Journal of Phytology 2011, 3(8): 28-33 ISSN: 2075-6240 www.scholarjournals.org www.journal-phytology.com 28 Effect of Aphid infestation on the Biochemical Constituents of Mustard (Brassica juncea) plant Pushpa Singh 1* and Vijay Kumar Sinhal 2 1 Swami Shraddhanand College, Departemnt of Zoology, University of Delhi, Delhi-110007, India. 2 Department of Botany, Maharaja Agrasen Mahavidyalaya, Bareilly, UP, India. Article Info Summary Article History Mainly two aphid species viz., Lipaphis erysimi (Kalt) and Myzus persicae (Sulzer) were recorded on mustard crop. The infestation of insect pests caused considerable damage to the individual parts (leaf, stem, inflorescence and seeds) of the crop plants and significantly reduced the nutritional constituents (lipid, carbohydrate, nitrogen and protein levels) of mustard plants at different growth stages. Lipaphis erysimi was found to be the most active pest of mustard. These aphids have appeared in the fields especially with the onset of flowering. The loss in biochemical nutritive of plant foliage due to aphid infestation would degrade the quality of the products made of from different parts of mustard crop. Received : 19-02-2011 Revised : 03-05-2011 Accepted : 07-05-2011 *Corresponding Author Tel : +91- 9718563301 Fax : +91-1127662203 Email: pushpa.ysingh@gmail.com ©ScholarJournals, SSR Key Words: Mustard crops, Aphid infestation, Biochemical analysis, Nutritional constituents Introduction The mustard is a multipurpose crop cultivated in different parts of world. Mustard is used in medicine, food and fodder. Mustard has considered a very nutritive fodder for cows and buffalos. Mustard is also used in traditional medicines for different kind of diseases in India. Among agricultural crops oilseeds are important in the national agricultural economy as they share about 13 % of the country’s gross cropped area; contribute about 5 % of the gross national product and 11 % of value of agricultural products. India has the distinction of being one of the world’s largest oilseed growers [1] (India 25.6 million hectares and world 125 hectares). Among oilseeds, rapeseeds and mustard are next to groundnut in both cropped area and production in the country and their corresponding share in oilseed production being about 32 % and 39 %. The mustard belongs to the family Cruciferae and has been placed in the genus Brassica. Indian mustard (Brassica juncea) commonly also known as ‘raya’, ‘rai’ or laha, is an important oil crop in India. The production of agricultural crops per unit area is limited by many factors, such as, availability of arable land, farming practices, quality of seeds and damages caused by insect pest. Among various insect pests inflicting severe damages to crop plants aphids have acquired a significant majority particularly due to their polyphagous nature and special mode of reproduction. Mainly two aphid species viz., L. erysimi and M. persicae were recorded from the mustard plants in which L. erysimi was found to be the most active pest of mustard. These aphids have appeared in the fields especially with the onset of flowering. The total population of L. erysimi peaked in the month of February was found to be 1515 aphids per plant in the year 2002-03. The maximum aphid population and growth rate was recorded during the last fortnight of February [2,3]. Infestation of insect pests caused considerable damage to the individual parts (leaf, stem, inflorescence and seeds) of the crop plants and it is expected that significantly reduced the nutritional constituents (lipid, carbohydrate, nitrogen and protein levels) of mustard plants at different growth stages. Materials and Methods Survey of aphid infestation on mustard plants was carried out at the Bilwa area near MJP Rohilkhand University of Bareilly, Uttar Pradesh (India) at fortnightly intervals to determine the effect of aphid infestations on mustard plants throughout the crop-season. The farmers were requested to follow the standard doses of N-fertilization (60 kg/ha of Urea) to be applied ½ of it at the time sowing and the remaining half at the time of first irrigation [4]. The Normal as well as infested plants was brought to the laboratory separately (leaf, stem, inflorescence and seeds) in the plastic bags and aphids were collected with a brush, forceps for their taxonomic identifications at different stages of the crop. The Plant parts were analyzed for the total nitrogen levels using Micro-Kjeldahl method [5] and the protein contents of different plant parts were determined by multiplying the contents of Kjeldahl nitrogen by a conversion factor calculated of 6.25 [6,7]. Carbohydrate contents of these plants were determined by the method of Morris [8] and Singh and Sinha [9], where as the lipid contents were estimated using Soxhlet Extraction procedure as described by Folch et. al., [10] and Singh and Sinha [9]. (i) Lipid For the determination of lipids the dried (70+ 1 º C; 48h) and weighed samples (leaf, stem, inflorescence and seeds) of mustard plants were extracted in a Soxhlet lipid extractor using a solvent of chloroform AR (CDH, India) and methanol AR (CDH, India) (2:1v/v). For this purpose the weighed samples of the plant parts were kept inside weighed and marked pouches