~ 150 ~ The Pharma Innovation Journal 2021; 10(2): 150-153 ISSN (E): 2277- 7695 ISSN (P): 2349-8242 NAAS Rating: 5.03 TPI 2021; 10(2): 150-153 © 2021 TPI www.thepharmajournal.com Received: 28-12-2020 Accepted: 30-01-2021 Amaresh H Department of Plant Pathology, Kittur Rani Channamma College of Horticulture, Arabhavi, Karnataka, India Kantharaju V Professor and Head ICAR- AICRP on Fruits, KRCCH, Arabhavi, Karnataka, India Amruta S Bhat Department of Plant Pathology, Kittur Rani Channamma College of Horticulture, Arabhavi, Karnataka, India K Ramachandra Naik Department of Post-harvest Technology, Kittur Rani Channamma College of Horticulture, Arabhavi, Karnataka, India Mahesh YS Director of Extension, Department of Plant Pathology, University of Horticultural Sciences, Bagalkot, Karnataka, India Corresponding Author: Amaresh H Department of Plant Pathology, Kittur Rani Channamma College of Horticulture, Arabhavi, Karnataka, India Biochemical characterization of resistance to root-knot nematode, Meloidogyne incognita in sweet potato Amaresh H, Kantharaju V, Amruta S Bhat, K Ramachandra Naik and Mahesh YS Abstract Sweet potato is a perennial vine, usually cultivated as an annual crop. Its storage roots are rich in energy and are an important source of carbohydrates, vitamin A. Root-knot nematode (Meloidogyne spp.) causes galls or knots in the roots and considerable yield loses of 10.2 per cent. Seventeen sweet potato genotypes were screened against root-knot nematode, M. incognita and were subjected for biochemical estimation of enzymes content viz., PO, PPO, PAL and total phenols, in both susceptible and resistant varieties. The results revealed that, the genotype Sree Bhadra has recorded the maximum activity of different enzymes viz., Peroxidase (3.12 abs/min/g), Polyphenol oxidase (0.127 abs/min/g), Phenyl Alanine Ammonia Lyase (22.37 nmol/min/ml), and total phenol (447.00 micro gram/g). The genotype Kanhangad Local has recorded minimum levels of Peroxidase (1.02 abs/min/g), Polyphenol oxidase (11.03 nmol/min/ml), Phenyl Alanine Ammonia Lyase (11.03 nmol/min/ml) and total phenol (107.67 micro gram/g). Keywords: Sweet potato (Ipomoea batatas(L.) Lam.,) root-knot nematode, biochemical characterisation Introduction Sweet potato, Ipomoea batatas (L.) Lam., is a dicotyledous plant that belongs to the family Convolvulaceae. It is originated from Central America and the North Western part of South America from where it was introduced to Europe by Columbus and to Asia, Africa and North America by Spanish and Portuguese explorers and traders. It is an herbaceous perennial crop with edible tuberous root that is usually long and tapered, with a smooth skin whose colour ranges between red, purple, brown and white. It can be cultivated throughout the tropical and warm temperature region wherever there is sufficient water to support its growth. It is a vegetable crop with great social, economic and nourishing importance, especially for the poorest regions of the planet, where it is one of the most important food sources (Oliveira et al., 2005) [7] . Sweet potato is a perennial vine, usually cultivated as an annual crop. Its storage roots are rich in energy and are an important source of carbohydrates, vitamin A and C, fibre, iron, copper, calcium and folic acid, especially the orange-fleshed sweet potatoes (Collins et al., 1999) [2] . Sweet potato is mainly grown in China, Nigeria, Tanzania, Ethiopia and Indonesia. The crop is grown in all states of India, except Jammu and Kashmir, Himachal Pradesh and Sikkim. It can be grown in different environments and it became an excellent supplement to staple foods. Biochemical studies in genotypes of sweet potato infested with M. incognita helps to know the differences in enzymatic activities viz., PO, PAL, PPO and total phenols. In future, the enhancement of respective enzymatic contents can be main objective for the resistance breeding in sweet potato against nematodes. Material and Methods A pot experiment was conducted in green house with seventeen sweet potato genotypes planted in plastic pots filled with sterilized soil. Thirty days after planting, the nematodes were inoculated at the rate of 6000 infective juveniles per 3000 g soil (two nematode per gram of soil), into four holes made in the soil around the base of each plant. Regular watering and weeding were followed. Three replications were maintained for each genotypes. The plants were carefully deported after completion of nematode life cycle.