Drought stress and Acacia seyal biochar effects on sorghum gas exchange and yield: A greenhouse experiment

Drought is the controlling abiotic stress factor affecting crop production in dryland environments and exposes millions of people to food insecurity in Africa and Asia. Although sorghum is drought tolerant, it is not sufficiently known if biochar can reduce drought-related losses in yields in clay soils for this particular crop. The stomatal morphology and gas exchange responses were investigated of a sorghum cultivar, ‘Wad Ahmed’ (widely grown throughout Sudan and South Sudan), to drought stress and Acacia seyal biochar application in a greenhouse pot experiment. The experiment was set up in a split-plot, randomized block design with two experimental factors: drought stress (60%, 40%, 20% of field capacity) and biochar (no biochar and 10 Mg/ha). The potting soil was clay textured with 5% carbon content. There were eight replicate pots of each treatment which were arranged randomly in six blocks giving a total of 48 pots. The experiment lasted 153 d from sowing, with 127 d of drought treatment. The results showed that while drought stress had a significant (p < 0.05) effect on gas exchange, water use efficiency, biomass and grain yield, biochar had no significant effect, and neither drought stress nor biochar had a significant effect on stomatal size and density. It may be that high doses of biochar are required to benefit crops grown under drought stress, particularly when the soils have initially high soil organic carbon content, with more time needed for any effect to become evident.Peer reviewe

Dovetailing biology and chemistry: integrating the Gene Ontology with the ChEBI chemical ontology.

BACKGROUND: The Gene Ontology (GO) facilitates the description of the action of gene products in a biological context. Many GO terms refer to chemical entities that participate in biological processes. To facilitate accurate and consistent systems-wide biological representation, it is necessary to integrate the chemical view of these entities with the biological view of GO functions and processes. We describe a collaborative effort between the GO and the Chemical Entities of Biological Interest (ChEBI) ontology developers to ensure that the representation of chemicals in the GO is both internally consistent and in alignment with the chemical expertise captured in ChEBI. RESULTS: We have examined and integrated the ChEBI structural hierarchy into the GO resource through computationally-assisted manual curation of both GO and ChEBI. Our work has resulted in the creation of computable definitions of GO terms that contain fully defined semantic relationships to corresponding chemical terms in ChEBI. CONCLUSIONS: The set of logical definitions using both the GO and ChEBI has already been used to automate aspects of GO development and has the potential to allow the integration of data across the domains of biology and chemistry. These logical definitions are available as an extended version of the ontology from http://purl.obolibrary.org/obo/go/extensions/go-plus.owl