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

Transgenic animals, T ra n sge n i c animals There are various d...

T ra n sge n i c animals There are various definitions for the term transgenic animal . The transgenic animal is an animal in which there has been a deliberate modifica

Define points to remember regarding to food processing, Define Points to Re...

Define Points to Remember regarding to Food Processing? 1. Conversion of raw materials and ingredients into acceptable consumer products is referred to food processing, which c

What is replication, Question 1 Write a short note on the following- ...

Question 1 Write a short note on the following- Structure of DNA. Satellite DNA Transcription. pBR 322 vector Cytokines Microarrays Question 2 What is

Contact osteogenesis, Contact Osteogenesis: In this the osteogenic cells at...

Contact Osteogenesis: In this the osteogenic cells attach to the implant surface and the new (de novo) bone is formed on the implant surface first. The developing bone matrix can d

Define most probable number (mpn) method, Define Most Probable Number (MPN)...

Define Most Probable Number (MPN) Method? The MPN method is like agar shake tube method where no agar is used. The dilutions of the microbial suspension are made in liquid medi

Animal reproduction, Animal Reproduction - Reproduction is the ability ...

Animal Reproduction - Reproduction is the ability to produce new organism of its own type. It is meant to increase their number. Reproduction includes - (i) Replication o

What are the products and reagents of fermentation, Q. In general what are ...

Q. In general what are the products and reagents of fermentation? In fermentation glucose sugar is degraded into pyruvic acid each glucose molecule forms two pyruvic acid molec

Guidelines for diabetic patients for healthy coping, Q. Guidelines for Diab...

Q. Guidelines for Diabetic Patients for Healthy Coping? Generally, a diabetic patient adapts to day to day stress effectively, as they accept their disease condition with the s

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