Amaranth is a nutritious traditional food and vegetable crop with incomparable health benefits. However, very little research has been carried out to study diversity of amaranth in Nepal. An experiment was conducted in the research field of the Institute of Agriculture and Animal Science (IAAS) at Sundarbazar, Lamjung, Nepal, during 2021 growing season to assess twelve amaranth accessions based on agromorphological characters. Seed materials were collected from the Nepal Agriculture Genetic Resource Center (NAGRC), Khumaltar, and the experiment was conducted in alpha-lattice design with 3 replications. Early maturing accessions had inflorescence at 42.33 days while late maturing accessions were after 82 days. ANOVA test for quantitative traits revealed significant differences among the accessions for all traits studied except stem girth. Similarly, from frequency distribution of agromorphological characters, high variability was found in stem pigmentation, terminal inflorescence shape, inflorescence color, and seed color. Diversity indices (Shannon–Weaver diversity index and Simpson’s index of diversity) were also estimated in which inflorescence color, terminal inflorescence shape, seed color, stem pigmentation, leaf shape, branching index, and leaf pigmentation exhibited high variation confirming the presence of tremendous diversity in Amaranthus. Accessions NGRCO 6977, NGRCO 6969, and NGRCO 6871 had low disease incidence showing the potential of developing resistant varieties through précised breeding in the future. High yield attributing traits were possessed by accessions NGRCO 6977, CO 2435, NGRCO 6904, and CO 1239. Accession NGRCO 6977 was found superior among twelve accessions with highest grain yield and least disease occurrence which can further be evaluated in successive years as a promising variety in mid-hill region.

1. Introduction

Amaranth (Amaranthus spp.) is one of the traditional crops with prolonged history dating 6000–8000 years ago but was lost due to the fall of ancient civilization. Later on, it was rediscovered and distributed worldwide [1, 2]. Amaranthus genus belongs to Amaranthaceae family of Caryophyllales order with more than 60 species [3]. It weighs as the most important crop among three pseudocereals—Chenopodium spp., Fagropyrum spp., and Amaranthus spp. [4].

Amaranth is well-known for both nutritious grain and leaf [5]. The grain, popularly called “Superfood” is gluten-free with high-quality protein, fiber, and micronutrients [6]. Likewise, leaves are rich in protein, minerals, vitamins, and antioxidants [7]. Besides this, amaranth can be grown as ornamentals or may appear as weeds [8]. Amaranth holds several captivating characteristics including biotic and abiotic stress tolerance, and high adaptation in diverse agroecological zones [9, 10]. It can be grown in both winter and summer seasons in Nepal ranging from Himalayan region to Terai region [11].

Amaranth shows high variation in morphological and phenological characters attributable to genetic composition, growing environment, and interaction [12]. Agromorphological variation helps to identify the species and leads to the selection of suitable germplasm for breeding programs [13]. Although amaranths are highly diversified, only a few research activities have been carried out in Nepal. Thus, the collection, and preservation of existing amaranth diversity are of utmost importance. This ensures broader genetic variability which provides genes of favorable traits (high productivity, large seed, diseases and insect resistance, and stress resistance) and crop improvement in future [14, 15]. Thus, this research was conducted to study agromorphological diversity of twelve Amaranthus accessions and evaluate the accessions for yield attributing traits and disease occurrence which may aid impending breeding programs of amaranth.

2. Materials and Methods

Twelve amaranth accessions were collected from Nepal Agriculture Genetic Resource Center (NAGRC), Khumaltar, Lalitpur (Table 1) and cultivated for grain production at the Institute of Agriculture and Animal Science (IAAS) research field at Sundarbazar, Lamjung, Nepal from March to June, 2021. The research was conducted in alpha-lattice design with 3 replications. Each replication consisted of 4 blocks and 3 treatments within each block. For each treatment, the plot size was 2.4 m × 1.2 m. Each plot contained 4 lines with a row spacing of 40 cm and plant-to-plant distance was maintained 40 cm by thinning.

Primary tillage was performed by using a tractor, and the soil was made fine by using a rotavator. Seed was manually sown after mixing with sand to maintain appropriate seed distribution. Thinning was done twice at 3 WAS (weeks after sowing) and 4 WAS [16]. Manual weeding was done thrice at 3, 6, and 9 WAS. Chemical fertilizers were applied as per recommended dose (NPK @ 100 : 50 : 50 kg/ha) in the form of urea, DAP, and MoP. Half dose of nitrogen and full dose of phosphorus and potassium were applied as basal dose whereas remaining half dose of nitrogen was applied as 2 split doses at 30 and 60 DAS (days after sowing) [17]. No insecticides or pesticides were used in the experiment to evaluate amaranth accessions for yield and disease occurrence under natural conditions.

Data were recorded for 13 quantitative traits and 21 qualitative traits according to the descriptor mentioned in IPGRI [18] and Yadav et al. [19]. In addition, scoring of amaranth accessions was done for anthracnose (Colletotrichum gloeosporioides), Cercospora leaf spot (Cercospora canescens), Rhizoctonia blight (Rhizoctonia solani), and Pythium stem canker (Pythium aphanidermatum) at the physiological maturity stage according to scales mentioned by Manandhar et al. [20] and Mihail and Champaco [21].

