GROWTH RESPONSE OF OKRA TO WATER DEFICIT (STRESS)
A practical experiment to determine the growth responses of okra; Abelmoschus esculentus to water deficit. Okra seeds was planted for this experiment, sixteen (16) nylon pots were employed. There were four (4) treatments and four (4) replicates. The plants were arranged in a completely randomized design (CRD). The number of leaves, leaf area, number of fruits and plant height were significantly increased, (P<0.05) when plants were watered daily and once per week. There was a general increase in these parameters when watering was done twice per week. However, there was a significant increase in the root fresh weight when plant was watered thrice per week. Although, there was a general reduction detected among the parameters watered thrice per week. The implications of the results obtained have been discussed.
1.1 ORIGIN AND GEOGRAPHICAL DISTRIBUTION
Okra (Abelmoschus esculentus) (L moench), is a vegetable crop belonging to the family Malvaceae. It is widely cultivated in the tropics for its young fresh leaves and fruits used in thickening soup as vegetable in many countries of the world (Nwangburuka et al, 2011).
In south eastern parts of Nigeria, okra is an important vegetable in traditional draw soup which is a delicacy among Efik, Ibibio and Igbo tribes. Okra seeds are good sources of quality edible oil and protein while the whole fruit contain vitamins, minerals such as calcium and potassium, calories and amino acids (Berry et al, 1988). On the whole, okra is regarded as a popular health food as it has high fiber, vitamin C and foliate contents (Corleone, 2004).
Okra (Abelmoschus esculentus) is cultivated throughout the tropical and temperate regions of the world for its fibrous fruits or pods containing round, white seeds. It is among the most heat-and drought- tolerant vegetable species in the world and will tolerate soils with heavy clay and intermittent moisture but frost can damage the pods. In compounds farms in the rainforest of South eastern Nigeria (Okafor and Fernandez 1986). Vegetables are important protective food for the maintenance of good health and prevention of disease. It contains valuable food ingredients, which can be successfully utilized to build up and repair the body (Bakhru 2003, Edet and Etim 2007). Vegetables are valuable in maintaining alkaline reserve in the body. They are valued mainly for their high vitamin and mineral content (Bakhru 2003). The production of vegetable has become very popular in many countries of the world due to its importance in the diet of the people. The production of vegetable has been recognized as the most affordable and accessible sources of micronutrients, which increasingly regarded as a catalyst for rural development and as a means of generating and increasing foreign exchange in Africa (AVRDC 2004). Okra production constitutes about 4.6% of the total staple food production in Nigeria in 1970-2003 (CBN, 2004). Okra is the most important fruit vegetable crop and a source of calorie (4550kcal/kg) for human consumption. It ranks first before other vegetable crops (Babatunde et al, 2007). It is one of the most commonly grown vegetable crops in the tropics. Okra cultivation and production has been widely practiced because of its importance to the economic development and can be found in almost every market in Africa.
Varieties vary by plant, height, size of fruit, color, early or late maturity e.t.c viz white velvet, green velvet, long pod, lady finger, dwarf green pods (Udoh et al, 2005). The presence of vitamin c and foliate makes it a good source of antioxidants. The stem bark is good for making fibers and ropes. Cultivation of okra in Nigeria and most west African countries is done by small scale farmers with low inputs who often do not get maximum yield possible for this crop in the available marginal soils yield. Those of them that can afford depend on heavy inorganic fertilizers in most soils of the tropics has been reported to be accompanied by soil acidity problems (Kang et al, 1990).
The geographical origin of okra is disputed, with supporters of South Asian, Ethiopian and West African origins. Supporters of a South Asian origin point to the presence of its proposed parents in the region. Supporters of a West African origin point to the greater diversity of okra in that region.
The Egyptians and Moors of the 12th and 13th centuries used the Arabic word for the plant, bamya, suggesting it had come from the east. The plant may have entered south west Asia across the Red sea or the Bab-el-mandeb strait to the Arabian Peninsula, rather than north across the Sahara or from India. One of the earliest accounts is by a Spanish Moor who visited Egypt in 1216, who described the plant under cultivation by the locals who ate the tender young pods with meal (“okra or Gumbo”, from Africa, tamu.edu). From Arabia, the plant spread around the shores of the Mediterranean Sea and eastward. The plant was introduced to the Americas by ships plying the Atlantic slave trade (“okra Gumbo and rice” by Sheila, Walker, the news courier) by 1658, when its presence was recorded in Brazil. It was further documented in Suriname in 1686. Okra may have been introduced to South eastern North America from Africa in the early 18th century. By 1748, it was being grown as far north as Philadelphia. Thomas Jefferson noted it was well established in Virginia by 1781. It was common place throughout the southern united states by 1800, and the first mention of different cultivars was in 1806 (“Okra or Gumbo, from tamu.edu).
