Distribution record of Musa borneensis var. sarawakensis Becc. and Musa campestris var. sarawakensis Becc. in West Kalimantan, Indonesia

ABSTRACT Borneo Island has a large number of wild banana species. As a part of Borneo Island, West Kalimantan has limited information about the diversity of wild bananas. This research aims to update the record distribution of wild bananas from Bonti District of Sanggau Regency and to determine their morphological characteristics. Exploration method and resident information were used in this study. Two species of wild bananas have been identified and considered as new distribution records in West Kalimantan Province, namely-Musa borneensis var. sarawakensis with morphological character pseudostem red-purple colour, sparse black-purple blotches at petiole base, leaf base shape rounded on both sides, male bud red-purple colour and Musa campestris var. sarawakensis with morphological character pseudostem yellow-green colour, inflorescence erect, leaf base one side rounded and one-pointed, the dorsally pink-purple and ventrally pink-purple colour of bract.

Borneo Island is the third largest island in the world. Borneo Island is located on the equator, has high mountains which provide many different habitats as part of the centre of the primary banana diversity centre, which has a large number of wild banana species (Häkkinen, 2004a). The exploration to find out the diversity of wild bananas in Borneo Island has been carried out intensively in Sabah, Sarawak, and Brunei Darussalam. Häkkinen (2004a) also reported 20 species of endemic wild bananas were found in Borneo, but only 15 species have been previously described. Borneo Island is divided into three-state territories, namely Indonesia, Malaysia, and Brunei Darussalam. In Indonesia, the island of Borneo is known by the name Kalimantan which is divided into five provinces. However, the forest fire and resultant haze have potential impacts on Kalimantan's biodiversity such as habitat loss, forest fragmentation, and low sunlight on forest trees (Horrison et al., 2016). The exploration, inventory, and conservation of wild bananas in West Kalimantan need to be done before the wild banana species are lost due to forest fire.
The information on the diversity and distribution of wild bananas in West Kalimantan are needed to improve the quality of cultivated banana using genetic manipulation in the future and for conservation management of wild bananas in West Kalimantan. This study aimed to update the record distribution of wild bananas from Bonti District of Sanggau Regency and to determine their morphological characteristics.
The study on wild bananas species were conducted in Bonti Village, Bonti District, Sanggau Regency, West Kalimantan, Indonesia ( Figure 1). The study area was surrounded by Noyan and Kembayan Districts in the northern part, Parindu and Kapuas Districts in the southern part, and Tayan Hulu District in the western part. The average rainfall is 235 mm (BPS Sanggau, 2017). The topographic area in Bonti Sub-district is plains.
The exploration was carried out in March 2017. Morphological characters were documented with a digital camera. Morphological characterization was done under Descriptors for Banana (Musa spp.) from the International Plant Genetic Resources Institute (IPGRI, 1996). Morphological character records included the plant's general habit as well as characteristics of pseudostem, petiole, leaf, peduncle, male bud, male flower, fruit, and seed (shape and colour). Morphological characteristics obtained from the field were then crosschecked with references (Nasution & Yamada, 2001;Häkkinen, 2004b;  Häkkinen & Meekiong, 2005;Sulistyaningsih, 2017).
Based on the differences in 12 morphological characters, two species of wild banana were identified in Bonti District, West Kalimantan, i.e. Musa borneensis var. sarawakensis and Musa campestris var. sarawakensis (Table 1, Figure 2-3). Some morphological features of both species can be seen in Figures 2 and 3. In daily life, the villagers of Bonti District only utilized M. borneensis var. sarawakensis as food.
