Hybrid tomato seed production in Sri Lanka remains insufficient to meet the national demand, with less than 30% of the requirement fulfilled locally, primarily due to suboptimal site selection and climatic constraints. This study aimed to identify the most productive and climatically suitable locations for hybrid tomato (Solanum lycopersicum L.) seed production under protected cultivation across diverse Agro-Ecological regions of Sri Lanka. Secondary data were obtained from Department of Agriculture (DOA) seed testing laboratory reports covering the 2021–2025 period including KOPIA project implemented sites, representing seed l ots produced in polytunnels at s ix g overnment seed farms s ituated in distinct agro-ecological regions. Productivity (kg/100 m²) and germination percentage in seed lab report (B report) were compared among sites through multi-seasonal evaluations. Results revealed pronounced locational variation in both productivity and seed quality. Rahangala (IU3e) and Rikillagaskada (IM1a) demonstrated consistently superior performance, with seed yield productivity exceeding 1 kg 100 m² and germination percentages above 75% in most seasons, suggesting favorable thermal and relative humidity regimes that support optimal pollen viability, fertilization, and embryo development. Conversely, stations located in w armer, m ore humid z ones s uch a s Kundasale (IM3b), Thelijjawila (WL2a), and P asyala (WL3) recorded reduced productivity and lower germination, likely due to heat-induced reproductive stress and pathogen pressure. These findings highlight the decisive influence of microclimatic parameters, particularly temperature and humidity, on hybrid seed productivity and physiological quality. The study concludes that Mid country and Up country Intermediate Agro-Ecological Regions, notably Rahangala and Rikillagaskada, are the most suitable for large-scale hybrid tomato seed production. Future research integrating meteorological data and parental line performance is recommended to refine locational suitability models and optimize national hybrid tomato seed production strategies.

ABSTRACT
INTRODUCTION
MATERIALS & METHODS
RESULTS
SUMMARY & APPLICATION
적 요
ACKNOWLEDGMENTS
REFERENCES

• H.M.V.T. Welegama(Vegetable Breeding Division, Horticultural Crops Research and Development Institute, Sri Lanka) | 웰리가마 (스리랑카 원예연구소)
• E.A.V.S. Edirisinghe(Department of Crop Science, Faculty of Agriculture, University of Peradeniya, Kandy, Sri Lanka) | 에디리싱헤 (Peradeniya 대학교)
• E.R.G.I.C. Rajapaksha(Vegetable Breeding Division, Horticultural Crops Research and Development Institute, Sri Lanka) | 라자팍사 (스리랑카 원예연구소)
• S.S. Kotandeniya(Vegetable Breeding Division, Horticultural Crops Research and Development Institute, Sri Lanka) | 코탄데니야 (스리랑카 원예연구소)
• M.S.F. Safra(Vegetable Breeding Division, Horticultural Crops Research and Development Institute, Sri Lanka) | 사프라 (스리랑카 원예연구소)
• Pyung-Sik Park(KOPIA Sri Lanka Centre, Director & Expert, Department of Agriculture, P.O. Box 11, Sri Lanka) | 박평식 (KOPIA 스리랑카센터) Corresponding author
• Young Chae(KOPIA Sri Lanka Centre, Director & Expert, Department of Agriculture, P.O. Box 11, Sri Lanka) | 채영 (KOPIA 스리랑카센터)