Tag Archives: large plastic pots for plants

Post structural theories like Actor-Network Theory move beyond the material to include the symbolic lives of commodities

Despite the extensive and growing literature on local and alternative food networks , this form of inquiry, which consists of “following the thing,” has not been extended to local commodities, including those produced through urban agriculture. Unlike global commodities, the products of urban agriculture are often equated with accountability and transparency and do not receive the same kind of critical scrutiny. We challenge this notion which conflates local with ethical by arguing that local food products, like global commodities, have complex symbolic and material lives that mask social relations. Their commodity circuits are shaped by socio-natural relationships involving people, places, things and forces that produce value both discursively and materially. This research builds on the commodity chain concept by implementing the sort of multi-locale ethnography employed by Cook to examine the local commodity circuits and micro-geographies of urban agriculture in San Diego County. In recent years, urban agriculture has seen a surge of interest in cities throughout the United States. This growing curiosity has been accompanied by increasing diversity in the networks of human and non-human actors enrolled in urban agriculture. For instance, the introduction of new production methods – namely, soilless hydroponic, aquaponic, and aeroponic growing – has increased the heterogeneity of urban agriculture networks in cities. This type of diversification, in particular, is the focus of this paper. Soilless and soil-based urban agriculture networks embody different, although sometimes overlapping, urban political economies and political ecologies . Further, the food commodities they produce are entangled in unique, locally articulated networks of human and non-human actors that materially and discursively shape the way food is planted, grown, harvested, marketed, desired, and consumed in the city. Inspired by Cook and Actor-Network Theory , we juxtapose vignettes from various nodes in the commodity circuits of soil-based and soilless urban agriculture products to better understand the place-based, socio-natural relationships that scaffold different urban agriculture commodities in San Diego County. Our contribution lies primarily in the comparative approach we adopt to study the networks underlying and shaping the activities of three urban growing sites in San Diego: Coastal Roots Farm, Solutions Farm,large plastic pots for plants and Mount Hope Community Garden, chosen based on their growing practices, discursive similarities and dissimilarities, and unique socio-spatial settings .

Rather than focusing on a single food item, such as a papaya, we consider the output of urban agriculture more broadly – whether it is a head of hydroponic lettuce or a radish pulled from the soil. Vignettes related to these three enterprises are the result of mixed method research that combines interview, media, US Census , and participant observation data. Thirty-four semi-structured interviews and participant observation were conducted between 2016 and 2018 at multiple sites in the local urban agriculture networks of the three case sites. The interviews were approximately an hour in length and covered institutional histories, actors’ personal motivations for participating in urban agriculture, their growing practices, their perceptions of the local food environment, and the struggles and barriers they perceive to urban agriculture. These data were analyzed using exploratory spatial data analysis , which allowed us to examine the socio-economic landscapes that are the setting for these actor-networks, and multi-locale ethnographic analysis, which included emergent coding in Dedoose online coding software . When coding the interviews, we paid particular attention to the race-, class-, and gender-based power dynamics that accompany different urban agriculture commodities as they travel from place to place gaining meaning and value. Combining and analyzing this data was necessary for examining the “people, connections, associations, and relationships across space” that influence justice narratives and practices. The comparative focus we take is a response to popular claims that soilless growing is incompatible with justice and calls for more reflexive, nuanced understandings of justice . The concept of local commodity circuits provides an innovative approach to analyze the power relations underlying various forms of urban agriculture and shaping their capacity to promote food justice. Finally, this research illustrates the practicality of a post-capitalist approach to justice that acknowledges incremental, but still important, steps towards building more just food systems in the absence of structural change. This theory builds on from the authors’ concept of “diverse economies” which recognizes “each individual economic transaction and practice as a possible site of struggle and ethical decision-making” and rejects a priori judgments that classify certain economic practices as “good or bad” . This position, we argue, provides a fruitful avenue for examining the placed, context-dependent justice practices that unfold in the “here and now” . Especially important is its ability to recognize everyday actions that can “support conditions for positive social and economic transformation” .

