This study evaluated the effects of plant growth-promoting rhizobacteria (PGPR) isolates in enhancing upland rice growth and yield. Bacteria were isolated, screened for growth-promoting activities in vitro, biochemically identified, and tested under screenhouse conditions at the Philippine Rice Research Institute (PhilRice). Isolates exhibited growth-promoting activities, such as indole-3-acetic acid (IAA) production, tricalcium phosphate solubilization, 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, siderophore production, and starch hydrolysis. The screenhouse experiment was conducted with upland rice (PSB Rc23) as the test crop, sterilized and natural soils, and recommended rate of inorganic fertilizers (RRIF) as other source variables. Results showed that significantly heavier shoot and root fresh weights are evident in plants grown in sterilized soil. Plants treated with full RRIF exhibited superior growth in terms of plant height, shoot and root weights, and grain yield. Among inoculated and fertilized plants, comparable growth promotion was obtained with Acidovorax delafieldii combined with half inorganic fertilizer rate, in terms of root fresh weight, shoot and root dry weights, plant height, grain yield, and nitrogen, phosphorus, and potassium (NPK) uptake. Overall findings show that PGPR ( A. delafieldii ) in combination with 50% RRIF is as effective as full RRIF in enhancing growth and yield of PSB Rc23 rice, implying that dependence on chemical fertilizer can be reduced utilizing this PGPR. However, further evaluation of these bacterial isolates in actual field conditions is necessary to uncover their efficiency as potential biofertilizer.

中文翻译：

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旱稻生长和产量对施用促生根际细菌的响应

本研究评估了植物生长促进根际细菌 (PGPR) 分离株在促进旱稻生长和产量方面的作用。在菲律宾水稻研究所 (PhilRice) 的筛选条件下分离细菌、筛选体外促进生长的活性、生化鉴定和测试。分离株表现出促进生长的活性，例如吲哚-3-乙酸 (IAA) 生产、磷酸三钙增溶、1-氨基环丙烷-1-羧酸 (ACC) 脱氨酶活性、铁载体生产和淀粉水解。筛网试验以旱稻（PSB Rc23）作为试验作物，经过消毒的天然土壤，以及推荐的无机肥料用量（RRIF）作为其他来源变量。结果表明，在无菌土壤中生长的植物明显更重的芽和根鲜重。用完全 RRIF 处理的植物在株高、地上部和根重以及谷物产量方面表现出优异的生长。在接种和施肥的植物中，在根鲜重、地上部和根干重、株高、籽粒产量以及氮、磷和钾 (NPK) 方面，Acidovorax delafieldii 结合一半的无机肥料获得了可比的生长促进摄取。总体研究结果表明，PGPR ( A. delafieldii ) 与 50% RRIF 的结合在促进 PSB Rc23 水稻的生长和产量方面与完全 RRIF 一样有效，这意味着利用这种 PGPR 可以减少对化肥的依赖。然而，