This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: PLB143S11: Final Examination Study Questions Lecture 13 Definitions Yield potential • Yield of a cultivar when grown in environments to which it is adapted, with nutrients and water non-limiting and with pests, diseases, weeds, lodging and other stresses effectively controlled • Yield potential of crops has been a much used but elusive concept which has proved difficult to define in a rigorous way • Mainly for measured comparisons of cultivars • The most important trait o Subsistence agriculture: food or other products o Marker-linked agriculture: income • Two types of genes: o Yield genes (increased yield) o Stress-resistance genes (prevent yield reductions) • Ex: the higher level of N availability also made selection for increased chlorophyll and rubisco content in wheat, and longer stay green in maize raising the yield potential • For maize and rice, yield potential is correlated with the number of background land races, but this may be fortuitous • If everything goes right no disease, pest, ideal environment Potential yield • Defined as the maximum yield which could be reached by a crop in given environments, as determined, for example, by simulation models with plausible physiological and agronomic assumptions • Potential yield: theoretical maximum yield given physiological and environmental conditions • Realized yield • Mainly for comparisons between different crops and different environments, as well as for estimating plausible future limits to crop yields. • Ex: Redwood is really high so water circulation needs to be better • Biophysical and biochemical characteristics • Treating plant like a machine o Theoretical concept o Don’t discuss stress and pests and diseases • Ex: transport of water in a redwood tree (biophysical) Ideotype • Idealized plant type to achieve high yield in a specific environment and cropping system • Traits o Short stem (no lodging..but less competitive) o Fewer leaves (just enough to intercept available light) o Single, nonbranching stem (don’t waste resources contesting space w/neighbors) o Early flowering (longer grain fill period) o High harvest index (more grain, less leaf + stem) o Erect leaves (high RUE—spreads available light over more leaf area) • Strong increase in yield with no end in sight • Diverse routes to higher yields o By design o Empirical testing • Ex: the original tropical rice breeding and physiology team at IRRI probably represents one of the best example of deliberate and successful pursuit of such an ideotype • Ex: wheat Questions 1) Ack! Your major professor has just asked you to put together an ideotype for the orphan crop Professorium geptsium with which you will be working for your PhD. P. geptsium is a grass species your group is hoping to breed for increased grain yield. Describe the ideotype for P. geptsium , including the importance of each trait included....
View Full Document
- Spring '07
- Genetics, ex, yield potential