Abstract: The nutritional composition such as moisture, ash, lipid protein, carbohydrate, total chlorophyll, crude fibre, phenol, β-carotene, vitamin-B1, vitamin-B2, vitamin-C, Calcium, phosphorus and iron content of four varieties of healthy and Phyllectinia corylea infected mulberry leaves at mature stage has been analyzed. The mulberry leaves are considered as a good sources of starch, protein, crude fibre, minerals, vitamin-C, β-carotene and were estimated about 6-7, 4.0-4.6, .0, .0-3.5, 15-132, 00-120 mg%, respectively. Moisture, ash, lipid, crude fibre, carbohydrate, vitamins and minerals content were decreased significantly but protein and phenol content were increased after infected of mulberry leaves with fungus, Phyllectinia corylea.
INTRODUCTION
Mulberry (M. alba Linn.) is the sole host plants of the silkworm Bombyx mori Linn which produces silk. It belongs to the family Moraceae under genus Morus. is a deep rooted perennial plant widely distributed in Asia, Europe, Africa and Latin America on a wide range of climatic conditions varied from temperate to topical. Mulberry leaves are the sole sources of nutrients e.g., protein, carbohydrate, vitamins, minerals etc. for silkworm’s growth. Protein provides the chief structural elements of the muscle, glands and other tissues (Zoadur and Absar, 2001; Hossain et al., 1999). It was known that various microorganisms seriously infected the mulberry leaves. Of these microorganisms, fungus is most important because they cause many diseases; as a result the mulberry leaves are unsuitable to feed silkworm. In Bangladesh, mainly Cercospora moricola and Phyllactinia corylea are infected mulberry leaves widely and the diseases are called leaf spot and powdery mildew respectively, as a result decreased the production of quality leaves by 50% which greatly effect on silkworm rearing as well as the Sericulture Industry (Nomani et al., 1970; Sullia and Padma, 1987; Sikdern et al., 1979; Gavindaiah et al., 1990). Jeyarajan reported that these pathogens infect mulberry leaves and reduces not only yield but also nutritional values, thus making the leaves unsuitable for silkworm feeding (Bakshi et al., 1972). Phyllactinia corylea parasite infected mulberry leaves that causes powdery mildew in most part of India and Bangladesh during dry season from late September to February and serious outbreak in November to January when the weather is cold and relative humidity is comparatively low (Bakshi et al., 1972). As a result production of poor quality of leaves which can not produce good quality cocoons and thus causing a serious set back to sericulture industry. The objective has been ascertained the changes of nutrient content of four varieties mulberry leaves at mature stage.
MATERIALS AND METHODS
The freshly and fungus Phyllactinia corylea infected mulberry leaves were collected from Bangladesh Sericulture Research and Training Institute, Rashahi, Bangladesh. The experiment was performed in the month of November-March at the protein and Research laboratory in the year of 2001. Ash and crude fibre content were determined following the methods (AOAC, 1980). Chlorophyll content of the healthy and disease infected mulberry leaves tissues were estimated following the method described by Methods in Physiological Plant Pathology (Mahadevan and Sridar, 1982). Total protein and water soluble protein content of mulberry leaves were determined by the method of Micro-Kjeldahl as described in Laboratory Manual in Biochemistry and Lowry method (Jayaraman, 1981; Lowry et al., 1951), respectively. Lipid content of mulberry leaf was determined by the method of Bligh and Dyer (1959). Total sugar and starch content of mulberry leaves were determined by the method as described in the Laboratory Manual in Biochemistry (Jayaraman, 1981). Reducing sugar content was determined by dinitrosalicylic acid method.
Estimation of phenol with Folin-Ciocalteu reagent is based on the reaction between phenol and an oxidizing agent phosphomolybdate, which results in the formation of a blue complex (Bray and Thrope, 1954) . Calcium and vitamin-C content were determined by titrimetric method (Bernard, 1965; Vogal, 1961). Phosphorus and iron contents of mulberry leaves were determined by the method of Vogel (Bessey and King, 1933). β-carotene, vitamin B1 and vitamin B2 contents were determined following the procedures as described in Methods of Vitamin Analysis (Anonymous, 1960).
