Nitrogen Assimilation by Plants Physiological, Biochemical and Molecular Aspects

About this book

While nitrogenous fertilizers have significantly helped in increasing the yield of farm produce since the 1950s, the non-assimiliated nitrates which are carried by drainage water from soils are responsible for polluting the ground water. Moreover, nitrates that accumulate in harvestable vegetative organs are considered to be sources of potential danger for human health. It is therefore necessary to view sustained and enhanced agricultural yields in relation to the quality of the environment by increasing the efficiency of nitrogen assimilation by plants. This text contains pertinent information acquired over 20 years of research in the area of nitrogen metabolism and envisages new strategies to improve plant species of agronomic value by devising new techniques for growing them.

Contents

Nitrate assimilation - historical resume. Part 1 Assimilation of nitrate and ammonium: sources of nitrogen, nitrogen cycle, root structure and nitrogen assimilation; transport of nitrate by roots; nitrate assimilation - nitrate and nitrite reductases; ammoniacal nutrition of plants; ammonium assimilation; integration of nitrate uptake in the whole plant. Part 2 Symbiotic assimilation of nitrogen: symbiotic nitrogen fixation; symbiotic signals in Rhizobium; nitrogenase - biochemical, molecular, and genetic aspects; nitrogen assimilation by ecotmycorrhizal symbiosis; plant growth enhancement by rhizobacteria; rice field cyanobacteria - ecology contribution to soil fertility and practical utilization. Part 3 Synthesis and transport of amino acids and carbon/nitrogen relationships: synthesis of amino acids; transport of amino acids in plants; co-ordination between nitrogen photosynthetic and respiratory metabolism; nitrogen (NO3) nutrition and distribution of carbon in the plant. Part 4 Distribution of nitrogen during plant growth and development: 15N methodology; mobilization of nitrogen reserve in herbaceous plants; management of nitrogen in ligneous species; protein synthesis in grains and seeds; proteolysis in higher plants - nature, function and regulation. Part 5 Nitrogen - ecophysiology and agronomy: nitrogen nutrition and growth of cultivated swards; nitrogen - crops production and environment; nodular diagnosis - agronomic basis for an integrated improvement of symbiotic nitrogen fixation and the N2-dependent yield of grain-legumes; nitrogen and pollution.

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