Agrobiodiversity

Objectives: Description of the land use techniques in agriculture, investigation of the social and economic aspects of crop and livestock agriculture, calculation of nutrient budgets (vertical and  horizontal fluxes).

Contact Person: Prof. Dr. Andreas Bürkert and Prof. Dr. Eva Schlecht, Institute of Crop Science, University of Kassel, Germany

Email: tropcrops@uni-kassel.de OR tropanimals@uni-kassel.de

Scientific staff: Dr. Jens Gebauer, Prof. Dr. Karl Hammer, Dr. Eike Luedeling, Dr. Katja Brinkmann, Dr. Annette Patzelt, Dr. Maher Nagieb, Dr. Sulaiman Al Khanjari, Prof. Dr. Andreas Buerkert

Study area: Covering the different parts of Oman but focusing on the mountain oases of Balad Seet, Maqta and Al Jabal al Akhdar in Northern Oman

Duration: 2005-2008

Agro-horticultural biodiversity in mountain oases of northern Oman

Several botanical studies have been conducted in different parts of Oman, but knowledge about agro- horticultural biodiversity in the rapidly changing ancient mountain oases remains scarce. This is perhaps because cultivated plants are usually neglected by botanists and collectors of crop genetic resources, who often follow crop-specific programs and are therefore less interested in the wealth of species found. We inventoried the crop species of three mountain oases in the Oman Mountains using a GIS-based field survey and farmer interviews.

Overall, 107 different crop species were identified belonging to 39 families. Species number was highest among fruits (33 spp.), followed by vegetables (24 spp.) (Figure 1). Intensive irrigation allows cultivation of a broad range of species at all oases. However, the number of species varied significantly between sites. Fruit species diversity and homogeneity of distribution of individual fruit species was highest at Balad Seet and lowest at Maqta as indicated by respective Shannon indices of 1.00 and 0.39 and evenness values of 32% and 16%. At Balad Seet and Maqta, date palm (Phoenix dactylifera L.) was the most common fruit crop with 2690 and 2128 specimens, respectively, while in Al Jabal al Akhdar pomegranate (Punica granatum L.) was most frequent with 5894 specimens. For date palm, 16 and 13 varieties were cultivated at Balad Seet and Maqta, with an average yield of 32 and 8 kg (palm yr)–1, respectively.

Figure 1.Plant species of different use categories of the three oases in northern Oman.

In Balad Seet 18 cultivated black mulberry (Morus nigra L.) trees were identified with a considerable tree-to-tree variation regarding fruit size. Average fruit length and diameter varied from 11 to 79 mm and from 8 to 10 mm, respectively. However, farmers did not distinguish between different varieties. Temperate fruit trees such as walnut (Juglans regia L.), apple (Malus domestica Borkh.), apricot (Prunus armeniaca L.), plum (Prunus domestica L.) and pear (Pyrus communis L.) were only cropped at the high altitude of Al Jabal al Akhdar. However, long-term temperature records indicate that the number of chilling hours decreased dramatically over the past 24 years, with a mean decrease of 17.4 hours per year leading to recent crop failures in the traditional horticultural systems at Al Jabal al Akhdar.

In Balad Seet and Maqta all fruits are consumed by members of the households, whereas fruits produced in Al Jabal al Akhdar are sold outside the oasis. Century plant (Agave americana L.), faba bean (Vicia faba L. var. minor Peterm. em. Harz) and lentil (Lens culinaris Medik.) were identified as relict crops, supporting oral reports of past cultivation and providing evidence of genetic erosion. Some species, such as the temperate fruits of Al Jabal al Akhdar, were exclusively found at the coolest site, while others only occurred at the hotter locations. Overall greatest species similarity was found between Balad Seet and Al Jabal al Akhdar as indicated by a Sørensen coefficient of similarity of 67%. Most cultivated terraces had different vegetation layers making them typical agroforestry systems. Greatest species richness was recorded in the lowest stratum.
Overall the study shows a location-specific but surprisingly diverse mosaic of crops in Omani mountain oases which merits further studies and conservation efforts.

