Test And Study On Combined Effects Of Increased Air Temperature And CO₂ Concentration On The Stress And Dynamic Accumulation Of Mineral Elements In Crops

Mineral stress is still one of the difficult environmental problems for agricultural production,and also is the driving force for the problem of "Hidden Hunger".It will become more complex and difficult to solve in the context of accelerating changes of the global climate.To solve this problem effectively is related to the stability of global ecosystem,human health and food safety,and is also the important basis of predicting the agricultural input and pushing forward the reform of agricultural in the future.So far,there is still few studies concerning this environmental problem in details.The increase of the air temperature and the increase of the CO₂ concentration,as an important featurethe and driving factor of global warming,will be an important starting point to decipher this problem.To explore the influences of combined elevated temperature and CO₂ concentration on the mineral stress and dynamic accumulation of mineral elements in crops has become an urgent task for human beings to deal with the climate change.Therefore,in this paper,an artificial intelligence climate greenhouse was used to simulate climate warming through increasing the temperature and CO₂ concentration?1?+50ppm;2?+100ppm;3?+150ppm?,in semiarid area of Dingxi,Gansu.This study was focused on three aspects: 1.The soilless cultivation method was used to explore the combined effects of elevated temperature and CO₂ concentration on the dynamics of accumulation and distribution of Cd,Zn and other mineral elements included Cu,Fe,Mn,K,Ca and Mg in the tissues and the subcellular fractions?cell wall,organelle and cell soluble fraction?of Triticum aestivum L with single stressing of Cd or Zn and the combined stress of Cd and Zn.The possible mechanismes in the process were analyzed.2.The field planting method was used to study the combined effects of elevated temperature and CO₂ concentration on the dynamics accumulation and distribution of mineral elements in different tissues of solanum tuberosum L.3.The simulated climate warming test was conducted to evaluate the combined effects of elevated temperature and CO₂ concentration on the agrochemical property of soil,the total content of mineral elements and the biological availability of mineral elements in the soil.1.Results of soilless culture experiment of wheat seedlings?1?The Cd stress test results showed that the combined elevated temperature and CO₂ concentration treatments had striking effects on Cd accumulation in Triticum aestivum L shoots and roots.The BF?Bioaccumulation Factor?values of Cd in the shoots and roots significantly rose with increasing temperature and CO₂ concentration.The largest Cd concentration increase was 3.37 times that of the control.The Cd mainly accumulated in the roots of wheat seedlings.The BF values of Zn,Cu,Fe,Mn,K,Ca,and Mg elements decreased in different degrees respectively?except for the Mn in shoots?.The highest decrease was 0.64,0.28,0.42,0.51 and 0.53 times that of the control respectively.The elevated temperature and CO₂ concentration treatments significantly affected the Cd and other mineral elements subcellular compartment concentrations.The Cd concentrations in the shoots and roots of wheat seedlings subcellular compartments increased with temperature and CO₂ increasing,but other mineral elements decreased with that,except for the Mn in shoots.The largest Cd concentration increase was observed in the cell soluble fraction of shoots under the stress of the high Cd concentration and with an increase of 258.9% compared to the control.The combined effects of elevated temperature and CO₂ concentration on the distribution of mineral elements in different subcellular fractions were complex with some uncertainty.In different treatment scenarios,the proportion distribution of those elements showed greater fluctuation,but there is no obvious regularity were observed.The TF?Translocation Factor?values of Cd significantly rose with temperature and CO₂ concentration increasing under the stress of Cd,and the highest Cd TF increase was 1.8 times that of the control;Zn and Cu showed fluctuation;Fe decreased in the first and then increased;Mn showed increased trend;K,Mg and Ca maintained relatively stable.?2?The Zn stress test results showed that the BF values of Zn and other mineral elements decreased with increasing temperature and CO₂ concentration under the stress of Zn,and the highest decrease Zn of BF values was 0.50 times that of the control.The subcellular compartment concentrations of mineral elements showed decrease too.The largest Zn concentration decrease was