Improvement of crop performance is a continuous process because of the necessities to improve agricultural productivity and nutritional quality in the face of ever changing climates, pressures from evolving insects, pests, and weeds, and the need to contribute to agricultural productions systems that are increasingly sustainable and help to conserve lands and biodiversity. The improvement of crop yields is dependent upon an increase in yield due to genetic change (genetic gain) interacting with the environmental effects of weather and the agronomic management abilities of individual farmers. We will focus on the genetic aspects of crop improvement with a review of inheritance of single genes and the more prevalent and agronomically important multi-genic traits. We will review basic concepts of plant breeding including selection intensity, heritablity, genetic gain. inbreeding depression and hybrid vigour. We review basic principles of plant breeding by investigating why US farmers had not been successful in raising corn yields before the era of hybrids. The only thing that is “traditional” about agriculture and plant breeding is that methods are always changing. We will review new methods available to breeders and discuss future approaches that may be required to continue past success of plant breeding into the future.
Variety Testing & Development:
Without high quality variety testing both advancement by breeding and more effective farm management, including choice of variety to plant would be stymied. Effective variety testing requires excellence in agronomy, biology, physiology, basic genetics, statistical design and analysis. Variety testing is vital to identify the best fit of new genetic combinations developed by breeding with target agronomic environments and farm management practices. To disentangle genetic from environmental effects it is necessary to develop a full knowledge of both the testing locations and the target production environment. Appropriate field trial and plot design are critical. Variety testing is crucial at each stage of the breeding process, becoming increasingly rigorous as numbers of potential new varieties is reduced to the best of the best for commercial release. Trials are required for both base germplasm, for genetically modified event selection, and for base germplasm when combined with genetically modified traits. Variety testing does not end at commercialisation as fresh data on genotype x environment x management continues to provide further knowledge useful both to breeders and to farmers to optimise fits of genotype x environment x crop management. Variety testing is also important to obtain intellectual property protection of new varieties to encourage further investment and innovation in plant breeding.