The effects of elevated CO2 on plants

Effects of Rising Atmospheric Concentrations of Carbon Dioxide on Plants

The effects of elevated CO2 on plants can vary depending on other environmental factors. While elevated CO2 makes carbon more available, plants also require other resources including minerals obtained from the soil. Elevated CO2 does not directly make these mineral elements more available and, as noted above, may even decrease the uptake of some elements. The ability of plants to respond to elevated CO2 with increased photosynthesis and growth may therefore be limited under conditions of low mineral availability. This effect has been best documented for nitrogen. In FACE experiments, there is less enhancement of photosynthesis by elevated CO2 under low than high soil N conditions (Ainsworth & Long 2005; Ainsworth & Rogers 2007). Crop yield in FACE also appears to be enhanced by elevated CO2 to a lesser extent under low-N than under high-N (Ainsworth & Long 2005; Ainsworth 2008; Long et al. 2006). Across studies using all types of CO2 fumigation technologies, there is a lower enhancement of biomass production by elevated CO2 under low-nutrient conditions (Poorter & Navas 2003). Crops grown with low amounts of N fertilization also show a greater decrease in protein concentrations under elevated CO2 than crops grown with higher N fertilization (Taub et al. 2008).

Another environmental factor that interacts with elevated CO2 is atmospheric ozone (O3), a gaseous toxin. Ground-level O3 concentrations have been increasing worldwide (and are expected to continue to increase) due to increased emissions of pollutants that react to produce O3 (Vingarzan 2004). High atmospheric concentrations of ozone can cause damage to leaves and decreased plant growth and photosynthesis (Feng et al. 2008; Morgan et al. 2003). The primary location of O3 injury to plants is the internal tissues of leaves. Decreased openness of stomata under elevated CO2 can therefore decrease exposure of sensitive tissues to ozone. Elevated CO2 substantially decreases the negative effects of high ozone on photosynthesis, growth, and seed yield in both soybeans and rice (Feng et al. 2008; Morgan et al. 2003). Across experiments with all plant species, the enhancement of growth by elevated CO2 is much greater under conditions of ozone stress than otherwise (Poorter & Navas 2003).

Current evidence suggests that that the concentrations of atmospheric CO2 predicted for the year 2100 will have major implications for plant physiology and growth. Under elevated CO2 most plant species show higher rates of photosynthesis, increased growth, decreased water use and lowered tissue concentrations of nitrogen and protein. Rising CO2 over the next century is likely to affect both agricultural production and food quality. The effects of elevated CO2 are not uniform; some species, particularly those that utilize the C4 variant of photosynthesis, show less of a response to elevated CO2 than do other types of plants. Rising CO2 is therefore likely to have complex effects on the growth and composition of natural plant communities.

model of compost piles

A two dimensional, reaction-diffusion model of compost piles
Thiansiri Luangwilai, Harvinder Sidhu, Mark Nelson

Abstract

We consider the self heating process in a two dimensional spatially dependent model of a compost pile which incorporates terms that account for self heating due to both biological and oxidation mechanisms. As moisture is a crucial factor in both the degradation process and spontaneous ignition within a compost pile, this model consists of four mass-balance equations, namely, energy, oxygen, vapour and liquid water concentrations. Analyses are undertaken for different initial water contents within the compost pile. We show that when the water content is too low, the reaction is almost negligible; whereas when it is too high, the reaction commences only when the water content evaporates and the water ratio drops to within an appropriate range. However, for an intermediate water content range, the biological reaction is at its optimum and there is a possibility of spontaneous ignition within the compost pile. Continue reading “model of compost piles”

Sustainable Diets

Understanding Sustainable Diets: A Descriptive Analysis of the Determinants and Processes That Influence Diets and Their Impact on Health, Food Security, and Environmental Sustainability¹,²,³

The confluence of population, economic development, and environmental pressures resulting from increased globalization and industrialization reveal an increasingly resource-constrained world in which predictions point to the need to do more with less and in a “better” way. The concept of sustainable diets presents an opportunity to successfully advance commitments to sustainable development and the elimination of poverty, food and nutrition insecurity, and poor health outcomes. This study examines the determinants of sustainable diets, offers a descriptive analysis of these areas, and presents a causal model and framework from which to build. The major determinants of sustainable diets fall into 5 categories: 1) agriculture, 2) health, 3) sociocultural, 4) environmental, and 5) socioeconomic. When factors or processes are changed in 1 determinant category, such changes affect other determinant categories and, in turn, the level of “sustainability” of a diet. The complex web of determinants of sustainable diets makes it challenging for policymakers to understand the benefits and considerations for promoting, processing, and consuming such diets. To advance this work, better measurements and indicators must be developed to assess the impact of the various determinants on the sustainability of a diet and the tradeoffs associated with any recommendations aimed at increasing the sustainability of our food system.

