Leaf yield of Amaranthus hypochondriatus L. (Imbuya), affected by irrigation systems and water quality

Abstract

Family scale vegetable production should be enhanced in rural areas in order to prevent vitamin A deficiencies. A soil-less water-use-efficient ‘Ebb-and-Flood’ production system, developed for areas with limited water resources, was compared with two conventional soil irrigation systems, using Amaranthus hypochondriatus L., locally known as Imbuya. The soil-grown plants were flood- and drip irrigated once every week, using nutrient solutions at two electrical conductivity (EC) levels of 1.80 mS cm−1 and 3.60 mS cm−1. The same volumes of nutrient solution were applied to these soil-irrigated plots as was used in the preceding week by the soil-less ‘Ebb-and-Flood’ system. With the soil-less ‘Ebb-and-Flood’ system, plants were fertigated five times per day and the containers were randomly allocated between the soil-grown field plots. Leaf yield as well as water use efficiency was highest when the high EC nutrient solution was drip irrigated. As part of the drip treatment, the dripper lines were covered with white plastic soil mulch to limit soil moisture losses. Due to rain before transplanting, the field-grown drip- and flood-irrigated treatments received extra water from the soil. In spite of this, the ‘Ebb-and-Flood’ system out yielded the flood treatment, when the nutrient solution with an EC of 3.60 mS cm−1 was used, probably due to insufficient root aeration in the flooded soil or due to better water uptake by the ‘Ebb-and-Flood’ system under saline conditions.