2.1. Statistical Analysis

Analysis of variance (ANOVA) test was performed for quantitative data using R software version 4.2.1. Qualitative data were analyzed with MS excel to calculate diversity indices, and disease incidence and severity percentage using the following formula.

Shannon–Weaver diversity index was calculated according to Shannon [22]:where n is the frequency of phenotypic class of that character and N is the total number of observations for that character.

It is categorized as mentioned by Ulfah et al. [23].

Less than 1 = low diversity, 1–3 = moderate diversity, and greater than 3 = high diversity.

Simpson’s index (D) was calculated using the formula [24]:where n is the frequency of a phenotypic class of that character and N is the total number of observations for that character.

Simpson’s index of diversity = 1 − D.

Its value ranges from 0 to 1 where 0 means low diversity and 1 means high diversity in particular area.

Evenness (E) was calculated as follows [25]:where H′ = diversity index and S is a total number of variation cases.

Disease incidence was calculated with the formula [20]:

While disease severity was calculated using the formula according to Wheeler [26]:

3. Results and Discussion

3.1. Analysis of Variance of Quantitative Traits

Analysis of variance showed significant differences among the tested accessions for all traits except stem girth indicating the presence of substantial variation. The mean performances of twelve amaranth accessions for 13 quantitative traits are summarized in Tables 2 and 3. Accession CO 1239 had early inflorescence at 42.33 days which is significantly at par with accessions NGRCO 6864, CO 2435, CO 6958, NGRCO 5177, and NGRCO 6904, respectively, whereas CO 6124 had late inflorescence at 82 days showing long vegetative growth period. Significant variation ranging from 88.27 cm for accession CO 2428 to 152 cm for accession NGRCO 6977 was observed for plant height. For inflorescence length, accession CO 2435 (49.81 cm) was found superior which is significantly at par with accession CO 1239. Panicle length varied significantly from 1.20 cm for accessions CO 2428 and CO 6124 to 27.96 cm for accession CO 1239. Similarly, the grain yield was highest (929.74 kg·ha−1) for accession NGRCO 6977 which was followed by accessions CO 2435, CO 1239, NGRCO 6904, CO 7790, NGRCO 6964, NGRCO 5177, and CO 6958, respectively. Significant difference among the amaranth genotypes was stated by Lokeshkumar and Murthy [27] for plant height, panicle length, and grain yield; Nyasulu et al. [28] for plant height, leaf length, leaf width, and inflorescence length; Olusanya [29] for plant height, number of leaves, leaf length, leaf width, number of branches, thousand seed weight, and grain yield. Akaneme and Ani [30] described broad variability in plant height, leaf length, leaf width, and 100 seed weight of amaranth. Similar results were also obtained in studies reported by Erum et al. [31] and Wu et al. [32].

3.2. Frequency Distribution of Qualitative Traits

The frequency distributions of 21 qualitative traits in amaranth are depicted in Table 4 and graphical representations of important traits in Figures 1(a)1(h). Most of the characteristics studied showed significant variation excluding growth habit, spines in leaf axil, and petiole length. Among the studied accessions, 41.67% had no branch, 16.67% had few branches all near the base of stem, 8.33% had many branches all near the base of stem, and 33.33% had many branches all along stem. For stem pigmentation, high variation of yellowish green (50%), orange (8.33%), pink (8.33%), red (16.67%), and reddish green (16.67%) were reported. Leaf margin also showed variation in crenate (16.67%), undulate (41.67%), and entire (41.67%). Leaf shape included lanceolate (33.33%), elliptical (16.67%), cuneate (33.33%), and ovatainate (16.67%). For leaf pigmentation, normal green (58.33%), dark green (17.67%), basal area pigmented leaf (8.33%), margin and vein pigmented leaf (8.33%), and one pale green/chlorotic spot on normal green leaf (8.33%) were observed. Inflorescence color showed high variability with light yellow (8.33%), yellowish green (16.67%), orange (8.33%), pink (33.33%), pinkish green (16.67%), and reddish green (16.67%). Terminal inflorescence shape also had adequate variation with spike (dense) as predominant class. Inflorescence length was short for two-thirds accessions and medium for one-third accessions. Terminal inflorescence attitude among the accessions varied equally between erect and drooping type. For seed color, creamish (25%), pale yellow (16.67%), brown (8.33%), black (41.67%), and golden (8.33%) were found. Results in parallel to our study were reported by Rahman et al. [33] for leaf pigmentation, leaf shape, and terminal inflorescence attitude; Jacques et al. [34] for leaf pigmentation, stem pigmentation, and seed color; Shah et al. [35] for stem pigmentation, leaf pigmentation, and inflorescence color. Similarly, marked variation in stem pigmentation and inflorescence color was revealed by Yadav et al. [19]. Thapa and Blair [36] confirmed wide variability in stem pigmentation, leaf shape, branching index, and inflorescence color. High variation in morphological traits was also supported by Stoilova et al. [37]. The multitudes of morphological characters present in the amaranth are utilized to distinguish accessions [38]. It also manifests the potential of amaranth accessions for agromorphological traits that can be used in selection and hybridization [39].