Characteristics: Mature pseudostem up to 4 m high, sheaths red-purple colour. Sucker Closed to parent and vertical growth. Petiole up to 42-93 cm long, petiole canal wide with erect margins, petiole bases corrugated auricles with sparse black-purple blotching. Leaf habit erects up to 400-470 cm long, 78-82 cm wide, colour of upper surface is green, lower surface is green-yellow, and leaf bases asymmetric and rounded on both sides, midrib dorsally yellow, midrib ventrally light green. Inflorescence first horizontal then pendulous, peduncle 37-48 cm long, 8 cm in diameter, hairless, and red-green. Male bud rounded, normal male bud, apex obtuse and split with green tips, dorsally redpurple, ventrally yellow of bract, revolute bract behaviour, lifting two bracts at a time, and rachis position horizontal. Male flower compound tepal cream with cream lobes, free tepal translucent white, oval, with triangular apex, style straight, ovary straight. Fruit 6 fruits per hand, individual fruit 14 cm long, straight in shape, without any floral relicts, and apical part bottle-necked shaped. Seed obpyriform and brown (Figure 2). Variations morphology were found between M. borneensis var. sarawakensis in Bonti, West Kalimantan, and M. borneensis var. sarawakensis in Serian-Sri Aman, Sarawak. Musa borneensis var. sarawakensis in Bonti, West Kalimantan had red-purple pseudostem. Sucker closed to parent. Dorsally red-purple and ventrally yellow of bract (Table 1). However, M. borneensis var. sarawakensis in Serian-Sri Aman, Sarawak had purple-brown pseudostem. Sucker far from the parent plant. Dorsally pink-purple and ventrally yellow of bract (Table 1) (Häkkinen & Meekiong, 2005).
Local people in Bonti village consume the young pseudostem of M. borneensis var. sarawakensis. The young pseudostem of M. borneensis var. sarawakensis boiled in water then cooked with coconut milk. Punan tribe consume the young pseudostem of M. borneensis var. flavida and as a land certificate (Sulistyaningsih & Wawo, 2011).
Characteristics: Pseudostem sheaths yellowgreen colour. Sucker closed to parent and vertical growth. Petiole up to 42-93 cm long, petiole canal straight with erect margins. Leaf habit erect up to 210-285 cm long, 30-42 cm wide, colour of upper surface dark green, lower surface green, and leaf bases one side rounded and one-pointed, midrib dorsally yellow, midrib ventrally green. Inflorescence erect. Peduncle red-purple in colour. Male bud ovoid, normal male bud, apex slightly pointed, dorsally pink-purple, ventrally pink-purple colour of bract, not revolute bract behaviour, lifting one at a time, and rachis position erect. Male flower compound tepal cream with yellow lobes, free tepal translucent white, rectangular, with obtuse apex, style straight, ovary straight. Fruit 5 fruits per hand, individual fruit18 cm long, straight in shape, without any floral relicts, and apical part blunt-tipped. The Seed is obpyriform and brown color (Figure 3). Variations morphology were found between M. campestris var. sarawakensis in Bonti, West Kalimantan and M. campestris var. sarawakensis in Kg. Jambu, Sarawak. M. campestris var. sarawakensis in Bonti, West Kalimantan had yellow-green pseudostem colour. Leaf bases one side rounded and one-pointed. The Dorsally pink-purple and ventrally pink-purple colour of bract (Table 1). However, M. campestris var. sarawakensis in Kg. Jambu, Sarawak had yellow-red purple pseudostem colour. Leaf bases both sides rounded. The dorsally purple and ventrally palepurple colour of bract (Table 1) (Häkkinen, 2004). M. campestris var. sarawakensis can be found on forest border in Bonti village, Sanggau District, West Kalimantan and also considered as a new distribution record (Figure 3). Previously, M. campestris var. sarawakensis was reported in Sarawak, Malaysia (Häkkinen, 2004b) and on foothill in Nek Rokon hill, Raya Pasi Natural Resource area, Singkawang, West Kalimantan (Sulistyaningsih & Irawanto, 2011).
Local people in Bonti village have not utilized M. campestris var. sarawakensis. However, local people in Keritan Ulu, Mongool, Senagang Ulu villages, Sabah, consume the heart of inner shoot and flower inflorescence as a salad with chilli sauce or sambal biris (Noweg et al., 2003).
The Key character of M. campestris var. sarawakensis from Bonti West Kalimantan is pseudostem yellow-green colour, inflorescence erect, leaf base one side rounded, and one-pointed, the dorsally pink-purple and ventrally pink-purple colour of bract.
The two wild bananas species were successfully identified from Bonti district, Sanggau Regency, West Kalimantan i.e. M. borneensis var. sarawakensis and M. campestris var. sarawakensis and it is considered as new distribution records. The Conservation of M. borneensis var. sarawakensis, M. campestris var. sarawakensis, and other wild bananas in Indonesia is important to be prioritized both in-situ and/or ex-situ before it goes to extinction caused of deforestation and forests fragmentations. Conservation of wild bananas will provide long term and sustainable conservation of genetic diversity, that's important resources to improve the quality of cultivated banana using genetic manipulation in the future.