تربية محاصيل لكفاءة استخدام النايتروجين

الملخص EN

In this review, recent developments and future speculations that explain the regulation of nitrogen use efficiency (NUE) of some crops are presented.

It is considered essentially to get best knowledge of mechanisms that control on optimal NUE in plants to reduce fertilizer application rates, underground and irrigated water pollutions and in the same time, producing acceptable yield by using genotypes grown under agronomic conditions at low and high nitrogen rates.

It is possible to develop integrated physiological researches on whole plants include genes, proteins to determine the different steps that contributing in nitrogen uptake, assimilation and recycling to final deposit sites in seeds.

It is still a big challenge face plant breeders to improve crops have high potential NUE particularly cereal that NUE is not exceed 50% .The performance of genotypes consider acceptable at low nitrogen input fertilizer rates when the yield deficiency will be no more 35-40% .The main reason of lower canopy photosynthesis crops that suffer from nitrogen application results from reducing leaf area expansion , thus the intercepted photo-radiation efficiency may be reduced more than radiation itself.

The genetic modification of crops may be a new approach of discovering proteins that controlling on nitrogen assimilation and translocation in plants.

Especially, by identifying much of quantitative traits loci (QTLs) that code enzymes contribute in photosynthesis pathway .This support the opinions that confirm of nitrogen importance in carbohydrates assimilation and increasing of grain filling .

Our knowl- edge has improved about physiological and molecular control on nitrogen assimilation in crops at different environmental conditions by using integrated approaches depending basically on physiology and quantitative genetics.

Current knowledge and prospects for future to develop application for breeding crops adapted to lower fertilizer input taking into account the world economic and the environmental constrains in the next century.