The Responses of Root Growth Characteristics and Leaf Epidermal Structure of Drought-Resistant Broomcorn Millet to Water Stress
Longmi 4 and Jinshu 7 were used as materials and anti-canopy was used throughout the growth period.Four different water stress treatments were carried out including normal water supply(CK,the soil water content is 65％-75％of the field water holding capacity),mild water stress(55％-65％),moderate water control(45％-55％)and severe stress(35％-45％)of whole broomcorn millet growth stage,the leaf microstructure of different drought-resistant broomcorn millet varieties was observed,root length,total root surface area,root-shoot ratio,root activity of different drought-resistant millet varieties were compared under whole growth period.The results showed that root length,total root surface area,root-shoot ratio and root activity of two millet varieties were increased under mild water stress.However,root length,root surface area,root-shoot ratio and root activity were decreased as the water stress increasing,and the root-shoot ratio and root activity of broomcorn millet significantly reduced under severe water stress.The root-shoot ratio of Longmi 4 and Jinshu 7 were decreased by 11.90％and 24.38％,respectively,the root activities were decreased by 18.73％and 58.11％on average in maturity period under severe water stress,and the degree of root activity inhibition of Jinshu 7 was significantly greater than that of Longmi 4.In the same multiple,by scanning electron microscopy,the varieties with strong drought resistance had dense stomata,long cells,dense waxy,and had siliceous cells on the upper surface at the same ratio by stem observation method.In short,all indexes of Longmi 4 had a lower decrease under severe water stress than Jinshu 7 because it had good root morphology,strong root vitality and siliceous cells for adapting to drought environment.
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