Despite the likely increasing co-occurrence of drought and heat stress, not least in equatorial regions, due to climate change, little is known about the combinational effect of these stresses on rice productivity and quality. This study evaluated the impact of simultaneous drought and temperature stress on growth, grain yield, and quality characteristics of seven rice cultivars from Rwanda, grown in climate chambers. Two temperature ranges—23/26 °C night/day and 27/30 °C night/day—together with single or repeated drought treatments, were applied during various plant developmental stages. Plant development and yield were highly influenced by drought, while genotype impacted the quality characteristics. The combination of a high temperature with drought at the seedling and tillering stages resulted in zero panicles for all evaluated cultivars. The cultivar ‘Intsindagirabigega’ was most tolerant to drought, while ‘Zong geng’ was the most sensitive. A “stress memory” was recorded for ‘Mpembuke’ and ‘Ndamirabahinzi’, and these cultivars also had a high content of bioactive compounds, while ’Jyambere’ showed a high total protein content. Thus, climate change may severely impact rice production. The exploitation of genetic diversity to breed novel rice cultivars that combine drought and heat stress tolerance with high nutritional values is a must to maintain food security.

Potato production in the mountainous region of Central Africa (CA) remains very low (10–15 T/ha), while the commonly cultivated varieties have a genetic potential to reach more than 40 T/ha. This low productivity is due, among other reasons, to a low quality of propagation material (seed tubers). Certified potato seed tubers are not only expensive but also not sufficient on the market to cover the needs of potato producers, leading them to use year-to-year seeds potatoes already infected by diseases and totally degenerated. Due to constraints of getting appropriate facilities for good Potato seeds production among producers, various cutting methods to obtain quality potato seeds have been developed. Indeed, in several experiments carried out in Rwanda and in other countries, the use of good healthy propagation material has increased yields by more than 35%. Since this mountainous zone of Central Africa is very suitable for the cultivation of potatoes for its climatic conditions, the methods developed in this chapter for producing quality potato seeds and appropriate agricultural practices (crop rotation, good fertilization, disease control and pests) will make it possible to significantly increase yields, and thus allow the varieties grown in Central Africa to express their genetic potential of more than 40 T/ha.

Sarocladium and Fusarium species are commonly identified as causal agents of rice sheath rot disease worldwide. However, limited knowledge exists about their genetic, pathogenic, and toxigenic diversity in sub-Saharan African (SSA) countries, where an increasing incidence of this disease has been observed. This study aimed at identifying, characterizing, as well as assessing the genetic, pathogenic, and toxigenic diversity of the pathogens associated with rice sheath rot disease in Mali, Nigeria, and Rwanda. In this study seventy fungal isolates were obtained from rice plants displaying disease symptoms on research and farmer’s fields in Mali, Nigeria, and Rwanda. Thus, an extensive comparative analysis was conducted to assess their genetic, pathogenic, and toxigenic diversity. The Fusarium spp. were characterized using the translation elongation factor (EF-1α) region, while a concatenation of Internal Transcribed Spacer (ITS) and Actin-encoding regions were used to resolve Sarocladium species. Phylogenetic analysis revealed four Fusarium species complexes. The dominant complex in Nigeria was the Fusarium incarnatum-equiseti species complex (FIESC), comprising F. hainanense, F. sulawesiense, F. pernambucatum, and F. tanahbumbuense, while F. incarnatum was found in Rwanda. The Fusarium fujikuroi species complex (FFSC) was predominant in Rwanda and Mali, with species such as F. andiyazi, F. madaense, and F. casha in Rwanda, and F. annulatum and F. nygamai in Mali. F. marum was found in Nigeria. Furthermore, Fusarium oxysporum species complex (FOSC) members, F. callistephi and F. triseptatum, were found in Rwanda and Mali, respectively. Two isolates of F. acasiae-mearnsii, belonging to the Fusarium sambucinum species complex (FSAMSC) were obtained in Rwanda. Isolates of Sarocladium which were previously classified in three phylogenetic groups were resolved into three species which are: attenuatum, oryzae and sparsum. S. attenuatum was dominant in Rwanda, while S. oryzae and S. sparsum were found in Nigeria. Also, the susceptibility of FARO44, a rice cultivar released by Africa Rice Centre (AfricaRice) was tested against isolates from the four Fusarium species complexes and the three Sarocladium species. All isolates evaluated could induce typical sheath rot symptoms albeit with varying disease development levels. In addition, liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine variation in the in vitro mycotoxins of the Fusarium species. Regional differences were observed in the in vitro mycotoxins profiling. Out of the forty-six isolates tested, nineteen were able to produce one to four mycotoxins. Notably, very high zearalenone (ZEN) production was specific to the two F. hainanense isolates from Ibadan-Nigeria, while Fusarium nygamai isolates from Mali produced high amounts of fumonisins. To the best of our knowledge, it seems this study is the first to elucidate genetic, pathogenic, and toxigenic diversity of Fusarium species associated with the rice sheath rot disease complex in selected countries in SSA.