Nitrogen metabolism in flag leaf and grain of wheat in response to irrigation regimes

• Published in: Journal of plant nutrition and soil science 2006-02, Vol.169 (1), p.118-126
• Main Authors: Xu, Z.Z, Yu, Z.W
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; biosynthesis; chemical constituents of plants; cultivars; developmental stages; drought tolerance; enzyme activity; filling period; free amino acids; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; genetic variation; glutamate-ammonia ligase; grain filling; irrigation; irrigation water; key enzymes; leaves; malondialdehyde; net assimilation rate; nitrate reductase; nitrogen; nitrogen content; nitrogen metabolism; photosynthesis; plant growth; protein content; proteinases; quantitative analysis; seeds; Soil science; soil water content; Soil-plant relationships. Soil fertility; Soil-plant relationships. Soil fertility. Fertilization. Amendments; Triticum aestivum; water stress; wheat
• ISSN: 1436-8730; 1522-2624
• DOI: 10.1002/jpln.200420418

Although scarcity of irrigation water is one of the key limiting factors for wheat production in many regions of the world, by using partial irrigation at strategic times during the growing season, it might be possible to enhance productivity. We measured the changes in various parameters related to nitrogen (N) metabolism in flag leaf and grain of wheat (Triticum aestivum L.) plants (cv. Jinan 17 and Lumai 21), which were subjected to five irrigation regimes until physiological maturity. Severely deficient or excessive irrigation during grain filling decreased the photosynthetic rate (A), the concentrations of N, free amino acid, and soluble protein, as well as the activities of nitrate reductase (NR) and glutamine synthetase (GS) and increased malondialdehyde (MDA) accumulation and endopeptidase (EP) activity, though grain protein concentration might mainly depend on genotype. The activities of NR and GS were significantly positively correlated with A, but those of EP were significantly negatively correlated with A. The results indicate that while severe water stress aggravates the adverse effect on nitrogen metabolism, excessive soil moisture is also not useful during the grain‐filling stage, resulting in lower grain yield and quality. Our results suggest that applying an optimal irrigation regime in wheat fields still plays an important role in the improvement of grain yield and quality.