Precision phenotyping and association between morphological traits and nutritional content in Vegetable Amaranth (Amaranthus spp.)

Amaranth (Amaranthus spp.) is an important leafy vegetable and grain crop which is a good source of nutrients and bioactive compounds, widely consumed in several parts of the world. However, varieties of different Amaranthus species show great phenotypic variation and may also have different nutritional attributes. This study aimed to phenotype vegetable amaranth accessions of four different species (Amaranthus hypochondriacus, Amaranthus cruentus, Amaranthus dubius and Amaranthus blitum) and relate the morphological data to nutritional attributes of the leaves. Ten selected amaranth accessions obtained from the World Vegetable Center collections in Arusha and Taiwan were subjected to a high throughput phenotyping system to determine digital biomass, greenness, plant height and hue of the leaves using 3D scanning. These phenotypic data was correlated with the nutritional traits including carotenoids, flavonoids, vitamin C, minerals and oxalate contents of the various accessions. The analysis of variance for both morphological and nutritional traits showed significant (P≤0.05) difference for most traits recorded between the accessions. The A. blitum (AM1909) had the slowest daily increases in morphological traits compared to other accessions. Significant correlations were also recorded among the various morphological traits. Amaranth accession AM1908 (A. dubius) and AM1910 (A. dubius) had the highest content of most nutrients, while AM1902 (A. hypochondriacus) and AM1903 (A. hypochondriacus) had the lowest nutrient content. Significant correlations were observed between greenness with oxalate and vitamin C contents, as well as between hue values and carotenoids. We conclude that only some of the morphological traits of amaranth are associated with the nutritional content of the leaf. Based on the findings, we recommend that leaf color can be used as breeding trait to target nutritional attributes

The World Vegetable Center Amaranthus germplasm collection: Core collection development and evaluation of agronomic and nutritional traits

Amaranth (Amaranthus spp.) is an underutilized crop increasing in popularity as a grain and as a leafy vegetable. It is rich in protein, minerals, and vitamins, and adapts well to a range of production systems. Currently, the lack of improved cultivars limits the use of the crop. Breeding-improved cultivars requires access to large collections of amaranth biodiversity stored in genebanks. The task of searching such vast collections for traits of interest can be eased by generating core collections, which display the diversity of large collections in a much smaller germplasm set. The World Vegetable Center amaranth collection contains around 1,000 accessions of 13 species; among them, there are 281 accessions of four species important for use as vegetable amaranth in Africa (A. cruentus, A. hypochondriacus, A. caudatus, and A. dubius). Based on single nucleotide polymorphism (SNP) marker genotype diversity, a core collection (CC) of 76 accessions, cultivars, and selections was assembled. To a large extent, it represents the diversity of the whole collection. The CC was evaluated for yield and nutritional parameters during the cool and warm seasons in Tanzania and Taiwan and a pretest for variation of drought tolerance in the CC has been performed. Cultivar Madiira 2, an improved cultivar developed for vegetable production in Africa, outperformed all other tested cultivars in terms of yield stability, but several CC accessions had higher yield, lower wilting score, and higher nutrient content than Madiira 2. This indicates the core collection can be used for further improvement of amaranth cultivars