Phenotypic Evaluation of Heritability, Agro-Morphological and Yield Characters of Sixteen Amaranthus Linn. Genotypes

Corresponding Author: Onuoha Samuel Ogechi Genetics and Molecular Biology Unit, Department of Botany, University of Ibadan, Ibadan, Nigeria Email: sam4christ2005@gmail.com Abstract: The field experiment was conducted to evaluate the heritability, genetic variance, agro-morphological and yield characters of Sixteen Amaranthus genotypes. The seeds of the sixteen (16) genotypes of Amaranthus evaluated in this study were; NG/AA/MAY/09/027, NG/AA/03/11/010, NG/AO/11/08/042, NG/AO/11/08/039, NG/SA/DEC/07/0423, NG/SA/DEC/07/0412, NGB01667, NGB01601, NGB01283, NGB01271, NGB01276, NGB01259, NGB01644, NGB01234, NGB01613 and NGB01662. The results showed that there were variability performances in growth and yield characters of Amaranthus genotypes. NG/AA/MAY/09/027 and NG/AO/11/08/039 had the best growth characters while NG/AO/11/08/042 had best yield performance compared to other genotypes. The stem length recorded the best heritability estimate of 95.5% while weight of dry leaf, weight of fresh and dry inflorescent had least (47.7%). The plant height had a positive significant correlation with number of leaf (r = 0.53), leaf width (r = 0.57), number of branches (r = 0.56) but a strong positive correlation with stem length (r = 0.97), stem girth (r = 0.75), number of inflorescent (r = 0.68), inflorescent length (0.64) and inflorescent width (r = 0.72). Prin. 1 accounted for the highest variation in growth and yield characters with proportion of 0.3376 and eigen value of 4.7269, while Prin. 14 was the least with proportion of 0.0003 and eigen value of 0.0038. Therefore, there could be genetic improvement of NG/AA/MAY/09/027 and NG/AO/11/08/039 genotypes for further improvement of Amaranthus.


Introduction
The genus Amaranthus of the order Caryophillalales comprises of more than 60 species C4 dicotyledonous herbaceous plants. Amaranthus species are cultivated in Central and South America, Africa and some parts of Asia as ornamentals, some are a source of highly nutritious pseudo-cereals and vegetables while others are notoriously weeds (Holm et al., 1997;Steckel, 2007). It has received attention due to its essential nutrients for the human diet (Tucker, 1986;Bressani et al., 1992). Amaranthus species are tolerant to infestation by herbivorous insects under field conditions and can grow successfully under varied soil and agro-climatic conditions such as bright sunlight, high temperatures and low moisture (Prakash and Pal, 1991;Brenner et al., 2010;Angel and Paulina, 2011). It can also tolerate a variety of unfavorable soil conditions such as high salinity, acidity, or alkalinity (Tucker, 1986). Besides other crops, cultivation of this vegetable will not only increase food production but also provide balanced nutrition, food security, health security and poverty alleviation (Buragohain et al., 2013).
Despite the perceived usefulness and untapped potentials of this vegetable, Amaranthus are underutilized making their potential economic value remaining "underexploited". It has also been reported that it has been neglected for many years by researchers, policy makers and funding agencies and thus currently threatened by extinction. Hence, improvement of this vegetable is highly needed to ensure maximum agronomic yield and high productivity of Amaranthus with a view to conserve the germplasm.
This study aimed at evaluating the heritability, genetic variance, agro-morphological and yield characters of Sixteen Amaranthus genotypes so as to improve the production of Amaranthus spp. for proper documentation of Amaranthus germplasm.

Experimental Site and Amaranthus Germplasm
This study was carried out at the Nursery Farm of the Department of Botany, University of Ibadan, Oyo state, Nigeria. The site lies between Latitude 7°02' 49″ and 7°43′ 21″ N longitude 3°31′ 58″ and 4°08′ 20″ E with an altitude of 150 m in the valley at 275 m above sea level at moderate annual rainfall of 1,205 mm (Amanambu and Egbinola, 2013). The seeds of the sixteen Amaranthus spp. Genotypes were sourced from the National Centre for Genetic Resources

Experimental Design, Plant Spacing and Planting Method
The Experiment was a complete Randomized Design with the polythene bags properly spaced at a distance of 65 cm between genotypes and 45 cm within genotypes. The young shoots were transplanted in pairs in each labeled polythene bags replicated four times. The seeds were first planted in the nursery through broadcasting for three weeks before transplanting in pairs to the well-labeled experimental polythene bags at the Nursery Farm of the Department of Botany, University of Ibadan, Oyo state, Nigeria. The cultivation was monitored and watered daily to resist drought.

