Effects of asparagus decline on nutrients and phenolic compounds, spear quality, and allelopathy

Abstract

Asparagus (Asparagus officinalis) decline is an important issue that decreases both crop production and quality causing economic losses. The main bioactive compounds in asparagus are phenolics. Several studies have related these compounds with the decline and also with the replanting issues in which when asparagus plants are replaced by new plants, their productivity is low. The asparagus physiological state and the spear quality have not been studied yet in field plots showing decline symptoms. Therefore, the aim of this study was to study the effect of asparagus decline on leaf nutrients accumulation and on the yield and quality of commercial spears. Another aim was to analyze the possible allelopathic effect on another species. For this, mineral nutrients, phenolic compounds and quality indicators were analyzed in plants and spears from two asparagus plots (with and without decline symptoms) and germination tests were conducted using lettuce seeds. Decline plants did not show great changes in macronutrient concentration but they showed low B and high Fe concentrations. Leaves and rhizomes from the plot with decline presented higher phenolic compounds, highlighting caffeic acid in rhizomes. However, spears did not present higher phenolic compounds. Likewise, decline decreased the market spear quality and yield but slightly increased some quality indicators such as chlorophylls, carotenoids, ascorbate, and antioxidant capacity. On the other hand, extracts from the decline plot reduced lettuce germination and epicotyl growth suggesting an allelopathic effect. The obtained results are useful to a better understanding of the decline issue and provided valuable information for producers to manage and control its effects on asparagus quality.