| Ramie is a special economic fiber crop in China,enjoying the reputation of "Chinese grass" and "Source of national textile,Wannian Yi Zu ".In order to explore the tolerance of ramie to water stress,the varieties with strong drought resistance or waterlogging tolerance were selected from different genotypes of ramie.Since ramie is a perennial fiber crop,the growth and development of the aboveground and underground parts,the metabolism of substances and their regulation,and then according to the characteristics of different climatic conditions in different regions to select ramie varieties planting,especially important for stable and high yield of ramie,but also for the same,perennial crops have reference effect.This study used 8 different root-type ramie varieties as experimental materials,and used indoor stainless steel trough soil culture test,using conventional irrigation(soil water content has been maintained at about 80% of field water holding capacity)as control(CK),drought stress treatment as no irrigation(soil water content eventually to 20%?40% of field water holding capacity),waterlogging stress treatment as daily irrigation(water content of soil reached saturation).To explore the main agronomic characters,yield and main yield composition,root growth and physiological response,soil nutrients and soil of different genotypes of ramie cultivars under water stress microbial effects,and the physiological and biochemical mechanism of genotype difference of ramie.Its main findings are as follows:1.compared with CK,eight different genotype ramie varieties under drought stress and waterlogged stress main agronomic traits were affected by large,for various ramie varieties of plant height,stem diameter,fresh weight,aboveground fresh weight,fresh skin thickness,leaf SPAD and plant agronomic traits difference comparison analysis,in combination with water stress under the changes of soil nutrients and soil nutrients and agronomic traits of correlation analysis,screening drought resistance strong ramie varieties under drought stress to the Zunyituandouma,and Bijieyuanma stain resistance under waterlogged stress is relatively strong for Lechanghuangpima.Compared with CK,plant height of Bijieyuanma increased by 17.30%,stem diameter increased by 13.71%,leaf SPAD value increased by14.98%,and Zunyituandouma fresh weight of compliance stump increased by 20.88% under drought stress;Lechanghuangpima compared with CK,plant height increased by 19.42%,aboveground fresh weight increased by 67.92%,and fresh tare weight increased by 140.00%under water-logging stress.Other agronomic traits were negatively affected by water stress.Under drought stress,soil nutrient total nitrogen content,alkali-hydrolyzed nitrogen content and available potassium content all showed a very significant increase trend,while under waterlogging stress,soil nutrient indexes all showed a very significant decrease trend.2.Ramie root system is mainly responsible for absorbing water and nutrients,and the growth of ramie root system is closely related to the occurrence of ramie root-rotten.Under drought stress,the fresh root weight of 8 ramie varieties with different genotypes decreased,among which Biejieyuanma had the lowest decreasing rate(31.59%).Under the stress of waterlogging,the weight of fresh root of Zunyi group was the highest,reaching 632.67 g,indicating that the root of Zunyituandouma had strong resistance to stain.The root activity of ramie cultivars was significantly different under water stress,among which the root activity of ramie cultivars increased under drought stress and waterlogging stress,only Changshungoupima was found to have stronger root activity.The physiological response of ramie roots under water stress varied greatly,and there were great differences among different cultivars.The SOD activity of root system of ramie varieties under drought stress and waterlogged stress were significantly enhanced,eight ramie varieties of the whole root POD activity showed a trend of increase under drought stress,the Zunyituandouma root SOD activity and POD activity of the root increased most significantly under drought stress,increased by 313.47% and 367.06% respectively compared with CK,the root POD activity showed a trend of weakening in wet conditions.Under water stress,CAT activity of the roots of all ramie varieties showed an overall trend of decrease,and MDA content of the roots of all ramie varieties was the lowest under drought stress and waterlogging stress was Xiangzhu-3,which decreased by 4.92% and 29.85% compared with CK.The correlation analysis showed that the growth and physiological indexes of ramie roots were not consistent with the main agronomic traits.The ramie yield was positively correlated with fresh root weight and root activity,but negatively correlated with antioxidant enzyme activity and MDA content of roots.3.Soil was cultivated in the biolog-ECO plate.After incubation for 48 h under all water treatment conditions,AWCD presented an increasing trend with the extension of time.AWCD's rising trend was: CK > drought stress > waterlogging stress,which leveled off after204 h.The dynamic changes of the ramie soil microbial community diversity index with time were affected by water stress,and the richness index(S),Mc Intosh index(U),Shannon index(H)and Simpson index(D)were all reduced under drought stress and waterlogging stress.Under different water treatment,soil microorganisms had significant differences in carbon source utilization of 6 types.Under drought stress,carbon source utilization of esters and amines was enhanced,and the difference of one type of carbon source utilization of amines was significant(P<0.05).The utilization ability of other 4 types of carbon sources was weakened,among which,the utilization ability of sugars and carboxylic acids was significantly different(P<0.05).Under the stress of waterlogging,the utilization ability of amines was enhanced by ramie soil microorganisms,which was significantly different from that of CK(P<0.05).The utilization ability of other 5 types of carbon sources was weakened.The results showed that water stress reduced the ability of ramie soil microorganisms to use carbon sources,soil microbial community metabolism slowed down,and the influence was greater under water-logging stress.Correlation analysis showed that soil microbial diversity index,soil microbial capacity to carbon source utilization and main agronomic traits of ramie were all positively correlated,indicating that the rhizosphere soil microenvironment of ramie promoted the growth of ramie,and the improvement of soil microenvironment could reduce the phenomenon of ramie root-rotten. |
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