Amaranth grain production as affected by watering regimes and day length in southern Mozambique

Abstract

The high nutritional value of amaranth grain makes it attractive for the diet of rural people living in dry semi-arid areas of southern Mozambique. A study was implemented with Amaranthus hybridus and A. tricolor in sandy soil aiming to assess (1) the effect of different watering regimes (80%, 50% and 20% of total available water) on reproductive stage and grain crude protein content of the two species during the rainy and dry seasons, and (2) the effect of day length and minimum temperature on the time to flowering. Six field trials were conducted in Maputo in a randomised complete block design with a 2 × 3 factorial layout with six replications. This study revealed that panicle and internode lengths as well as straw and grain yields of both species decrease when the soil water content decrease. Conversely, the time to flowering and the grain crude protein contents were unaffected by the water deficit. The onset of flowering was significantly delayed by long days. The highest grain yield and harvest index were produced by A. tricolor under day lengths above 12 h d−1. When irrigation was applied to maintain soil water content at 80% of total available water, both species produced all year long.