Genetic Designing of Plant Architecture in Wheat

Wheat plant architecture has been continually evolving over the past many years primarily in response to increase in the yield potential. One of the most important factors for improvement in the wheat yield potential was the use of Rht genes in the early 1960s. Use of rye chromatin is a successful approach for introducing yield-enhancing genes into elite genetic backgrounds; for example, the use of the lines with 1BL/1RS translocation contributed to productivity and disease resistance. In addition, the role of plant architectures has been analyzed for manipulation of various traits responsible for light capture, photosynthesis, interactions between them and their suitability under various geographic conditions affecting the availability of sunlight. Recent works suggest that this was not just due to shorter stems, but more efficient investment of dry matter in spikes and grains may also be related to more erect canopies and greater leaf photosynthetic activity improving crop photosynthesis around flowering, to more grain sites per unit spike dry matter, and to more stored carbohydrates in stems at flowering. The combined use of Ppd1 and Ppd2 genes also has noticeable individual effects on flowering, but when only one of these genes is active, it results in an intermediate flowering effect. The influence of these genes in making wheat mature at very early, intermediate and late durations is tremendous. The major yield contributing factors in wheat are harvest index, number of grains per meter, in addition to high nitrogen use efficiency which may be used for improving assimilates (source) capacity, including early vigor, stay-green leaf-angle, and remobilization of stem reserves. For developing genotypes with better capacity for utilizing stored assimilate, particularly under stress environments, emphasis should be given for key traits, e.g., grain growth, grain yield, and its components associated with stem reserve mobilization