Morphological diversity in purple nutsedge from four agro-ecological zones in Ghana.

Purple nutsedge (Cyperus rotundus L.) exhibits plasticity and are morphologically different under different conditions. Due to these differences, the weed might respond differently to weed management. Here, we examined the morphological characteristics of purple nutsedge from southern Ghana relative to those reported from other countries and further assessed differences in ecotypes from four agro-ecological zones in Ghana. A total of 46 purple nutsedge samples: 40 samples from 40 communities across the study area and three each from two research stations were used for the study. The plants were multiplied, planted into pots and laid out in Completely Randomized Design with three replications. Qualitative and quantitative assessments were carried out on both underground and aboveground morphological traits of the weed samples. The qualitative traits of the samples generally conformed to those reported in other countries and did not vary significantly between the agro-ecological zones (P > 0.05). The quantitative (growth) parameters showed significant differences among agro-ecological zones (P < 0.05) and were generally smaller than those reported in other countries, suggesting morphological adaptation of the weed in Ghana. Samples from the transitional zone were significantly smaller and this could facilitate easier management of the weed in that area. The principal component analysis gave four latent factors, which mainly pointed to photosynthetic structures and growth characteristics as the major components determining variations in the collection. Cluster analysis gave four clusters (at 0.7 similarity index), which were related neither to their geographic origin nor to the agro-ecological zones.

Virtual water flows under projected climate, land use and population change: the case of UK feed barley and meat.

The flow of water through food commodity trade has been rationalized in the virtual water concept. Estimates of future virtual water flows under climate, land use, and population changes could have instrumental value for policy and strategic trade decisions. This paper estimated the virtual water flows associated with feed barley and meat imports to the UK under projected climate, land use, and population changes from the 2030s to the 2050s. The results show that future virtual water inflows associated with barley imports to balance domestic deficits are larger than total volume of water used in domestic barley production in the UK. Mean virtual water associated with total UK barley production ranged from 206 to 350 million m3. This is much less than the mean total virtual water associated with barley imports (if total barley produced in the UK is used for feed), which ranged from 2.5 to 5.6 billion m3 in the 2030s to the 2050s for all land use and climate change scenarios. If domestic barley production is distributed to the different end uses, the total virtual water inflows associated with imports to balance domestic feed barley supply could be as high as 7.4 billion m3. Larger virtual water inflows (as high as 9.9 billion m3) were associated with feed barley equivalent meat imports. While the UK barley production would be entirely green, imports of either barley or meat would result in large blue water inflows to the UK. Virtual water inflows increased across the time slices for all emissions scenarios, indicating weak effectiveness of yield or productivity gains to moderate virtual water inflows. While increase in yield and land allocated to barley production should be adaptive targets, the UK needs to take policy and strategic actions to diversify trade partners and shift imports away from countries where blue water flows can exacerbate existing or potential water stresses.

Impacts of climate change and mitigation policies on malt barley supplies and associated virtual water flows in the UK.

Barley is a major ingredient for the malting industry which is highly sensitive and vulnerable to malt barley supply. The United Kingdom (UK) has the second highest malting capacity in the EU and the third largest malting industry in the world, supplying malt to major global breweries. Premium whisky, which has both economic and cultural significance for the UK, also makes sustainable malt barley supply critical for the UK. There is paucity of information on the sustainability of future supplies of malt barley in the UK, as much as it is in the world. This study applied a food balance approach to assess the combined effects of climate change and mitigation policies on UK malt barley balances for the 2030s, 2040 s, and 2050 s. Future yields of spring barley were simulated under the low, medium and high emissions scenarios (or LES, MES, and HES, respectively) for the three time slices. Future areas of land for barley production were obtained via land use change simulation in response to climate mitigation policies and aspirations of the UK. Future yields and land areas were combined to obtain total barley production, which served as a basis of supply. Per capita malt barley consumption was combined with future population to obtain demand. The gaps between demand and supply were then assessed. The results show large deficits in malt barley supplies for all combinations of climate change, land use and population, with adverse implications for the malting industry. Total malt barley supplies under current land area for barley and using the 90th percentile yield, ranged from 1899 (LES, 2030s) to 2,437 thousand tonnes (HES, 2050s). The largest supply under climate mitigation land use scenarios ranged from 1,592 (LES, 2030s) to 2,120 thousand tonnes (HES, 2050s). Deficits in supply were observed for all climate mitigation land use scenarios and time slices, ranging from 128 to 585 thousand tonnes at 90th percentile yield. However, surpluses were observed from the 2040s if current land area for barley remains unchanged. Imports to balance the observed deficits would result in large inflows of blue water to the UK, with adverse implications for global freshwater supply and environmental sustainability. It is concluded that even though spring barley yields in the UK could increase under projected climate change, reductions in croplands (due mainly to climate mitigation policies and aspirations) could combine with population growth to undermine the sustainability of malt barley supplies, both nationally and internationally.

Challenges and opportunities for quantifying roots and rhizosphere interactions through imaging and image analysis.

The morphology of roots and root systems influences the efficiency by which plants acquire nutrients and water, anchor themselves and provide stability to the surrounding soil. Plant genotype and the biotic and abiotic environment significantly influence root morphology, growth and ultimately crop yield. The challenge for researchers interested in phenotyping root systems is, therefore, not just to measure roots and link their phenotype to the plant genotype, but also to understand how the growth of roots is influenced by their environment. This review discusses progress in quantifying root system parameters (e.g. in terms of size, shape and dynamics) using imaging and image analysis technologies and also discusses their potential for providing a better understanding of root:soil interactions. Significant progress has been made in image acquisition techniques, however trade-offs exist between sample throughput, sample size, image resolution and information gained. All of these factors impact on downstream image analysis processes. While there have been significant advances in computation power, limitations still exist in statistical processes involved in image analysis. Utilizing and combining different imaging systems, integrating measurements and image analysis where possible, and amalgamating data will allow researchers to gain a better understanding of root:soil interactions.