Abstract
Background:
The low utilization rate of improved cassava-planting materials in Tanzania is attributed to the traditional propagation method, which has a low seed multiplication rate of 1:10 cuttings. New propagation technologies, such as tissue culture, produce many disease-free cassava-planting materials within a short period. However, the production efficiency of these technologies depends on the shootlet size, the health of the mother plants, and the regeneration method used. The nutrient content, surface area for regeneration, stress tolerance, and response to multiplication signals all influence shootlet size during multiplication.

Aim:
This study assessed the effects of shootlet size on cassava seed multiplication during the 2022/2023 growing season.

Methods:
Five cassava shootlet sizes of 6, 9, 12, 15, and 18 cm long were laid out in a completely randomized design experiment with three replications. Data on ratooning frequency, number of shootlets and roots, root length, and shootlet survival rate were collected and analyzed using the R program.

Results:
Large-sized shootlets (≥ 12 cm) had significantly higher performance than smaller ones. Although high ratooning frequency produced numerous small shootlets (<12 cm), most failed to develop roots and did not survive. Multiplication success was measured by shootlet survival and root development.

Conclusion:
Therefore, this study recommends shootlets of 15 cm in length for maximum cassava seed production under greenhouse conditions, while further research is suggested to improve the survival rates of smaller-sized shootlets.

Key words: Cassava, Seed multiplication, Seed production, Shootlets size, Tanzania