Phenotypic diversity and chemical properties of pawpaw fruit quality in Ugandan germplasm

Abstract

Pawpaw (Carica pawpaw L.) fruit production and utilisation have been on the increase in Uganda. However, challenges related to identification of phenotypes with inherent characteristics for improvement of fruit shelf life have limited identification of better varieties. The objective of this study was to evaluate the phenotypic diversity and shelf life determinants of Uganda’s pawpaw accessions and their variations based on selected quality parameters. Nineteen accessions were collected as seeds from different markets of Uganda, germinated and planted in Namulonge-Wakiso district, central Uganda. The accessions were significantly (P<0.05) variable in terms of fruit weight parameters, with dry matter ranging from 14 - 19% and fruit weight of up to 3.9 kg; while pulp weight was up to 3.2 kg per fruit. Pulp firmness parameters were also significantly variable (P<0.05) and highly correlated with shelf life of the fruit, which ranged from 7 - 13 days depending on the accession. Fruit pulp pH ranged from 4.4-5.6; while titratable acidity of the fruit ranged from 0.03-0.08%. The accessions were clustered in four main clusters depending on the fruit firmness properties, fruit shelf life, fruit weight, pH and titratable acidity as definitive parameters. These accessions were distinguished based on morphological parameters, and henceforth defined for nutritional and economic uses. Accessions with high fruit firmness (>5 kg F) such as 16/20’ 16/16, 16/17 and 18/1; and external pulp thickness (>2 cm) such as 16/16, 16/17 and 18/1 had improved fruit shelf life and are recommended for marketability and processing.