Effect Of Fertilizer Treatments On Physio-ecological Indices And Yield Of Different Drought Resistant Fagopyrum Tararicum Varieties Under Drought Stress

The water regulation method during the whole growth stage of different drought-resistant F.tararicum varieties（drought-tolerant variety‘Diqing kuqiao’and drought-sensitive variety‘Heifeng 1’）in the condition of pot planting was used to study a combined effects of different water conditions（drought stress and normal irrigation）,nitrogen fertilizer levels(the content of N was 0 g·kg^-1,0.1 g·kg^-11 and 0.2 g·kg^-1)and phosphorus fertilizer levels(the content of P₂O₅ was 0 g·kg^-1,0.1 g·kg^-11 and 0.2 g·kg^-1)on agronomic traits,physiological characteristics and yields,aiming at revealing the root morphological obtaining high yield and physiologically reciprocal mechanism for different drought-resistant F.tararicum varieties and seeking the best ratio of nitrogen and phosphorus fertilizer under different water conditions.At the same time,in order to further verify the effects of nitrogen and phosphorus fertilizer on yield of different F.tararicum varieties and explore the internal relationship between yield and soil ecological environment,yields,soil nutrients and enzyme activities in different depths were studied at different fertilization levels in field experiments where the soil on loess plateau was used as experimental soil.The main results were as follows:（1）The pot experiment results show that given same irrigation amount,sole nitrogen fertilizer slows down the growth of overground part（plant height,stem diameter,leaf area and dry weight of stem and shoot）and underground part（total root length,root surface area,dry weight of root）.But once phosphorus fertilizer is applied,the growth of the aboveground and root system is promoted,which shows that applying phosphorus fertilizer can alleviate the inhibiting effect of sole nitrogen fertilizer on aboveground and root growth.Furthermore,significantly improved chlorophyll content,root activity,root nitrate reductase activity,SOD,POD activities,soluble protein content,plant total nitrogen or phosphorus contents,aumulation of nitrogen or phosphorus nutrients and yield are obtained.However,MDA content,free proline content,utilization levels of nitrogen and phosphorus are decreased significantly.Under the same fertilization condition,the root SOD activity,POD activity,soluble sugar content,MDA content,free proline content,nitrogen utilization efficiency of nitrogen and phosphorus for the two F.tararicum varieties increase with the decrease of irrigation amount,while the other indexes show a decreasing trend.（2）In field experiments,nitrogen and phosphorus fertilizer treatment can significantly increase the content of alkali-hydrolyzed nitrogen,available phosphorus and available potassium in the rhizosphere soil at different soil layers when potassic fertilizer as base fertilizer,but there is no significant difference in the content of alkali-hydrolyzed nitrogen in the rhizosphere soil of 20-30cm deep.Urease,alkaline phosphatase,hydrogen peroxide and sucrase activities in rhizosphere soil are increased,which improves the biological environment of soil and then promote the growth of F.tararicum and obtain high yield.With the deepening of soil depth,the contents of alkali-hydrolyzed nitrogen,available phosphorus,available potassium and enzyme activities in the rhizosphere soil show a decreasing trend.The reason why the increase of yield of reclaimed land on the loess plateau might be that the increase of nutrient content and the subsequent increase of enzyme activities in the rhizosphere soil after fertilization promote the organification of the reclaimed land as soon as possible.（3）Comparison of the differences between varieties shows that,with the combined action of adding nitrogen and phosphorus,‘Diqing kuqiao’could control root growth more effectively than‘Heifeng 1’,improve chlorophyll content of leaves,maintain higher root activity,NR activity and nitrogen（or phosphorus）accumulation.At the same time,the changing amplitude of various indices of different F.tararicum varieties under drought stress are different.The effects on‘Diqing kuqiao’were relatively less than that on‘Heifeng 1’,indicating that‘Diqing kuqiao’has stronger adaptability under drought stress.In addition,soil nutrient contents and enzyme activities of drought-tolerant variety‘Diqing kuqiao’in the rhizosphere soil from 0 to 30cm deep are significantly influenced by nitrogen and phosphate fertilizer than that of drought-sensitive variety‘Heifeng 1’,and which improves the physicochemical property of deep soil and then promote the biological characteristics of rhizosphere soil and obtain higher yield.These factors laid an important physiological foundation for higher yield of drought-tolerant of F.tararicum variety.Considering the status of soil moisture regime and deficiency of soil nitrogen and phosphorus,and basing on the results of different combined treatments on the root¹morphology,physiological indexes and yield of F.tararicum in the hilly area of Loess Plateau of Shanxi Province,‘Diqing kuqiao’can be widely planted.It was more suitable for production at moderate nitrogen fertilizer(0.1 g·kg^-（16）N application)and high phosphorus fertilizer condition(0.2 g·kg^-（16）P₂O₅ application).