Effects of pigeonpeas (cajanus cajan (L.) millsp.) genotypes on pod and green pea yield and the nutiutlonal quality as influenced by storage condition

Abstract

Seeds of nine pigeonpea (Cajanus cajan (L.) Millsp.) genotypes (lCPLs 93047, 93066, 87091, 93020, 93015, 93016, 93027, 90029, and 'ICP 7035') obtained from ICRISAT -Kenya were grown under field conditions at Kabete and Kiboko Field Stations between November 1998 and March 1999, to determine their yield, storage stability and acceptability. The crop was grown under supplemental irrigation. Both pod and pea yields were recorded at each harvest for seven harvests in Kabete and four harvests in Kiboko. The shelling percentage was also determined for all the genotypes. Peas and pods from the genotypes were stored at ambient, refrigerated and freezing temperatures during which they were analyzed for moisture, reduced ascorbic acid, total soluble solids (TSS) content, total titratable acidity (1'1'A), chlorophyll content, soluble sugars, protein content, and mass loss. In order of decreasing yield 'ICPL 87091' was followed by 'ICPL 93047', 'ICPL 93027', 'ICPL 93064', 'ICPL 93015', 'ICPL 93016', 'ICPL 93066', 'ICPL 93020', and 'ICPL90029'. A longer podding duration of six weeks, was observed in the high yielding genotypes, for example, 'ICPL 87091'. In contrast, the low yielding' ICPL 90029', had the shortest podding duration showing maximum harvest at the 3rd week. However, no total pod and pea yield differences among genotypes were recorded at Kiboko. In this study, the high yielding genotypes ICPL 87091 and ICP 7035 for Kabete and Kiboko respectively, had high 100-seed masses, although a low yielding genotype ICPL 90029 showed high 100-seed mass. It is, therefore, apparent that in order to select consumer preferred, but economical genotypes, 100-seed mass alone is not an adequate criterion, but has to be combined with other characteristics such as podding duration and shelling percentage. The contents of reduced ascorbic acid, total titratable acidity (TT A), total soluble solids (1'SS), and moisture content (MC) as well as mass loss differed among genotypes shelled or unshelled, at all storage temperatures. Shelling of the peas and storage at ambient temperatures (21±3°C) led to the highest losses of reduced ascorbic acid, mass, moisture and soluble sugars, but increased total titratable acidity. Refrigerated storage resulted in very little changes in reduced ascorbic acid, soluble sugars, and moisture contents of the vegetable. The results from this study show that, low temperature storage (4± 1°C and blanching before freezing) minimises loss of nutrients such as sugars and protein and more loss of TTA hence may be adopted during postharvest handling of vegetable pigeonpeas. Freezing without blanching, however led to most decrease in nutrients such as total sugars and protein content and less loss of TTA, hence may not be adopted as a postharvest technology. 'ICPL 87091' and 'ICP 7035' were recommended for vegetable pigeonpea since they have a high 100-seed mass and high shelling percentage. Low temperature storage was recommended for extension of shelf life of vegetable pigeonpeas.