Morphological Characterisation of Harumanis Mango (Mangiferaindica Linn.) in Malaysia
Abstract
Harumanis is avery popular green eating mango variety which has been planted commercially in the State of Perlis, Malaysia. However, several variations such as fruit shape and tree architecture which are apparent on field have caused confusing to the farmers as well as consumers of the ‘genuine’ Harumanis. This study was designed to observe the variation among Harumanis population at several locations in Malaysia. Samples were classified into two treatments based on their tree architecture: droop Harumanis and erect Harumanis. The samples were collected from six farmers’ plot in Perlis, Kedah and Johor. Samples were subjected to fruit quality and branch strength analysis. Fruit quality characterisations and branch strength analysis revealed significant variation among treatments. Fruits harvested from droop Harumanis tree was bigger than erect Harumanis. Droop Harumanis fruit samples recorded higher value for relative water content, moisture content and modulus of elasticity while erect Harumanis recorded higher value for fresh-weight basis density and modulus of rupture. This study indicated that morphological characterisations play an important role in determining phenotypic variation in inter-variety population including Harumanis.
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Introduction
The mango (Mangiferaindica L.)is among the widely grown tropical and subtropical fruit of the world including Malaysia and is a diploid fruit tree with 2n = 40 chromosomes[1], [2]. Until 2016, there was about 5,816.4 hectare of mango cultivation in Malaysia with 17,429.7 metric tonne of production worth more than RM57 million [3]. There are several varieties of mango grown in Malaysia; the better known cultivars are Golek (MA 162), Masmuda (MA 204), Maha 65 (MA 165), Chok Anan (MA 224), Nam Dok Mai (MA 223), Sala and Harumanis. Harumanis among them, the most popular clone, which was registered as MA128 by the Department of Agriculture, Malaysia [4], [5], yielding at 2.69 tonne/ha in 2014 [6]. As described by JabatanPertanian Malaysia (2015), the fruit shape of Harumanis is oblong, has a prominent beak, the skin colour is green with a little bit of glossy and will turn to yellowish green when ripen, the fruit size varies ranging from 300 to 650 gram, has 16-17°Brix and the flesh is orange colour and sweet. Harumanis is very suitable for the export market as it has desirable colour and sweetness and good eating quality with good aroma [7].
Harumanis was believed to be originated from Indonesia and being domesticated in Malaysia ever since it was registered by the Department of Agriculture, Malaysia on May 28, 1971 [4]. Like many other cultivars derived from SouthEast Asia, Harumanis is polyembryonic, i.e. the seeds have nucellar embryos that are genetically identical to the mother plant [8]. Because of this, polyembryonic cultivars have generally been propagated by seed and Harumanis is no exception to this rule. A viable zygotic embryo is also present in the seed of some polyembryonic mango cultivars [8]. As reported by Schnell & Knight (1992), the number of zygotic off types in seedling populations varied and can be as high as 64% in the cultivar Golek and as low as 0% in the Israeli cultivar 13-1.
Harumanis is well accepted by Malaysians and were planted by many as well as by commercial planters. In the state of Perlis alone, 1,037 hectare of land were planted with Harumanis [10]. However, a few reports by the growers of Harumanis in Perlis indicated that there are variations in term of fruit size, flesh colour and number of fruits per panicle (Mohd Azhar Hassan, personal communication, October 6, 2017). There are some cases where the growers found that the flesh colour of matured Harumanis fruits are yellow instead of orange. This phenomenon is not new in mango cultivation. There were reports of identification of intra-cultivar variation in mango such as in Sala [5], Chok Anan [11], Indian mango [12] and Kensington mango [8]. Khan, Ali, & Khan (2015) also reported that extensive differences exist among mango genotypes of the similar clones in any particular orchard, specifically with the respect to fruit shape, size, colour, aroma, flavour eating quality and texture in which, usually caused by either outcrossing or natural mutations. The presence of fruits in the evaluation of morphological variations in fruit crop is crucial. Nevertheless, in off fruiting season, breeders still need to identify dissimilarity among mango varieties/cultivars. Therefore, other morphological characteristics namely differences in tree architecture type need to be defined. A basic knowledge of the strength properties of mango wood such as moisture content, bending strength, elasticity and etc. are essential and interesting to explore. There is a need to study the variations in Harumanis population whether the variations, if any, could lead to economic and social importance, as well as to the scientific values. Morphological characters evaluation is the first step that should be carried out before advanced biochemical or molecular studies are carried out. Hence, justify the objective of this study.
Generally, morphological characterisation is an evergreen methodology that uses the ocular estimate method with the help of several qualitative and quantitative measuring tools to score and distinguish tropical fruits including mangoes. The characters include tree height, growth habit, flowering pattern, disease resistant, inflorescence shape, colour and type of flowers, fruit shape and shape, shoulder position and type of seedsi.e. monoembryonic or polyembryonic.
Conclusion
A conclusion section must be included and should indicate clearly the advantages, limitations, and possible applications of the paper. Although a conclusion may review the main points of the paper, do not replicate the abstract as the conclusion. A conclusion might elaborate on the importance of the work or suggest applications and extensions. There are rooms for Harumanis improvement through breeding as there are a good collection of variants that could be used as parents or shall be introduced as new variant in Harumanis cultivation. Although identification and evaluation of mango varieties/cultivars is quite possible with morphological characterisation, but the markers also have certain limitation especially in such cases when the cultivars are differentiated on the basis of growth habit, panicle, fruit characteristics [13]. In this study, significant differences were observed for fruit length, fruit-length-to-diameter ratio, stem RWC and moisture content, fresh-weight basis stem density, stem MOR and MOE. Morphological characters alone cannot really define whether the variation among cultivars/varieties exist at DNA level as phenotypic traits may affected by different environmental and growing conditions. In conclusion, droop and erect Harumanis showed a little variation phenotypically. However, thorough evaluation with modern approaches such as the use of Chroma meter to record flesh and skin colour, and molecular markers to differentiate variants at DNA level should be used in future.