Objective: To assess the effect on ryegrass (Lolium perenne L.) as a response to phytoregulators produced in digestates obtained from the anaerobic digestion of cow manure, at different initial pH.Design/methodology: Anaerobic cow manure digestions were set up at different initial 5, 6.5, 7.5 and 8.5 pH values and 4, 8 and 20 days of digestion, from these, gibberellic acid (AG3) and indole acetic acid (IAA) were quantified. The digestates were applied to ryegrass grown in pots: a) on 6 months pastures applying all the digestates and b) on 45 days pastures applying digestates at 4 days of digestion. The assessed variables were height, fresh and dry weight and number of stems. The control was developed on unfertilized soil.Results: The initial pH of the digestion influenced the production of phytoregulators, being higher at pH 5.5 and 6.5; no IAA production was recorded at basic pH. The application of the digestates had a different effect depending on the pastures age, was greater on the leaf weight variable. In 6 months pastures the increase was between 21 and 24%, in young pastures from 48 to 115% respect to the control. Likewise, there were between 50 and 60% greater number of stems than in the control, applying digestate at 4 days of digestion.Limitations/Implications: The study took place on ryegrass, it would be of interest in the area to evaluate it in other crops.Findings/Conclusions: The initial manure pH has a higher effect on the digestates properties as well as the time of digestion. Digestates can be a fertilizer for ryegrass, its effect is better in young grasses. The digestate even with 4 days of digestion has a positive effect on ryegrass development.
