A Comparative Study on The Nutritional Quality of four Varieties of Healthy and Disease Affected Mulberry Leaves and Determination of Factors Associated with the Disease

Abstract

The causal organisms, Cercospora moricola Cooke and Phyllactinia corylea Pers Karst responsible for leaf spot and powdery mildew diseases of mulberry leaf respectively were isolated, identified and characterized from the following observation, organisms are obligate parasite under the form of class Deuteromycetes and A5comycetes, optimum temperature 28-30°C and 20-25°C; Optimum pH 5.0-6.0 and 5.0; optimum relative humidity 90-100% and 70% for conidial germination respectively. The conidium of Q. moricola germinates better in rain water and 2.0-2.5% glucose solution whereas P. corylea germinates better in dew and 2.0% glucose solution. Out of the four varieties of the mulberry leaves examined, BM-2 is more resistance of leaf spot disease while BM-4 is more resistance of powdery mildew. The disease severity of leaf spot increases during the month of August while powdery mildew increases during the month of Febnmry. Among the six fungicides tested, Dithane M-45 and Bayleton-25wp were the most suitable fungicide for the control of leaf spot and powdery mildew disease respectively. The physiochemical compositions such as TT A, pH, moisture, ash, chlorophyll, protein, lipid, total sugar, reducing sugar, non-reducing sugar, starch, crude fibre, phenol, vitamin-c, vitamin-B 1, vitamin-B2, ~-carotene and minerals as well as content of enzymes such as amylase, protease, invertase, cellulase, polyphenol oxidase, ascorbic acid oxidase and peroxidse in four varieties of healthy, tukra disease affected, leaf spot disease affected and powdery mildew disease affected mulberry leaves at mature stage were compared. In general healthy mulberry leaf contained about 322-255 mg% chlorophyll, 71- 74% moisture, 3.08-3.40% ash, 4.08-4.62% protein, 1.97-2.10% lipid, 2.7-3.0% total sugar, 0.59-0.71 % reducing sugar, 2.06-2.31 % non-reducing sugar, 6.38- 7.22% starch, 6.08-7.04% crude fibre, 145-160 mg% phenol, 116-132 mg% vitamin-c, 98-120 mg% P-carotene, 44-60 mg% vitamin Bi and 0.47-0.53 mg% vitamin B2• The present data indicated that the contents of most of the chemical compositions such as ash (10-15% ), chlorophyll ( 50-60% ), lipid (25-30% ), total sugar (40-50%), reducing sugar (40-50~/o), non-reducing sugar (40-50%), starch (35-40%), crnde fibre (25-40%), vitamin-C (20-35%), vitamin-Bi (25-35%), Vitamin-B2 (25-30%), P-carotene (30-45%), calcium (35-40%), phosphorous (35- 400/o) and iron (40-50~/o) were decreased while the contents of protein (25-30%) and phenol (30-50%) were increased significantly after infection of healthy mulberry leaves with diseases. The enzyme contents some hydrolytic enzymes such as amylase (45-55%), invertase (30-40%), protease (40-45%) and cellulase (50-55%) were decreased while that of the oxidative enzymes such as polyphenol oxidase (50-80°1<>), ascorbic acid oxidase (85-125%) and peroxidase (45-75%>) were increased remarkably after infection of mulberry leaves with diseases. The above mentioned crnde enzymes were also characterized with respect to their temperature optimum, pH optimum, heat stability, Km and Ymax•