Leaf area, root lenght and grain yield of Amaranthus hypocondriacus L. grown on a highly compacted soil

Abstract

A highly compacted soil layer was detected in an amaranth field in Tulyehualco, México. The purpose of the present work was to analyze the effect of soil compaction on the crop of amaranth. Two plots with superficial (S) (10-15 cm) and intermediate (I) (20-25 cm) levels of compaction were compared. Several crop physiology parameters were studied and soil resistance was measured with a digital penetrometer. The cone Index values of both compacted soil layers were > 3 MPa. Amaranth plants from the S plot had 46% smaller leaf area (p<0.01) and were 12% shorter (p<0.01) than those from the I plot. The grain yield was significantly higher in plants from I compared to plants from S (68 vs 38 g/plant, p< 0.03). Concerning the root growth, the main roots of plants from S were 34% shorter than those from I (p<0.01). The adventitious roots emerging from the stem base were very prolific in both plots (non statistical differences were appreciated). Adventitious roots were 4-4.8 times longer than main of plants from either plot. In summary, our results show that the depth of compacted soil layer has a direct effect on the amaranth crop. Superficial soil compaction rendered short plants with lower grain yield whereas intermediate compaction resulted in taller plants with higher grain yield.