Tracking of Diversity among a Wide Local Collection of Bitter Gourd (Momordica charantia L.) Landraces in Bangladesh

Bitter gourd (Momordica charantia L.),is an important monoecious and cross-pollinated vegetable crop of the family Cucurbitaceae grown in Bangladesh. It is locally known as karala/uchha.It is extensively cultivated throughout the country under two situationsi.e. rainy season (July to August) and summer season (February to March). According to Chakravatry (1959), bitter gourd is believed to have originated in the tropics of the old world and is widely distributed in China, Malaya, India, tropical Africa and certain other countries. In terms of nutritive value, bitter gourd ranks first among cucurbits, the most important nutritional contribution being vitamins and minerals especially iron, phosphorus and ascorbic acid. Fruit also contains two alkaloids viz., momordicin and cucurbitacin, momordicin is the momordicosidesglycosides of tetracyclic triterpinoides with cucurbitaneskeleton (Chandra Vadana and Subhash Chandra, 1990).Bitter gourd contains a reasonable amount of different nutrients such as proteins, carbohydrates, fats, minerals and vitamins A, B2, and C etc. Rajasekaran and Shanmugavalu (1984), reported very high amount of vit. C (95 mg/100g) and protein (16.5%) found in some Indian bitter gourd variety. The fruits are bitter to taste due to the presence of substance called cucurbitacin. Bitter gourd is also reported to use against diseases like paralysis, indigestion and vomiting pain and diabetes (Mier and Yaniv, 1985). Fruits and other part of bitter gourd are reported to have cooling, stomachic, appetitising, carminative, antipyrietic, antihelminthic, aphrodisiac and vermifuge properties (Blatter et al., 1935). Various medicinal uses with clinical properties of insulin have been isolated from this species (Baldwa et al., 1977). Among the traditional vegetables bitter gourd occupied important position in export trade. The fruits are used as fried, stuffed, dried and pickled (Morton, 1967). However, inspite of its importance, adoptability and export potential, research priority given to this crop is quite meagre especially on genetic improvement. Among the cucurbits, it is considered a prized vegetable because of its high nutritive values especially ascorbic acid andiron (Behera, 2004). A compound known as charatin present in the bitter gourd is used in the treatment of diabetes to lower blood sugar levels (Shetty et al., 2005). During, 2011-2012 bitter gourds were grown over an area of 9311.74 hectares and its annual production was 46000 Mt (BBS, 2012). During 2013, bitter gourds were grown over an area of 24000 acres, it’sper acre yield 2177 kg and annual production was 52000 ton. In Bangladesh, vegetable production is not evenly distributed throughout the year and most of the vegetable are produced during winter (Quasem, 2003; BARI, 2006). Hence there is a severe deficiency of vegetables during summer season due to adverse climatic conditions (Chowdhury, 1993; Ali et al., 1993 and Rashid, 1999). The bitter gourd production can meet up the crisis. It grows more or less in every areas of Bangladesh. Young shoots and leaves are extensively used as vegetable in the Philippines where the plants are found in the wild in waste places. The juice of the leaves and fruits of bitter gourd has been used as an anthelmintie, and is applied externally for malignant ulcers (Oliver, 1960). According to Ayensu (1984), the leaves are also used traditionally in the treatment of breast cancer. Bitter gourd may contribute to the nutritional shortage of the people of Bangladesh. Particularly, it can provide added proteins, minerals and vitamins to the diet. Although bitter gourd is an important vegetable crop, there is no recommended variety in Bangladesh and very little is known about its improvement practice. The considerable increases in bitter gourd production is no doubt remarkable, but the fact remains that the bitter gourd growers are surrounded with a number of problems, like the pests and diseases, high labour charge etc. Very few research works relating to diversity of bitter gourd have been conducted in Bangladesh. So, intensive research efforts are needed in several areas, particularly, selection of superior genotypes. There are a lot of variabilities among the existing bitter gourd germplasm of Bangladesh. An understanding of the nature and magnitude of the variability among the genetic stocks of bitter gourd is of prime importance for the breeder. A good knowledge of genetic wealth might also help in identifying desirable cultivars for commercial production. Because of its nature of high cross pollination, hardly any genetically pure strain is available to the growers. Among the local cultivated varieties, a wide range of genetic variability exists in this crop which can be exploited for its improvement. The basic key to a breeder is to develop high yielding varieties through selection, either from the genotypes or from the segregates of a crop. Expression of different plant character is controlled by genetic and environmental factors. In a hybridization program knowledge of interrelationship among and between yield and yield components is necessary. Path analysis partitions the components of correlation co-efficient into direct and indirect and visualizes the relationship in more meaningful way (Bhatt, 1973). Estimation of genetic diversity is considered as an important factor, which is also essential prerequisite for hybridization program for developing high yielding variety. Multivariate analysis is a useful tool in quantifying the degree of divergence between biological populations at genotypic level. Based on the information, the present study was undertaken to know the yield potentiality of genotypes and to know the genetic diversity among the genotypes for future hybridization program.