| Low available phosphorus（P）in soil has become key nutrient factor limiting the high yield of crops,roots are the mainly vegetative organ to absorb P in soil for plants,excavating the potential of roots to acquire soil P in low P environments,and selecting and cultivating the highly effective P varieties,which are a kind of economical and sustainable agricultural development path and the scientific problem that agriculture solves urgently.Crops ameliorated the water and nutrient uptake via the plastic changes of root functional traits,which has been a momentous mechanism for crops in respond to low P stress.This study took 11 common leguminous crops（soybean,faba bean,pea,cowpea,common bean,lentil,adzuki bean,chickpea,grass pea,red kidney bean and common vetch）as materials to carry out a pot experiment so that exploring their roots in respond to low P stress during flowering period.The related research results lay a foundation for further research on the expression and localization of related genes involved in rhizosphere phosphorous activation.The main research results are as follows:（1）P deficiency significantly inhibited the shoot and root growth and P accumulation of leguminous crops,and the plants promoted P uptake and alleviated P hunger by enhancing P utilization efficiency.However,there were significant differences among different crop varieties.Low P stress significantly inhibited the shoot（16.9%）and root dry weight（24.7%）,and P accumulation（23.6%）of leguminous crops,and significantly enhanced the soybean（9.1%）,pea（9.7%）,common bean（9.4%）,adzuki bean（18.4%）,chickpea（15.5%）and grass pea（22.4%）.（2）Leguminous crops can adapt to phosphorus deficiency environment by increasing organic acid secretion and acid phosphatase activity and limiting root growth.Low P stress significantly inhibited the root length（10.5%）,root surface area（7.9%）,number of nodules（28.8%）and adventitial root density（23.8%）of legumes,and significantly decreased the vesicle richness of coarse roots（11.7%）,significantly increased organic acid exudations（78.1%）and acid phosphatase activity（16.8%）in roots.（3）Mycorrhizal symbiosis induced by P deficiency showed the rule that mycelium infection rate increased and vesicle colonization decreased.In general,low P stress had no significant effect on the total infection rate of arbuscular mycorrhizal fungi（AMF）.（4）Different legume crops showed various response strategies to low P stress.For example,under low P treatment,root length,root surface area and root volume of soybean were significantly increased,specific root length,adventitious root angle and lateral root angle of faba bean were significantly increased,lateral root densities were significantly increased in chickpea and red kidney bean,common bean had high organic acid contents(574.2 mg·g-1 RDW)and lentil had high acid phosphatase activity(30.8ug·g-1·h-1 RDW)compared with other legume crops,organic acids secreted by roots in common vetch significantly increased,acid phosphatases secreted by roots in adzuki bean significantly increased,and the AMF infection rate significantly increased in pea,adzuki bean and chickpea roots.（5）Correlation analysis and principal component analysis showed that the influence of root morphology traits（such as root length and root surface area）on P accumulation was greater than that of root exudations and mycorrhizal symbiosis under low P stress.There was a correlation between root secretion of acid phosphatase and the development degree of fine roots.The organic acids and acid phosphatase activities secreted by roots interacted with the AMF colonization.In conclusion,leguminous crops respond to low P stress by increasing organic acid and acid phosphatase secretion in roots.This study elucidates the excitability responses and strategies of root morphology and configuration,root exudates and mycorrhizal symbiosis in leguminous crops in response to low phosphorus stress. |
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