Effects of microbial inoculants and chemical fertilizers on the production performance and quality of Phleum pratense

In this study, we investigated the effects of different proportions of microbial inoculants and chemical fertilizers on the growth of Phleum pratense. We tested the effects of 100% (375 kg·ha⁻¹), 85% (320 kg·ha⁻¹), 70% (263 kg·ha⁻¹), and 55% (206 kg·ha⁻¹) chemical fertilizer combined with microbial inoculants on the agronomic traits, root morphology, and nutritional quality of P. pratense through field trials. The results showed that 85% chemical fertilizers with microbial inoculants significantly increased P. pratense fresh grass yield, below-ground biomass, plant height, root length and stem thickness by 50.11%, 85.11%, 30.33%, 27.53% and 36.80%, respectively, compared with the control (no fertilizer P < 0.05). Compared with the control, the relative feeding value (RFV) of treated with microbial inoculants and 85% chemical fertilizers was significantly increased by 46.39% (P < 0.05).The 85% chemical fertilizer (320 kg·ha⁻¹) treatment with microbial inoculants (75 L·ha⁻¹) resulted in the best total root length, root surface area, and root diameter of P. pratense for each treatment. The 70% chemical fertilizer (263 kg·ha⁻¹) treatment with microbial inoculants (75 L·ha⁻¹) increased the root volume significantly (by 89.79%) compared to the control (P < 0.05). Principal component analysis indicated that 85% chemical fertilizer (320 kg·ha⁻¹) with microbial inoculants (75 L·ha⁻¹) was the most effective treatment to promote P. pratense growth. This study aimed to select the optimal microbial inoculants and reduced chemical fertilizers application scheme for P. pratense in Minxian County.