Screening Of Foxtail Foxtail Millet Varieties With Tolerance To Low-potassium And Study On Its Physiological And Biochemical Mechanis

Foxtail millet is a special cereal crop in northern China,and its demand is increasing day by day.Potassium is an essential element for crop growth.However,China’s soil is generally short of potassium and potassium supply is in short supply.Therefore,it is an effective measure to breed foxtail millet varieties that are resistant to low potassium and have high potassium utilization efficiency.In this study,we conducted pot experiments on 20 different genotype foxtail millet,set two types of potassium treatment,low potassium LK(0.10 mmol/L)and normal potassium NK(5.00 mmol/L).Comparative study on morphology,physiological and biochemical characteristics of foxtail millet under low potassium stress for 21 d.At the same time,selected six different foxtail millet varieties with low potassium tolerance for field trials,and set low potassium(LK,0kg /hm2),normal potassium(NK,120kg/hm2),and high potassium(HK,240kg/hm2)three potassium fertilizer dosages.To study the effects of different potassium application rates on photosynthetic characteristics,agronomic traits and yields(thousand-grain weight,ear grain weight,ear weight)of different foxtail millet varieties.Finally,it provides a theoretical basis for breeding low-potassium and high-yielding foxtail millet varieties,and determines a reasonable amount of potassium fertilizer.The main results of this study are as follows:1.A single index cannot screen out the genotype of low-potassium-resistant foxtail millet,so the principal components are used to transform ten traits into three comprehensive indexes.And use the membership function to obtain the comprehensive index evaluation D value.Cluster analysis of the D value can be used to classify the low-potassium tolerance of foxtail millet into four categories at a genetic distance of 5.0.Finally,the low-potassium resistant variety Zhangzagu 13 and the low-potassium sensitive variety Dabaigu were selected.2.Potassium deficiency will reduce the plant height and leaf area of foxtail millet,inhibit foxtail millet root development,and significantly affect foxtail millet accumulation of potassium.Compared with normal potassium treatment,potassium deficiency will reduce the chlorophyll and carotenoid content of the plant and increase the root-to-root ratio;potassium deficiency(LK)causes(Fv / Fm),(Fv / Fo),(Y(∥))in the leaves,(ETR),(q P)decreased,indicating that the PSⅡ system was damaged by potassium stress.At this moment,the NPQ increases,indicating that the plant leaves dissipate the excessive excitation energy by starting the heat dissipation mechanism to reduce the stress damage;Potassium deficiency will significantly increase the activity of SOD,POD,and CAT in foxtail millet.The average growth rate of low-potassium-tolerant varieties is greater than that of low-potassium-sensitive varieties,indicating that it can cope with adversity by increasing enzyme activity.3.There are differences in potassium utilization efficiency among different foxtail millet varieties.Increasing potassium concentration will effectively increase the potassium content and potassium accumulation of foxtail millet.Potassium deficiency will increase the utilization efficiency of foxtail millet potassium.Low-potassium-tolerant foxtail millet varieties have high potassium utilization efficiency in a potassium-deficient environment,which may be a strategy for foxtail millet to cope with low potassium stress.4.Potassium application can significantly improve the photosynthetic intensity of crops,enhance leaf water retention capacity,and increase the accumulation of foxtail millet biomass.The yield composition of foxtail millet during maturity showed that: ear length,ear thickness,ear weight,thousand-grain weight,and yield all reached the maximum at 120 kg/ hm2 of potassium fertilizer application,which provided a theoretical basis for rational application of potassium fertilizer.