The Chicago Council⁸ found in its study, Bringing Agriculture to the Table, that diet-related noncommunicable diseases are on track to rise by 15% by 2020 if current trends in the global commercialization of processed foods continue to be overconsumed by an increasingly less active global population (1). Currently, the global food system is estimated to contribute to 30% of global greenhouse gas emissions (GHGEs). With the global population expected to rise to 9 billion or more people by 2050, the Foresight Project⁹ found that rising demand to transport, store, and consume the most resource-intensive food types (namely dairy and meat) in developing economies will further increase the contributions of food and agriculture to environmental degradation and climate change (4). At the same time, the Livewell Project¹⁰ found that UK diets could in fact be rebalanced in line with the government’s dietary guidelines (the Eatwell Plate) to achieve GHGE targets for 2020 by substantially reducing meat and dairy consumption (19). However, looking to GHGE targets for 2050, researchers noted that changes would be needed in both food production and consumption to reach these longer-term targets (7). Recent analysis of the new Nordic Diet found that improvements in GHGEs and other environmental wins could be achieved by improving production, reducing transportation, and changing food types (20). Similar recommendations followed an analysis of dietary shifts in France (21).

Permaculture

Permaculture is a branch of ecological design, ecological engineering, environmental design, construction and integrated water resources management that develops sustainable architecture, regenerative and self-maintained habitat and agricultural systems modeled from natural ecosystems.^[1]^[2] The term permaculture (as a systematic method) was first coined by Australians Bill Mollisonand David Holmgren in 1978. The word permaculture originally referred to “permanent agriculture” ^[3] but was expanded to stand also for “permanent culture,” as it was seen that social aspects were integral to a truly sustainable system as inspired by Masanobu Fukuoka‘s natural farming philosophy.

Permaculture is a philosophy of working with, rather than against nature; of protracted and thoughtful observation rather than protracted and thoughtless labor; and of looking at plants and animals in all their functions, rather than treating any area as a single product system.

—Bill Mollison, ^[4]

Mollison developed permaculture after spending decades in the rainforests and deserts of Australia studying ecosystems. He observed that plants naturally group themselves in mutually beneficial communities. He used this idea to develop a different approach to agriculture and community design, one that seeks to place the right elements together so they sustain and support each other.

Today his ideas have spread and taken root in almost every country on the globe. Permaculture is now being practiced in the rainforests of South America, in the Kalahari desert, in the arctic north of Scandinavia, and in communities all over North America. In New Mexico, for example, farmers have used permaculture to transform hard-packed dirt lots into lush gardens and tree orchards without using any heavy machinery. In Davis, California, one community uses bath and laundry water to flush toilets and irrigate gardens. In Toronto, a team of architects has created a design for an urban infill house that doesn’t tap into city water or sewage infrastructure and that costs only a few hundred dollars a year to operate.

Bill Mollison Permaculture Lecture Series, On-Line
Note: NetWorks Productions Inc. holds the copyrights to this on-line series. We ask that our copyrights be honored. In addition, “Permaculture” is a copyrighted word. Only those who have completed a 72-hour design course are authorized to use the word in commerce.

What is Permaculture?

Who is Bill Mollison?

These videos are documents from two design courses taught by Bill Mollison at the Fossil Rim Wildlife Center in Glen Rose Texas in 1994 and 1995. They are a definitive selection from our original 16 part series. These tapes bear many viewings and will benefit anyone who wants to learn how to help regenerate the earth – from back yard to bio-region. Teachers of permaculture have found these tapes to be a valuable coaching tool – edited to one hour.

Auxin regulates aquaporin function to facilitate lateral root emergence

Abstract

Aquaporins are membrane channels that facilitate water movement across cell membranes. In plants, aquaporins contribute to water relations. Here, we establish a new link between aquaporin-dependent tissue hydraulics and auxin-regulated root development in Arabidopsis thaliana. We report that most aquaporin genes are repressed during lateral root formation and by exogenous auxin treatment. Auxin reduces root hydraulic conductivity both at the cell and whole-organ levels. The highly expressed aquaporin PIP2;1 is progressively excluded from the site of the auxin response maximum in lateral root primordia (LRP) whilst being maintained at their base and underlying vascular tissues. Modelling predicts that the positive and negative perturbations of PIP2;1 expression alter water flow into LRP, thereby slowing lateral root emergence (LRE). Consistent with this mechanism, pip2;1 mutants and PIP2;1-overexpressing lines exhibit delayed LRE. We conclude that auxin promotes LRE by regulating the spatial and temporal distribution of aquaporin-dependent root tissue water transport.

Half-Pint Homestead Garden Barrel Construction

Published on Apr 14, 2013

Want to grow your own food and herbs but don’t have the soil or the space? These Garden Barrels can make a big difference. They hold over 50 plants in just 4 square feet and incorporate composting worms for aeration and fertility. This video will take you step by step though the construction process.

Accessories for the Garden Barrel at www.half-pinthomestead.com

the Kratky method

Published on May 4, 2014

Learn how to build and maintain a hydroponics without needing any pumps or other electric equipment. Low in maintenance, this system is ideal for beginners who want to grow fruit, vegetables, spices or herbs. This DIY video will explain everything you need to know to get started.

Click here for the original scientific paper:
http://www.ctahr.hawaii.edu/hawaii/do…

http://www.instructables.com/id/Kratkys-non-circulating-hydroponics/

a Grow Barrel with a worm feeding tube

Published on May 28, 2014

Vertical Gardening: Build a Grow Barrel with a worm feeding tube.
Build a strawberry barrel and grow 30 plants or even more in the space of one Vertically. Maximize your strawberry growing space or any other plants by converting a barrel into a vertical garden.