Symbiotic nitrogen fixers - nutrient cycles, Biology

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.

Posted Date: 1/19/2013 2:12:01 AM | Location : United States







Related Discussions:- Symbiotic nitrogen fixers - nutrient cycles, Assignment Help, Ask Question on Symbiotic nitrogen fixers - nutrient cycles, Get Answer, Expert's Help, Symbiotic nitrogen fixers - nutrient cycles Discussions

Write discussion on Symbiotic nitrogen fixers - nutrient cycles
Your posts are moderated
Related Questions
What is Physiologically corrected transposition of arteries? Physiologically corrected Transposition of the great arteries (ZTGA): Atrio- ventricular connections are also inapp

What is agar-agar? Agar-agar is a sulphonated mucopolysaccharide containing mainly D-galactose, D-glucuronic acid and 3,6 anhydro L-galactose. It is derived from red sea weed e

Agroup of realated genera are classified as-?

Types of Surgery :  Pulmonary valve replacement using pulmonary or aortic allograft is the procedure of choice. It increases R.V. ejection fraction, decreases R.V. end diastolic p

are viruses cellular organisms

Define the Public Nutrition Public nutrition is concerned with improving nutrition in populations in both poor and industrialized countries, linking with continuity and public

Influence of Associated Ions The second important factor influencing the plant uptake of a given cation is the effects of the ions held in association with it. For instance, as

Of which type of defense cell do worm infections stimulate the multiplication? The major leukocytes that generally multiply and participate in the defense against worm infectio

R in d e rp es t It is also known as cattle plague resulting in high fever, diarrhoea and high mortality rates. In year 2006, OIE has declared that India is free from rin

PRODUCT S OF HEMP PLANT - Four drugs - bhang, ganja, charas & marijuana obtained from Cannabis indica and C. sativa of family Moraceae . Main alkaloid is tetrah