| The pot experiment(0,1.95,3.9,7.8 g· kg-1)and field experiment(0,197.4,394.8,789.45 kg·hm-2)were used in this study.Using Jingu 21 and Zhangza 10 as experimental materials,the effects of selenium mineral powder on the physiological characteristics,photosynthetic characteristics,yield and grain selenium content of millet were studied.The purpose is to clarify the correct application amount of millet selenium ore powder in the grain field,and provide theoretical basis and practical application value for the planting and production of selenium-enriched millet.（1）The pot experiment showed that the plant height,leaf length,leaf width,fresh weight,dry weight,root-to-shoot ratio of the two varieties of millet seedlings under the treatment of 3.9g·kg-1（T2）of selenium mineral powder Compared with the control group,both reached a significant level.Compared with the control group,the plant height,leaf length and leaf width of the seedlings of Zhangzagu 10 increased by 7.21%,8.36%,and 17%,respectively;Jingu 21 increased by 8.23%,5.32%,and 13.4%,respectively;Jingu 21 The fresh weight of the above-ground part of Jingu 21 and Zhangza 10 increased by 23.21% and 17.35% respectively compared with the control group;the fresh weight of the underground part increased by 18.18% and 23.91% respectively;the dry weight of the above-ground part of the seedlings of Jingu 21 and Zhangzagu No.10 It increased by 23.68% and 13.21%;the dry weight of underground parts increased by 35.29% and 33.33%,respectively;the root-shoot ratio increased by 11.36% and 13.64%,respectively.Suitable application of selenium mineral powder（T2）could significantly increase the photosynthetic rate,chlorophyll and carotenoid contents and chlorophyll fluorescence parameters of millet seedling leaves.When the soil selenium content reached 10mg·kg-1,the net photosynthetic rate（Pn）of the seedlings of Jingu 21 and Zhangzagu 10 increased by 21.82% and 23.06% respectively compared with the control group;Gs increased by 27.53%,respectively.34.71%;Compared with the control group,Tr increased by 17.3% and 24.65%,respectively;Ci reached the lowest value and reached a significant level compared with the contra.Both photosynthetic pigment content and chlorophyll fluorescence parameters reached the highest value at T2 level and were extremely significantly higher than the control group.With the increase in the amount of selenium mineral powder,the superoxide dismutase（SOD）,peroxidase（POD）,catalase（CAT）enzymes and glutathione peroxidase（GSH-Px）in the leaves of millet seedlings)Both activity and soluble protein content showed a trend of first increasing and then decreasing, and reached the highest value under T2 treatment;the content of malondialdehyde（MDA）showed a trend of first decreasing and then increasing,and reached the lowest value during T2 treatment.（2）Field experiments showed that the application of 394.8 kg·hm-2（T2）selenium mineral powder in soil could promote the growth and development of millet at each growth stage.The plant height and leaf area of Zhangzagu 10 increased by 13.15% and 14.03% in T2 treatment at joisting stage,respectively.Jingu 21 increased by 6.76% and 6.79%,respectively.T2 treatment had the most significant effect on ear weight,grain weight per ear,1000-grain weight and grain yield,and the grain yield of Jinju 21 and Zhangza 10 increased by 8.64% and 6.64%,respectively,compared with the control.After being treated by T2,the photosynthetic rate of millet in the jointing stage,heading stage and filling stage reached the maximum.Compared with the control,Zhangzagu 10 increased by 27.48%,27.34%,27.77%,and Jingu 21 increased respectively.35.34%,41.88%,28.58%,all reached a significant level.At the same time,reducing the intercellular CO2 concentration of millet during each growth period,the heading dates of Zhangzagu 10 and Jingu 21 were reduced by 12.17% and 32.39%,respectively.The SPAD value increased the most in the jointing stage,which increased by 23.06% and 20.43% respectively compared with the control.After being treated by T2,the activities of SOD,POD and CAT in each growth period of millet increased significantly,and the content of MDA decreased significantly.The activities of the three peroxidases SOD,POD and CAT in the leaves of the two millet varieties all increased the most during the heading stage.Zhangzagu No.10 increased by 28.17%,28.6%,and 38.8%,respectively;Jingu No.21 increased respectively.42.11%,48.86%,30.89%.The MDA content in the jointing stage decreased the most,with a decrease of 17.18% and 37.74% respectively.The application of selenium mineral powder can increase the selenium content in the grains of two millet varieties.Under T2 treatment,the selenium content in the grains of Jingu 21 and Zhangza 10 reached 0.131 mg·kg-1 and 0.125 mg·kg-1,respectively.Compared with the control,it increased 3.5 times and 3.2 times,respectively.In summary,comprehensive analysis of various morphological and physiological indicators and the relationship with yield formation,T2 treatment,that is,the soil selenium application amount of selenium ore powder of 394.8 kg·hm-2 can be used as the recommended application for the recommended dosage. |
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