|Title||Biochar effects on plant ecophysiology|
|Publication Type||Book Chapter|
|Year of Publication||2015|
|Authors||Kammann, Claudia, and Graber Ellen R.|
|Book Title||Biochar for Environmental Management: Science and Technology and Implementation|
The central aim of this chapter is to evaluate biochar effects from a plant-centered perspective. Astonishingly little work has been done in this area so far, considering that the interaction between plant roots and biochar is at the crux of the envisaged positive feedback loop of biochar use in soils. Thus the following chapter addresses the ‘plant perspective’ on biochar effects: soil-plant –water relations ranging from aridity and osmotic stress to O2-deficiency (hypoxia), root-shoot assimilate partitioning, root architecture and root foraging in response to biochar in soil; soil biota – rhizosphere interactions; and biochar-elicited (phyto)hormonal signalling and impacts on plant resistance to disease. Although plant nutrition is an important factor in plant ecophysiology, it is not the main focus of this chapter since it is addressed in detail in Chapter 15. One of the reasons for the shortage of plant ecophysiology studies with biochar may lay in th restricted view of plants fron the narrow agronomic perspective of ‘yield’. Plants are regarded as simple nutrient- and water-supply driven photosynthesis machines that deliver agronomic yields and/or crop residue. Moreover, they are often erroneously considered passive-reacting (feed-back response) and enduring, due to their ‘rooted to the spot’ nature. In fact, these perceptions are too narrow: a large biomass or fruit/seed yield may be good from the human perspective, but not necessarily for the plant’s long-term survival strategy. Second, plants can actively modify unfavourable conditions, for example, by root exudation, root foraging, mycorrhizal interactions, or N2-fixing symbiosis in root nodules. In addition, they can sense and prepare for current and coming stresses (known as a feed-forward response), both environmental (abiotic) and biotic. A well-known example is autumnal leaf senescense, triggered by temperature and photo-periodicity, where plants reallocate valuable nutrients to perennial tissue before they shed their leaves.