| Objective:In this experiment,alfalfa was taken as the research object.Different water and phosphorus were given by drip irrigation to study the dynamic changes on production performance and root of alfalfa affected by water and phosphorus.To reveal the influence mechanism of alfalfa on water and phosphorus,and the effect of water and phosphorus on the water-phosphorus use efficiency of alfalfa.The growth and death dynamic on fine roots of alfalfa were monitored by micro-canal technique under the condition of water-phosphorus coupling,and the dynamic characteristics of water and phosphorus application on fine root turnover and distribution of different soil layers were determined.The research objects were Bacillus megaterium and Bacillus subtilis,which have the effect of phosphorous dissolving,and Funneliformis mosseae and Glomus etunicatum,which can coexist with alfalfa roots,in pot culture,the mechanism of alfalfa growth was affected by the individual strains and the combination of two strains.Then the optimal combination of water and phosphorus bacteria coupling test was selected to provide a theoretical basis for the artificial cultivation of alfalfa and the development of high-efficiency microbial fertilizer.Methods:1)The experimental treatments were the factorial combinations of three irrigation rates:5250m3·ha-1?W1?,6000 m3·ha-1?W2?and 6750 m3·ha-1?W3?.The four phosphorus fertilizer rates in the experiment were?as P2O5 equivalent?0 kg·ha–1?P0?,50 kg·ha–1?P1?,100 kg·ha–1?P2?and 150 kg·ha–1?P3?,the consisted of 12 treatments for water-phosphorus coupling,he P fertilizer was applied together with irrigation water under drip irrigation.CI-600 root monitoring system in situ observed the changes of alfalfa root growth under different water and phosphorus treatment,and then used root image analysis software?WINRHIZO TRON 2009a?to process the image.2)Single factor randomized block design was used in the experiment,four kinds of bacteria were selected,Bacillus megaterium?Bm?and Bacillus subtilis?Bs?with high phosphorus-solubilizing ability,and Funneliformis mosseae?Fm?and Glomus etunicatum?Ge?,which can coexist with alfalfa roots,were mixed with BmBs,BmFm,BmGe,BsFm,BsGe and FmGe,respectively.After inoculation the bacteria to determine the hay yield,plant height,stem diameter,crude protein concentration,neutral detergent fiber,acid detergent fiber,phosphorus concentration,taproot length,root biomass of alfalfa,and pH value,total phosphorus,available phosphorus concentration of soil.the effect of single and double inoculation on alfalfa was evaluated by membership function analysis.3)L16?43?experimental design was adopted in this study.There are four levels of moisture concentration,phosphorus application and bacterial inoculation in potted plants.The determination of various processing alfalfa above-ground biomass,plant height,stem diameter,crude protein content and neutral detergent fiber,acid detergent fiber,alfalfa plant phosphorus content,taproot length,underground biomass,soil pH,soil total phosphorus and available phosphorus content,the indicators by principal component analysis comprehensive evaluation of the effects on alfalfa of treatment.Results:1)Under the same irrigation amount,the total hay yield,water use efficiency and phosphorus use efficiency of alfalfa were P2 was significantly higher than P1 and P3?P<0.05?,and the total hay yield of alfalfa was increased by 7.43%29.87%when P was applied,among which P1,P2 and P3 were increased by 7.43%16.88%,12.55%29.87%and 8.02%18.94%when P was applied.With the increase of irrigation amount and phosphorus application amount,alfalfa fine root stock,yield and death increased first and then decreased,and reached the maximum under W2P2 condition.2)Compared with CK treatment,the underground biomass,plant height and stem diameter increased by18.57%24.49%,8.59%21.33%and 3.86%9.54%in PSB alone.increased by 9.15%22.09%;2.51%18.60%and 4.59%11.31%in AM alone,increased by 7.66%7.03%,7.4432.85%and5.58%26.61%in combination of AMF and PSB,respectively.3)Compared with 1 treatment,other treatments in above-ground biomass,plant height and stem diameter of alfalfa had significantly less higher 1 treatment?P<0.05?,and reached a maximum under the 11?W3P2J0?treatment(25.13 g·pot-1,45.39 cm and 3.47 mm,respectively).The hay yield of alfalfa in W2?5,6,7 and 8?,W3?9,10,11 and 12?and W4?13,14,15 and 16?treatments were significantly higher than in W0?1,2,3 and 4?treatment?P<0.05?.Taproot length and underground biomass in J1?2and 15?,J2?7,9 and 14?and J3?10?treatments were significantly higher than in J0?1 and 16?treatment?P<0.05?.Conclusion:1)Considering the hay yield,nutrient quality,WUE and PUE of alfalfa,the optimal water-phosphorus coupling model is the W2P2 treatment,i.e.,irrigation capacity of 6000 m3·ha-1 and P2O5 application of 100 kg·ha-1.This is a suitable water-phosphorus combination model for alfalfa to produce high quality and high yield under drip irrigation in the oasis region of Xinjiang in China.And the application of phosphorus increased the amount of fine roots product,reducing the amount of fine root mortality.2)The effect of simultaneous inoculation of PSB and AMF on alfalfa plant growth and phosphorus nutrition was better than that of single inoculation of PSB or AMF,and the effect was related to the types of PSB and AMF.3)Severe water stress?35%soil water holding capacity?seriously inhibited the growth and development of alfalfa.Simultaneous inoculation of Bacillus megaterium?PSB?and Funneliformis mosseae?AMF?could effectively alleviate the damage and improve tolerance to drought of alfalfa by mild water stress?50%soil water holding capacity?,and the inoculation effect was PSB+AMF>AMF>PSB. |
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