Enhancing plant growth and carbon harvesting for sustainable agriculture

Society is in dire need of solutions to address complicated threats like climate change. To do this will require redesigning many of our current infrastructure and processes. Agricultural systems are one essential part of supporting society that could be made more sustainable. If efficiency is increased and plant growth enhanced, this would also contribute to balancing carbon dioxide (CO2) fluxes by increasing carbon harvesting, which can help address climate change. The impact of environmental parameters affected by climate change was incorporated through a manipulative greenhouse study to understand the impact of the increased intensity of precipitation on spinach yield and crop quality. Excess water treatments consistently increased levels of secondary chemicals. Impacts of the higher intensity storm treatment were seen in limited growth and a stress response in the roots. This could inform management of crops for nutritional quality. To enhance growth and optimize efficiency of crop production in new agricultural spaces like rooftop gardens and farms, a system was developed to apply indoor air with high CO¬2 concentrations from human respiration to rooftop crops through exhaust vents. The CO2 resource was first characterized finding levels averaging above 1000 ppm in classrooms during the daytime throughout the week and above 800 ppm from exhaust vents. Growth of spinach and corn besides vents increased by 2 to 4 fold indicating the effect of other characteristics besides CO2 concentration as contributing to growth effects. These systems could increase efficiency and success of rooftop gardens and farms. Decreasing fertilizer usage through use of a more sustainable plant enhancer would decrease impacts on surrounding environments, while still enhancing production. A lithotrophic gas fermentation system was used to grow a hydrogen-utilizing bacterium, Cupriavidus necator, which was engineered to produce lipochitin oligosaccharides (LCOs), a plant growth enhancer. LCO production was confirmed and the product was applied to relevant crops and a growth enhancement was attained. By understanding and increasing crop growth in creative ways, this study provides options for developing a more sustainable agricultural system, which works synergistically with nature and assists in increasing carbon harvesting and finding a sustainable path for society

Effects of Extreme Climate Events on Tea (Camellia sinensis) Functional Quality Validate Indigenous Farmer Knowledge and Sensory Preferences in Tropical China

Climate change is impacting agro-ecosystems, crops, and farmer livelihoods in communities worldwide. While it is well understood that more frequent and intense climate events in many areas are resulting in a decline in crop yields, the impact on crop quality is less acknowledged, yet it is critical for food systems that benefit both farmers and consumers through high-quality products. This study examines tea (Camellia sinensis; Theaceae), the world’s most widely consumed beverage after water, as a study system to measure effects of seasonal precipitation variability on crop functional quality and associated farmer knowledge, preferences, and livelihoods. Sampling was conducted in a major tea producing area of China during an extreme drought through the onset of the East Asian Monsoon in order to capture effects of extreme climate events that are likely to become more frequent with climate change. Compared to the spring drought, tea growth during the monsoon period was up to 50% higher. Concurrently, concentrations of catechin and methylxanthine secondary metabolites, major compounds that determine tea functional quality, were up to 50% lower during the monsoon while total phenolic concentrations and antioxidant activity increased. The inverse relationship between tea growth and concentrations of individual secondary metabolites suggests a dilution effect of precipitation on tea quality. The decrease in concentrations of tea secondary metabolites was accompanied by reduced farmer preference on the basis of sensory characteristics as well as a decline of up to 50% in household income from tea sales. Farmer surveys indicate a high degree of agreement regarding climate patterns and the effects of precipitation on tea yields and quality. Extrapolating findings from this seasonal study to long-term climate scenario projections suggests that farmers and consumers face variable implications with forecasted precipitation scenarios and calls for research on management practices to facilitate climate adaptation for sustainable crop production

Effects of water availability and pest pressures on tea (Camellia sinensis) growth and functional quality

Extreme shifts in water availability linked to global climate change are impacting crops worldwide. The present study examines the direct and interactive effects of water availability and pest pressures on tea (Camellia sinensis; Theaceae) growth and functional quality. Manipulative greenhouse experiments were used to measure the effects of variable water availability and pest pressures simulated by jasmonic acid (JA) on tea leaf growth and secondary metabolites that determine tea quality. Water treatments were simulated to replicate ideal tea growing conditions and extreme precipitation events in tropical southwestern China, a major centre of tea production. Results show that higher water availability and JA significantly increased the growth of new leaves while their interactive effect was not significant. The effect of water availability and JA on tea quality varied with individual secondary metabolites. Higher water availability significantly increased total methylxanthine concentrations of tea leaves but there was no significant effect of JA treatments or the interaction of water and JA. Water availability, JA treatments or their interactive effects had no effect on the concentrations of epigallocatechin 3-gallate. In contrast, increased water availability resulted in significantly lower concentrations of epicatechin 3-gallate but the effect of JA and the interactive effects of water and JA were not significant. Lastly, higher water availability resulted in significantly higher total phenolic concentrations but there was no significant impact of JA and their interaction. These findings point to the fascinating dynamics of climate change effects on tea plants with offsetting interactions between precipitation and pest pressures within agro-ecosystems, and the need for future climate studies to examine interactive biotic and abiotic effects

