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

Define nervous system and the it's related disorders, Define Nervous System...

Define Nervous System and the it's related disorders? In this unit, we learnt about nervous system and the related disorders, which are termed as 'neurological disorders'. Neur

What are the three periods into which interphase, Q What are the three peri...

Q What are the three periods into which interphase are divided? Interphase is the preceding phase to the mitotic division. It is divided into three periods, G1, S and G2 the le

What do you mean by varices, Q. What are varices? Why are they more common ...

Q. What are varices? Why are they more common in the inferior limbs? Varix means abnormal enlargement of veins and the Varices occur when excessive pressure against the normal

Porifera - regeneration in invertebrates, Porifera - Regeneration in Invert...

Porifera - Regeneration in Invertebrates Sponges have immense regenerating ability and show two ways of doing so as displayed below. : (a) Regeneration from small segments-

How to repair the defects in post myocardial , How to repair the defects in...

How to repair the defects in post myocardial ? Repair of Defect :  The approach to the defect is through ventriculotomy over the infarcted area. The defect is repaired

Colibacillosis of poultry, Colibacillosis of poultry Colibacillosis is...

Colibacillosis of poultry Colibacillosis is an important disease among poultry, especially among broiler chicks aged 6-9 weeks and less frequently of young chicks during first

Protoplasmic theory, Protoplasmic Theory The living matter which forms ...

Protoplasmic Theory The living matter which forms the bodies of all living being is a special type of highly organized jelly like viscous semi fluid, and named Sarcode by Dujar

What is the phase of the menstrual cycle, Q. In general what is the phase o...

Q. In general what is the phase of the menstrual cycle when copulation may lead to fecundation? Although this is not a rule, to be effective fecundation in general must occur w

Why food which can be taken in plenty, Food Which can be Taken in Plenty an...

Food Which can be Taken in Plenty and Food to be Avoided Lastly, in the context of changing the diet, we should know the foods to be avoided and the food to be taken in plenty

Mycoplasmosis, Mycoplasmosis Mycoplasmas are the aetiological agents o...

Mycoplasmosis Mycoplasmas are the aetiological agents of bovine pleuropneumonia in cattle caused by Mycoplasma mycoides subsp. mycoides, caprine pleuropneumonia in goats cause

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