Knowledge for Development

Improvement of papaya productivity for commercial application

Author: Fredah Karambu Rimberia, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya

Date: 28/03/2014


Dr Rimberiawas rewarded the fifth prize in the Women in Science competition. She explains to Knowledge for development that the most relevant result of her project is the finding that the production of clean and healthy papaya plantlets of known sex can solve the farmers’ inability to differentiate among the papaya’s 3 sex types at seedling stage. She found that healthy orchards with the correct mix of one male to nine female plants will increase fruit yield greatly compared to the current situation where farmers use guess work. Farmers will be able to grow more fruits and the papaya industry will be able to produce more yoghurt and beauty products. ‘This award will increase my visibility in the research community and that of my university. Hopefully, it will help me get a promotion at my university and more funding for research projects. In five years time ‘I will be an associate professor with four patents to my name and many scientific publications.’  


Papaya fruits are rich in vitamin A, and have the potential to contribute to fighting vitamin A deficiency in Kenya and other countries if included as part of a diverse diet. Production of papaya has decreased in the recent past due to lack of improved varieties and devastating viral diseases. The objectives were to collect and characterise papaya germplasm, evaluate its agronomic qualities, produce tissue culture planting material and develop value added consumer products for fruits and seeds.  

Germplasm for Carica papaya L. and a related species, Vasconcellea cundinamarcensis was collected from Coast, Nyanza, Western, Rift Valley, Eastern and Central provinces of Kenya. Morphological data on 60 accessions were submitted to neighbour joining cluster analysis. Seeds of 43 randomly selected accessions were evaluated for height, fruit yield and quality. Tissue culture was attempted in order to develop protocols for mass propagation. Morphological characterisation revealed considerable diversity among 60 papaya accessions. Plant height at 100 days and yield were significantly different among papaya germplasm. An efficient protocol for meristem culture was also developed.  

The diversity in morphological, agronomic and fruit characteristics among papaya accessions points to the possibility of obtaining desirable traits for varieties with superior productivity. Shoot tip culture of papaya has been reported, but reports on commercialisation of planting material are rare. In this study, shoot tip culture of papaya regenerated plantlets that were further rooted, and evaluated for agronomic performance, led to the development of a commercially viable protocol for rapid multiplication of papaya of known sex.  

To popularise the fruits and introduce it in day-to-day diets, papaya-based yoghurts were developed. Oil with high oleic acid content was extracted from papaya seeds and used to make soap and lotion. Increased production, sale and consumption of papaya fruit have the potential to improve the health and wealth of poor farming communities and the realisation of the Millennium Development Goals.