Post Harvest Spoilage of Sweetpotato in Tropics and Control Measures

Abstract

Sweetpotato storage roots are subjected to several forms of post harvest spoilage in the tropical climate during transportation from farmers' field to market and in storage. These are due to mechanical injury, weight loss, sprouting, and pests and diseases. Sweetpotato weevil is the single most important storage pest in tropical regions for which no control measures or resistant variety are yet available. Several microorganisms (mostly fungi) have been found to induce spoilage in stored sweetpotatoes. The most important among them are Botryodiplodia theobromae, Ceratocystis fimbriata, Fusarium spp., and Rhizopus oryzae. The other less frequently occurring spoilage microorganisms include Cochliobolus lunatus (Curvularia lunata), Macrophomina phaseolina, Sclerotium rolfsii, Rhizoctonia solani, Plenodomus destruens. Microbial spoilage of sweetpotato is found associated with decrease in starch, total sugar, organic acid (ascorbic acid and oxalic acid) contents with concomitant increase in polyphenols, ethylene, and in some instances phytoalexins. Several methods are used to control microbial spoilage. Curing to promote wound healing is found as the most suitable method to control microbial spoilage. Curing naturally occurs in tropical climates where mean day temperature during sweetpotato harvesting season (February-April) invariably remains at 32-35 degrees C and relative humidity at 80-95%. Sweetpotato varieties varied in their root dry matter content, and low root dry matter content attributed for their high curing efficiency. Curing efficiency of varieties also differed in response to curing periods. Fungicide treatment, bio-control, gamma irradiation, hydro warming, and storage in sand and saw dust were found to have intermediate impacts in controlling spoilage and enhancing shelf life of sweetpotato roots. Breeding program has to be chalked out to develop new varieties suitable to curing under tropical conditions in addition to developing varieties having multi-spectrum resistance to major post harvest rot pathogens and sweetpotato weevils.

Effect of plant spacing and variety on weed and performance of orange-fleshed sweet potato in humid agro-ecological zone of Nigeria

“…Among the crops grown in the tropics, sweet potato ranks second after cassava (Ray and Ravi, 2005). Within sub-Saharan Africa, its ranks third after cassava and yam (Hahn and Hozyo, 1998).…”

PERUBAHAN KADAR AIR DAN PATI UBI JALAR (Ipomea batatas L.) SEGAR PADA SISTEM PENYIMPANAN SEDERHANA

“…Cara yang sama dilakukan pada pembuatan kurva standar dimana larutan glukosa murni (0,5 ml) yang masing-masing mengandung 0, 10,20,30,40,50,60,70 dan 80 µg larutan glukosa, ditempatkan ke dalam tabung reaksi dan dianalisis sampelnya hingga mendapatkan nilai absorbansinya. Nilai absorbansi tersebut kemudian dibuat persamaan dari kurva standar larutan glukosa dengan konsentrasi larutan glukosa sebagai sumbu x dan absorbansinya sebagai sumbu y.…”

Wound healing and dry matter content of orange-fleshed sweetpotato cultivars as influenced by curing methods

“…Curing induces suberisation of exposed parenchyma cells and development of wound periderm (Ray and Ravi 2005). The field-piled curing resulted in high wound healing score than the in-ground curing because the fieldpiled provides an ideal atmosphere for the suberisation process of the parenchyma cells and wound periderm development of sweetpotato.…”