31 Harvested cassava (Manihot esculenta Crantz) roots deteriorate quickly and they can’t be stored satisfactorily for more than two to three days under ambient conditions. This phenomenon is unique to cassava roots and is known as Postharvest Physiological Deterioration (PPD). The extent of PPD damage and speed of symptom development in roots depends on the genotypic as well as the environmental conditions. (reviewed by Ravi and Aked 1996, Reilly et al. 2004). The PPD is considered one of the main postharvest constraints for farmers, traders, food and starch industries. The short shelf-life of harvested roots makes the long distance transport of cassava for marketing or industrial purpose unviable either due to loss in transit or low quality raw material for food processing industry. 1 Senior Scientist (e mail: rajusar@gmail.com), 3 Principal Scientist (e mail: veluravi03@yahoo.co.in), 4 Principal Scientist (e mail: sheelactcri@yahoo.co.in), 6 Director (e mail: skc_cpri@yahoo.co.in), ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala; 2 Associate Professor (e mail: roykau@gmail.com), College of Agriculture, Vellayani, 5 Research Scholar (e mail: jaymakasana@gmail.com), SV National Institute of Technology, Ichchanath, Surat, Gujarat Evaluation of postharvest physiological deterioration in storage roots of cassava (Manihot esculenta) genotypes SARAVANAN RAJU 1 , ROY STEPHEN 2 , VELUMANI RAVI 3 , SHEELA MADHAVI NEELAKANTAN 4 , JAYANTIKUMAR MAKASANA 5 and SWARUP KUMAR CHAKRABARTI 6 ICAR-Central Tuber Crops Research Institute, Thiruvananthapuram, Kerala 695 017 Received: 1 June 2015; Accepted: 1 July 2015 ABSTRACT Cassava (Manihot esculenta Crantz) is an important tropical root crop grown worldwide for food, feed and industrial purposes. Harvested cassava roots quickly deteriorate and loose the shelf-life due to a phenomenon called postharvest physiological deterioration (PPD). PPD symptom starts within 24 hr after harvest, initially as blue black discolouration in the storage parenchyma and quickly spread to entire root. The roots become unfit for consumption within 2-3 days after the harvest in most cases. Identification of delayed PPD genotypes in cassava will help breed superior varieties tolerant to deterioration with long shelf-life. Low molecular weight phytochemicals produced during PPD are reported to have significant role in PPD development. We analyzed the biochemical changes associated to secondary metabolites in 61 cassava genotypes during storage and evaluated the relationship with PPD. PPD evaluation was done visually at specified intervals by taking transverse sections at 25, 50 and 75% along length of roots from proximal to distal end and the roots were categorized into different PPD classes based on the visual scoring. Root morphological, starch, and carotene content had no direct correlation with PPD. The HPTLC chromatographic data on phytoconstituents of methanolic extract of cassava roots and its relation with PPD symptoms were analyzed and polymorphic bands were assessed for grouping the genotypes based on PPD expression levels. Cluster analysis revealed a close association between PPD expression and phytochemical constituents of stored roots and this can help to categorize the genotypes based on PPD. Key words: Cassava, Evaluation, Postharvest physiological deterioration, Storage roots Cassava root PPD limits the expansion of cassava production in developing countries, and has become one of the major constraints compared to other root crops, due to root discounting, waste and added costs (Wenham 1995, Westby 2002, Reilly et al. 2004). Cassava roots develop blue/black vascular streaking initially during PPD, followed by discoloration of storage parenchyma with brownish or blackish occlusions (Reilly et al. 2007). The roots become unpalatable and unfit for consumption after two to three days. Changes in many enzymes of secondary metabolism, cell wall modification and wound healing were reported (Ravi and Aked 1996). The PPD of cassava roots is an active and complex process involving gene expression and protein synthesis. Phenolic compounds associated with PPD include scopoletin, scopolin, esculin, proanthocyanidins, (+) - catechin and (+) gallocatechin (Tanaka et al. 1983, Rickard 1981, 1985; Wheatley and Schwabe 1985). Scopoletin has a crucial role in the development of physiological deterioration of cassava root (Wheatley and Schwabe 1985). When applied to freshly cut roots, scopoletin produced intense and rapid discoloration of the tissue. Scopoletin, identified as a fluorescent compound (Rickard 1982), is absent or has very Indian Journal of Agricultural Sciences 85 (10): 1279–84, October 2015/Article https://doi.org/10.56093/ijas.v85i10.52251