RESULTS AND DISCUSSION
Moisture plays an important role in the growth activities of plants, herbs etc. Water is indispensable to the absorption and transportation of food to carry on photosynthesis, metabolism of materials and the regulation of temperature. It is also essential for most of the physiological reactions in plant tissue and in its absence life does not exist (Rangaaswami et al., 1976). The moisture content was decreased slightly (about 6-7%) after infection with P. corylea of four varieties mulberry leaves (Table 1).
Most of the inorganic constituent or minerals are present in ash. The result clearly indicated that the mineral contents of mulberry leave were decreased significantly after infection with P. corylea. The ash content of healthy and disease infected mulberry leaves varied between 3.05-3.40 and 2.56-2.83%, respectively (Table 1).
The chlorophyll is most important component of plant. The healthy leaves contained about 255-322 mg% whereas P. corylea infected leaves contained 110-202 mg% of total chlorophyll (Table 2).
| Table 1: | Moisture, dry matter and ash content of healthy and diseased mulberry leaves at mature stage |
The result indicated that the total chlorophyll content of mulberry leaves was decreased drastically after infection with P. corylea. The result indicated that both chlorophyll-a and chlorophyll-b content were decreased and also indicated that chlorophyll-b content was more pronounced decreased than chlorophyll-a. The similar result indicated by (Tang et al., 2005; Hossain et al., 1999 and Subba et al., 1979).
Disease development causes impairment in the photosynthetic pigments that affects the utilization of the light energy by the plants. Disease developments affect not only the total chlorophyll-a and chlorophyll-b (Mahadevan and Sridhar, 1982).
Protein as essential nutrient for growth and development is found to be present in good amount in mulberry leaves as compared to that in other fruits and vegetables. The total protein content of healthy leaves were 4.08-4.62% while diseased leaves contained 5.02-5.28% protein, but the healthy and disease infected mulberry leaves contained 3.12-3.32 and 3.72-3.97% water soluble protein (Table 3), respectively.
The mulberry leaves are considered as good source of starch, protein, crude fiber, minerals, vitamin-C and β-carotin and their contents were foumd to be about 6-7, 4-4.6, 3, 3.0-3.5, 115-132 and 100-120 mg%, respectively (Kashem et al., 2003). Nutrients content of Moringa fruit such as moisture, total sugar, starch, total soluble solid, vitamin-C are decreased why ash, total protein, total lipid and reducing sugar contents were decreased after infection with Rhizopus Stolonifer infected disease (Zoadur and Absar, 2001). Nutrients contents of mango leaves such as lipid, total sugar and reducing contents decreased significantly while protein, calcium and iron content increased moderately after infection (Hossain et al., 1999).
The total protein content of healthy leaves were 4.12~4.62 g% while diseased leaves contained 5.02~5.28 g% protein while the water soluble protein content of healthy leaves was 3.12~3.32 g% and diseased leaves was 3.89~3.96 g% (Table 3). The result indicates that in both cases the protein content of pyllactinia corylea infected leaves increased significantly. Similar result was also reported by Nuhu et al. (1960) in purple vein virus infected tomato leaves.
According to Hayashi (1962) the accumulation of nitrogen is due to increase in the activity of amino acid activating enzymes, suggesting that an increase in protein content in virus infected leaves is due to synthesis of viral protein by the causative organism.
| Table 2: | Chlorophyll content of healthy and diseased mulberry leaves at mature stage |
| Table 3: | Protein, lipid and crude fibre content of healthy and diseased mulberry leaves at mature stage |
| Table 4: | Carbohydrates content of healthy and diseased mulberry leaves at mature stage |
| Table 5: | Minerals and Phenol content of healthy and diseased mulberry leaves at mature stage |
Crude fibre has pronounced effect on the digestion and absorption processes of nutrients. The mulberry leaves contained about 7% crude fibre that was decreased about 30-40% after infection with disease. Tang found that crude fibre content was decreased of mulberry leaves after infection with Cercospora moricola (Tang et al., 2005). The lipid content of mulberry leaves decreased remarkably after infection with disease. The healthy mulberry leaves contained about 2% lipid. While the fungus infected leaves contained between 1.30-1.42% lipid (Table 3).
