Potatoes (Solanum tuberosum L.) have been grown for decades for home consumption and commercial use in highlands of
Burundi where temperature is lower than in the lower lands. All attempts to introduce them in the lowlands of Burundi failed because
the material tested always appeared not to be suitable to this hot environment with regard to tuber yield and other agronomic
characteristics. A set of 15 potato genotypes presented as more tolerant to high temperatures was hence introduced in 2004 from the
International Potato Center (CIP) and tested together with nine local varieties in various environments for three years. From the
coolest environment (16.9°C) to the hottest one (26°C); fresh tuber yield, dry tuber yield, tuber dry matter concentration and harvest
index decreased significantly. However, combined analysis indicated that, if heat tolerant cultivars are grown in the lowlands of
Burundi, a fresh tuber yield of 13 t ha-1 or more should be expected whereas a non suitable cultivar like Ndinamagara (Cruza 148)
would produce only 2.7 t ha-1. Contrary to what was expected, an early maturing variety (Victoria) and a late maturing clone
(395194.9) performed satisfactorily in both cool (highlands) and warm conditions. Four clones (390663.8, 395194.9, 388972.22 and
388611.22) and one variety (Victoria) were found to be the most suitable for the Imbo region (warm areas). Furthermore, the hot
climate negatively influenced the tuber set, and therefore, tuber number was lower (23.3 tubers per plant in highlands and 7.1 in
lowlands). The agronomic implication is that the Imbo region could be appropriate for consumer potatoes but not economically
appropriate for seed production. The seed could be multiplied in highlands and then brought to Imbo for commercial production.
Despite the satisfactory fresh tuber yields obtained by these genotypes under high temperatures in comparison with other genotypes
or the average national potato yield reported to be 2.7 t ha-1 by FAO, we believe that their potential was not achieved and higher yields
could be obtained with better crop management. Therefore, there is need to carry out complementary studies on agricultural
techniques aiming at increasing the yields obtained so far