plant health by measuring alterations in PSII activity, in response to different biotic and abiotic stresses. In the present investigation, rice seeds were bio-primed with two bacterial spp. (e.g. Bacillus subtilis and B. megaterium) and one fungal strain (i.e. Trichoderma erinaceum). The induction of defence against BB disease by bio-priming with biotic agents, was studied as response in alteration of PSII and defence enzymes activity. Field experiment was conducted with the best biotic agent; i.e. B. subtilis obtained from all experiments to study whether defence induction by it have any side effect on rice yield and biomass. Net house and field experiments have suggested that among all the biotic agents studied, bio-priming of rice seeds with B. subtilis has protected the photosynthetic machinery of plants from being damaged by BB without having any detrimental effect on rice grain yield.

稻瘟病菌（Xanthomonas oryzae pv ）引起的细菌性疫病（BB）。菌（白叶枯病）是水稻生产的主要威胁，因为它占的损失高达每年稻谷产量的50％。Xoo引起叶片组织坏死，结果是植物光合作用机制的下调。叶绿素的测定一个荧光是一种简单，快速，非侵入性的，并且可用于通过测量在改变活动PSII，响应于不同的生物和非生物应力了解植物健康高度敏感的技术。在目前的调查中，水稻种子用两种细菌属物种进行了生物引发。（例如枯草芽孢杆菌和巨大芽孢杆菌）和一种真菌菌株（即木霉木霉）。研究了通过用生物制剂进行生物引发来诱导对BB疾病的防御反应，作为PSII和防御酶活性改变的反应。用最好的生物制剂进行了田间试验；即从所有实验中获得的枯草芽孢杆菌，以研究其防御诱导是否对水稻产量和生物量有任何副作用。网房和田间试验表明，在所有研究的生物制剂中，用枯草芽孢杆菌对水稻种子进行生物引发保护了植物的光合作用机制不受BB的损害，而对水稻籽粒的产量没有任何不利影响。