Foliar application of methyl jasmonate and methyl jasmonate plus urea: effect on nitrogen compounds in Tempranillo grapes over two vintages

The effects of foliar application of methyl jasmonate and methyl jasmonate plus urea on the amino acids content of Tempranillo grapes were evaluated during two seasons (2019 and 2020). In 2019, the foliar treatments favored an increase in ammonium nitrogen (N), amino N and yeast assimilable N when compared to the control grapes; whereas, in 2020, treatments did not affect N parameters in grapes. In 2019, foliar application of both treatments was effective in improving amino acids content in grapes, being significantly higher the effect of methyl jasmonate plus urea treatment than methyl jasmonate treatment. However, in 2020, the effect of both treatments on amino acid content was minor. The different effect among seasons could be explained by environmental conditions and by the differences in N content in grapevines. A multifactorial analysis and discriminant study were carried out, showing that both treatments enhanced amino acid content in grapes. The effect of methyl jasmonate plus urea was stronger than the effect of methyl jasmonate treatment. Also, a great effect of season on amino acids composition was observed.