| Peanut is an important oil crop and economic crop in China,and Henan Province is the largest peanut growing province in China.Magnesium is one of the essential nutrients for normal crop growth and is an important element affecting protein synthesis and photosynthesis.With the increased use of chemical fertilisers and reduced use of organic fertilisers,as well as the widespread planting of high-yielding and fertilisertolerant varieties,the replanting index is increasing.Crops high in magnesium continue to carry magnesium out of farmland,resulting in a decrease in the level of magnesium availability in farmland soils and an increase in magnesium deficient areas year on year.To investigate the effect of Mg fertilizer dosage on peanut yield and nutrient uptake,field trials were conducted in Wangfuzhuang village,Langgongmiao Town,Xinxiang City,Henan Province,China,from 2021 to 2022.High oleic acid peanut Kainong 1715 and Yuhua 133 were used as the test varieties,and different Mg fertilizer rates were set:0(T1),20 kg/hm2(T2),40 kg/hm2(T3)and 60 kg/hm2(T4).The effects of different levels of Mg application on the growth and development,dry matter accumulation,nutrient uptake,yield and leaf photosynthetic characteristics and physiological indicators of high oleic acid peanut plants were studied.The aim is to clarify a reasonable amount of magnesium fertilizer to provide theoretical support for high peanut yields and nutrient efficiency.The main findings are as follows:1.When magnesium was applied,plant height increased at maturity in both peanut varieties compared to no magnesium,by 4.56% to 11.58% and 2.41% to 9.19% respectively.There was a significant difference in the number of branches at the flowering and hypocotyl stage of peanut,with increases of 12.78% to 21.80% and 2.65%to 9.93% respectively compared to no Mg fertilisation.The application of magnesium fertilizer significantly promoted the accumulation of dry matter in peanut,and the accumulation of dry matter at maturity in peanut was increased by 4.35%-10.71% and3.52%-15.09% respectively in the two years of magnesium fertilization treatment compared to no magnesium fertilization(T1).The growth rate of peanut dry matter accumulation decreases when too much magnesium is applied.2.The application of magnesium fertilizer increased the yield of peanut pods,with the maximum result of 5463.4 kg/hm2 and 5200.0 kg/hm2 under T3 treatment(40kg/hm2)in both trials,respectively.The treatments with magnesium fertiliser increased yields by an average of 12.40% and 10.99% compared to no magnesium fertiliser.The application of magnesium fertiliser increased the number of fruits per plant,the weight of 100 fruits,the weight of 100 kernels and the rice yield of peanuts.Compared with no magnesium fertilizer,the number of fruits per plant increased by 9.45% and 9.77%;the weight of 100 fruits increased by 3.60% and 9.24%;the weight of 100 kernels increased by 6.58% and 5.84%;the rice yield increased by 2.83% and 2.92%.3.The application of magnesium fertiliser promoted nutrient uptake and improved nutrient accumulation in all parts of the peanut.Among them,peanut nitrogen,phosphorus,Potassium,calcium and magnesium uptake increased by an average of6.41%,9.86%,5.61%,15.91% and 20.36% in two years.From the different organs,nutrient accumulation in the roots and seeds increased to different degrees and reached a maximum at 40 kg/hm2 treatment.Further increases in the amount of magnesium fertiliser will reduce nutrient content and accumulation.4.Magnesium application significantly increased SPAD,chlorophyll a,chlorophyll b and chlorophyll a/b in peanut leaves throughout the entire reproductive period,all reaching a maximum at 40 kg/hm2 of magnesium application.The net photosynthetic rate(Pn),transpiration rate(Tr)and stomatal conductance(Gs)of peanut leaves increased with increasing Mg application,while Pn,Tr and Gs all decreased at 60kg/hm2 of Mg.When peanut entered the expansion period,the overall Pn,Tr and Gs of the leaves decreased significantly,and the Pn,Tr and Gs of the leaves increased under the T2,T3 and T4 treatments compared to the T1 treatment,showing significant differences.It shows that the application of magnesium fertilizer facilitates the increase of photosynthetic efficiency of leaves.5.The application of magnesium significantly increased the activity of Rubisco in the leaves,reaching its maximum activity at pod set,with an average increase of 7.09% in the upper leaves and 2.31% in the lower leaves compared to no magnesium fertilisation,with a decrease in fruit expansion.As Mg application increased,leaf Rubisco activity increased and then decreased.Magnesium application increases leaf superoxide dismutase(SOD)and catalase(CAT),reduces proline(PRO)content and improves the overall antioxidant capacity of peanut leaves.On the whole,the yield,dry matter accumulation,nutrient uptake and photosynthetic characteristics and antioxidant capacity of peanut reached the best when magnesium sulphate was applied at 40 kg/hm2,and further increase in the amount of magnesium fertiliser would reduce the indicators. |
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