Influence of row spacing on canopy and seed production in grain amaranth (Amaranthus cruentus L.)

A new crop recently introduced in Italy is amaranth. Studies involving agronomic techniques on this plant are limited. The aim of the present research was to assess the effect of distance between rows on both seed yield and ground cover in Amaranthus cruentus L. Sowing treatments included two single row spacing designs (18 and 60 cm) and one double row spacing design (18 + 60 cm). At the six true leaf stage, in the single row design of 60 and 18 cm row spacing, ground cover was 16% and 47% respectively. An intermediate coverage of 31% was evident in the double rows. At the ten true leaf stage, plants cultivated in single rows at 18 cm covered the ground early, thereby attaining a ground cover of 85%. Regarding yield, a seed production of 0.92 t ha was obtained from plants in the double row design compared to the respective single row spacing designs of 18 and 60 cm, where yields were 0.85 and 0.70 t ha respectively. The selection of one mode of sowing over another will largely depend on the type of equipment available to the farm. Whilst single row spacing distances of 18 cm displayed a net of advantage against weeds, difficulties were encountered in the case of managing weeds by mechanical equipment. The use of double rows permitted taking advantage of a slightly better ground cover than single rows, together with the possibility of mechanical intervention for the control of weeds, and importantly also provided a higher yield.