Data Collection
After one week of transplanting, data taken weekly on growth characters included plant height (cm), number of leaves, stem length (cm), stem girth (cm) and leaf area (cm 2 ). The plant height, stem length and leaf area were measured using a meter rule while stem girth was measured with a vernier caliper. Quantitative and qualitative data on flower characters were collected at maturity for six (6) weeks, this included number of inflorescence, inflorescence width (cm), inflorescence length (cm) and number of branches. The number of inflorescence and number of branches were done by counting, while inflorescence width and inflorescence length were determined by measurement using a metre rule. The inflorescence color and plant color were also determined by observation. After harvesting, the biomass of fresh and dry inflorescence and leaves were determined for each of the genotype using weighing balance. Heritability and genetic variance was also determined using these formulas:

Statistical Analysis
The data were subjected to Analysis of Variance (ANOVA) and difference in means was separated using DMRT at 95% probability level (p<0.05). The relationship among the quantitative and qualitative traits were established using Pearson correlation coefficient and Principal Component Analysis (PCA). In addition, Heritability, Phenotypic Coefficient of Variance (PCV), Genotypic Coefficient of Variance (GCV) were also determined.

Qualitative Traits in Amaranthus Genotypes
The qualitative traits observed in genotypes of Amaranthus are shown in Table 1. Genotypes NG/AA/MAY/09/027, NG/AA/03/11/010, NG/AO/11/08/039, NGB01601, NGB01271, NGB01276, NGB01259, NGB01644, NGB01234 and NGB01662 had a plant and spike/inflorescence color of green while NG/AO/11/08/042, NG/SA/DEC/07/0423, NG/SA/DEC/07/0412, NGB01667, NGB01283 and NGB01613 had plant and spike/inflorescence color of green but with a shade of purple. The spike/inflorescence colors were observed to vary from green to green with a shade of purple. The grain colors were observed to be TAN which is a light-brown color across all the genotype.

Mean Square Variance of Growth Characters in Amaranthus Genotypes
The result of the mean square variance of growth character for Amaranthus from Table 2 shows that the genotype and weeks after planting produced significant (p<0.01) effect on Plant height, Number of leaves, Stem length, Stem girth and Leaf width but non-significant on Leaf length for both genotype and week.

Mean Square Variance of Yield Characters in Amaranthus Genotypes
The result of the mean square variance of yield characters in Table 3 shows that the genotype and weeks after planting produced significant effect (p<0.01) on Number of Inflorescence, Inflorescence length, Inflorescence width, Number of branches, Fresh leaf biomass, Weight of dry leaf, Weight of fresh inflorescent and Weight of dry inflorescent. 575 * = Significant at p<0.05, ** = Highly significant at p<0.01, *** = Highly significant at p<0.001, ns = Non-significant, Df = Degree of freedom 03 Corrected total 575 * = Significant at p<0.05, ** = Highly significant at p<0.01, *** = Highly significant at p<0.001, ns = Non-significant, Df = Degree of freedom

Genotypic Effect of Growth Characters in Amaranthus Genotypes
The result of the mean performance of genotypic effect on growth character of Amaranthus reveals significant (p<0.01) effect on Amaranthus genotypes as shown in Table 4. NG/AA/MAY/09/027 was significantly higher for Plant height and Stem length compared to other genotypes. Also, leaf width produced significant effect for NGB01271 while Stem girth and Leaf length were significantly higher for NG/AO/11/08/039 but different from other genotypes. NGB01644 was significantly higher for Number of leaves than other genotypes.

Heritability and Genotypic variance of Growth and Yield Traits of Amaranthus Genotype
The result of the component of variance for growth and yield traits in Amaranthus shown in Table 6 reveals that the phenotypic variance of both growth and yield characters were higher than the genotypic variance in all the characters evaluated. The values for the phenotypic and genotypic variance were highest at Number of leaves but least at weight of dry leaf. The stem length recorded the best heritability estimate of 95.5% while weight of dry leaf, weight of fresh and dry inflorescent had least (47.7%).

Principal Components Analysis (PCA) of Growth and Yield Characters of Genotypes of Amaranthus spp.
The result from Table 7 delineates the Amaranthus genotype into fourteen principal component axes; Prin. 1,2,3,4,5,6,7,8,9,10,11,12,13 and 14. Prin. 1 which constituted the highest accounted for 0.3376 of the total proportion with eigen value of 4.7269, while Prin. 14 was the least with proportion of 0.0003 and eigenvalue of 0.0038. Weight of dry leaf from Prin. 1 had the highest eigen vector of 0.3973 while Number of leaves was the least with (-0.0793). Also Prin. 2 produced the highest eigen vector for Leaf length at 0.3805 while weight of fresh leaf biomass had the least at 0.1669. Prin. 3 produced the highest eigen vector at 0.5883 for number of inflorescent while Leaf length produced the least at (-0.0073). Prin. 4 produced the highest eigen vector at 0.6181 for Number of branches while Inflorescent length had the least at (-0.0206). Prin. 5 produced the highest eigen vector at 0.4813 for Plant height while weight of fresh leaf biomass had the least at (-0.0132). Prin. 6 produced the highest eigen vector at 0.6235 for Number of leaves while Number of Inflorescent had the least at (-0.0233). Prin. 7 produced the highest eigen vector at 0.4703 for leaf length while Weight of fresh leaf biomass had the least at (-0.0095). Prin. 8 produced the highest eigen vector at 0.4288 for number of inflorescent while Weight of fresh leaf had the least at (-0.0066). Prin. 9 produced the highest eigen vector at 0.6692 for inflorescent width while Weight of fresh inflorescent biomass had the least at (-0.0428). Prin. 10 produced the highest eigen vector at 0.7038 for Leaf width while Plant height has the least at (-0.1351). Prin. 11 produced the highest eigen vector at 0.8057 for Weight of fresh leaf biomass while leaf length has the least at (-0.0607). Prin. 12 produced the highest eigen vector at 0.3997 for Weight of dry leaf biomass while leaf length has the least at (-0.0051). Prin. 13 produced the highest eigen vector at 0.6030 for plant height while number of Branches has the least at (-0.0217). Prin. 14 produced the highest eigen vector at 0.7029 for Weight of dry inflorescent biomass while Stem length has the least at (-0.0012).

