Browsing by Autor "Lachlan Lake"

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Associations between yield, intercepted radiation and radiation-use efficiency in chickpea
(CSIRO Publishing, 2017) Lachlan Lake; Víctor O. Sadras
Relationships between yield, biomass, radiation interception (PARint) and radiation-use efficiency (RUE) have been studied in many crops for use in growth analysis and modelling. Research in chickpea (Cicer arietinum L.) is limited, with variation caused by environment and phenological stage not adequately described. This study aims to characterise the variation in chickpea PARint and RUE with phenological stage, line and environment and their interactions, and the impact of this variation on yield. Chickpea lines (six desi and one kabuli) previously identified as varying for yield, competitive ability, crop growth rate and phenology were compared in four environments resulting from a combination of two sowing dates and dry and irrigated water regimes. Yield varied from 0.7 to 3.7 t ha–1. Line, environment, phenological stage and the interactions line (G) × environment (E) and environment × stage affected both RUE and PARint. Line × stage interaction also affected RUE. High PARint and RUE were associated with high yield, but the interaction between environment and phenological stage dictated this relationship; higher PARint and RUE were observed in irrigated environments. Some environment × phenological stage combinations resulted in no significant associations, particularly before flowering in dry environments. These results emphasise the importance of understanding the effects of G × E on capture and efficiency in the use of radiation and have implications for growth analysis, modelling and breeding.
Patterns of water stress and temperature for Australian chickpea production
(CSIRO Publishing, 2016) Lachlan Lake; Karine Chenu; Víctor O. Sadras
The environment is the largest component of the phenotypic variance of crop yield, hence the importance of its quantitative characterisation. Many studies focussed on the patterns of water deficit for specific crops and regions, but concurrent water and thermal characterisations have not been reported. To quantify the types, spatial patterns, frequency and distribution of both water stress and thermal regimes for chickpea in Australia, we combined trial and modelled data. Data from National Variety Trials including sowing time, yield and weather from 295 production environments were entered into simulations. Associations between actual yield, in a range from 0.2 to 5.2 t/ha, actual temperature and modelled crop water stress were explored. Yield correlated positively with minimum temperature in the 800 degree-days window bracketing flowering and the correlation shifted to negative after flowering. A negative correlation between maximum temperature over 30°C and yield was found from flowering through to 1000 degree-days after flowering. Yield was negatively correlated with simulated water stress from flowering until 800 degree-days after flowering. Cluster analysis from 3905 environments (71 locations × 55 years between 1958 and 2013) identified three dominant patterns for both maximum and minimum temperature accounting for 77% and 61% of the overall variation, and four dominant patterns for water stress accounting for 87% of total variation. The most frequent environments for minimum and maximum temperature were associated with low actual yield (1.5–1.8 t/ha) whereas the most frequent water-stress environment was associated with the second lowest actual yield (1.75 t/ha). For all temperature and water-stress types, we found significant spatial variation that is relevant to the allocation of effort in breeding programs.