Abstract

      A 16-week study using 2 certified land races of Telfairia occidentalis Hook F plants, to ascertain the effectiveness of calcium in prolonging the shelf life of the leaves and identify the pathogens that cause leaf rot of the plant was carried out. The two varieties were subjected to 5 levels of calcium carbonate treatments (0.25, 0.50, 0.75, and 1 g and control (0 g) in 20 kg polythene bags and grown in the field for 120 days using completely randomized block design. The results obtained were subjected to analysis of variance at probability of 0.05. The rates of chlorophyll disintegration, respiration (CO₂ evolution) and calcium accumulation were measured from Days 1 to 6 after harvest using the 5th upper most fully expanded leaves (120 days old) for each variety per treatment. However, plants that received 1 g CaCO₃ died two weeks after germination. Significant differences were observed in the chlorophyll concentrations of the two varieties that received different calcium carbonate treatments and control (untreated leaves). On Days 5 and 6, the levels of chlorophyll were lowest in control and highest in leaves that received 0.5 and 0.75 g CaCO₃. The varieties did not vary significantly in chlorophyll disintegration on different days of storage and in different calcium treatments. The two varieties with different treatments showed a gradual decrease in chlorophyll concentrations from Days 1 to 6 and from Treatments 0 to 0.75 g. However, there was no significant variation in the two varieties on the rate of respiration (CO₂ production). Both varieties showed a gradual increase in CO₂ evolution from Days 1 to 6 and the leaves treated with 0.5 and 0.75 calcium carbonate fertilizer produced least CO₂, while the highest CO₂ evolution was observed on untreated plant. The results showed that the two varieties did not differ significantly on the rate of calcium accumulation. Leaves treated with 0.5 and 0.75 g CaCO₃ accumulated the highest calcium, 0.25 g accumulated low calcium while the control had the least calcium 120 days after planting. The pathogens isolated include Erwinia carotovora and Pseudomonas syringae. The sensitivity test of calcium treatments on the growth of the pathogens, showed that calcium did not inhibit the growth of the isolated pathogens.

Key words: Telfairia occidentalis, vegetable, preservation, calcium, disease, shelf-life, pathogens.