土壤水分条件对甘薯水分利用效率和稳定性碳同位素影响

Effect of Water Deficit Condition on Water Use Efficiency and Carbon Isotope Discrimination in Sweet Potato

以我国大面积种植的典型旱地作物甘薯为研究对象,进行可控条件的不同水分处理的盆栽试验,研究了水分胁迫下甘薯各典型生育期各器官碳同位素判别值(Δ13C)、水分利用效率(WUE)及其之间的关系。试验设3个水分条件:分别为田间持水量的50%(W1),75%(W2),100%(W3)。结果表明,各生育期各器官生物量均随着水分增加而增加,在W3处理时达到最大,各生育期WUE则在W1处理时达到最大。尽管W3处理最终总生物量积累及产量最高,但高水分处理下将降低光合同化物向地下部的分配比例;同时,甘薯光合速率和Ru Bis CO活性之间呈正相关关系;甘薯不同生育期不同部位的Δ13C各不相同,其中根的Δ13C最小,然后依次为叶柄、茎秆、叶片,表明甘薯叶片光合同化物质在各器官中分配时发生碳同位素的分馏作用;在甘薯的各生育期,各器官Δ13C和瞬时WUE呈一致性的负相关关系。综上所述,碳同位素可以作为灵敏简单、快速准确的甘薯WUE的评价方法。

A pot experiment was conducted to study the variation of water use efficiency （WUE） and carbon isotope discrimination in maize under water deficit conditions and their relationship. Three water regimes were imposed and they took up the fraction of field capacity of the soil were： 50% （W1）, 75% （W2）, 100% （W3）. The results showed that the biomass of various organs of sweet potato increased with moisture increases, and reaching the maximum in the 100% of field capacity （W3）. WUE under 50% of field capacity （50%） was highest. However, the high moisture treatment reduced the proportion of the photoassimilates distributed to the underground; meanwhile, photosynthetic rate positively correlated with RuBisCO activity; Alac of different organs of sweet potato were different during different growth stages under the three water treatments. △13C in root was the smallest, and then followed by petioles, stems, leaves, indicating that the carbon isotope fractionation occurred when the photoassimilates distributed in various organs, △13C of various organs presented consistent negative correlation with WUE during different growth stages. In summary, the carbon isotopes can be used as a simple, quick and accurate method for evaluating WUE of sweet potato.