Elevated carbon dioxide plus chronic warming causes dramatic increases in leaf angle in tomato, which correlates with reduced plant growth

• Published in: Plant, cell and environment Vol. 42; no. 4; pp. 1247 - 1256
• Main Authors: Jayawardena, Dileepa Madushanka, Heckathorn, Scott Alan, Bista, Deepesh Raj, Boldt, Jennifer Kay
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.04.2019
• Subjects: Carbon dioxide; Carbon Dioxide - metabolism; Circadian Rhythm; climate change; Correlation; Food production; Global Warming; heat stress; High temperature; Hot Temperature; hyponasty; Interception; Leaf angle; Leaf area; leaf cupping; leaf shape; Leaves; Light interception; Lycopersicon esculentum - anatomy & histology; Lycopersicon esculentum - growth & development; Lycopersicon esculentum - metabolism; Okra; petiole angle; Photosynthesis; Plant growth; Plant Leaves - anatomy & histology; Plant Leaves - growth & development; Plant Leaves - metabolism; Solanum lycopersicum; Soybeans; Tomatoes; Water stress; heat stress; global warming; Solanum lycopersicum; leaf cupping; leaf shape; hyponasty; petiole angle; climate change
• ISSN: 0140-7791; 1365-3040
• DOI: 10.1111/pce.13489

Limited evidence indicates that moderate leaf hyponasty can be induced by high temperatures or unnaturally high CO2. Here, we report that the combination of warming plus elevated CO2 (eCO2) induces severe leaf hyponasty in tomato (Solanum lycopersicum L.). To characterize this phenomenon, tomato plants were grown at two levels of CO2 (400 vs. 700 ppm) and two temperature regimes (30 vs. 37°C) for 16–18 days. Leaf hyponasty increased dramatically with warming plus eCO2 but increased only slightly with either factor alone and was slowly reversible upon transfer to control treatments. Increases in leaf angle were not correlated with leaf temperature, leaf water stress, or heat‐related damage to photosynthesis. However, steeper leaf angles were correlated with decreases in leaf area and biomass, which could be explained by decreased light interception and thus in situ photosynthesis, as leaves became more vertical. Petiole hyponasty and leaf‐blade cupping were also observed with warming + eCO2 in marigold and soybean, respectively, which are compound‐leaved species like tomato, but no such hyponasty was observed in sunflower and okra, which have simple leaves. If severe leaf hyponasty is common under eCO2 and warming, then this may have serious consequences for food production in the future. Elevated CO2 plus chronic warming induced severe leaf hyponasty in tomato, and it was slowly reversible upon transfer to control temperature and CO2. Severe leaf hyponasty correlated with decreases in leaf area and plant biomass, which could be explained by decreased light interception and thus in situ photosynthesis, as leaves became more vertically oriented. Further investigation showed elevated CO2 plus warming driven hyponasty occurred in compound‐leaved species (soybean and marigold) but not in simple‐leaved species (sunflower and okra).