Abstract:
This study was conducted to identify the causal organism of necrotic spot disease on
Hylocereus polyrhizus and determine the effect of sanitation treatment and storage
temperature on fruit physiological and microbial changes. The fruit with necrotic spot
had been collected from Johor, Malacca and Terengganu. Thirty-two of Fusarium
species were isolated from the symptom with 40.63% of F. solani, 28.13% of F.
proliferatum, 21.88% of F. semitectum and 9.38% of F. oxysporum. Only F. solani
and F. proliferatum were confirmed pathogenic after inoculation with disease severity
index (DSI) varied from 0.11 to 4.67 for F. solani and 0.11 to 3.69 for F.
pro/iferatum. Thus, F. solani are more pathogenic compare to F. proliferatum. The
sanitation treatment and storage temperature were involved in physiological and
microbial changes of the fruit. For sanitation treatment, sodium hypochlorite treatment
and distilled water treatment showed no significance differences (p>0.05) for
chemical and physical aspects compare to unwashed fruits. While for the microbial
infection, sodium hypochlorite 200ppm can reduce the microbial growth and act as a
good sanitizing agent compare to distilled water and unwashed. The storage
temperature also can prolong the shelf-life of dragonfruit. Fruit stored at room
temperature can maintain the freshness for 6 days but result showed that it can be
extended until 14 days for 14 °C and 21 days for 6
°
C.
