methods to increase nodulation and nitrogen fixation in plants

Explain the reason why legume plants are able to fix nitrogen but cereal plants are not

How do leguminous plants contribute to the nitrogen cycle?*1 pointThey absorb nitrogen compounds from the atmosphere.They facilitate denitrification in the soil.They fix nitrogen gas into ammonia.They release nitrates into the soil.

Nitrogen Fixation and Agriculture- Crop rotation- Takes advantage of the agricultural benefits ofsymbiotic nitrogen fixation- Year 1: A non legume plant such as maize is planted- Year 2: A legume is planted=> Restore the concentration of fixed nitrogen in the soilFungi and Plant Nutrition- Mycorrhizae are mutualistic associations of fungi androots- The fungus benefits from a steady supply of sugar fromthe host planthttp://archive.bio.ed.ac.uk/jdeacon/FungalBiology/mycorhiz.htm http://www.bbc.com/news/science-environment-22462855http://ecomyc.com/mycorrhizae/The host plant benefits because the fungus increases thesurface area for water uptake and mineral absorptionMycorrhizal fungi also secrete growth factors that stimulateroot growth and branching- Two the most important groups- Ectomycorrhizae- 10% of plant familiespine, oak, birch, and eucalyptus- Arbuscular mycorrhizae- In about 85% of plant species,-Including grains and legumesFigure 37.13a (a) EctomycorrhizaeCortexEpidermis Mantle (fungal sheath)EpidermalcellEndodermisFungalhyphaebetweencorticalcells (LM) 50 μmMantle(fungal sheath)(Colorized SEM)1.5 mmIn ectomycorrhizae, the mycelium of the fungus forms adense sheath over the surface of the rootThese hyphae form a network in the apoplast, but do notpenetrate the root cellsFigure 37.13b(b) Arbuscular mycorrhizaeCortical cellEndodermisFungalvesicleCasparianstripArbusculesPlasmamembrane (LM)10 μmCortexEpidermisFungalhyphaeRoothairArbuscular mycorrhizae: Association of a fungus with plantroots where the hyphae grow into tubes formed by theinvagination of the plant cell’s membranesEpiphytes, Parasitic Plants, and Carnivorous Plants- Some plants have nutritional adaptations that useother organisms in non mutualistic ways- Three unusual adaptations are- Epiphytes- Parasitic plants- Carnivorous plants- An epiphyte grows on another plant and obtainswater and minerals from rainFigure 37.14aStaghorn fern, an epiphyteAn epiphyte grows on another plant and obtains water and minerals fromrainhttp://picssr.com/tags/epiphyten/page2A.CzerednikEpiphytesFigure 37.14b Parasitic plantsMistletoe, a photosynthetic parasiteRafflesia, a non-photosyntheticparasiteIndian pipe, a non-photosyntheticparasite ofmycorrhizaeThey hurt but do not kill their hostLathraea clandestina(purple toothwort)

While researching a topic, a student has taken the following notes: Certain plants live in a mutually beneficial relationship (symbiosis) with nitrogen-fixing bacteria.One example is plants in the Fabaceae family, commonly called legumes, which exist in harmony with the bacteria that live inside nodules on their roots.From the plants' roots, the bacteria extract sugar that allows them to conduct a process called nitrogen fixation.During nitrogen fixation, the bacteria extract atmospheric nitrogen (N2) and convert it into ammonia, a compound that the plant can metabolize into amino acids, nucleic acids, and chlorophyll, all important to the plant's development.The student wants to make and support a generalization about the relationship between legumes and nitrogen-fixing bacteria. Which choice most effectively uses relevant information from the notes to accomplish this goal?Some bacteria feed on the sugars provided by plant roots in a process called nitrogen fixation. eliminateLegumes derive the nitrogen they need from atmospheric nitrogen converted into ammonia.eliminateLegumes and nitrogen-fixing bacteria have a symbiotic relationship: the bacteria use sugars from the plants' roots to capture nitrogen from the atmosphere, a process which provides important molecules to the plants. eliminateOne example of a relationship between organisms in nature is a symbiosis, wherein both organisms derive something from the relationship and benefit from it.

Nitrogen fixation is a process that:a) Recycles nitrogen compounds from dead and decaying materialsb) Converts ammonia to nitratec) Releases nitrate from the rock substrated) Converts nitrogen gas into ammonia