First record of Grewia tenax (Forssk.) Fiori in northern Oman, a valuable fruit producing shrub

Grewia tenax (Forssk.) Fiori is a under-utilised fruit species with multiple uses in different parts of the Tropics and Subtropics. It is common on the Arabian Peninsula and has also been recorded in southern Oman. To date, no record of the species exists for the northern part of Oman.

To close this distributional gap, in summer 2005 and spring 2006, comprehensive botanical surveys were conducted in the northern Omani wadis Bani Awf, Khabbah and Muaydin with particular emphasis on plant species of the genera Grewia. Plant material was collected and verified with material in the herbarium of Sultan Qaboos University and the National Herbarium at the Oman Natural History Museum in Muscat.
During the field survey, several individual plants of Grewia tenax were identified in Wadi Bani Awf and Wadi Muaydin, being a new record to the flora of northern Oman. However, in Wadi Khabbah no specimens could be identified. In this survey, G. tenax shrubs were found growing up to an elevation of 1850 m a.s.l. at the upper edge of Wadi Muaydin (Figure 2).

Figure 2.Grewia tenax shrub growing at an elevation of 1850 m a.s.l. at the upper edge of Wadi Muaydin, Oman.

The up to 3 m high, deciduous and thornless G. tenax shrubs flowered in March and April and fruited in August and September. In Wadi Muaydin people are used to eat the (1–)2–4 paired orange-coloured fruits and consider them delicious. In addition to G. tenax, 9 woody perennials with edible fruits were found during the botanical survey. Fruits of Sideroxylon mascatense (A. DC.) Penn. and Ziziphus spina-christi (L.) Willd. are still collected by the people and sold at local markets. G. tenax was found to be heavily grazed by the high number of free roaming domestic animals indicating its palatability. Leaves and young twigs of the species have been reported to be very palatable to goats and sheep. Only some plants in the oasis Balad Seet and a few plants in steep cliffs were less heavily grazed.
The very scarce occurrence of G. tenax combined with its high palatability can lead to the local extinction of the species and to the loss of this genetic resource in northern Oman. The new record of G. tenax in northern Oman extends its known distribution and represents its easternmost occurrence.

Oman at the cross-roads of inter-regional exchange of cultivated plants

During the past years the Sultanate of Oman has been studied for its cultivated plant genetic resources. Data from this study, that commenced in 2002 and information from the literature have been combined to document the millenia-old cultivation history of many agri- and horticultural crop plants in this country at the cross-roads of inter-regional exchange. The resulting checklist comprises 194 species from 133 genera and 53 families and 11 geoelements of 136 selected species. Notable inputs came from South and Southeast Asia with 21.3%, from the Near East and East Mediterranean with 20.6%, and from Central and South America with 15.4%. Most elements are allochthonous while real autochthonous elements such as Boswellia sacra Flueck. and Prunus arabica (Oliv.) Meikle are rare. A remakable infraspecific variation in several crop species and evidence of introgession were found indicating an evolutionary power of Oman that is similar to that of South Italy.

Wheat landraces and Date palms

Results of a botanical survey conducted in Balad Seet and other oases of northern Oman indicate that there exists considerable morphological variation within and among five traditional landraces of wheat cultivated in this area. Ten new botanical varieties (Triticum aestivum var. baladseetense, Triticum aestivum var. maqtaense, T. aestivum var. sedabense T. aestivum convar. rigid-compactum var. omanense, T. aestivum var. sedayriense, T. aestivum var. ibreense, T. durum var. mahsinense, T. aethiopicum var. hajirense, T. durum var. dense-menelikii (sedarenense) and T. var. nov.) were identified. Their agronomic properties, in particular tolerance to drought and heat, and their nutritional value are still under investigation (Photo 1). Also discovered and newly described was an ancient Asian AAA-type banana variety which together with the botanical wheat varieties reflect the once important role of Oman in inter-regional trade. A survey on the diversity of date palms revealed 16 different varieties of which three nevertheless dominated the plantations: 74% of all date palms belonged to the varieties Naghul (37%), Fardh (22%), and Khasab (15%) (Photo 2).

Photo 1. Triticum aestivum var. baladseetense
(Al-Maskri, M., Nagieb, M., Hammer, K., Filatenko, A.A., Khan, I. and Buerkert, A. 2003)

Photo 2. Date palms (Buerkert 2000-2004)

Publications

	Al-Maskri, M., Nagieb, M., Hammer, K., Filatenko, A.A., Khan, I. & Buerkert, A. 2003. A note about Triticum in Oman. Genetic Resources and Crop Evolution 50 (1), 83-87
	Al khanjari, S., Hammer, K., Buerkert, A., Khan, I. & Al-Maskri, A. 2005. A survey of Wheat landraces in Oman. Plant Genetic Resources Newsletter (FAO-IPGRI, Rome, Italy) 141, 7-10.
	Al Khanjari, S., Hammer, K., Buerkert, A., & ROEder, M.S. 2007. Molecular diversity of Omani wheat revealed by microsatellites: I. Tetraploid landraces. Genetic Resources and Crop Evolution. http://dx.doi.org/10.1007/s10722-006-9110-8.
	Al Khanjari, S., Hammer, K., Buerkert, A., & Röder, M.S. 2007. Molecular diversity of Omani wheat revealed by microsatellites: II. Hexaploid landraces. Genetic Resources and Crop Evolution (submitted 23.02.2006, in press 15.10.2006).
	Al Khanjari, S., Filatenko, A.A., Hammer, K. & Buerkert, A. 2008. Morphological spike diversity of Omani wheat. Genetic Resources and Crop Evolution 55: 1185-1195
	Buerkert, A., Nagieb, M., Siebert, S., Luedeling, E., Quintern, M. & Al Khanjari, S. 2005. Plant genetic diversity, irrigation and nutrient cycling in traditional mountain oases of Northern Oman. pp. 1072-1073. In Li, C.J. et al. (Eds.). Plant Nutrition for Food Security, Human Health and Environmental Protection. Tsinghua University Press, Beijing, China.
	Buerkert, A., Al Khanjari, S., Al-Saady, N.A., De Langhe, E., HOElscher, D., Gebauer, J., Behrendt, S., Happe, S., Brinkmann, K. & Schlecht, E. 2010. Uralter Toleranzmechanismus im Oman entdeckt: Wie sich Oasen-Bananen gegen ihre Feinde wehren. Biologie Unserer Zeit, DOI:10.1002/biuz.201010432
	Brinkmann, K., Gebauer, J., Patzelt, A., Schlecht, E. & Buerkert, A. 2007. Vegetation and biodiversity on Jebel al Akhdar. Pride. Al Roya Press and Publishing House, Muscat, Oman, pp. 90-96.
	Gebauer, J., Nagieb, M. & Buerkert, A. 2006. Obstbau in einer Bergoase im Norden Omans. Erwerbs-Obstbau 48, 9-16.
	Gebauer, J., Luedeling, E., Hammer, K., Nagieb, M. & Buerkert, A. 2007. Mountain oases in northern Oman: an environment for evolution and in situ conservation of plant genetic resources. Genetic Resources and Crop Evolution 54, 465-481.
	Gebauer, J., Patzelt, A., Hammer, K. & Buerkert, A. 2007. First record of Grewia tenax (Forssk.) Fiori in northern Oman, a valuable fruit producing shrub. Genetic Resources and Crop Evolution 54: 1153- 1158.
	Gebauer, J., Luedeling, E., Hammer, K. & Buerkert, A. 2009. Agro-horticultural biodiversity in mountain oases of northern Oman. Acta Horticulturae 817, 325-332.
	Filatenko, A.A., Hammer, K., Al Khanjari, S. & Buerkert, A. 2010. Six botanical varieties of Triticum from Oman. Genetic Resources and Crop Evolution 57, 1135-1139.
	Hammer, K., Filatenko, A.A., Alkhanjari, S., Al-Maskri, A. & Buerkert, A. 2004. Emmer (Triticum dicoccon Schrank) in Oman.. Genetic Resources and Crop Evolution 51, 111-113.
	Hammer, K., Gebauer, J., Al Khanjari, S. & Buerkert, A. 2009. Oman at the cross-roads of inter-regional exchange of cultivated plants. Genetic Resources and Crop Evolution 56, 547-560.