1.2 BOTANICAL CHARACTERISTICS OF OKRA
Okra plant has a deep taproot its stem is semi woody and sometimes pigment with green or reddish tinges color, it is erect, variable in branching, with many short branches to thick semi woody stem. The stem attains heights from 3 feet in dwarf varieties to 7 0r 8 feet in others. The woody stems bear leaves that are lobed and are hairy, some reaching up to 12 inches in length. Leaves are chordate (heart shaped) simple, usually palmately 3-7 lobed and veined leaves are subtended by a pair of narrow stipules. The okra is dark green in color and resembles a maple leaf.
The flowers are borne vertically only on the orthotropic axis every two or three days. The flower axillary and solitary borne on a peduncle 2.0-25cm long. The flowers are large around 2 inches in diameter with the five white to yellow petals with a red or purple spot at the base of each petal and flower will last only for a day. Each blossom develops a small green pod. The flowers are almost always bisexual and actinomorphic. The perianth consists of 5 valvate distinct or basally connate sepals and 5 distinct petals that are usually basally adanate to the androecium. The androecium consists of numerous monadelphous stamens with typically divergent filaments bearing 1-celled anthers. The gynoecium is a single compound pistil of 2-many carpel, an equal number of styles or style branches, and a superior ovary with 2-many locules, each bearing 1-numerous ovules. The calyx is completely fused to form a protective case for the floral bud and splits into lobes when the bud opens. The calyx, corolla and stamens are fused together at the base and fall off as one piece after anthesis.
1.3 SCIENTIFIC CLASSIFICATION
Kingdom: - plantae
Species: A. esculentus
⦁ Fruit contain abundant pectin, mucilage, starch, some fat, 4% water, 80.7% and ash, 1.4%
⦁ Roots yield gum, 16% and the seeds yield vitamin c.
⦁ Seeds yield palmitic acid, 27.33%, stearic acid, 2.75% arachidic acid, 0.05%, oleic acid, 43.74%, linolic acid, 26.62%, unsaponified matter, 0.37%.
Whole plant is aromatic, with an odor resembling cloves. Very mucilaginous when cooked. Parts utilized are the leaves, young pods, seeds and roots.
1.4 NUTRITIONAL VALUE OF OKRA PER 100g (3.502) OKRA AS FOOD
Energy 33kcal (140kj)
Dietary fiber 3.2g
Vitamin A equiv. (5%) 36ug
Thiamine (B1) (17%) 0.2g
Riboflavin (B2) (5%) 0.06mg
Niacin (B3) (7%) 1mg
Vitamin C (28%) 23mg
Vitamin E (2%) 0.27mg
Vitamin K (30%) 31.3ug
Calcium (8%) 82mg
Iron (5%) 0.62mg
Magnesium (16%) 57mg
Potassium (6%) 299mg
Zinc (6%) 0.58mg
Okra leaves may be cooked in a similar way to the greens of beets or dandelions (M.S Milliken and S.Feniger, 1996).
Since the entire plant is edible, the leaves are also eaten raw in salads. Okra seeds may be roasted and grounded to form a caffeine-free substitute for coffee (Tamu. edu).
When importation of coffee was disrupted by the American civil war in 1861, the Austin state Gazette said “an acre of okra will produce seed enough to furnish a plantation of fifty negreves with coffee in every way equal to that imported from Rio (Austin state Gazette Tex, Nov.9, 1861).
Okra is a popular health food due to its high fiber, vitamin C, and foliate content. Okra is also known for being high in antioxidants. It is also a good source of calcium and potassium (Duvauchelle, Joshua May 26, 2011).
1.5 JUSTIFICATION OF STUDY
In Nigeria, vegetable such as okra are important protective food for the maintenance of health and prevention of disease. It contains valuable food ingredients, which can be successfully utilized to build up and repair the body (Bakhru, 2003, Edet and Etim 2007). Okra production constitutes about 4.6% of the total staple food production in Nigeria from 1970-2003 (CBN, 2004). Okra is the most important fruit vegetable crop and a source of calorie (440kcal/kg) for human consumption. It ranks first before other vegetable crops (Babatunde et al, 2007). It is one of the most commonly grown vegetable in the tropics also has an added advantage of short maturity period. Therefore the turn over is rapid while farmers make quick returns in a short time.
Therefore need there is a need to investigate the growth responses of the vegetable to water deficit, when known, the best watering regime and its responses to water stress (deficit) will be introduced to the populace for utilization.
1.6 AIM AND OBJECTIVES
To determine the growth responses of okra to high and low watering concentrations.
i. To determine the best watering regime for okra plant.
ii. To establish a fact about the growth responses of okra plant to less water volume..