J. M. Bompard
2.8 Conclusion
Taxonomy and Systematics 35
It is highly probable that the eventual introductions of superior cultivars of polyembryonic mangoes from the south-west coast of India, ‘between the 6th and 14th century, the height of classical South-east Asian civilization and also the golden age of early south Indian civilization’ (Hall, 1985), were not the fi rst ones.
During the 16th and 17th centuries, the Portuguese and Spaniards con- tributed to the widest distribution of superior varieties in the archipelago, espe- cially to the east. The name mango itself derives from the Tamil ‘man-kay’ or
‘man-ga’ (see Mukherjee and Litz, Chapter 1, this volume), which the Portu- guese adapted as ‘manga’ and ‘mangueira’ when they colonized west India.
Superior Philippine cultivars originated through introduction of culti- vars from Indonesia, for example ‘Dodol’ into Mindanao, and from Indo- china, for example ‘Carabao’ and ‘Pico’ in Luzon, the Visayas and northern Mindanao (Wester, 1920; Bondad et al., 1984). However, these introductions dating from the fi rst half of the 17th century were also preceded by the intro- duction of primitive races of the common mango as well as other species into the Sulu Archipelago and Mindanao through contacts with north Borneo, as attested by their local names quoted by Wester (1920), that is mampalam (M. indica, and possibly also M. laurina), baonoh (M. caesia) and wannih (M.
odorata).
The South-east Asian M. indica germplasm includes many races that defy classifi cation. Natural cross-pollination has undoubtedly occurred with native species, such as M. laurina, which was also brought into cultivation in several areas before the introduction of M. indica.
J.M. Bompard 36
Mangifera indica ‘Madu’ in Java, and M. laurina in Sabah have been used as rootstocks for M. casturi. Trials of grafted M. caesia on M. indica (Wester, 1920) and M. indica on M. kemanga or M. caesia (Ochse and Bakhuizen, 1931) were unsuccessful, as these two species have distinct bark features and only remote affi nity with the common mango. Better compatibility can be expected using species more closely related to the common mango within the subgenus Mangifera. In West Kalimantan, M. laurina is occasionally used as a rootstock for the common mango on periodically inundated riverbanks. It has been tried as a rootstock by the Department of Agriculture in Sabah (Lamb, 1987).
Campbell (2004) reported that M. casturi, M. griffi thii, M. laurina, M. odorata, M. pentandra and M. zeylanica grafted on M. indica had a high percentage of success.
Several species that can grow in permanently inundated areas (i.e. M.
gedebe, M. quadrifi da, M. griffi thii and other species of the section Rawa) repre- sent a potential source of rootstock for the development of mango cultivation on poorly drained soils or in areas liable to prolonged fl ood. Other species may be a source of dwarfi ng rootstocks.
Hybridization
From our observations in Borneo, natural interspecifi c hybridization involv- ing various cultivated Mangifera species can occasionally occur. Suspected hybrids were observed between wild M. gedebe and cultivated M. laurina in the lakes area along the Mahakam River in East Kalimantan, where impor- tant populations of M. gedebe occur; between cultivated M. foetida and M. pajang, two species showing close affi nity, in different areas of Kalimantan where both species are grown together; and between closely related M. caesia and M. kemanga in cultivation. A hybrid origin has been suggested for M. odorata (M. indica × M. foetida), which is unknown in the wild (Ding Hou, 1978a).
Based on AFLP analysis, Teo et al. (2002) and Kiew et al. (2003) have con- fi rmed that M. odorata is a hybrid between M. foetida and M. indica. The index of similarity showed that M. odorata is closer to M. foetida (76% similarity) than it is to M. indica (66%). Yamanaka et al. (2006) showed a high genetic similarity among 11 landraces of M. odorata from the Malaysian Agricultural Research and Development Institute (MARDI) gene bank. Higher variability can be expected from Sumatra and Java samples.
Existing information about experimental interspecifi c hybridization is scarce. According to Mukherjee et al. (1968), successful crosses between M. odorata and M. zeylanica were made in India.
Potential of wild species
There is little doubt that wild mangoes are potentially valuable in breeding programmes. Some species have important horticultural implications as they demonstrate many desirable characteristics (Bompard, 1993). Fairchild (1948)
Taxonomy and Systematics 37
noted that crosses between the common mango and related fi ve-stamen spe- cies of the section Euantherae might produce hybrids with better pollinating quality. Mangifera pentandra, which is grown in peninsular Malaysia and Sabah, is a prolifi c bearer, due to its high proportion of hermaphrodite to male fl owers.
Stress resistance
In the Malesian rainforests, wild mangoes thrive well under an ever-humid climate, without a prolonged dry season, i.e. is in areas with an annual rain- fall > 4000 mm and no monthly mean < 100 mm and where the common mango cannot be grown satisfactorily. Species, occurring in subtropical areas, including primitive races of the common mango, or in high altitude tropical forests, should be evaluated for cold tolerance, opening up the possibilities for mango production in subtropical and Mediterranean areas. Mangifera lau- rina and other species related to the common mango that grow in the rainfor- est (e.g. M. minor in New Guinea) are apparently immune to anthracnose.
Sharma and Choudhury (1976) also observed that trees of an unknown wild race found in the Tripura State (north-eastern India) were free from mango malformation.
Potential new fruits
Extensive, yet largely unrecorded variability also exists among the non-indica species under cultivation. Sadly, this gene pool is barely represented in exist- ing collections, and is rapidly vanishing. An increasing number of horticul- turists are demonstrating a keen interest in the wild relatives of the mango.
It is hoped that local peoples who have contributed to the recognition and maintenance of these species can benefi t from future innovative mango breeding.
Since early times, local peoples have planted seeds collected from trees that were observed to produce better quality fruits in the forests around their settlements. In areas now completely devoid of lowland primary forest, espe- cially in Sumatra and Borneo, the only wild relatives still found are those which have been integrated into indigenous agroforests which represent gene banks for an amazing diversity of fruit trees. A tenuous but constant selection pressure over many centuries has resulted in improved selections of several species. Today, some of these selections hold economic importance for their intrinsic characteristics. In Malesia, forms of M. odorata and M. foetida with sweeter and less fi brous fl esh have been identifi ed. The ‘wani’, a form of M. caesia from Bali and Borneo, has green-skinned fruit with milky white soft fl esh and a sweet taste quite different from the fruit of common forms of M.
caesia. In addition, there are many interesting selections of M. casturi, M. grif- fi thii and M. torquenda.
Further improvement of these wild mangoes is especially desirable owing to their local economic importance in the wet tropical regions. Use of vegetative propagation methods must be encouraged. With proper selection, there is every reason to believe that other Mangifera species can become valu- able commercial fruits.
J.M. Bompard 38