The Of Different Application Of Calcium On The Ability Of Resisting Stain Of Peanut Seedlings

The pre-harvest season of peanuts in southern China is in a rainy and cold season,which often leads to the occurrence of waterlogging.In some years,too much rainfall in summer can also cause waterlogging.However,for a long time,the study of peanut water stress mainly focused on the the research on the drought resistance,and the research on the waterlogging was not deep enough.The regulation of calcium on peanut seedlings at the seedling stage had not been reported.Deeply exploring the effect of calcium on the physiological indicators of peanut drowning at seedling stage and the key gene regulatory mechanism,it was expected to provide an important theoretical basis for disaster reduction and disaster avoidance of peanut production in the south.In this study,the large fruit variety Xianghua 2008 was used as experimental material in 2016-2017.Three calcium gradients were set: 0 mg/kg(not applied),800 mg/kg(medium calcium),and 1600 mg/kg(high calcium).Code Ca0,Ca800,Ca1600,2 water treatments: normal treatment,waterlogging treatment,on the 0th,2nd,4th,6th,and 8th days,study calcium application to flooding.The effect of calcium on the regulation of peanut seedlings was studied by the effects of environmental factors on the agronomic traits,photosynthetic performance of leaves,root physiological and biochemical characteristics,and the key genes related to waterlogging resistance in roots.The main findings was as follows:(1)The application of calcium fertilizer significantly promoted the growth and development of the whole plant of peanut seedlings.Under normal conditions of water treatment,compared with non-calcium fertilization,the shoot fresh weight of the seedlings increased by 35.16%-45.12%,the underground fresh weight increased by 16.78%-29.02%,and the total root length and total surface area rose.15.92%-22.75% and 4.02%-42.58% higher,the root activity increased 30.58%-119.82%;under the waterlogging stress conditions,compared with the non-calcium application,the aboveground fresh weight of the seedling increased by 11.65%-20.76 %,the fresh weight in the underground increased by 24.55%-40.91%,the total root length and total surface area of the roots increased by 40.21%-46.49% and 28.18%-42.31%,respectively,and the root activity increased by 72.22%-186.11%.Calcium deficiency reduces chlorophyll content and photosynthetic rate.Applying calcium fertilizer increased leaf chlorophyll content and photosynthetic rate.In the normal treatment,the chlorophyll of the plants increased by 3%-4% after the application of calcium fertilizer,and the net photosynthetic rate of the plants increased by 28%-88% after the application of calcium fertilizers;when the waterlogging was applied,the chlorophyll of the plants increased after the application of calcium fertilizers.3%-7%,the net photosynthetic rate of plants after applying calcium fertilizer increased by 53%-76%.(2)The application of calcium fertilizer enhanced the photosynthetic performance of peanut seedlings.Under normal water treatment conditions,compared with no calcium application,the chlorophyll content slightly increased by 3.22%-4.42%,while the net photosynthetic rate increased by as much as 27.87%-88.01%;under calcium stress conditions,calcium application and insemination did not occur.Compared with calcium,the chlorophyll content of seedlings increased by 3.25%-7.14%,and the net photosynthetic rate increased by 53.66%-74.94%.(3)The application of calcium greatly improved the permeability of roots of peanut seedlings and improved the stress resistance of roots.Under normal conditions of water treatment,the changes of soluble protein and proline content were not significant under the conditions of calcium deficiency,normal calcium application,and double calcium application.Under waterlogging stress conditions,calcium was applied to the roots of seedlings compared with no calcium application.The soluble protein content increased by 4.50%-25.48% and the proline content increased by 16.06%-39.37%.(4)The application of calcium significantly enhanced the stress resistance of the roots of peanut seedlings and reduced the content of harmful substances.Under normal conditions of water treatment,no changes were observed in protective enzymes SOD,CAT,POD,and MDA content of cell membranes in the absence of calcium,normal calcium application,and double calcium application;under calcium and soil stress conditions,calcium application and no Compared with calcium application,SOD activity in seedling roots increased by 27.91%-35.26%,CAT activity increased by 12.19%-21.31%,POD activity increased by 14.23%-22.99%,and MDA content decreased by 6.63%-21.72%.(5)The application of calcium significantly increased the expression of the stain-associated genes in the roots of waterlogged peanuts.Under normal conditions of water treatment,no significant difference was found in the expression of calmodulin(CaM)and peanut non-symbiotic hemoglobin(Ah-GLB)under conditions of calcium deficiency,normal calcium application,and calcium supplementation.Compared with no calcium application,CaM expression in roots of seedlings increased by 65.20%-226.38%,and the increase in Ah-GLB expression was as high as 113.45%-325.83%.Based on the above results,calcium application not only significantly improved the phenotypic traits of peanut seedlings,increased the related physiological and biochemical functions,but also significantly increased the expression level of peanut waterlogging-resistance genes,there by improving the waterlogging resistance of seedlings.