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

Mammalian testis, Normal 0 false false false EN-IN X-...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Autotomy and regeneration, Autotomy and Regeneration Shedding of body...

Autotomy and Regeneration Shedding of body parts in self-defense to avert the attention of the predator-enemy or in any other emergency is a type of autotomy (auto: self, tom

Adapting to health changes in the older adult, You are soon to be registere...

You are soon to be registered as a nurse and have applied to work in a unit where you will be caring for a diverse range of clients with medical and surgical complexities. You know

Angiotensin - vertebrates, Normal 0 false false false E...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Migration - population dispersal, Migration - Population Dispersal Dis...

Migration - Population Dispersal Dispersal is affected by the presence or absence of the barrier and vagility which means inherent power of movement also called dispersal powe

5.4 assessment from the book, Briefly explain why cutting a flatworm into p...

Briefly explain why cutting a flatworm into pieces would not kill it

Differences between axon and dendrite, DIFFERENCE S BETWEEN AXON AND DENDR...

DIFFERENCE S BETWEEN AXON AND DENDRITE (DENDRON)     AXON   DENDRIT E (DENDRON) 1. It is single per neur

Neuropsychological assessmnet of older children, Neuropsychological assessm...

Neuropsychological assessmnet of older children In the recent years, the field of child neuropsychology has undergone tremendous growth. There has been a burgeoning interest in

Right atrial pressure, RAP can be determined semiquantitatively by assessi...

RAP can be determined semiquantitatively by assessing collapse of the inferior vena cava during inspiration. The inferior vena cava is imaged subcostally and its diameter is exa

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