The absence of the short arm of chromosome 7B produces inhibition of N mobilization and decreases grain protein concentration in wheat (Triticum aestivum L.) cv. Chinese Spring

The ditelosomic line CSDT7BL of wheat (Triticum aestivum L.) cv. Chinese Sp ring (CS), in which the short arm of chromosome 7B is missing, has been des cribed as accumulating less protein in the grain than the normal line. In t he present paper, we studied the protein accumulation and N mobilization in CSDT7BL and CS grown in the field under two N fertilization regimes, over two successive years in field-grown plants. The N treatments applied as ure a were 0 or 300 kg N/ha in the first year, and 0 or 200 kg N/ha with 50% ea r amputation in the second year. Tn both years, the ditelosomic line showed a lower protein concentration in the grain than CS only in the fertilized treatment, while no differences were observed without N fertilization. CSDT 7BL had a higher N concentration in the straw at maturity under N fertiliza tion, indicating inefficient N mobilization under high N supply. Ear excisi on increased grain protein concentration only in the normal line and not in the ditelosomic line. It is concluded that in the short arm of wheat chrom osome 7B, there is genetic information which determines N remobilization at high N supplies.