Improved lodging resistance has contributed significantly to the dramatic increase in cereal yields observed in many countries during recent decades. Several advances in understanding lodging have been made since the last major review of lodging in 1973. These include: (1) a more thorough quantification of the effects of lodging on grain yield and quality, (2) collaborative studies by biologists and engineers have elucidated the mechanisms of stem and anchorage failure and the way in which cereal shoots interact with the wind and rain, (3) the development of models of the lodging process and (4) explanations for how crop husbandry decisions affect lodging. This review collates the new understanding of lodging and attempts to set out cultural and genetic-based approaches for the continued reduction of lodging risk in high-yielding cereals. The review demonstrates that the prospects for continuing to reduce lodging risk through the selection of shorter genotypes may be limited because there appears to be a minimum crop height that is compatible with high yields. There does appear to be significant scope for increasing lodging resistance by strengthening the stem and the anchorage system by exploiting the wide genetic variation in these plant characters and through crop management decisions.

Understanding and Reducing Lodging in Cereals

Effects of Restricted Water Availability and Increased Temperature on the Grain Filling, Drying and Quality of Winter Wheat

Wheat grain dormancy is a multigenic trait controlled both by R genes conferring red testa pigmentation and by other genes, at least one of which has a major effect in the embryo. Enhanced grain dormancy and red test colour are inherited as pleiotropic effects of dominant R alleles at triplicate loci in hexaploid wheat. However, polymorphism for R genes cannot account for the wide variation in dormancy observed among different redgrained varieties. A variety of different dominant R alleles all have equivalent effects on dormancy when introgressed into white-grained wheats, although the latter vary in dormancy both in the absence and in the presence of dominant R alleles. As a result, certain redgrained genotypes can exhibit intermediate dormancy, similar to that of some white-grained genotypes with different genetic backgrounds. A new major gene (Phs) was identified as controlling the difference between two red-grained cultivars with widely different dormancies. The Phs gene appeared to exert its effect in the embryo of the grain, in contrast to R gene expression in maternal testa tissue. Discrete genetic functions thus underlie physiologically distinct mechanisms of coatimposed dormancy and embryo-imposed dormancy in wheat

Daryl J. Mares

Papers

Fourth International Symposium On Pre-harvest Sprouting In Cereals