Cassava is the most important crop in DRC, where it is both a staple and a cash crop. Over the last years, cassava productivity seems increasingly constrained by climate disturbances. To respond to these climatic disturbances, farmers opt to adjust the planting period to spread the risk by optimizing their chances to receive the most regular rainfall in the crucial first 100 days after planting. To investigate the potential of varying cassava planting time to mitigate the effect of changes in rainfall patterns, a full-factorial field experiment was conducted in two contrasting sites in South Kivu (DRC) including Kalehe, a highland and forest region and Uvira, a dry savannah at medium altitude. Effects of three planting periods (November 2018, January 2019, and March 2019), with and without potassium nutrients (NP and NPK), were assessed on the growth parameters of two cassava cultivars, Obama (improved) and M′Bailo (landrace). The growth parameters included stem number, stem height, score of leaf retention and leaf lobe length and width in both sites up to four months after planting (MAP). Yield data on both the above-ground (stems and leaves) and the storage roots and related harvest index was only collected in Kalehe at 12 MAP. The highest storage root yield of 47 and 14 t ha⁻¹ for Obama and M′Bailo respectively were achieved when the cultivars were planted in November 2018 and received NPK fertilizer. Compared to the early planted cassava (November 2018), cassava planted in January and March 2019 produced 29% and 79% fewer storage roots. Similarly, at the fourth month of each planting, growth parameters of early planted cassava were higher than those of late planted cassava although the later planted crop was exposed to more intensive and regular rains in the early stages. Hence the highest aboveground biomass was observed for Obama planted in November while the cassava planted in January and March produced 41% and 76% less above-ground biomass, respectively. Obama storage root yield represented on average 1.7 times M′Bailo storage root yield. K in the fertilizer amendment increased the storage root yield by 14% for M′Bailo and 20% for Obama as compared to no K fertilization. Obama had a better and more stable harvest index of 55% while the M′Bailo was 40%. Stem number, stem height, lobe length, and stem diameter were higher for both cultivars when planted in November 2018. This study revealed that the earlier the cassava was planted, the larger the yield. Thus, deciding to delay cassava planting to expose it to more regular rains in early stages can lead to an aggravation of the adverse effects of climate change. Although this study highlights the importance of combining early planting with improved cultivars for better yields, it did not establish evidence that the application of potassium could attenuate the negative effect of climate change on cassava productivity under rainfed conditions.

木薯是刚果民主共和国最重要的作物，既是主食又是经济作物。在过去的几年里，木薯的生产力似乎越来越受到气候干扰的限制。为了应对这些气候干扰，农民选择调整播种期，通过优化他们在播种后关键的前 100 天内获得最规律降雨的机会来分散风险。为了研究改变木薯种植时间以减轻降雨模式变化影响的潜力，在南基伍省 (DRC) 的两个对比地点进行了全因素田间试验，包括高原和森林地区 Kalehe 和干旱的 Uvira中等海拔的大草原。三个种植期（2018 年 11 月、2019 年 1 月和 2019 年 3 月）的影响，有和没有钾营养素（NP 和 NPK），对两个木薯品种 Obama（改良）和 M'Bailo（长白）的生长参数进行了评估。生长参数包括种植后长达四个月 (MAP) 的两个地点的茎数、茎高、叶片保留分数和叶瓣长度和宽度。地上部分（茎和叶）和贮藏根的产量数据以及相关的收获指数仅在 MAP 12 时在 Kalehe 收集。最高储藏根产量分别为 47 和 14 t ha⁻¹Obama 和 M'Bailo 分别在 2018 年 11 月种植品种并接受 NPK 肥料时实现。与早期种植的木薯（2018 年 11 月）相比，2019 年 1 月和 2019 年 3 月种植的木薯的贮藏根减少了 29% 和 79%。同样，在每次播种的第四个月，早播木薯的生长参数高于晚播木薯，尽管晚播作物在早期暴露于更密集和更规律的降雨。因此，11 月种植的奥巴马的地上生物量最高，而 1 月和 3 月种植的木薯的地上生物量分别减少了 41% 和 76%。Obama 贮藏根产量平均为 M'Bailo 贮藏根产量的 1.7 倍。与不施钾肥相比，施肥改良剂中的钾肥使 M'Bailo 的贮藏根产量提高了 14%，使 Obama 提高了 20%。奥巴马的收获指数更好、更稳定，为 55%，而 M'Bailo 为 40%。2018 年 11 月种植的两个品种的茎数、茎高、叶长和茎直径均较高。这项研究表明，木薯种植越早，产量越高。因此，决定推迟木薯种植以使其在早期阶段接受更规律的降雨可能会加剧气候变化的不利影响。尽管这项研究强调了将早播与改良品种相结合以获得更高产量的重要性，