Comparison of Agronomic Parameters and Nutritional Composition on Red and Green Amaranth Species Grown in Open Field Versus Greenhouse Environment

Abstract

Previously, researchers have not paid attention to indigenous African leafy vegetables such as nightshade and kale, however, amaranth species have recently gained popularity due to their adaptability to various climatic conditions and their cultivation in both open fields and hydroponics. Amaranth species are ranked among the underutilized leafy vegetables with medicinal properties, economic values, nutritional and health benefits. This study aimed to compare the growth parameters and nutritional composition of two consumed red (Amaranthus Cruentus L.) and green (Amaranthus Graecizans L.) amaranth species in South Africa, cultivated in an open field versus a greenhouse. The findings showed a high chlorophyll content and large leaf area under open field conditions on red and green species. The number of leaves and stem height were higher in the greenhouse cultivation system. In open field cultivation, minerals such as calcium, magnesium, phosphorus, iron, zinc, aluminium, copper and manganese for both species were significantly higher whilst potassium, sodium, boron, sulphur were significantly higher in the greenhouse production. The sufficient total nitrogen and ash were recorded in the open field production, and no significant difference was observed between the open field and greenhouse on moisture and ash content of A. Cruentus. In conclusion, A. Cruentus and A. Graecizansn grown in an open field had higher proximate and mineral composition over the greenhouse cultivation system.

1H NMR-Based Metabolomics Profile of Green and Red Amaranthus Grown in Open Field versus Greenhouse Cultivation System

“…Itsani village has a Latitude of −22.94786, a Longitude of 30.47276, and an altitude of approximately 1140 m above sea level. During the summer planting period (October to March), temperatures range from 26–32 °C with an average rainfall of ±500 mm annually [ 11 ].…”

“…According to Managa and Nemadodzi [ 11 ] the high nutritional value of Amaranthus leaves, specifically Amaranthus graecizans L., has made it the most sought-after vegetable in the rural areas among the poor citizens in the Limpopo province of South Africa. The leaves are usually cooked in supplements with other green leafy vegetables such as mallow jew, pumpkin leaves, blackjack, and nightshade, and consumed with starch made of hard porridge commonly known as “Vhuswa” by the VhaVenda tribe, “Vuswa” by the VaTsonga tribe, and “Bokgobe” by the BaPedi tribe.…”

Response of Black Nightshade to Different Cropping Systems and the Effect on Physiological Parameters and Mineral Composition

“…The open field trial was carried out at Itsani Matieni village, found in Thulamela Local Municipality under Vhembe District (Latitude: −22°9ʹ47.86ʺ; Longitude: 30°47ʹ27.6ʺ) with 550 m altitude, Limpopo Province, South Africa. The planting took place in the summer season when temperatures ranged between a minimum of 26 and a maximum of 32°C and annual rainfall of AE500 mm in October-March [43]. The experiment lasted for 4 months (October-December 2021) for both cropping systems.…”

“…In both cropping systems, direct sowing in sandy loam soil was used as a planting method. The potting plant of 20 cm in diameter, with a height of 17.5 cm, and 20 cm width were laid at 0.3 m by 0.25 m interand intrarow spacing, respectively, as prescribed by Managa and Nemadodzi [43] with crop density established at 30 plants per 7 m 2 . Cultivation was done without fertilisers as adopted from Van Rensburg et al [45].…”

“…Leaf chlorophyll content was measured using a spectrophotometer (Konica Minolta SPAD-502 PLUS Chlorophyll Meter, 2 × 3 mm, −9.9 to + 199.9 SPAD) the non-destructive approach method was used to determine leaf chlorophyll in fresh, healthy edible leaves in (SPAD units) as described by Bvenura and Afolayan [49] and Zhang et al [50]. Furthermore, plant height was measured with a tape measure as prescribed by Managa and Nemadodzi [43].…”