This weaves productively with the everyday, nuanced justice advocated by Goodman, Dupuis and Goodman in their reflexive theory of justice. Indeed, Chatterton and Pickerill note the need for “detailed empirical accounts of the messy, gritty and real everyday rhythms as activists envision, negotiate, build and enact life beyond the capitalist status quo in the everyday” . This research seeks to answer this call by examining the multiple openings for justice found throughout local urban agriculture commodity circuits. Commodity circuits are scaffolded by ‘geographical knowledges’– peoples’ understandings of specific places . These knowledges and/or imaginaries include the settings, biographies, and origins and are “fragmentary, multiple, contradictory, inconsistent and, often, downright hypocritical” . The concept of geographical imaginations builds on Marxism’s commodity fetishism, which recognizes commodities as more than physical – “they are both things and relations” that have social and geographic lives and trajectories that are hidden behind their exchange value .Here, commodities are hybrid actants, as much social as they are natural, that exist in networks held together by their relations . The idea of ‘actants’ is unique to Actor-Network Theory. Latour notes, “An actant can literally be anything provided it is granted to be the source of action” , recognizing the importance of things, which lack the motivations typically associated with human actors, in driving action . Agency, as result, is less about intentional actions, and more about associations or network . In this research, we focus on stakeholders and organizations and refer to them as ‘actors’ because they have motivations and particular agendas that drive their action. We do not intend to simplify or ignore the role of actants such as narratives, growing materials, permits, and more that “authorize, allow, afford, encourage,permit, suggest, influence, block, render possible, forbid, and so on” action . Agency is a “distributed effect” of the associations between these things and actors in Actor-Network Theory . Examining these associations “allows us to explain the mechanism of power and organization in society and to understand how different things … come to be, how they endure over time, or how they fail” . However, critics of Actor-Network Theory note that agency is not evenly distributed and that this question of power differentials is missing from the theory. In fact, “some actants ‘marshall’ the power of others and, in doing so,plant pots with drainage limit the latter’s agency” . This gap, we argue, is remedied by intersecting Actor-Network Theory with commodity circuit analysis in which power relations are a central characteristic of networks.

Geographies of food undoubtedly lend themselves to the use of Actor-Network Theory , although researchers have questioned the transformative potential of research that describing lived experiences and associations without explicitly engaging larger structures such as the political economy. Goss argues that this ‘cultural turn’ “risk[s] throwing out the babies with the bathwater: rejecting a caricature of commodity fetishism they lose a concept that provides insight into the relationship between the material and symbolic” . However, in response, Cook argues that the theory exists “between the lines” and exploring the everyday associations that underlie commodities does inspires empathy and political transformation . Despite their disagreement, the two vantage points have much to offer one another. We agree that if we, as researchers, are to be agents of change and inspire effective, political action, we must engage and embed audiences in the lives of ‘others’ to inspire empathy and challenge faulty geographical imaginaries. However, we must be more than story-tellers hoping that the pieces come together in the minds of our readers – we must use theory to articulate the connections that we hope audiences would find ‘between the lines’. This research seeks to do just that in its examination of local, urban agriculture commodity circuits. This research uses Actor-Network Theory to unravel the geographical imaginations that structure the people, places, things, and forces – the “dots” –in our networks. Seeing the dots as relational, hybrid, and situated allows us to untie anterior narratives around the socialness and/or naturalness of actants in our networks and focus instead on relations and connections as they relate to food justice. We do attempt to make sense of the connections for readers; however, we do not see this as creating a ‘critical knowledge’ for consumption as Cook and Crang have described it. Instead, we see it as handing our readers a map of the theoretical trails we have identified that they may follow or stray from as they examine and build their own understandings of these networks. This theoretical map is built from a series of vignettes presented side by side that allow readers to make connections and develop their own critical understandings as they “follow the thing” before we input our own critical understandings. This research does not end with these pages, but is a continuing collaborative effort between the actors and actants outlined in its vignettes, its readers, and ourselves. Cool, humid, bright. The greenhouse at Solutions Farms vibrates with slow, continuous activity.