Enhancing crop growth in rooftop farms by repurposing CO2 from human respiration inside buildings

Peer reviewed: TrueAcknowledgements: We would like to thank Sidney Hare and Tony Pham for their assistance collecting samples. The entire community at the Boston University Academy, especially Paige Brewster, Travis Bain, and Cynthia Taylor, also were essential in carrying out this project. This content also appeared in the PhD thesis titled Enhancing plant growth and carbon harvesting for sustainable agriculture (Buckley, 2020).Integrating cities with the surrounding environment by incorporating green spaces in creative ways would help counter climate change. We propose a rooftop farm system called BIG GRO where air enriched with carbon dioxide (CO2) produced through respiration from indoor spaces is applied through existing ventilation systems to produce a fertilization effect and increased plant growth. CO2 measurements were taken inside 20 classrooms and at two exhaust vents on a rooftop at Boston University in Boston, MA. Exhausted air was directed toward spinach and corn and plant biomass and leaf number were analyzed. High concentrations of CO2 persisted inside classrooms and at rooftop exhaust vents in correlation with expected human occupancy. CO2 levels averaged 1,070 and 830 parts per million (ppm), reaching a maximum of 4,470 and 1,300 ppm CO2 indoors and at exhaust vents, respectively. The biomass of spinach grown next to exhaust air increased fourfold compared to plants grown next to a control fan applying atmospheric air. High wind speed from fans decreased growth by approximately twofold. The biomass of corn, a C4 plant, experienced a two to threefold increase, indicating that alternative environmental factors, such as temperature, likely contribute to growth enhancement. Enhancing growth in rooftop farms using indoor air would help increase yield and help crops survive harsh conditions, which would make their installation in cities more feasible.</jats:p

Effects of Precipitation Variability on Tea Prices.

<p>Farmers at the study site have experienced an average decrease of 51% in on-farm tea prices received during the Monsoon tea harvests compared to the dry spring tea harvests.</p

Effects of Precipitation Variability on Total Phenolic Concentration and Antioxidant Activity.

<p>Increased precipitation from the spring drought to the monsoon tea harvest resulted in significantly higher total phenolic concentration (TMC) and antioxidant activity of tea leaves. Sampling periods not connected by the same letters are significantly different. Values are means ± one standard error.</p

Effects of Precipitation Variability on Tea Growth.

<p>Increased precipitation from the spring drought to the monsoon tea harvest significantly increased tea leaf weight and length. Sampling periods not connected by the same letters are significantly different. Values are means ± one standard error.</p

Increased Inter-annual Variability and Total Precipitation.

<p>Precipitation data at the study site shows inter-annual variability from 1979 through 2010. The shaded section of the figure represents the period comprising 90% of annual rainfall. In addition to increasing variability since 1990, the monsoon season is arriving earlier as indicated by the downward shift of the trend line.</p

Historical Precipitation Trends During the Dry Spring and Monsoon Tea Harvests.

<p>Comparison of average rain rate for dry spring (top) and monsoon (bottom) tea harvests during the following periods: a) 1979–1984, b) 1985–1989, c) 1990–1994, d) 1995–1999, e) 2000–2004, f) 2005–2010. The study site is located at the dot in the middle of each map.</p

Effects of Precipitation Variability on Tea Polyphenolic Catechins.

<p>Increased precipitation from the spring drought to the monsoon tea harvest resulted in significantly lower concentrations of (a) epicatechin 3-gallate (ECG), (b) epigallocatechin 3-gallate (EGCG), (c) epigallocatechin (EGC), (d) gallic acid (GA), (e) gallocatechin (GC), (f) gallocatechin gallate (GCG) as well as catechin (C) and catechin gallate (CG; not shown). Sampling periods not connected by the same letters are significantly different. Values are means ± one standard error.</p