Torulaspora globosa: rhizosphere yeast promoting lettuce growth on seedlings and under field conditions

ABSTRACT Among soil microorganisms, one group stands out as beneficial to agricultural activities: a plant growth-promoting rhizobacteria (PGPM). These microorganisms support plants through phytohormone production, nutrient provision and plant health maintenance. Among these PGPM, yeasts have a high potential, which is still not very well known.This study aimed to evaluate the effect of inoculation with the rhizosphere yeast Torulaspora globosa (strain 5S55) on development of lettuce (cv. Crocantela). The first research consisted of inoculating seeds with yeast (100 cells/seed), and inoculating seeds, 7 and/or 15 days after emergence (DAE) (1x106 cells/plant). The second one consisted of transplanting seedlings from the first experiment to field. Inoculation of seeds and seedlings provided a significant increase of seedling root dry mass; we observed the significant increase of 27% in productivity of lettuce under field conditions, of shoot fresh mass and a raise of number of leaves per plant. However, studies on inoculation methods, inoculum formulation, cell concentration are essential to optimize the results in growth promotion and to establish technology.

摘要 在土壤微生物类群中，有一类对农业生产极具裨益的微生物：植物促生根际菌（plant growth-promoting rhizobacteria，PGPM）。此类微生物可通过合成植物激素、供给养分及维持植物健康等方式助力植物生长。在该类群微生物中，酵母菌拥有极高的应用潜力，但目前对其研究仍相对不足。
本研究旨在评估接种根际酵母球托鲁索酵母（Torulaspora globosa）菌株5S55对生菜（品种Crocantela）生长的影响。第一项试验包含两种接种方案：其一为以100个细胞/种子的剂量接种生菜种子；其二为在出苗后7天、15天（days after emergence，DAE）分别以1×10^6个细胞/植株的剂量进行接种。第二项试验将第一项试验培育的幼苗移栽至大田开展种植。
试验结果显示，对种子与幼苗实施接种处理可显著提升幼苗根系干重；大田栽培条件下，生菜产量提升27%，同时植株地上部鲜重与单株叶片数均显著提高。不过，后续仍需针对接种方法、菌剂配方以及细胞浓度开展深入研究，以优化促生长效果并推动相关技术的产业化落地。