Okra (Abelmoschus esculentus) is belongs to family Malvaceae genus Hibiscus . Later delimited in a genus named Abelmoschus . According to Siemonsma , this genus encompasses 14 species with several sub-species. Okra is widely distributed from Africa to Asia, subtropical and warm temperate regions around the world [4–6]. Although the plant grows fast in well-drained humus-rich fertile soil, in full sunlight, humid and upland areas, okra tolerates a wide range of soil types and pH from 5.5 to 8.0 . The plants grow best during the warm months. In the tropics, this plant can flower throughout the year and continuously harvested . Okra is a dicotyledonous and largely self-pollinated herbaceous plant mostly with annual but rarely perennial habit often with various range of chromosome number but 2n = 4x = 130 is the most common one [8, 9]has a deep taproot, the stem is erect, stout, robust, leaves are around 10–20 cm long, flowers of okra are axillary and solitary. The pod or fruit is 10 to 25 cm long containing numerous oval, kidney-shaped seed .
Okra has various local names in different countries. In many English speaking countries, it is known as okra, ladies finger, and gumbo . In Ethiopia, it is known as Bamia (in Oromiffa/Amharic/ Tigrigna), Kenkase (in Berta), Andeha (in Gumuz) languages .
At the varied stage of growth, different parts of okra plants have food, non-food and medical applications [7, 13]. Okra immature fruits are used in salads, soups and stews [8, 12]. Hulls and fiber can be used for animal feeds. Moreover, okra’s tender fruit, seeds and leaves are endowed with low saturated fat, cholesterol, various minerals (like calcium, phosphorus, iron, sodium, potassium, copper, sulfur), starch, valuable phenolics, flavonoids, antioxidants, dietary protein and fiber, Vitamin A, thiamine, riboflavin, nicotinic acid, and Vitamin C [6–15]. There is no toxic substance reported in the edible part of okra .
Okra consumption prevents several ailments such as gastro intestinal tract disorders (diarrhea, dysentery diabetes, irritation of stomach and bowel, sore throat), respiratory disease (lung inflammation, catarrhal infections), sexual transmitted disease (syphilis, gonorrhea), renal disfunction (renal tubulointerstitial disease, dysuria, and irritation of kidneys), hepatitis, cancer, ulcers, [16–19] and okra mucilage have been reported to have a strongly demulcent action and used as a plasma replacement, washing away toxic substances and bad cholesterol [9, 20].
Okra is propagated sexually using seeds [8, 9]. Conventional propagation of okra in a large scale is limited due to bacterial, fungal, viral disease and seed dormancy [21, 22] which result in great economic losses . Therefore, micropropagation offers great potential to overcome such problems and increasing the commercial availability of such useful species.
In vitro propagation of A. esculentus is reported by using explants such as cotyledonary node , nodal segment and shoot tips of in vitro grown seedlings , hypocotyl, cotyledon, cotyledonary node and leaf segment [6, 26] by varying growth regulators and using additives. Successful regeneration of this plant is an elusive process because of exudation of phenolic compounds, tissue browning, and necrosis of explants, media composition, culture conditions, carbon sources, and culture vessels .
Therefore, considerable efforts are still required to discover efficient in vitro propagation methods of this nutritionally and medicinally enriched plant. As to our knowledge, there are no reports on the effect of different MS strength, various sucrose concentration and different pH levels for in vitro propagation of A. esculentus on both liquid and solid media of Ethiopian okra. Thus, this study was intended to investigate the effective of MS strength, sucrose concentration and pH level on in vitro propagation A. esculentus from shoot tip explants in liquid media so that to optimize best basal medium (MS) strength for shoot multiplication and rooting of A. esculentus from shoot tip explants, to determine the optimum concentration of sucrose for multiplication and rooting of in vitro rooted A. esculentus plantlets and to optimize the best pH protocol for the multiplication and growth of A. esculentus in liquid media.