Dissecting and modelling the comparative adaptation to water limitation of sorghum and maize: role of transpiration efficiency, transpiration rate and height

Maize is considered less drought-tolerant than sorghum, but sorghum is commonly grown as a short triple dwarf (3dwarf) type, so difference in plant height confounds the species comparison. The objectives of this study were to experimentally determine effects of species and plant height differences on transpiration efficiency (TE) and transpiration rate per unit green leaf area (TGLA) and use findings to explain input parameters in a simulation study on the comparative adaptation of 3dwarf sorghum and maize in environments with contrasting water availability. Maize, tall double dwarf (2dwarf) and short 3dwarf sorghum genotypes were grown in two lysimeter experiments in 2011 in SE Queensland, Australia. Each plant was harvested after anthesis and total transpiration, shoot and root dry mass were measured to estimate TE. Daily TGLA was used to compare transpiration rates. Species and height had limited effect on TE, but significantly affected TGLA. This was associated with differences in biomass allocation. The similar TE but higher TGLA in maize compared with 3dwarf sorghum meant it potentially produces more biomass, consistent with published differences in biomass accumulation and radiation use efficiency (RUE). The simulation study, which used similar TE for maize and 3dwarf sorghum, but captured differences in TGLA through differences in RUE, predicted crossover interactions for grain yield between species and total water use. The greater TGLA of maize decreased grain yield in water-limited environments, but increased yields in well-watered situations. Results highlight that similarity in TE and differences in TGLA can influence comparative adaptation to water limitation

Does increased leaf appearance rate enhance adaptation to postanthesis drought stress in sorghum?

Increased leaf appearance rate (LAR) could reduce preanthesis water use of sorghum [Sorghum bicolor (L.) Moench] by restricting plant size via reduced tillering. The aim of this paper was to assess LAR as a potential pathway for adaptation to postanthesis drought stress. Four hybrids with different LAR were grown in four semicontrolled experiments under well-watered conditions or postanthesis drought stress and in two irrigated field experiments. Observations included leaf area dynamics, transpiration, transpiration efficiency (TE), leaf N, biomass, and grain yield. ATx642 hybrids (0.0306 leaf degrees C d(-1)) had signifi cantly greater LAR than AQL39 hybrids (0.0279 leaf degrees C d(-1)) and this increased early main shoot vigor. Under low plant density, this reduced tiller number and hence leaf area and biomass around anthesis. As hybrids had similar TE and differed little in phenology, this can reduce preanthesis water use. Water availability at flag leaf determined grain number per plant (adjusted R(2) = 0.80, p < 0.01) and hence grain yield. However, the effect of increased LAR on reduced plant size was temperature dependent. Under high temperature, genotypic differences in tillering were reduced and main shoot leaf number increased more in hybrids with greater LAR. This increased responsiveness of leaf number could increase plant size and water use at anthesis. Hence, greater LAR may confer drought adaptation only in specific environments unless it is also associated with critical aspects of biomass partitioning

Integrating modelling and phenotyping approaches to identify and screen complex traits: transpiration efficiency in cereals

Following advances in genetics, genomics, and phenotyping, trait selection in breeding is limited by our ability to understand interactions within the plant and with the environment, and to identify traits of most relevance to the target population of environments. We propose an integrated approach that combines insights from crop modelling, physiology, genetics, and breeding to characterize traits valuable for yield gain in the target population of environments, develop relevant high-throughput phenotyping platforms, and identify genetic controls and their value in production environments. This paper uses transpiration efficiency (biomass produced per unit of water used) as an example of a complex trait of interest to illustrate how the approach can guide modelling, phenotyping, and selection in a breeding programme. We believe that this approach, by integrating insights from diverse disciplines, can increase the resource use efficiency of breeding programmes for improving yield gains in target populations of environments

The psychometric evaluation of a three-dimension elementary science attitude survey

This study describes the development of an instrument to investigate elementary students attitudes toward science. As a result of the instrument development process employed, the finalized instrument consisted of 28-items separated into three dimensions. The instrument was found to exhibit acceptable ranges of internal consistency. Confirmatory Factor Analysis showed three factors that clustered into the three dimensions of attitude identified and concurrent validity was evidenced as correlations were found when comparing attitude measures with the instrument to students’ perceptions of their science classrooms. Based on the analyses completed, the instrument appears to be useful for assessing student attitude toward science

Integrating modelling and phenotyping approaches to identify and screen complex traits : transpiration efficiency in cereals

Following advances in genetics, genomics, and phenotyping, trait selection in breeding is limited by our ability to understand interactions within the plants and with their environments, and to target traits of most relevance for the target population of environments. We propose an integrated approach that combines insights from crop modelling, physiology, genetics, and breeding to identify traits valuable for yield gain in the target population of environments, develop relevant high-throughput phenotyping platforms, and identify genetic controls and their values in production environments. This paper uses transpiration efficiency (biomass produced per unit of water used) as an example of a complex trait of interest to illustrate how the approach can guide modelling, phenotyping, and selection in a breeding program. We believe that this approach, by integrating insights from diverse disciplines, can increase the resource use efficiency of breeding programs for improving yield gains in target populations of environments

Managing Componentware Development --

We present the characteristics of component-based software engineering and derive the requirements for a corresponding development process