高温和干旱胁迫对西红柿幼苗生长、养分含量及元素利用效率的影响

Effects of high temperature and drought stress on growth, nutrient concentration, and nutrient use efficiency of tomato seedlings

全球气候变化将增加未来高温与干旱的发生频率和强度,然而高温与干旱的交互作用对农作物生长、养分含量及其利用效率的影响还不甚清楚。因此,研究高温与干旱交互作用对农作物生理生态的影响将为准确评价农作物对未来极端气候条件的响应提供科学依据。选取全球第四大经济作物——西红柿为研究对象,在人工智能气候箱中模拟高温和干旱环境。共设置两个水分处理(正常浇水;干旱)与两个温度处理(常温-26℃/19℃(白天/夜间);高温-42℃/35℃(白天/夜间)(7d))。主要测定指标包括生物量以及生物量分配、比叶面积、养分含量(全氮、全磷)、光合元素利用效率(光合氮素利用效率、光合磷素利用效率)。研究表明,高温、干旱单独作用以及交互作用均显著降低了根、茎、叶生物量以及总生物量,并且高温干旱交互作用使总生物量降低最多。在生物量分配方面,高温单独作用显著降低了根质量分数以及根冠比,而干旱单独作用增加了根质量分数、茎质量分数以及根冠比,但降低了叶质量分数。在养分含量方面,高温单独作用导致叶片全氮、全磷含量显著降低、茎全磷含量显著增加、根全磷含量显著降低。干旱单独作用导致叶片、茎全磷含量显著降低、根全氮含量显著升高。高温与干旱交互作用对生物量分配及养分含量的影响与干旱胁迫单独作用类似。在光合元素利用效率方面,高温、干旱单独作用均降低了幼苗光合氮素利用效率、光合磷素利用效率,并且高温加剧了干旱对光合磷素利用效率的影响。因此,在未来气候变化情况下,高温与干旱交互作用可能会对农作物产生更大威胁。

Concurrent high temperature and drought are predicted to occur more frequently with global climate warming,although their interactive effects on crop growth,nutrient concentrations,and nutrient use efficiencies are still poorly understood.Therefore,an improved understanding of how high temperature and drought interactively affect crops is crucial for accurately predicting crop response to future climates.Herein,we examined effects of simulated high temperature and drought stress on tomato seedlings in growth chambers.Tomato seedlings were grown under two soil water conditions(well-watered and drought stress)and two temperature treatments(ambient temperature—26℃/19℃(day/night)and high temperature treatment—42℃/35℃(day/night)(7 days)).Biomass production and allocation,specific leaf area(SLA),nutrient(total nitrogen—TN,total phosphorus—TP)concentrations,photosynthetic nutrient use efficiencies(photosynthetic nitrogen use efficiency—PNUE,photosynthetic phosphorus use efficiency—PPUE)were examined.The results showed that individual and interactive effects of high temperature and drought treatments reduced the biomass of roots,stems,leaves,and the whole plant,and the combination of the two treatments had the greatest effect on the whole plant.The individual high temperature treatment significantly reduced the root mass fraction(RMF)and root shoot ratio(R/S),whereas drought stress increased the RMF,stem mass fraction(SMF)and R/S,but decreased the leaf mass fraction(LMF).Furthermore,high temperature induced declines in leaf TN and TP and root TP concentrations,but increased stem TP concentration.Drought reduced leaf and stem TP concentrations,whereas it increased root TN concentration.The interactive effects of high temperature and drought treatments on biomass allocation and nutrient concentration were similar with that of the drought stress alone.We found that high temperature and drought interactively reduced PNUE and PPUE,and the effect of drought stress on PPUE was exacerbated by high temperature.Hence,drought combined with high temperature may generate greater risks on crops under future climates.