The regulation of nitrogen accumulation in the grain of wheat plants (Triticum aestivum)

Abstract

Nitrogen accumulation in the ear of wheat plants (Triticum aestivum L. cv. Klein Chamaco) during ear growth was studied under 4 experimental conditions. Plants were grown in pots with Perlite or soil, and fertilized with nutrient solutions. In one experiment the plants were grown in a greenhouse and supplied with high (16mM) or low (1.6 mM) N in the nutrient solutions until anthesis, and then with or without nitrogen supply until ripening. In a second experiment the plants were grown with high N supply until anthesis, and then for half of the plants light intensity was decreased by 50%, and at the same time. N supply was terminated for half of the plants within each light treatment. A third experiment was similar to the previous one, but was carried out in a growth cabinet under 20% of the maximal irradiance in the greenhouse. In a fourth experiment half the ear was excised at anthesis in half of the plants, and these plants were then supplied with or without nitrogen. In all experiments there was a linear relation between the rate of N accumulation and the rate of ear growth. A wide range of final individual grain weights and N concentration was observed among the experiments. The same maximum N concentration was observed for all grain sizes, although the N concentration could be different between grains of the same size. The grain N concentration correlated with the rate of N accumulation per unit of ear weight increase during ear growth. It is suggested that in wheat plants there is a dependence of nitrogen transport on carbon transport to the ear, and to the ear, and that the final grain N concentration is determined by the N/C ratio exported from the vegetative tissues.

Antisense-inhibition of ADP-glucose pyrophosphorylase in Vicia narbonensis seeds increases soluble sugars and leads to higher water and nitrogen uptake

“…The main driving force for water influx is probably sugar accumulation. From our results and those of others (Jenner et al 1991;Barneix et al 1992), it can be concluded that accumulation of sugars in seeds is tightly controlled and occurs by a saturable uptake system (Weber et al 1997). On the other hand, N accumulation is much less controlled and is dependent on N availability (Barneix et al 1992;Hayati et al 1996).…”

“…The flow into starch increases or decreases in response to low or high nitrogen (Champigny et al 1992). On the other hand, in wheat endosperm the rate and duration of protein deposition seem to be independent of starch biosynthesis (Jenner et al 1991), suggesting that the pathways of starch and protein biosynthesis are not directly connected (Barneix et al 1992). However, in mutant seeds with deletions in the starch-formation pathway, storage-protein accumulation is also affected (Casey et al 1998).…”

Nitrogen Translocation in Wheat Plants Under Soil Water Deficit

“…However, the present study showed that the proportion utilizing N in the fertilizers decreased under water deficit, suggesting more water deficit treatment in the present experiment might negatively affect the ability to derive N from fertilizers. Leaves are the main N reservoir of the plant during vegetative growth (Barneix et al, 1992;Guitman et al, 1991;Sheehy et al, 2004a). The present study showed that the leaves had more N translocation into grains, indicating that the leaf is a major N storage organ.…”

Improvement of pistillate flowers yield with GA3 in heavy metals treated plants

“…This inferred that the physiological regulation of C and N substrates on protein and starch synthesis in wheat grains could be general for different genotypes. Barneix et al (1992) also reported that although protein concentration in cereal grains is a genetic character, it could be modified by environmental conditions.…”

“…Barneix et al (1992) proposed that the content of grain N was not regulated by itself, but by the rate of input N and fraction of redistributed N in wheat. This explains why the changed amino acid content in grains regulated protein synthesis in the present study ( Figure 2).…”