Exogenous Calcium Chemical Priming Alleviates Arachis Hypogaea L. Photosynthetic Disorder Under Low Diurnal Temperature Stress

Peanut?Arachis hypogaea?is an important oil and cash crop in the world and plays an important role in ensuring the safety of edible oil in China.The soil fertile climate in the cultivation area of northern China is cold,the content of aflatoxin in the soil of this region is very low,and the peanut produced is famous for its high quality and no aspergillus flavus toxin,which is favored by consumers all over the world.The early spring cold damage occurs from time to time in the north,and the cold damage comes quickly,which has a great influence on the growth of peanut seedling stage,which directly leads to the lack of seedlings and the breaking of ridges,which seriously limits the yield and quality formation.Our previous study found that exogenous calcium can effectively improve the cold tolerance of peanuts.However,it is not clear about the regulation of photosynthetic disorder and the regulation of exogenous calcitonin in peanut under low diurnal temperature stress.?Those include cross-stress of low diurnal temperature rhizosphere under black plastic mulch coverage?.For this reason,the test material was "Fenghua No.1",a common peanut cultivar with large fruit type.Artificial climate chamber was used to simulate the diurnal low temperature environmental conditions under different cultivation scenarios?high temperature of mulching rhizosphere,low temperature of non-diaphragm covering rhizosphere,etc.?.The effect of exogenous calcium on the regulation of diurnal low temperature photosynthetic disorder was studied by spraying calcium was studied by spraying calcium the leaf surface.The main findings are as follows:1.Effects of exogenous calcitonin on peanut growth under low diurnal temperature stress.?1?Under low diurnal temperature stress,the stomatal limitation of plant leaves increased,and the intercellular carbon dioxide concentration decreased,which in turn led to the decrease of photosynthetic efficiency.At the same time,the low temperature caused the root activity to decrease,the growth decreased,the amount of water transported to the ground decreased,the water content in the leaves decreased,the abscisic acid content increased,and the photosynthetic metabolism was once again inhibited,which in turn fed back to the root system in the form of reduced photosynthetic products.?2?Under black plastic mulch coverage,the root configuration changes and root activity decreases due to low temperature stress during the day.The evapotranspiration rate of the leaves increased dramatically due to the warming of the root system,and the stomatal restriction caused by excessive transpiration affected the photosynthetic efficiency of the leaves.The metabolic transport of photosynthetic products was inhibited,which further inhibited the decline of root activity,resulting in the inhibition of overall plant growth.?3?Effects of exogenous calcium on photosynthetic inhibition of peanut leaves under low diurnal temperature stress and black plastic mulch coverage.2.Effects of short-term low diurnal temperature stress on plant light system.?1?Under low diurnal temperature stress,the initial damage site of leaf optical system was OEC,QA-QB electron transfer restriction,and the PQ library became slow reduction prototype.?2?Under low diurnal temperature stress with black plastic mulch coverage,the OEC damage is more severe,PSII the excess light quantum leads to Y?NO?initiation,and because the transfer between linear and ring electrons is seriously blocked,the ring electron transfer cannot start,and the Y?ND?rises significantly,cannot produce zeaxanthin,producing reactive oxygen species accumulation.Exogenous calcium application can effectively alleviate the photochemical inhibition caused by two kinds of low temperature stress.However,calcium application inhibitor EGTA exacerbated the inhibition of photochemical activity.3.Effects of exogenous calcium on light system under low diurnal temperature stress.The response law and feedback mechanism of light system under low temperature stress and plant growth inhibition were clarified.and clarify how calcitonin alleviates light and inhibition and action sites throughout the process.It was found that the evaporation rate of leaves increased significantly due to the warming of roots,the leaves lost water,and the transportation and distribution of water and organic matter from roots to the ground appeared obstacles,which reduced chlorophyll,flavonoids,anthocyanins and nitrogen content to varying degrees.As the transpiration rate decreased,the stomatal limit was increased,but the stomatal conductance and intercellular carbon dioxide concentration decreased,which resulted in the decrease of CO₂ assimilation rate.growth inhibition and photosynthetic rate decrease of plants only affect the photochemical activity of the optical system,which is manifested as Y?ND?rise and become the direct cause of visible injury.By promoting the maintenance of stomatal conductance,the repair of damaged sites in optical system such as OEC significantly alleviates photosynthetic inhibition.