Effect of Deficiencies of Nitrogen, Potassium and Sulfur on Chlorogenic Acids and Scopolin in Sunflower

Abstract

Helianthus annuus, an important species in the first stage of succession in infertile old-fields in Oklahoma and Kansas, was previously found to produce chlorogenic acid and scopolin which are inhibitory to many plants of the same successional stage. Consequently, investigations were made to determine effects of age and fertility on concentrations of those phenolics and related compounds in H. annuus. Concentrations of chlorogenic acid in control leaves of Helianthus annuus increased with age of the plant, and also in stems up to the 4th week of experimentation. Scopolin concentrations increased with age in old leaves and remained stable in the stems during most of the experimental treatment. Scopolin was not present in measurable amounts in young leaves or in roots. Chlorogenic acid concentrations were generally significantly higher in stems and leaves of mineral-deficient plants than in controls. Except for nitrogen-deficient plants, young leaves accumulated greater concentrations of chlorogenic acids than old leaves. Concentrations in roots were variable and no definite trends occurred. Band-510 (4-0-caffeoylquinic acid) and neochlorogenic acid were present in all plant tissues but not at all sampling times. Concentrations of both were generally higher in potassium-deficient stems, nitrogendeficient old leaves and stems, and sulfur-deficient old leaves, young leaves and stems than in controls. In addition neochlorogenic acid was generally higher in potassium-deficient young leaves than in controls. Band-510 was usually lower in concentration in nitrogen-deficient young leaves and roots, and neochlorogenic acid was generally lower in potassium-deficient roots than in controls. The concentrations of scopolin increased considerably, compared to the amounts in controls, in potassium-deficient old leaves, young leaves and stems during the last 3 weeks of treatment. In sulfur-deficient stems the scopolin concentration decreased with age but was generally not significantly different from the concentration in controls. Nitrogen deficiency decreased the concentration of scopolin in stems but had no other effects. The increased concentration of chlorogenic acids in sunflower with increase in age of plants and with mineral deficiencies probably increases the allelopathic effects of that species in the first stage of succession in infertile old-fields.