Effect Of Sowing Depth On Seedling Quality And Yield Formation Of Peanut

This experiment was carried out at the Agricultural Experiment Station of Shandong Agricultural University and the State Key Laboratory of Crop Biology from 2017 to 2018.To identify and assess the effects of sowing depth on seedling quality,the growth progress,physiological characteristics,pod yield and quality in peanut.Therefore,a 2-year field study was conducted using Shanhua108 with seven levels of sowing depth(SD3,SD5,SD7,SD9,SD11,SD13 and SD15)and uneven sowing depth(SDH)by ridging and mulching under the suitable soil moisture condition.The main results were as follows: 1 Effect of sowing depth on seedling quality of peanutCompared with different sowing depth treatments,sowing depth of 5 cm improved seedling emergence rate,uniformity,leaf area,dry matter accumulation and seedling vigor index,which was beneficial to the cultivation of healthy seedlings.Too shallow sowing(3 cm),the soil is prone to moisture drought,which is not conducive to germination.Too deep sowing((29)7 cm),the seedling plant height and hypocotyl length were significantly increased,root lemgth,root number,root area,stem diameter,leaf number and dry matter accumulation were decreased.Uneven sowing depth,seeding emergence time gradually lengthended,the uniformity decreases significantly.Too deep sowing,shallow or uneven sowing depth significantly reduced the emergence rate,resulting in a significant reduction in the number of plants per unit area.2 Effect of sowing depth on the growth progress of peanutThe seeding depth significantly affected the time when peanut plants entered each growth stage.Too deep sowing((29)7 cm),shallow(3 cm)or uneven,extension of seedling emergence time,and then into the corresponding growth stage of the time are extended.Among them,compared with SD5 treatment,SDH,SD3 and SD15 treatment delayed seedling emergence by 3.5 d,1.5 d and 5 d,and yield formation period shortened by 1.5 d,0.5 d and 2.5 d.In the later stage of too deep sowing treatment,the growth process was accelerated and the plant senescence was accelerated,resulting in a significant decrease in leaf area index(LAI).3 Effect of sowing depth on the physiological characteristics of peanutCompared with other sowing depth treatments,sowing depth 5 cm significantly improved the leaf chlorophyll content and photosynthetic rate,nitrate reductase(NR)activity,root activity,and the accumulation of dry matter of plants.Moreover,the activity of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)significantly improved,the content of soluble protein increased,the content of MDA decreased.It can reduce the accumulation of reactive oxygen species,reduce the damage degree of leaf membrane system,delay leaf senescence,prolong the functional period,and promote the accumulation of photosynthetic products.4 Effect of sowing depth on the yield and quality of peanutThe seeding depth significantly affected peanut pod yield.Compared with other sowing depth treatments,the pod and kernel yield was the highest at a depth of 5 cm.The pod yield and kernel yield decreased with the increase of sowing depth of more than 5 cm.The pod yield and kernel yield of SDH,SD3 and SD15 treatment reduced by 9.2%,5.3%,13.7% and 12.3%,7.4% 18.3%,compared to the SD5 treatment.The main reasons for the reduced yield were the decrease in the number of plants per unit area and the number of pods per plant,and the increase in the number of kilograms of pod and rotten pod.At the same time,sowing too deep,the length of underground stem increased and cotyledon was not unearthed,which affected the development of the first pair of lateral branches,resulting in a decrease in branches pod rate.The seed depth significantly affected the kernel quality of peanut seeds.Compared with each sowing depth treatment,the seed kernel quality of sowing depth 5 cm was the best.Uneven sowing depth,shallow or deep sowing depth,the soluble sugar content of peanut seed kernel increased,while the fat,protein content and oleic acid/linoleic acid decreased.which was not conducive to the conversion of sugar to protein and fat.In conclusion,under the ridging and film mulching planting mode,the suitable sowing depth of spring peanuts should be controlled at about 5 cm.