Effects Of Typical Environment Change On Rice-Wheat Growth And Mineral Metal Contents

At present,climate warming,solar radiation reducing,and O₃pollution have become typical global environmental problems,and their impact on agricultural production and food security has caused widespread concern.In order to further understand the effects of nighttime temperature increase,reduction of solar radiation,and increase of O₃concentration on the growth and quality of two important food crops,rice and wheat,passive temperature simulation was used to simulate nighttime temperature increase;different shades were used to simulate The solar radiation is reduced;the open-top air chamber is used to simulate an increase in near-surface O₃concentration.The research contents include chlorophyll content（SPAD）,leaf area index（LAI）of rice and wheat,gas exchange parameters（including net photosynthetic rate and stomatal conductance）,dry matter accumulation,yield and its composition,mineral metal element accumulation in different organs.The main findings are as follows:（1）The temperature increase at night increased the chlorophyll content and leaf area index of rice and wheat during each growth period,and the dry matter accumulation of stems,leaves,and ears increased,thereby increasing their biomass above ground,which led to increased yields;the gas exchange parameters of wheat（including net photosynthetic rate and stomatal conductance）increased under night temperature conditions.Its photosynthetic capacity was increased;the grains and glumes of rice and wheat harvested at night temperature increased,and the contents of most mineral metal elements in the stems and leaves of each growth period increased to varying degrees.（2）Shading reduced the leaf area index of rice and wheat,but increased their chlorophyll content,and reduced the dry matter accumulation of stems,leaves,and ears,thereby reducing their biomass above ground,which led to reduced yields;the gas exchange parameters of wheat（including net photosynthetic rate and stomatal conductance）were declined under shading conditions.The photosynthetic capacity was reduced;the grains and glumes harvested from rice and wheat under shading conditions,as well as the contents of most mineral metals in the stems and leaves of each growth period,increased in varying degrees.（3）The increase of O₃concentration reduced the chlorophyll content and leaf area index of rice and wheat during each growth period,and the dry matter accumulation of stems,leaves,and ears decreased,thereby reducing the above-ground biomass,which led to reduced yield.Increased O₃concentration caused rice and wheat gas exchange parameters（including net photosynthetic rate and stomatal conductance）to be reduced.Increased O₃pollution weakened its photosynthetic capacity;under the condition of increased O₃concentration,the content of most mineral metals in the stems and leaves of rice and wheat harvested at different growth stages increased in varying degrees.Increasing the temperature at night promoted the growth of rice and wheat,increased dry matter accumulation,and eventually increased its yield,while shade and increased O₃concentration inhibited the normal growth and development of rice and wheat,reduced their dry matter accumulation,leading to their obvious The reduction in production has had a negative effect on food production.At the same time,the three typical environmental changes all increased the content of Ca,Mg,Fe and other beneficial mineral elements in the plant,but the excessive absorption of Zn,Mn,Cu and other harmful mineral elements also increased.Therefore,the comprehensive impact of environmental change on food quality needs further research and exploration,with a view to finding a response plan in the context of global environmental change to ensure high yield,quality and safety of food.