observed in the organelle fraction of shoots under the stress of the high Zn concentration and with a decrease of 66.6% compared to the control.The proportion distribution of those elements showed no obvious regularity with different treatments.The combined effects of elevated temperature and CO₂ concentration on the TF of mineral elements were element type dependent and the Zn concentration dependent under the stress of Zn.The TF values of Zn and Fe fluctuated with increasing of temperature and CO₂ concentration;Cu showed decreased in the first and then increased;Mn and K showed increased trend,and the highest increase of TF value of Mn and K was 4.15 and 2.26 times that of the control respectively;Ca showed decreased trend under the the stress of the high Zn concentration,but decreased under the the stress of the low Zn concentration;Mg TF value was stable relatively.?3?The results of the combined stress of Cd and Zn showed that the BF values of Cd in the shoots and roots of wheat seeds increased with increasing temperature and CO₂ concentration;the BF values of Zn,K,Ca and Mg decreased,the highest decrease was 0.52,0.57,0.39 and 0.29 times that of the control respectively,Cu,Fe decreased in the first and then increased,shoot Mn increased and root Mn decreased with increasing temperature and CO₂ concentration.The combined effects of elevated temperature and CO₂ concentration on the TF of mineral elements were element type dependent and were influenced significantly by the concentration difference and the levels of Cd and Zn.2.Results of field soil experimentThe field experiment was carried out at the same time.The soil analysis was made before planting and after harvest of solanum tuberosum L.Soil analysis showed that all indexes of the agrochemical property of soil decreased with increasing temperature and CO₂ concentration,but there were no statistical differences between most treatments.The largest contents decrease of the organic matter,the total N,the available N,the available P,the available K and the pH in the tested soils by 11.97%,20%,16.63%,4.88%,3.15% and 3.87% compared to the control respectively.The elevated temperature and CO₂ concentration showed slight influence on the total mineral element contents,but induced increase of the biological availability of mineral elements in soil?except for K?.The largest increase of the contents of Zn,Cu,Fe,Mn,Ca,Mg,Cd and Pb by 39.61%,19.01%,18.10%,23.35%,18.51%,20.98%,29.55 and 11.27% compared to the control respectively.3.Results of solanum tuberosum L.field experimentConsidering the limitation of soilless culture experiment of single crop,the field experiment of solanum tuberosum L.was carried out at the same time.The results showed that the accumulation of Zn,Cu,Fe,K,Ca,Mg and Pb decreased in tuber and the largest decrease of the contents by 21.63%,19.53%,16.57%,15.47,27.21%,20.16% and 22.28% compared to the control respectively.The accumulation of Cd and Mn increased in tuber and the largest increase of the contents by 48.48% and 14.57% compared to the control respectively.Most mineral elements accumulation increased in leaves and stems of solanum tuberosum L with the increase of temperature and CO₂ concentration,only K and Pb decreased with that.Most mineral elements accumulation decreased in roots of solanum tuberosum L with the increase of temperature and CO₂ concentration,only Zn,Mn and Cd increased with that.The combined effects of elevated temperature and CO₂ concentration on the distribution of mineral elements in different tissues of solanum tuberosum L were unequal and element type dependent.The TF of mineral elements showed different change with increasing of temperature and CO₂ concentration,but it was no statistically significant in most cases.These above findings showed that the combined increased temperature and CO₂ concentration may have significant effects on the mineral stress,dynamic accumulation and the subcellular distribution of mineral elements in wheat seedling in different levels.As a result,wheat seedling increased the uptake of Cd,but decreased the uptake of Zn and other elements.The combined effects of increased temperature and CO₂ concentration on the distribution and migration of mineral elements in different tissues of solanum tuberosum L were unequal and element type dependent.As a result,the nutrient elements were decreased in tubers,but increased in leaves and stems,at the same time,the biological availability of mineral elements were increased in the planting soil?except for K?.This indicated that the food safety will be threaten by the climate change,the nutritional quality of food will be reduced,accordingly,the problem of "hidden hunger" will be exacerbated in the future.