Table 4 represents the total sugar, reducing sugar, non-reducing sugar and starch contents of healthy and disease infected mulberry leaves. The amount of total sugar, reducing sugar and non-reducing sugar were found to vary between 2.74-3.02, 0.59-0.71 and 2.06-2.31% in healthy leaves and 1.42-1.46, 0.34-0.38 and 1.07-1.08% in diseased leaves, respectively. The total sugar content of mulberry leaves decreased drastically (about 50%) after infection with disease. Starch is the storage carbohydrate of chlorophyll containing plants and the starch content of healthy and diseased mulberry leaves are between 6.38-7.22 and 3.94-4.14%, respectively (Table 4). The present data indicated that the starch content of mulberry leaves also decreased remarkably after infection with disease and the reduction in starch content may be due to the hydrolysis of starch by microorganism for their carbon source and synthesis of lower amount of carbohydrate because chlorophyll pigment decreases drastically. From the present data it can be concluded that the contents of all types of sugar in mulberry leaves decreased significantly after infection with fungus, P. corelia. The results showed good agreement with that reported for infected pods (Hedge and Manjol, 1967) and for infected betelvine leaves (Naik et al., 1988). Mehta also found that sugar content decreased due to fruit-rot disease of tomato (Mehta et al., 1995).
The four varieties of healthy mulberry leaves contained 145.24-160.86 mg% whereas disease affected leaves contained 208.38-218.65 mg% phenol (Table 5) indicating that the content of phenolic substances increased by (25-35%) after infection with fungus.
| Table 6: | Vitamin content of healthy and diseased mulberry leaves at mature stage |
Changes in phenolic substances of almost all the inoculated plants have been reported. Thind reported that phenol contents increased in date apple fruits infected with smut (Thind et al., 1977).
As given in Table 5, it was found that the minerals such as calcium, phosphorus and iron contents of healthy leaves 240~238, 75.81~76.78 and 11.82~14.00 g% while those of the disease leaves were 152, 44.25~50.42 and 6.44~6.75 g%. So it was found to decrease in P. corylea infected mulberry leaves about 30-45%, respectively. Hossain et al. (1999) found that the calcium and iron contents decreased in the mango leaves after infection with Colleotrichum gloeosphorioides while Prasad et al. (1976) reported that phosphorus content decreased in diseased condition of sunflower leaves.
From Table 6 it was found that the mulberry leaves contained good amount of vitamin-C, β-carotene and vitamin-B1. The amount of vitamin-C, β-carotene, vitamin-B1 and vitamin-B2 were found to vary between 116.00-132.75, 98.38-120.23, 44.23-60.79 and 0.468-0.523 mg% in healthy leaves and 74.25-82.44, 70.21-88.29, 33.33-49.21 and 0.272-0.326 mg% in disease infected leaves, respectively. Like minerals, the contents of all the above mentioned vitamins in mulberry leaves decreased after infection with disease and the content of vitamin-C, β-carotene, vitamin-B1 and vitamin-B2 were decreased by 40, 25, 30 and 35%, respectively. Agarwal reported that ascorbic acid content decreased in lemon, musambi and orange fruits induced by Colleotrichum gloeosporioides (Agarwal and Ghose, 1979). Singh found that A. flavus and A. parasiticus caused considerable losses in the quantity of ascorbic acid in Musambi fruits (Singh, 1982).
In conclusion, this study gave almost detailed nutrient analysis of four varieties of mulberry leaves were produced widely in Bangladesh. Further the nutritional quality of mulberry leaves was found to be seriously affected after infection with fungus, P. corylea.