3.3. Diversity Indices of Qualitative Traits

Shannon–Weaver diversity index, Simpson’s index of diversity, and Evenness of 21 qualitative traits in amaranth are presented in Table 5. Shannon–Weaver diversity index was found lowest for growth habit, spines in leaf axil, and petiole length with only one phenotypic class (monomorphic). Its value was highest (highly polymorphic) for inflorescence color (1.68) followed by terminal inflorescence shape (1.42), seed color (1.42), stem pigmentation (1.36), leaf shape (1.33), branching index (1.24), leaf pigmentation (1.23), petiole pigmentation (1.13), and leaf margin (1.03). Based on Simpson’s index of diversity, it was found that inflorescence color (0.86) had high diversity followed by terminal inflorescence shape (0.79), seed color (0.79), leaf shape (0.79), branching index (0.74), and stem pigmentation (0.74). Stem surface and terminal inflorescence attitude were equally distributed between the smooth and ridged class and erect and drooping class, respectively. This result is in accordance with the findings of Gerrano et al. [13] showing ample diversity for branching index, stem pigmentation, leaf margin, leaf pigmentation, petiole pigmentation, terminal inflorescence shape, and inflorescence color. Zavinon et al. [40] also calculated diversity index for morphological characters in peas and recorded abundant diversity in seed color and stem pigmentation. Wide diversity among the accessions means broader genetic pool which affords extensive opportunities for the selection of desirable traits while breeding [41].

3.4. Disease Evaluation of Amaranthus Accessions

Percentage disease incidence and percentage disease severity for anthracnose, Cercospora leaf spot, Rhizoctonia blight, and Pythium stem canker for each accession under study are presented in Figures 2(a)2(d). Accessions NGRCO 6971, CO 2428, and CO 6124 have high anthracnose incidence; however, the severity of anthracnose was low in all accessions studied. Cercospora leaf spot was significantly high in accessions NGRCO 5177, NGRCO 6864, NGRCO 6904, and CO 2435. In contrast, accessions NGRCO 6969, NGRCO 6971, NGRCO 6977, CO2428, and CO 6124 were devoid of Cercospora incidence. High incidence and severity percentage of Rhizoctonia blight were observed for NGRCO 6864, NGRCO 6904, and CO 7790; nonetheless, NGRCO 6969, NGRCO 6971, NGRCO 6977 were resistant to Rhizoctonia blight. Pythium stem canker was recorded in all accessions studied except NGRCO 6977. Zippora et al. [42], surveyed in Ghana and found incidence percentage of anthracnose ranging from 0 to 58.3% in amaranth, quite similar to our result. Celine et al. [43] also reported high attack of Rhizoctonia solani on amaranth accessions. Tested amaranth accessions exhibited a different level of susceptibility for each diseases providing information about genotypes showing resistance against particular disease [44].

3.5. Identification of Elite Accessions

Accessions holding value of yield attributing traits greater than sum of grand mean and standard error for that trait are considered elite accessions [45]. The elite accessions having desirable trait are listed in descending order in Table 6. Accession NGRCO 6977 was the only accession with six yield attributing traits out of seven traits followed by accessions CO 2435, and NGRCO 6904 with five favorable traits. Accession CO 1239 possesses four yield attributing traits out of seven traits.

The accessions with high yield attributing traits along with disease resistance are prerequisites for augmentation of the crop by selection. Accession NGRCO 6977 had maximum yield attributing traits and no disease occurrence except anthracnose. Therefore, it may hold genetic composition which can aid the development of more productive and resistant varieties. Furthermore, accessions CO 2435, CO1239, NGRCO 6904, NGRCO 6864, CO 6958, and CO 6124 can be selected for desired traits according to their performance for particular traits.

4. Conclusion

Considerable diversity is available for qualitative and quantitative traits among tested amaranth accessions which provides insight into the broad genetic base of Amaranthus accessions. Furthermore, it offers the selection from diverse characters and preserves the wide genetic pool without narrowing in future breeding activities. Scope of amaranth breeding for fungal disease resistance is established by the vast difference in the incidence and severity percentage of studied diseases among amaranth accessions. In present study, accession NGRCO 6977 was found most promising compared to other tested accessions and therefore should be evaluated further in mid-hill region to develop as an excellent variety. Other elite accessions included CO 2435, CO1239, NGRCO 6904, NGRCO 6864, CO 6958, and CO 6124. The genetic contribution of productive and resistant characters in these superior accessions should be analyzed at the molecular level. Through sophisticated breeding, we can utilize those favorable genes to develop outstanding varieties for sustainable production of amaranth.

Data Availability

The data used to support the findings of the study are available on request.

Conflicts of Interest

The authors declare that they have no conflicts of interest.


This study was supported by the Association of Nepalese Agricultural Professionals of Americas (NAPA) (NAPA RMG 2020-32).