Overcompensation Can Be an Ideal Breeding Target

Abstract

The phenomenon of overcompensation has been reported in various plant species although it has been treated by some as isolated incidents with only limited values. Reviewing reports on the extensive studies of defoliation in maize showed that different genotypes respond differently to defoliation, varying from phenomenal increase to significant loss in grain yield. The different responses of maize in kernel yield among genotypes to defoliation are confirmed in our experiments conducted in both China and Australia. Defoliated plants are likely to use less water during vegetative growth and that they also have better ability to extract water from the soil. We also found that defoliation dramatically delayed plant senescence under dry conditions, facilitating the production of high quality silage by widening the harvest window. As overcompensation occurs only in some genotypes, we believe that exploiting defoliation as a management practice directly for crop production can be risky. However, the fact that significant yield increase following defoliation does occur and that large genetic variation does exist meet the requirements for a successful breeding program. The detection of sizable quantitative trait locus (QTL) in the model plant species provides further evidence indicating the feasibility of exploiting this phenomenon through breeding. The stunning magnitudes of desirable responses reported in the literature suggest that overcompensation could become the most valuable breeding target in at least some species and its impact on crop production could be huge even if only a proportion of the reported variations could be captured.