| Rice is one of the most important food crops,and its water consumption is as high as 70% of agricultural water.Global climate change has led to a growing area of drought stress in rice,and how to maintain high grain yields in water shortages is critical to food security.In order to alleviate the contradiction between water scarcity and rice production,scientists have cultivated a new type of cultivated rice-water-saving and drought-resistant rice.To reveal root morphological and physiological changing characteristics of water-saving and drought-resistant rice under soil water deficit condition,and illuminate its specific physiological basis of water-saving and droughtresistance.The results showed that the physiological indexes and yield changes of different types of rice under drought treatment provided the theoretical basis for the cultivation of water-saving and high-yield rice.Pot experiment was conducted in 2015 and 2016,one water-saving and drought-resistant rice genotype(HY113)and one high-yielding rice genotype(YLY6)were used,three two water treatments(flooding irrigation,saturated irrigation and drought treatment)were carried out.Our main results are as follow:(1)Compared with traditional flooding,the growth period of two rice varieties under drought condition was prolonged,mainly because drought significantly prolonged the vegetative growth stage of rice.The plant height of the plant was significantly decreased,and the plant height of HY113 was significantly higher than that of YLY6.At the same time,drought stress significantly reduced the leaf water potential and air gap temperature,and HY113 could maintain high leaf water potential and air temperature difference under drought conditions.(2)Under the drought stress,the root activity of two rice genotypes both increased significantly.In 2015 and 2016,the average growth rate of HY113 was 38.7% during milky period,while the average growth rate of YLY6 wa s 22.8%,and the root activity of HY113 increased from 86 ?g.g-1.h-1 to 174 ?g.g-1.h-1 during milky period in 2015.Drought treatment also significantly reduced the root absorption area of the two cultivars,but the reduction of HY113 was significantly lower than that of YLY6.(3)Compared with the traditional flooding,the physiological and biochemical characteristics of the roots of the two cultivars were significantly changed under the drought condition.The soluble sugar content,SOD activity,POD activity and ABA content were significantly increased.Compared with YLY6,The results showed that HY113 osmotic regulation of plant water potential,anti-aging ability and leaf stomatal regulation ability were significantly higher than YLY6 in drought condition,so as to improve HY113 drought resistance.(4)In the case of water deficit,the thickening of the thick-walled cells at the edge of the outer cortex of the root can effectively prevent the diffusion of oxygen from the ventilated tissue to the root and prevent the collapse and disintegration of the ventilated tissue,so that the rice root is resistant to drought stress The same number of root ducts increased significantly,and the number of xylem ducts in HY113 increased significantly higher than that of YLY6,indicating that HY113 still maintained a strong water delivery capacity under water deficit.(5)Compared with high-yielding rice YLY6,the root number,root volume and root dry weight of HY113 were smaller,but its root activity and root absorption area were greater.The drought effects on root morphological and physiological traits of the two rice genotypes,and their relationship with aboveground biomass accumulation were studied.Compared with flooding irrigation,drought stress significantly r educed the dry matter accumulation of the two rice genotypes,the root-shoot ratio of HY113 was also significantly decreased(from 0.18 to 0.12),while the root-shoot ratio of YLY6 was not change.The water-saving and drought-tolerant rice genotypes HY113,possesses less root biomass but higher root uptake efficiency,and could adjust the root-shoot ratio in drought condition to make more dry matter stay in the aboveground part,so that the relatively high grain yield could be maintained. |
PDF Full Text Request