Use of Microbial Fertilizers in Grapevine Seedling Production

In Türkiye, grafted grapevine seedling production remains limited, and maintaining high seedling quality continues to be a major challenge. This study evaluated the effects of different microbial fertilizer (MF) formulations on seedling yield and quality in grafted grapevine production over two consecutive years (2024–2025). Scions of Vitis vinifera L. cv. Narince were grafted onto the 110 R rootstock and used as plant material. Seven microbial fertilizer treatments and two control groups (positive and negative) were tested. The microbial fertilizers contained either single microorganisms ( Methylobacterium symbioense, Glomus fasciculatum, Glomus iranicum, Bacillus megaterium, and Trichoderma harzianum ) or microbial consortia ( Pseudomonas fluorescens, Paenibacillus polymyxa, Pantoea agglomerans, and Glomus spp.). Treatments were applied to the basal ends of cuttings before planting. Seedling yield, shoot and root growht parameters were assessed two months after planting. Microbial fertilizers did not significantly affect shoot growth in the first year, whereas all treatments enhanced shoot growth in the second year compared with the controls. Root length, fresh root weight, and dry root weight increased significantly under all microbial fertilizer treatments. The highest total and first-grade seedling yields were obtained from the positive control (74.1% and 57.8%) and MF-B (71.2% and 57.0%) treatments. Strong positive correlations were observed between fresh and dry root weight (r = 0.96) and between first grade and total seedling yield (r = 0.96). Principal component analysis indicated that root morphology and seedling yield traits explained most of the total variation. These results demonstrate that microbial fertilizers can substantially improve seedling quality and production efficiency in grafted grapevine propagation by enhancing root system development.