Allelopathic influence of soils planted to Amaranthus cruentus L. On two tomato (Lycopersicon esculentum Mill.) cultivars

Abstract

Amaranthus cruentus L. is being evaluated as a potential high value niche market crop for small-scale farmers in South Africa. This is largely due to the demand for organically produced seed for the European health food market where it is used in a variety of products. Tomatoes were planted six months after a pilot planting of amaranth at Rust de Winter, near Pretoria. Problems with the growth and development of the tomato plants were noticed within a fairly short period. Investigations revealed no nutritional or pest and disease problems. Soil was collected from the problem field, as well as from an adjacent field with similar soil to investigate possible soil problems. Two tomato (Lycopersicon esculentum Mill.) cultivars (Rodade and Floradade) were grown in pots containing these soils in an air-conditioned glasshouse under natural light conditions. Both cultivars exhibited signs of significantly inhibited growth (reduced height, leaf area, leaf number and shoot mass) when grown in soil from the amaranth field. It was concluded that A cruentus residues were probably allelopathic to these two cultivars of tomato. © 2006, Taylor & Francis Group, LLC.