Correlation Co-efficient among Characters in Genotype of Amaranthus spp.
The correlation result is shown in Table 8

Dendogram Showing the Relationship of Yield Characters Among the Amaranthus Genotypes
The dendogram showing the relationship of Yield Characters among the Amaranthus Genotypes is shown in Fig. 1. There are two major clusters sub-divided into four (4) groups. Genotype NG/SA/DEC/07/0423 and NGBO1271 is closely related but different from genotype NGB01613 while genotype NGB01667 and NGB01283 is similar than genotype NGB01276. Also, genotype NGB01259 and NGB01644 are closely related compared to genotype NGB01662. Again, genotype NG/AA/03/11/010 and NG/AA/MAY/09/027 are closely related than genotype NGB01234 while genotype NG/AO/11/08/042 and NG/SA/DEC/07/0412 are similar as also observed in genotype NG/AO/11/08/039 and NGB01601.

Dendogram Showing the Relationship of Growth Characters Among the Amaranthus Genotypes
The relationship of Growth Characters among the Amaranthus Genotypes is depicted in the dendogram as shown in Fig. 2. There are three major clusters subdivided into five (5)

Discussion
The findings from this study showed that there are variations in the performance of growth and yield characters studied among the Amaranthus genotypes. This is in accordance with the reports of Nwangburuka et al. (2012) and Olawuyi et al. (2014) who considered genetic variability as essential in crop breeding. The genotypic effect also had significant expression on the traits evaluated in Amaranthus. Variability in performance of genotypes also affected the growth performance of Amaranthus. The variations shown by the characters were due to high genetic diversity, differences of growing type and differences on the type of adaptation (Kulakow, 1987;Mujica and Jacobsen, 2003).
The best performance of growth and yield characters exhibited by NG/AA/MAY/09/027, NG/AO/11/08/039 and NG/AO/11/08/042 genotypes ( Fig. 3 and Fig. 4) could be due to genetic variation of these genotypes. Selections based on this characters and the genetic diversity inherent in the plants could thus improve productivity considerably. These performances shown by Amaranthus also suggest hybridization breeding procedure for crop improvement with desired traits in the parents line.
The findings from correlation coefficient shows that the characters were mostly positively related as similarly observed by Olawuyi et al. (2012). The correlation between the characters implies that selection based on plant height will favour all growth and yield characters. This will enhance the rate of productivity and yield.
Prin 1 accounted for the highest variation as previously observed by Olowe et al. (2013) and Olawuyi et al. (2015). The results of the Principal components analysis reveals the pattern of variation among the characters studied and the characters that accounted most for variation within a group of entries (Ogunbodede and Omueti, 1997;Aremu et al., 2007). It implies that the Principal Component Analysis (PCA) can be quantified from the contribution of the different variable to each principal component as revealed by the eigen vector (Lezzoni and Pritts, 1991).
This phenotypic expressions might be due to environmental influences; exacerbating this problem is the presence of considerable morphological variation within cultivated populations (Sauer, 1967;Espitia, 1992). This shows that their genotypes and species genetic make-up played a huge role in the phenotypes expressed in this studies.
The phenotypic variance of both growth and yield characters were higher than the genotypic variance in all the characters studied. Heritability of growth traits were higher than yield traits in Amaranthus genotypes. This shows that the proportion of genotypic effect to phenotypic effect was higher at growth than maturity. This conforms to the report of Palaniappan et al. (1999) who observed an improvement in general crop performance. This supported the findings of Chadha and Paul, 1984;Gautam and Srinivas, 1992;Prasad et al., 2004;Singh and Kumar, 2005;Babu and Patil, 2005 who reported high heritability and genetic advance for yield characters for Solanum melongena.

Conclusion and Recommendation
The variations in the genotypes could be sufficient basis for crop improvement. NG/AA/MAY/09/027, NG/AO/11/08/039 and NG/AO/11/08/042 are promising genotypes that could be selected and explored for future breeding in improvement of Amaranthus vegetable. This will further enhance proper documentation and conservation of Amaranthus germplasm.