Benefits from Below: Silicon Supplementation Maintains Legume Productivity under Predicted Climate Change Scenarios

• Published in: Frontiers in plant science Vol. 9; p. 202
• Main Authors: Johnson, Scott N, Ryalls, James M W, Gherlenda, Andrew N, Frew, Adam, Hartley, Susan E
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 20.02.2018
• Subjects: alfalfa; aphids; atmospheric change; climate change; global warming; Plant Science; silica; alfalfa; atmospheric change; global warming; silicon; silica; aphids; climate change
• ISSN: 1664-462X; 1664-462X
• DOI: 10.3389/fpls.2018.00202

Many studies demonstrate that elevated atmospheric carbon dioxide concentrations (eCO ) can promote root nodulation and biological nitrogen fixation (BNF) in legumes such as lucerne ( ). But when elevated temperature (eT) conditions are applied in tandem with eCO , a more realistic scenario for future climate change, the positive effects of eCO on nodulation and BNF in are often much reduced. Silicon (Si) supplementation of has also been reported to promote root nodulation and BNF, so could potentially restore the positive effects of eCO under eT. Increased nitrogen availability, however, could also increase host suitability for aphid pests, potentially negating any benefit. We applied eCO (+240 ppm) and eT (+4°C), separately and in combination, to growing in Si supplemented (Si+) and un-supplemented soil (Si-) to determine whether Si moderated the effects of eCO and eT. Plants were either inoculated with the aphid or insect-free. In Si- soils, eCO stimulated plant growth by 67% and nodulation by 42%, respectively, whereas eT reduced these parameters by 26 and 48%, respectively. Aphids broadly mirrored these effects on Si- plants, increasing colonization rates under eCO and performing much worse (reduced abundance and colonization) under eT when compared to ambient conditions, confirming our hypothesized link between root nodulation, plant growth, and pest performance. Examined across all CO and temperature regimes, Si supplementation promoted plant growth (+93%), and root nodulation (+50%). abundance declined sharply under eT conditions and was largely unaffected by Si supplementation. In conclusion, supplementing with Si had consistent positive effects on plant growth and nodulation under different CO and temperature scenarios. These findings offer potential for using Si supplementation to maintain legume productivity under predicted climate change scenarios without making legumes more susceptible to insect pests.