| Foxtail millet is one of the main cereals in China,it present many advantages of excellent drought tolerance and well adaptability,especially with the obvious hybrid advantage,and its yield is 20%-40%higher than the conventional variety.At present,the hybrid method of foxtail millet is mainly characterized by the temperature-sensitive system and the dominant nuclear sterility system.However,there are many kinds of problems to be solved in these methods.As an important way of hybridization,it’s of great significance for chemical hybridization to develop the millet heterosis.In this experiment,three chemical hybridization agents(CHAs)(Ethephon,Maleic Hysrazide and SQ-1)were chosen to test the male sterilizing effect on three cultivars(Henggu 13,Yugu 18 and Jingu 21),containing the using period,using concentration and cultivar diversity.Meanwhile,the effects of SQ-1 on the floral organs,pollen vitality,and agronomic traits were also studied.Besides,the change of physiological and biochemical substances such as reactive oxygen species,antioxidant enzyme activities,soluble protein,praline,carbohydrate metabolism and hormones were further studied in SQ-1 induced physiological male sterile spikelets,which laid a certain theoretical basis and technical reserves for the foxtail millet breeding.The main findings are summarized as follows:1.The field test results showed that the male sterilizing effect varied with the difference of CHAs and the concentrations.At all of three ear differentiation stages:the early stage of the young ear differentiation(T1),branch differentiation stage(T2)and the early protogyny stage(T3),Ethephon(Eth)had the worst effect,and its male sterilizing effect was not obvious.For Maleic Hysrazide(MH),its male sterilizing effect was not obvious at the stage of T1 and T2.However,it had the complete sterility at the stage of T3.For SQ-1,it had the same effect as MH at the stage of T1 and T2.At the stage of T3,it had the ideal effect at the concentration of 3-6 kg hm-2 and can induce more than 85%male sterility for all of the three cultivars.2.For SQ-1,it had the best male sterilization effect at the concentration of 5 kg hm 2,which can lead more than 90%male sterility for three cultivars and had little damage to the pistil.In addition,it also had little influence on the agronomic traits.For MH,though it can induce higher male sterility,it severely damaged the pistil.Therefore,SQ-1 can be used as the CHA.3.The results showed that the plants presented shrunken anthers after the treatment of SQ-1.More importantly,the SQ-1 treated pollen was transparent and irregular after the staining test with I2-KI and had different degrees of crystallization.4.After the treatment of SQ-1,the production rate of H2O2 and the content of O2·-,MDA of the young spikelets were not the same.The content of H2O2 increased from 5 to 10 days after treatment,reaching the highest value on the 10th day,and then began to decline,showing a "low-high-low" trend.However,the content of O2·-and MDA showed a "low-high" trend.It had the lowest content on the 5th day and the highest on the 15th day.Compared with the same period after the spraying,the contents of O2·-,H2O2 and MDA in the treatment were significantly higher than those in the control,and the higher the concentration of SQ-1,the more the production of O2·-,H2O2 and MDA.5.After the treatment of SQ-1,the activity of POD in the spikelets was increased.The activity of SOD and CAT presented a "high-low-high" trend,and the APX activity presented a "low-high-low" trend.Compared with the same period,the POD activity gradually increased with the increase of the concentration of SQ-1.Besides,the activity in the treatment was higher than that in the control.However,the activity of SOD,CAT and APX were gradually decreased,and the activity in the treatment was lower than that in the control.6.After the treatment of SQ-1,the content of the soluble protein gradually increased from 5 to 10 days,and then decreased from 10 to 15 day,which showed a "low-high-low" trend.Compared with the same period,the content of the soluble protein in the young spikelet decreased with the increase of concentration of SQ-1,and the higher the concentration of SQ-1,the lower the content of the soluble protein.7.After the treatment of SQ-1,the content of the proline gradually increased after the application of 5-15 days,showed a "low-high" trend.Compared with the same period,the content of the proline in the young panicle decreased with the increase of concentration of SQ-1,and the content of proline in the treatment was lower than that in the control.8.After the treatment of SQ-1,the content of the soluble sugar continued decreased in three controls.While in the treatment,it was slightly increased on the 10th day,and then decreased,and the change was not obvious.Compared with the same period,with the increase of the concentration of SQ-1,the content of soluble sugar was gradually decreased in the young spikelet.After the treatment of SQ-1,the content of starch was accumulated in the control,and the change was not obvious in the treatment.Compared with the same period,with the increase of the concentration,the content of the starch was gradually decreased.The change of the sucrose and fructose in the spikelet was consistent,and the change in the treatment was the same as in the control.The content reached the highest value by the day 10,while the change in the control was larger than in the treatment.Compared with the same period,the content of sucrose and fructose was gradually increased with the concentration of SQ-1 at day 5 and 15.However,it was gradually decreased at day 10.9.After the treatment of SQ-1,the content of IAA was gradually increased in the control,while in the treatment it presented a "low-high-low" trend,and it reached the highest value by day 10.Compared with the same period,the content of IAA in the spikelet was gradually decreased with the increase of the concentration of SQ-1,and it was lower in the treatment than in the control.The content of ZR was gradually accumulated in the control and the treatment after 5-15 days of application,showing a"low-high" trend.Compared with the same period,the content of ZR was gradually decreased with the increase of concentration,and the content in each treatment was lower than in the control.The content of GA3 presented a "high-low-high" trend in the control and the treatment after 5-15 days of the application of SQ-1,and it reached the lowest value by day 10.Compared with the same period,the content of GA3 was gradually decreased with the increase of the concentration,and the content in each treatment was lower than in the control.The content of ABA presented a "low-high-low" trend in the treatment and the control after the application of SQ-1,and it reached the highest value by day 10.Compared with the same period,the content of ABA was gradually increased with the increase of the concentration,and it was higher in each treatment than in the control. |
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