Response of cassava to prolonged water stress imposed at different stages of growth
Response of cassava to prolonged water stress imposed at different stages of growth
复制标题
DOI：
10.1017/s001447970200306x
复制
发表时间：
2002-07-01
影响因子：
1.6
通讯作者：
Cadavid, LE
中科院分区：
文献类型：
--
作者：
El-Sharkawy, MA;Cadavid, LE
通过两年田间试验，研究了长期水分胁迫对木薯生产力、养分吸收利用效率的影响。四个对比品种提供了足够的施肥和浇水，除了当水被排除在不同时期的土壤覆盖塑料布，根据治疗：从两个到六个月，四到八个月，或从六到十二个月种植后（早期，中期和终端应力分别）。在种植后2、4、6、8和12个月进行连续收获，以确定叶面积指数和地上部和根系生物量。在最后收获，氮，磷，钾，钙和镁的含量在地上部和储存根测定。在早期和中期的胁迫，叶面积指数和地上部和根系生物量显着小于在所有品种的控制。恢复后，叶面积指数大大提高，干物质分配到茎，根产量接近对照。一个品种，CMC 40，在胁迫处理下具有更大的最终根产量。各品种根、地上部养分浓度在早期胁迫下均较低，根系生产各要素养分利用效率较高。在中期胁迫下，除氮素浓度保持不变外，其余各品种的地上部生物量均呈下降趋势，但叶面积指数不受终末胁迫影响。除CMC 40在胁迫下的最终根产量大于对照外，其他品种的最终根产量均小于对照。氮浓度在所有品种的根生物量，但在地上部生物量较少，导致较低的氮利用效率为根生产。在所有品种中，只有钾和镁的利用效率高于对照。CMC 40是唯一一个在终末胁迫下对氮、磷、钾、钙和镁的利用效率一直较高的品种。这种较高的养分利用效率主要是由于更大的根产量，而不是较小的养分浓度。该品种适合作为基因源用于改良木薯，以在胁迫环境条件下最大化每单位养分提取的根产量。
A two-year field trial was conducted to study the effects of prolonged water stress on cassava (Manihot esculenta) productivity, and on nutrient uptake and use efficiency. Four contrasting cultivars were supplied with adequate fertilization and watering, except when water was excluded by covering the soil with plastic sheets for different periods, depending on treatment: from two to six months, four to eight months, or from six to twelve months after planting (early, mid-season and terminal stress respectively). Sequential harvests were made at 2, 4, 6, 8 and 12 months after planting to determine leaf area index and shoot and root biomass. At final harvest, nitrogen, phosphorus, potassium, calcium and magnesium concentrations in shoots and storage roots were determined.During both early and mid-season stress, leaf area index and shoot and root biomass were significantly smaller than those in the controls across all cultivars. After recovery from stress, leaf area index was greatly enhanced with less dry matter allocated to stems, and root yields approached those in the controls. One cultivar, CMC 40, had greater final root yield under stress treatments. Nutrient concentration in roots and shoots was less in all cultivars with early stress and resulted in higher nutrient use efficiency in all elements for root production. The same trend was observed under mid-season stress, except for nitrogen concentration, which remained unchanged.Terminal stress did not affect leaf area index, but reduced the shoot biomass in all cultivars. Final root yields were smaller than those in the controls except for CMC 40 whose final root yield was greater under stress. Nitrogen concentration was greater in root biomass but less in shoot biomass of all cultivars, resulting in lower nitrogen-use efficiency for root production. Across cultivars, only potassium- and magnesium-use efficiencies were greater than in the controls. CMC 40 was the only cultivar with consistently greater use efficiency of nitrogen, phosphorus, potassium, calcium and magnesium for root production under terminal stress. This higher nutrient use efficiency was due, mainly, to a greater root production rather than to smaller nutrient concentration. This cultivar is suitable as a gene source for improving cassava in order to maximize root pro- duction per unit nutrient extracted under stressful environmental conditions.