Wheat grain yield and water use efficiency improved under climate change condition in semi-arid regions as predicted by APSIM crop model

The present study investigated the effect of climate change on crop productivity and water use efficiency at the regional scale. A general circulation model (HadCM3) was applied for two emission scenarios (A1B and A2) for three periods (2011-30, 2046-65 and 2080-2099) at nine locations in Fars province in central Iran. The APSIM crop model was used to simulate growth and development of wheat as well as water use efficiency under future climate scenarios. The results indicated that average temperature over the growing season increased from 12.15°C at baseline to 13.22°C in all future scenarios. The increase in CO2 concentration to 674 ppm in 2099 under A1B neutralized the negative effects of high temperature during the growing season and improved crop yield. Wheat grain yield increased from +10 to +41% over baseline for all future emission scenarios and periods at all study locations. The results indicate that, by the end of the century under the A2 emission scenario 10% to15% of Fars province will have a grain yield of more than 10 t ha-1 and about 65% will have a grain yield of 8 to 10 t ha-1. Averaged across locations, scenarios and periods, water use efficiency increased by 3.56 kg ha−1 mm−1 in the future scenarios over baseline. The improved water use efficiency under future climate change was largely the result of a significant increase in yield (from 6989.5 kg ha−1 at baseline to 8416.5 kg ha−1 in all future scenarios) and decreased evapotranspiration (from 506.8 mm at baseline to 478 mm in all future scenarios). A decrease in evapotranspiration as well as an increase in water use efficiency under future climate change could be beneficial for agricultural production systems, particularly under semi-arid conditions

Large-scale characterization of drought pattern: a continent-wide modelling approach applied to the Australian wheatbelt spatial and temporal trends

Plant response to drought is complex, so that traits adapted to a specific drought type can confer disadvantage in another drought type. Understanding which type(s) of drought to target is of prime importance for crop improvement. Modelling was used to quantify seasonal drought patterns for a check variety across the Australian wheatbelt, using 123 yr of weather data for representative locations and managements. Two other genotypes were used to simulate the impact of maturity on drought pattern. Four major environment types summarized the variability in drought pattern over time and space. Severe stress beginning before flowering was common (44% of occurrences), with (24%) or without (20%) relief during grain filling. High variability occurred from year to year, differing with geographical region. With few exceptions, all four environment types occurred in most seasons, for each location, management system and genotype. Applications of such environment characterization are proposed to assist breeding and research to focus on germplasm, traits and genes of interest for target environments. The method was applied at a continental scale to highly variable environments and could be extended to other crops, to other drought-prone regions around the world, and to quantify potential changes in drought patterns under future climates

Cross-resistance patterns of winter wild oat (Avena ludoviciana) populations to ACCase inhibitor herbicides

The level of resistance and patterns of cross-resistance to clodinafop, sethoxydim, and pinoxaden were examined in 12 putative resistant and one susceptible populations of winter wild oat (Avena ludoviciana) collected from Fars Province, in the southwest of Iran. The responses of biomass and length of coleoptiles to the increasing dosages of the three herbicides were determined in both whole-plant and seed bioassays. In the whole-plant bioassay, all 12 putative resistant populations were found to be resistant to clodinafop with resistance ratios (R/S) ranging from 1.76 to >47.04. Most clodinafop-resistant populations exhibited low levels of cross-resistance to sethoxydim. Three highly sethoxydim-resistant populations, F2, S2, and ES4, were slightly resistant to clodinafop. Six populations (M1, M2, F2, S2, S4, and ES4) showed high cross-resistance to pinoxaden with R/S values as large as 10.73 to 40.29. A highly clodinafop-resistant population, M2, was more sensitive to pinoxaden than the susceptible population. The results of the seed bioassay resembled those obtained from the whole-plant experiment suggesting seed bioassay as an inexpensive, rapid method for screening-resistant genotypes