Plant Growth-Promoting Rhizobacteria Applied Pre-Plant with Liquid Fertilizer Increased Russet Potato Yield Without Affecting Quality

Potato is a vital crop in the United States, and increasing its production is essential. Due to their differences in rooting characteristics and nitrogen (N) needs, each potato cultivar generally receives specific research-based N recommendations. However, limited research exists on how other fertilizer nutrients, including micronutrients and plant growth-promoting rhizobacteria (PGPR), affect potato yield and quality. This study evaluated the response of Mesa Russet potatoes to various pre-plant and foliar fertilizer treatments on sandy, alkaline soil in Colorado, USA for two growing seasons. Six fertilizer treatments were tested in a randomized complete block design with four replications: (1) 4-13-17-1S (control), also known as the Farmer’s Standard, (2) 3-10-13, (3) 3-10-13 + PGPR, (4) 3-10-13-1S-1Zn, (5) 9-15-3-1S-0.25Zn + K-acetate foliar, and (6) 9-15-3-1S-0.25Zn + 0-0-15-5S foliar. The results showed that treatment PGPR maximized tuber bulking rate by 1.5 g plant⁻¹ day⁻¹, and 3.3 g plant⁻¹ day⁻¹ in 2016 and 2017, respectively, compared to the control treatment. Also, treatment 3-10-13 + PGPR had the highest total and larger tuber (>114 g, >170 g and >284 g) yields in both years. In contrast, the control (4-13-17-1S) had the lowest yield in both years. Treatment 9-15-3-1S-0.25Zn + K-Ac foliar resulted in total yields in both years that were statistically similar to the PGPR treatment; this treatment had the highest N, P, and Zn applications compared to all other treatments. Treatment 9-15-3-1S-0.25Zn + 0-0-15-5S foliar exhibited marketable yields (tubers > 114 g) comparable to the PGPR treatment in both years; this treatment had the highest S application as compared to the others. Further testing of PGPRs, S, and Zn individually and in combination is needed to evaluate their impact on other Russet potato cultivars grown in sandy soils prior to broadening these recommendations.