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

What are plant hormones, What are plant hormones? Plant hormones, also ...

What are plant hormones? Plant hormones, also known as phytohormones, are substances that control the embryonic development and the growth of the adult plant.

Special structures of the avian digestive tube, Q. What are the special str...

Q. What are the special structures of the avian digestive tube and their respective functions? The crop has the function of temporary storage of ingested food and it is a more

Cow-pox (vaccinia), C o w - po x (vaccinia) E p ide...

C o w - po x (vaccinia) E p idemiology: This infection, although mostly occurring in cows, sometimes also occurs in buffaloes. Under natural conditions, t

Reproduction, what is the arrangement of microtubules in the sperm

what is the arrangement of microtubules in the sperm

Extracellular aging, Extracellular Aging The basic components of extra...

Extracellular Aging The basic components of extracellular space are mucopolysaccharides and fibrous proteins, particularly collagen and elastin. These proteins are synthesised

Signify the term - opercular gill, Signify the term - opercular gill. T...

Signify the term - opercular gill. The gill found in bony fish. Operculum is the outer covering of the gill. When it's drawn away from the body, it pulls water inside the bucca

Explain class oligochaeta - earthworms in details, Explain Class Oligochaet...

Explain Class Oligochaeta - Earthworms in details? This group of annelids includes the earthworms. Oligochaetes live in the soil or in fresh water habitats, and a few inhabit m

What are the types of good in the demand curve, What are the types of good ...

What are the types of good in the demand curve? Some types of good are as follows: • Normal good: When incomes of consumers/households increase the quantity demanded wo

What is the meaning of paraplegia, What is the meaning of Paraplegia Pa...

What is the meaning of Paraplegia Paraplegia (from the Greek para, "alongside of," and plegia,  "stroke") is a condition in which both lower limbs are paralyzed (quadriplegia i

New Technology, What is the best microscope to get a detailed view of the p...

What is the best microscope to get a detailed view of the parts inside of a preserved plant cell

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