Moringa stenopetala belongs to family Moringaceae that is represented by a single genus Moringa. The genus Moringa is represented by 14 species to which M. stenopetala belongs. The genus Moringa originated from sub-Himalayan tracts of Northern India, distributed worldwide in the tropics and sub-tropics [25, 27]. Moringa stenopetala is often referred to as the East African Moringa tree because it is native only to southern Ethiopia and northern Kenya [21]. Though it grows in many other parts of the tropics, it is not as widely known as its close relative, Moringa oleifera but often considered generally more desirable than M. oleifera. [7, 21] stated that the taxonomic position of the family is not clear. It has some features similar to those of Brassicaceae and Capparidaceae but the seed structure does not agree with either of the above families. Pollen studies have not provided any other suggestions and recent molecular studies have pointed to relationship with the Carricaceae. This indicates that the taxonomic position of the family is not yet settled and is open for further studies. Its seed physiology is also yet studied in the tropics in general and Ethiopia in particular [8].
The habitat where the genus occur in Ethiopia includes: rocky areas along rivers, dry scrub land, Acacia-Commiphora woodland, water courses with some evergreens, open Acacia-Commiphora bush land on gray alluvial soil and in cultivation around village. It is cultivated in terr aced fields, gardens and small towns [7, 11]. It is dominantly found in well-drained soils of southern Ethiopia at an altitudinal range of about 1100–1600 m.a.s.l. with annual rainfall ranging from 500–1400 mm and annual temperature ranging from 24–30 °C [34]. Due to its water storage capacity in the bottle-shaped stem, it is drought tolerant and remains green when the other forage is scarce during the dry season [1] and due to this character, it is called ‘camel crop’. Besides, one of the nicknames of the tree is “never dying” due to its incredible ability to survive in harsh climate and drought condition [29]. Cold temperatures are limiting factor for the cultivation of the species in Ethiopia because it does not tolerate frost or freeze may cause it to die back to ground level, where new sprouts may be produced. The species does not have any specific soil requirements, except it does not grow on waterlogged or swampy soils. The soil pH ranges from acidic to alkaline but mostly exhibit neutral reaction [26].
Moringa stenopetala has the following features: it is fast growing evergreen perennial flowering plant or deciduous soft tree, well adapted to semi-arid areas with annual rainfall as little as 500 mm and poor soil [30]. It is more drought tolerant - but less frost-resistant than M. oleifera [23]. Even though, Moringa stenopetala is more resistant to insect pests than other species in its family. It is affected by a caterpillar of Noorda trimaculalis [6].
M. stenopetala is propagated both by direct sowing of the seeds without pretreatment and vegetatively using branch cuttings [14]. The optimum temperature for the germination of M. stenopetala seeds was reported to be about 25 °C [5]. Optimum light for germination of all Moringa species is half shade. When sown in the hotter weather of mid-April, germination percentages for M. stenopetala and M. oleifera were only 54 and 40 percent, compared to 92 and 94 percent in half shade. Seeds should be planted about 2 cm deep in soil that is moist but not too wet [22]. The best suited season for sowing the seeds is March to August under Southern Ethiopian conditions. The time of sowing must be strictly adhered to because the flowering phase should not concede with rainy seasons, which results in heavy flower shedding [18].
M. stenopetala is one of the world’s most nutritious crops: All parts of the tree except the wood are edible. The leaf of Moringa is very popular vegetable in southern Nation Nationalities and Peoples Regional State of Ethiopia and valued for its special flavor [30]. The leaf is rich in carbohydrate, proteins, minerals and essential amino acids. It has more betacarotene than carrots, more protein than peas, more calcium than milk, more potassium than bananas, and more iron than spinach [1].
Many parts of the M. stenopetala plant have been used in medicinal preparations traditionally against different disease. The seed can be used for various purposes such as for food, medication, water purification and oil extraction [4]. Besides, its vital value for human and livestock nutrition, this plant is largely uninvestigated [3, 19]. Due to this, M. stenopetala is not known in most part of the world other than its area of cultivation (Southern Ethiopia and Northern Kenya). Currently, it attracted the attention of scientists across the globe for health management due to its nutritional and medicinal properties as well as easy of propagation and ability to thrive under harsh environments. It has the potential to end malnutrition, starvation, as well as prevent and treat many diseases. It has got a nick name as ‘truly a miracle plant’, ‘ mothers’ best friend’ and a ‘God gift’ for the nourishing and healing of man. Thus, it is emerging as a future crop considering its wider adaptability and tolerance to many abiotic stresses. Accordingly, it became essential to take stock of knowledge and develop a road map to harness its potential for the benefit of farmers as well as consumers [29]. Therefore, expansion of cultivation and utilization of this tree throughout the world especially in Africa is important. However, for such expansion, it needs good propagation system to supply adequate planting materials of superior genotypes.
Moringa species are associated with many production constraints, such as a relatively long period of fruit bearing, non-availability of planting materials, lack of alternative method of propagation, requirement for long rainy period in regions where water is scarce and vulnerability to pests and diseases [11, 35]. [6] reported that the pest destroys the leaves of the entire plant population of a village within a week. This pest could be a drawback for in situ conservation of the plant. Moreover, flowering does not commence until a critical tree size is attained, and after some years the tree branches stop producing fruits/seed. Therefore, vegetative propagation like cutting is a necessity to obtain uniformity in yield and quality. However, it is less successful due to its slow regeneration and also requires large size cuttings (1-1.5 m long) as well as trees grown from cuttings are known to have much shorter roots or a poor root system [16]. As a result, in vitro propagation methods are the best alternative for propagation of this plant with uniform genotypes within a relatively short period of time. Thus, this study was intended to optimize in vitro propagation protocol for Moringa stenopetala so that to evaluate the combined effect of NAA and kinetin and IBA and kinetin on shoot multiplication. As well, to evaluate the effect of NAA and IBA on rooting of multiplied shoots.