Amino acids, UPLC-MS phenolic metabolites and multivariate approach for elucidating the effect of two growing conditions on growth and yield attributes in okra pods and leaves

Okra is one of the highly nutritious indigenised food crops in Southern Africa. The study intended to evaluate plant growth, yield, amino acids, and untargeted semi-targeted phenolic metabolites grown concurrently at greenhouse and micro-plot under open-field conditions. Yield and growth attributes: stem diameter, plant height, number of branches per plant, number of pods per plant, pod weight, pod length and pod diameter were higher in the micro-plot under open-field conditions. Sixteen amino acids were quantified and arginine, serine, glycine, aspartate, glutamate, alanine, proline, histidine, threonine, methionine, lysine, tyrosine, leucine, valine, and isoleucine were higher in leaf samples grown in micro-plots under open-field than greenhouse samples. UPLC-MS phenolic metabolites associated with the two growth conditions were quercetin 3-galactoside, succinyl adenosine, quercetin 3-lathyroside, isotan b and icariside F2b which were either highly upregulated or downregulated. Growth conditions can be used to manipulate the accumulation of free amino acids and phenolic metabolites.