Abstract

Low phosphorus (P) availability in soils is one of the major limiting factors for crop production in Southern Chile. Although Si is considered non-essential element for vascular plants, its uptake and subsequent accumulation can provide benefits for crops exposed to stress conditions, including P deficiency. This research was aimed to evaluate the effect of Si fertilization on P/Si uptake, total phenol concentration and antioxidant capacity in barley (Hordeum vulgare L.) plants grown under different P supply at field conditions. A field experiment in an acid Andisol of Southern Chile was conducted by using two barley cultivars with contrasting tolerance to P deficiency (cv. Traveler, sensitive to P deficiency; and cv. Sebastian, tolerant to P deficiency). Different P fertilization doses (0, 200, 400 mg P kg-1 soil) were applied in combination with three Si doses (0, 250, 500 mg Si kg-1 soil). Plants were harvested at tillering state, and P and Si concentration, phenol concentration and free radical scavenging activity were evaluated. Silicon concentration increased in both cultivars as P dose rose, whereas P concentration remained unchanged at different levels of Si supplied. Silicon application to cv. Sebastian improved the concentration of total phenols irrespective of P fertilization dose. The highest phenol accumulation in cv. Sebastian was detected when 500 mg kg-1 Si was applied in combination with 400 mg kg-1 P. In contrast, Si applied to cv. Traveler reduced total phenols by about 19% at 200 mg kg-1 P supply. Even though no changes in antioxidant activity were detected in cv. Sebastian, a decrease of antioxidant activity was induced by Si in cv. Traveler fertilized with either 200 or 400 mg kg-1 P.