Position of amaranthus seed on the plant in relation to seed quality and productivity under varying water regimes.

Abstract

Amaranth is one of the important vegetables that are highly nutritious in protein, iron, vitamins A, C, and K. Its nutritional value can be used to reduce food insecurity, poverty and malnutrition problems in South Africa because it occurs naturally and it has the ability to tolerate drought and produce reasonable yield in infertile soils. Amaranth occurs in different species and landraces. In commercial agriculture, this is a serious weed plant. However, it is also utilised as a leafy vegetable crop in many developing countries. In South Africa, it is considered as an underutilized traditional crop with limited cultivation compared to other vegetable crops. The aim of the study was to determine seed quality, growth, and development of two amaranth landraces collected from three agriculture locations in KwaZulu-Natal, South Africa, where the plant is utilised for food security when it is available during the cropping season. Three positions on the plant were defined as equal thirdiles of the seed filled portion of the plant referred to as top, middle and bottom. Seed quality of the harvested original material was determined in terms of physical attributes (seed weight) and germination parameters, namely vigour, rate, and total. Then the original seeds were planted to produce plants under controlled environment conditions differing in water regimes from the seedling establishment to harvest maturity. The water regimes were 100% field capacity (FC), 50% FC and 30% FC to create adequate and stressed conditions. First-generation plant growth and development was determined in terms of morphology (plant height, leaf number, leaf area and aboveground biomass). This response was correlated with physiological parameter namely stomatal conductance and chlorophyll content index. Seed quality results showed that seed weight parameters namely, seed mass per landrace, seed mass per part, and thousand seed mass were significantly affected (p<0.05) by site, landrace, and position on the plant. Seed water content was significantly affected by landrace and water activity was significantly affected by sites only. Germination was significantly affected (p<0.05) by landrace, position, and site. Controlled tunnel results showed that plant height and leaf area were significantly (p<0.05) affected by site, landrace water regimes and the interaction of site, water regime, position, and landraces. However, in leaf number, site, landrace, position and water regimes were significantly (p<0.05) affected but the interaction of site, water regime, position, and landrace were not significantly (p˃0.05) affected. Both physiological parameters (chlorophyll content index and stomatal conductance) were not significantly (p˃0.05) affected by site, landrace, 5 position and their interaction, However, they were significantly (p<0.05) affected by water regimes. Leaf yield was significantly (p<0.05) affected by water regimes and the interaction of site and water regimes only. For both parent and first generations, seed quality differed with the position on the plant, where middle and bottom seed performed better than top located seed. Water stress reduced seed quality. It is concluded that seed quality of amaranthus is associated with a position on the plant, regardless of the location of harvested material. Water stress reduces plant growth and seed yield. Keywords: Amaranthus, position on the plant; seed quality, crop performance