Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1996
Publication Date: N/A
Citation: Interpretive Summary: Increased protein content of durum wheat is important in improving the cooking and nutritional quality of pasta products. Previous studies have indicated that a wild wheat from the middle east has seeds with increased protein content. These studies indicted that a single chromosome (6B) was largely responsible for this increased protein content. We asked the question: was the increased protein the result of increased uptake of nitrogen from the soil, or was it due to transfer of more nitrogen from the foliage to the seed. This study indicated that increased protein in the lines containing the 6B chromosome was the result of both increased nitrogen uptake from the soil and to transfer of a higher proportion of the nitrogen to the seed. The genes for increased grain protein content are being transferred to future durum wheat cultivars and should result in pasta with improved quality and nutritional content.
Technical Abstract: High grain protein content of durum wheat is important for improved cooking and nutritional quality. The objective of this research with selected LDN(DIC) chromosome substitution lines was to determine the biological reason for the increased protein content of seed of the LDN(DIC-6B) line as compared to Langdon and other chromosome substitution lines. The LDN(DIC-2A), LDN(DIC-4A), LDN(DIC-4B), LDN(DIC-5B), and three of the five LDN(DIC-6B) lines, Langdon, and Ward durum cultivars were grown in replicated field trials in 1992 and 1993. The accumulation and partitioning of dry weight and nitrogen in the above ground dry matter as compared to seeds was measured. The changes in accumulation and partitioning of dry weight and nitrogen across environments was consistent. Certain chromosome substitution lines altered the accumulation ratio (i.e. total plant nitrogen divided by total plant dry weight), but in others the partitioning ratio (i.e. nitrogen harvest index divided by harvest index). In some other lines both ratios were altered to affect grain protein content. The LDN(DIC-2A), LDN(DIC-4A), and LDN(DIC-4B) lines had lower grain protein content as a result of a decreased partitioning ratio. The LDN(DIC-5B) lines had a lower partitioning ratio than LDN, but had a much higher accumulation ratio. The LDN(DIC-6B) lines were the only lines tested that had both partitioning and accumulation ratios equal to or higher than the recurrent parent LDN. They were also the only lines that were always higher in grain protein content than LDN. It is concluded that both accumulation and partitioning are important in increasing grain protein content of these lines.