Morphological diversity of mango germplasm from the upper athi river region of eastern Kenya: An analysis based on non- fruit descriptors

Abstract

Phenotypic variation in plants can be evaluated by morphological characterization using visual attributes. Fruits have been the major descriptors for identification of different varieties of fruit crops. However, even in their absence, farmers, breeders and interested stakeholders require to distinguish between different mango varieties. This study aimed at determining diversity in mango germplasm from the Upper Athi River (UAR) and providing useful alternative descriptors for the identification of different mango varieties in the absence of fruits. A total of 20 International Plant Genetic Resources Institute (IPGRI) descriptors for mango were selected for use in the visual assessment of 98 mango accessions from 15 sites of the UAR region of eastern Kenya. Purposive sampling was used to identify farmers growing diverse varieties of mangoes. Evaluation of the descriptors was performed on-site and the data collected were then subjected to multivariate analysis including Principal Component Analysis (PCA) and Cluster analysis, one-way analysis of variance (ANOVA) and Chi square tests. Results classified the accessions into two major groups corresponding to indigenous and exotic varieties. The PCA showed the first six principal components accounting for 75.12% of the total variance. A strong and highly significant correlation was observed between the color of fully grown leaves, leaf blade width, leaf blade length and petiole length and also between the leaf attitude, color of young leaf, stem circumference, tree height, leaf margin, growth habit and fragrance. Useful descriptors for morphological evaluation were 14 out of the selected 20; however, ANOVA and Chi square test revealed that diversity in the accessions was majorly as a result of variations in color of young leaves, leaf attitude, leaf texture, growth habit, leaf blade length, leaf blade width and petiole length traits. These results reveal that mango germplasm in the UAR has significant diversity and that other morphological traits apart from fruits can be useful in morphological characterization of mango.

Diversity of a Large Collection of Natural Populations of Mango (Mangifera indica Linn.) Revealed by Agro-Morphological and Quality Traits

“…Similarly, Rymbai et al [41] studied eight mango cultivars from different agro-climatic areas in India and observed a monomorphism crown shape (semi-circular) for all the cultivars. These results are also in line with Toili et al [39] who evaluated 98 accessions from Kenya and showed that the crown shape of 70% of the germplasm was semi-circular with a growth habit predominantly spreading. However, Rajan et al [42] reported significant difference in canopy structure among 26 Indian mango cultivars.…”

“…The present study revealed a relatively low genetic diversity for traits related to the tree crown, leaf, and inflorescence contrary to the fruit related traits showing higher diversity within the mango germplasm. This confirms the importance of fruit related traits as good differentiation variables of mango accessions [39]. Phenological data showed that this germplasm was predominantly of medium flowering and maturity types.…”

Phenotype characterization and diversity assessment of mango (Mangifera indica L.) cultivars in Ethiopia

“…This suggested the cultivars varied for all the quantitative traits that could be used for further breeding work. Similarly, authors from India (Singh et al, 2012;Bajpai et al, 2016) and Kenya (Toili et al, 2016;Gitahi et al, 2016) also reported the presence of significant differences among mango cultivars they studied considering similar quantitative traits.…”

“…These characters are among the important attributes that could be utilized for classification of the cultivars (Sharma et al, 2016). Inline to this, Toili et al (2016), Krishnapillai and Wijeratnam (2016), Joshi et al (2013), Ribeiro et al (2013) and Raza et al (2017) report on mango cultivars in Kenya, Sri Lanka, Indian, Brazil and Pakistan, respectively showed significant variability with the aforementioned characters and suggested for **Significant at p<0.01, SE=standard error and CV (%) = coefficient of variation in percent. a Analysis of variance was not computed since the data were collected from a single tree.…”

“…The cross-pollination of mango cultivars could also result in specific gene recombination and selection made by growers for propagation might also lead to phenotypic diversity amongst the studied cultivars like most of the existing cultivars in different parts of the world originated (Singh et al, 2016). Although information is lacking on genetic divergence of mango cultivars in Ethiopia, similar study in neighbouring countries such as Kenya (Gitahi et al, 2016;Sennhenn et al, 2013;Toili et al, 2016), Sudan (Ahmed and Mohamed, 2015;Mohamed and Ahmed, 2015) and Egypt (Kheshin et al, 2016) confirmed the existence of phenotype diversity. Hence, the investigated result in Ethiopia is useful for efficient utilization and conservation of the cultivars (Majumder et al, 2013).…”