School of Biological Sciences, Monash University, Clayton, Vic., 3800, Australia.
Glob Chang Biol. 2016 Oct;22(10):3461-73. doi: 10.1111/gcb.13380. Epub 2016 Aug 4.
Cassava is an important dietary component for over 1 billion people, and its ability to yield under drought has led to it being promoted as an important crop for food security under climate change. Despite its known photosynthetic plasticity in response to temperature, little is known about how temperature affects plant toxicity or about interactions between temperature and drought, which is important because cassava tissues contain high levels of toxic cyanogenic glucosides, a major health and food safety concern. In a controlled glasshouse experiment, plants were grown at 2 daytime temperatures (23 °C and 34 °C), and either well-watered or subject to a 1 month drought prior to harvest at 6 months. The objective was to determine the separate and interactive effects of temperature and drought on growth and toxicity. Both temperature and drought affected cassava physiology and chemistry. While temperature alone drove differences in plant height and above-ground biomass, drought and temperature × drought interactions most affected tuber yield, as well as foliar and tuber chemistry, including C : N, nitrogen and cyanide potential (CNp; total cyanide released from cyanogenic glucosides). Conditions that most stimulated growth and yield (well-watered × high temperature) effected a reduction in tuber toxicity, whereas drought inhibited growth and yield, and was associated with increased foliar and tuber toxicity. The magnitude of drought effects on tuber yield and toxicity were greater at high temperature; thus, increases in tuber CNp were not merely a consequence of reduced tuber biomass. Findings confirm that cassava is adaptable to forecast temperature increases, particularly in areas of adequate or increasing rainfall; however, in regions forecast for increased incidence of drought, the effects of drought on both food quality (tuber toxicity) and yield are a greater threat to future food security and indicate an increasing necessity for processing of cassava to reduce toxicity.
木薯是超过 10 亿人的重要膳食成分，其在干旱条件下的产量能力使其成为应对气候变化下粮食安全的重要作物。尽管已知木薯具有响应温度的光合作用可塑性，但对于温度如何影响植物毒性或温度与干旱之间的相互作用知之甚少，而这一点很重要，因为木薯组织含有高水平的有毒氰基葡萄糖苷，这是一个主要的健康和食品安全问题。在一个受控的温室实验中，植物在 2 个白天温度（23°C 和 34°C）下生长，并在收获前 6 个月进行了充分浇水或经历了 1 个月的干旱处理。目的是确定温度和干旱对生长和毒性的单独和交互作用。温度和干旱都影响了木薯的生理学和化学特性。虽然温度单独影响了株高和地上生物量的差异，但干旱和温度与干旱的相互作用最影响块茎产量，以及叶片和块茎的化学特性，包括 C:N、氮和氰化物潜力（从氰基葡萄糖苷释放的总氰化物，CNp）。最能刺激生长和产量的条件（充分浇水和高温）降低了块茎毒性，而干旱抑制了生长和产量，并与叶片和块茎毒性增加有关。在高温下，干旱对块茎产量和毒性的影响更大；因此，块茎 CNp 的增加不仅仅是块茎生物量减少的结果。研究结果证实，木薯能够适应预测的温度升高，特别是在降雨充足或增加的地区；然而，在预测干旱发生率增加的地区，干旱对食物质量（块茎毒性）和产量的影响对未来粮食安全构成了更大的威胁，并表明越来越有必要对木薯进行加工以降低毒性。
