| In order to study the effect of millet under drought stress In order to study the effects of different sowing depth and seedling drought stress on the yield and quality of millet,so as to provide basis for suitable watering period,improving seedling management and cultivation technology,and improving yield and quality of millet,this experiment selects three representative varieties of Jingu 21,Changgu 1501 and Changsheng 07 as the research object,and the random area group was designed.The sowing depth was 2cm,5cm,8cm and 11cm and drought stress was 5d,10d,15d,20d and 25d.The physiological characteristics such as plant height,stem diameter,leaf area,germination rate,dry matter content,chlorophyll content etc.,photosynthetic characteristics such as photosynthetic rate,transpiration rate etc.,water use efficiency,yield and quality of three varieties were measured and analyzed:In addition,in the artificial climate chamber,natural drought and PEG simulated drought stress were used to compare the germination characteristics,growth and physiological and biochemical indexes of the seedling stage of 15 millet varieties,and the following conclusions were mainly drawn:1?Drought stress had significant effect on seedling height and dry matter accumulation at seedling stage.Drought duration was negatively correlated with plant height(p<0.05),and there was a negative correlation between drought duration and dry matter quality during seedling stage(p<0.05).After rehydration treatment,the difference of plant height and dry matter quality between the treatment group was gradually reduced.The effects of drought treatment in the seedling stage were basically eliminated by the time of the yellow ripening stage,and there was no significant difference between the various drought stress treatment groups in different varieties,and there was obvious "compensation or overcompensation effect".2?At seedling stage,the law of dry weight ratio for each organ of the three varieties under drought stress was:dry weight ratio>stem weight ratio>leaf dry weight ratio>sheath dry weight ratio ?root dry weight ratio.In addition,the results showed that the proportion of root dry matter of the three cultivars in the drought stress treatment group in different seedling stages was first promoted and then decreased,indicating that moderate drought at seedling stage increased the weight of root dry matter,while excessive dry matter decreased the proportion of root dry matter.3?In the indoor pot experiment,the effect of drought stress time on the total leaf area of seedling stage was significant,and the leaf area increased rapidly when the water was retreated.This result was on one hand due to plant leaf growth being affected by drought stress;On the other hand,when the millet is under drought stress at seedling stage,in order to reduce the leaf transpiration water consumption,the total leaf area can be properly reduced in order to improve the tolerance of the plants to the external arid environment.4?The results of pot experiment showed that for Jingu 21,Changgu 1501 and Changsheng 07,the maximum quality of dried grain was the 6-day drought stress treatment group.This result,in combination with the results of the total dry matter analysis,indicate that under moderate drought conditions at seedling stage,the total amount of millet dry matter and the quality of dried grain will increase,and the millet production will also increase.Excessive seedling drought will reduce the total amount of dry matter and the quality of dried grain,and the grain yield will also be reduced..5?The results of the experiment showed that the yield of millet was increased by moderate drought stress at seedling stage,and reduced by excessive drought stress.Moderate drought stress could increase the content of protein,fat and amylose in three varieties.Although the contents of protein,fat and amylose in all varieties of grain were first promoted and then decreased,the correlation between the three was not significant(p>0.05).The content of the three varieties was not increased or decreased at the same time,and the specific reasons need further research.In addition,the effect of sowing depth on the yield and quality of different millet varieties was not significant.6?Sowing depth has great influence on seedling emergence and dry matter accumulation.of Jingu 21,Changgu 1501 and Changsheng 07.The most suitable sowing depth of three varieties is between 2-5cm;The trend of emergence rate of each variety is:sowing depth 2cm>5cm>8cm>11cm.In the case of deep sowing,the emergence rate of Changgu 1501 is higher,and it is relatively resistant to deep sowing.7?The effect of sowing depth on plant height,leaf area and dry matter quality was significantly different,but has little effect on jointing stage.There is obvious compensation or over compensation effect.The law of dry matter quality in seedling period was:the depth of sowing depth 2cm>5cm>8cm>11cm.8?The depth of sowing has different effects on the quality of the dry matter of different organs,especially the proportion of root,which is positively related to the depth of sowing.Potted planting depth test results showed that the deeper the sowing depth,the greater the weight of the root dry matter.The reason may be that the sowing depth will increase the initial rooting and root depth of millet,thus affecting the proportion of future roots of millet.Further investigation is needed to understand the specific reasons.9?The results of PEG simulated drought show that 15 varieties of millet can be divided into 3 types,of which 3 varieties with strong drought resistance are Jingu 21,Longgu 10 and Changsheng 07.The other six germination drought resistance indexes can be used as indicators of drought resistance identification in germination period.Among which,dynamic drought resistance index and relative germination rate can be used as the primary index of drought resistance identification in the germination stage,the relative germination potential can be used as the secondary index of drought resistance identification in the germination stage,and the relative embryo length and relative radicle length can be used as the third level indexes of drought resistance identification in the germination stage.10?In the drought stress test,combined with plant height,quality of dry matter,yield and PEG simulated drought,it can be seen that in the seedling stage of the three cultivars,Jingu 21 is more tolerant to drought.In the experiment of sowing depth,combined with the results of seedling rate,plant height,quality of dry matter and yield,it can be seen that of the three varieties,Changgu 1501 is more tolerant to deep seeding. |
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