Symbiotic nitrogen fixers - nutrient cycles, Biology

Assignment Help:

Symbiotic Nitrogen Fixers - Nutrient Cycles

Of the symbiotic nitrogen fixing bacteria, species of Rhizobium form root nodules in legumes and are the most studied nitrogen fixers and the best understood. Species of Rhizobium are most specific to particular species of legumes. The rhizobia penetrate the root hair and once inside the root, the bacteria rapidly multiply and form swollen, irregular - shaped bodies in roots of legumes. Some non-legume w6ody plants also have root nodules and fix nitrogen symbiotically.

The organisms that cause the formation of nodule and fixation of nitrogen are actinomycetes (a kind of primitive fungus). Some examples of non-legumes are species of Alnus, Elaeagnus Myrica, Araucaria, Ginkgo, and Casuarina. Unlike legumes, which are largely tropical in origin, these nitrogen fixers originate in the temperate zone. Nitrogen fixation by blue green algae or cyanobacteria may take place in free living forms or in symbiosis with fungi as in certain lichens, mosses ferns and at least one seed plant. The fronds of the small free floating aquatic fern Azolla contain small pores filled with symbiotic blue green algae Anabaena that actively fix nitrogen. For centuries this fern has played an important role in the rice fields of China. Before the rice fields are planted the water filled paddy fields are covered with the aquatic fern which fixes enough nitrogen for the crop as it matures. This practice permits rice to be grown without further addition of nitrogen fertilisers. Symbiotic nitrogen fixers are more efficient than free living ones.


Related Discussions:- Symbiotic nitrogen fixers - nutrient cycles

Explain about the light sense, Explain about the Light sense You  must ...

Explain about the Light sense You  must be  aware that when you  enter  into a cinema hall, you  are unable  to  see  and  find  out your  seat  initially for  a few minutes; b

How successful are you at synthesizing genes, How successful are you at syn...

How successful are you at synthesizing genes with really high G/C content? A: We have an extremely low failure rate, which is about one out of five thousand or ten thousand gen

Which groups can the nitrogen-containing bases that form rna, Q. Into which...

Q. Into which two groups can the nitrogen-containing bases that form RNA and DNA be classified? What is the criterion used in to that classification? The nitrogen-containing ba

Cells, Cell theory exception

Cell theory exception

What is the typical vegetation of the grasslands, What is the typical veget...

What is the typical vegetation of the grasslands? Grasslands are mostly formed of herbaceous (nonwoody) vegetation: grass, bushes and small trees. Biomes - Image Diversity:

Digitalis toxicity, Symptoms of digitalis toxicity include anorexia, nausea...

Symptoms of digitalis toxicity include anorexia, nausea, headache, blurring or yellowing of vision, and disorientation. Cardiac toxicity may take the form of atrioventricular condu

What is the climax stage of an ecological succession, Q. What is the climax...

Q. What is the climax stage of an ecological succession? The climax stage is the stage of an ecological succession in which the community of an ecosystem turn into stable and d

Explain the health benefits of polyphenols, Explain the Health Benefits of ...

Explain the Health Benefits of Polyphenols ? Various health benefits have been attributed to polyphenols. These include: - anti-microbial - anti-viral - anti-oxidant - hy

List the causes of implant failure, List the causes of implant failure due ...

List the causes of implant failure due to improper surgical technique and placement. Failure due to surgical techniques and improper placement: a) Off axis / severe angulati

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd