Effects Of Seed Soaking With H₂O₂ On Germination Of Peanut Seeds Under Low Temperature Stress

Temperature is one of the important abiotic stress factors affecting crop growth and development.In actual production,it is often necessary to plant peanuts in advance for the first time in the market.However,sowing in advance may result in low temperature stress during germination of seeds.At the same time,it will also suffer from“spring chill”and other cold hazards.This paper uses the low temperature imbibition method,activity indexes such as percentage of the number of seeds with radicals breaking through testa(PSWRBT),germination rate and ratio of the length of bud to the length of seeds(RHRS)were measured.Finally,nine accessions of peanut germplasm were screened and identified by cluster analysis.Then the selection of hydrogen peroxide concentration gradient was carried out.The contents of MDA and Proline in peanut seeds were determined after treatment with the optimal concentration of H2O2.Peanut seeds were treated with the optimal concentration of H2O2,and the content of MDA and Proline during germination and the activity of three key enzymes during Proline metabolism were determined.The effect of H2O2 pretreatment on the germination of peanut seeds under low temperature stress was studied.The test results as follows:(1)Low temperature stress inhibited the germination of peanut seeds significantly.This is reflected in the decrease of activity indicators such as PSWRBT,germination potential,germination rate and RHRS.Different peanut germplasm showed different resistance under low temperature stress.The PSWRRT of Huayu9122 was the highest among all tested germplasm,reaching 62%,but the PSWRBT of Baisha1016 is only 18%.Finally,the 9 tested germplasm were divided into three categories:Huayugl22 is low temperature tolerant peanut cultivar;Wanhua2,Ji040-11-1,Huayu9301 is middle type peanut cultivar;Baisha1016,Huayu9510,Benghua482,Yu135 and Nongda402 is low temperature sensitive peanut cultivar..(2)Our study found that peanut seeds soaking in H2O2 can alleviate the damage under low temperature stress.And the mitigation effect varies with the concentration of H2O2.Under the treatment of 0.1%H2O2 concentration,the RHRS of Huayu9122 was the highest,reaching 0.434.Under the soaking treatment of 1%H2O2 concentration,the seeds of Huayu9122 and Baisha1016 had the highest vitality so it was the best immersion concentration.(3)MDA is a product of lipid membrane peroxidation,which can reflect the degree of membrane structure injury to some extent.And proline is the most effective osmotic regulatory substance in response to stress.Research shows that the contents of MDA and proline in two types of peanut seeds increased with the increase of low temperature stress time.After the study found that under low temperature stress,the content of MDA in peanut seeds treated with 1%H2O2 was lower than that without soaking treatment,proline content was higher than that without seed immersion treatment on the contrary.Finally we found that seed soaking treatment in H2O2 can improve the activity of key rate-limiting enzymes P5CS and OAT in the proline synthesis pathway under Iow temperature stress,the activity of ProDH,a key enzyme in the degradation pathway was also decreased.The accumulation of proline content was increased to alleviate the damage under low temperature stress.