Dave, a retired marine whose curiosity for the science of aquaponics led him to Solutions, reminds me not to take photographs of the workers – men and women from seemingly all walks of life – as they tend numerous rows of white, plastic trays overflowing with green and purple lettuces. The workers are participants in Solutions for Change’s program which seeks to break the cycle of homelessness in families throughout San Diego County. The program focuses on combining skills, knowledge, and resources to participants including “transformational” housing, health services, counseling, life skills like financial literacy, and job training. Get up, suit up, show up. The unofficial motto of the program stated by each team member I interview at Solutions Farms. Dots of red embellish the lettuces’ soft leaves like ornaments. Step closer and the dots come to life. Lady bugs crawling slowly across the leaves in search of aphids – small, pesky insects that feed on the lettuces’ sap and, ultimately, the farm’s profits. The fish – all male tilapia – live in 2,000-liter tanks in the aquaculture room next door. Warm, humid, dark. Dave conducts this orchestra of people, plants, fish, insects, fungus, bacteria, minerals, nutrients, moisture, and machinery. There’s more chemistry and biology and physics and engineering than you can shake a stick at 2 . He was a volunteer at the farm until their systems specialist put in his two weeks. An amalgam of people, places, objects, and forces shape and structure the local commodity circuits of soilless and soil-based urban agriculture described in the vignettes above. This research sought to connect the dots between these vignettes in order to “lift the veil” and uncover the social relations that underlie these often taken for granted circuits. We did so by combining commodity circuit analysis and Actor-Network Theory to examine and compare the socio-natural relationships that comprise the placed networks that structure the commodity circuits and influence their abilities to enact justice. This practice illustrates the nuanced nature of justice as it unfolds across urban agriculture commodity circuits and provides evidence of the relationships that create openings for justice to be enacted and/or co-opted by actors. In addition to examining the connections within and between the vignettes, we created a network diagram that encapsulates the people, places, and institutions enrolled in the separate urban agriculture actor-networks that span the three commodity circuits. The diagram illustrates the flows of knowledge, capital, labor, food, and other resources between actors.

Cell identity in the SAM is thus largely an issue of location rather than its developmental history

The astute student however, will note that this interpretation is not quite universal, as some researchers further postulate the existence of a fourth “Organizing Center” inserted between the CZ and RM tissues. Although not shown in Figure 2.0, the OC is equivalent to the rounded apex of L3, pushing the remaining part of the RM somewhat deeper into the stem. Until better genetic evidence is available though, only CZ, PZ, and RM will be used for the remainder of this dissertation. While the numbering system shown in Figure 12 does provide a useful set of spatial coordinates, it is also somewhat misleading as it implies that the SAM is static structure, unchanging over time. This could not be further from the truth. Instead, it must be remembered that the SAM is a site of plant growth, and as a result its cells are in a state of constant flux as they divide, grow, and differentiate. For example, the repeated perpendicular divisions that occur in L1 and L2 actually cause these layers to expand sideways, where the displaced cells eventually bend around the curve of the apical dome and become part of the cylindrical stem surface. The motion is reminiscent of the path taken by water droplets in an umbrella-shaped fountain, though the individual plant cells move considerably slower. If growth by lateral displacement is followed to its logical extremes, it is important to note that all of the founding cells will be pushed off to the sides over time, while new ones take their place in the middle. No single cell in the SAM is a permanent resident. The overall shape and size of an SAM is perhaps more analogous to a standing wave,growing pot where stability is the illusion caused by a dynamic equilibrium. Maintaining that wave is of course a difficult challenge, as the inputs to that equilibrium must be precisely matched to its outputs at all times.

Failure todo so would quickly rob the plant of its ability to grow, with obvious consequences for survival. Exactly how this balance is maintained is not fully understood, but the motion of the cells makes at least one part of the process perfectly clear: the cells must change their identity as they are moved from one place to another. Those that start in the CZ for example, switch to PZ gene expression patterns as they move further away from the middle, and may later adopt leaf and flower identities as they are incorporated into mature organs.The ability of a cell to determine its location within the SAM structure is thus of paramount importance, yet it must do so in the absence of any stationary reference point. So far as currently understood, each cell solves this problem in exactly the same way a person would do so: it talks to its neighbors. Based on what the individual cell sees and what its neighbors report seeing, it is possible to work out exactly where the cell is located in the overall plant structure. Of course in actual plant tissues such communication occurs largely through to the exchange of proteins, hormones, and RNA molecules, though increasingly evidence suggests that mechanical forces in the cell wall may also contribute some information [2]. Some molecules can travel further distances than others, some are modified en-route in order to become functional, and still others move from cell to cell in precise patterns, much like the knight in a game of chess. When these molecules are produced in different areas of the plant, the surrounding cells can estimate their relative locations to each other simply by reading the chemical bar-code in their local milieu, and then develop accordingly. At the present time, only a few such routes of chemical communication have been identified, two of which are plant hormones: auxin and cytokinin. Auxin is best known for increasing the volume of cells, though it also has roles in apical dominance and tropism growth patterns. Cytokinin meanwhile is known for stimulating cell division, in addition to other roles in senescence and pathogen responses.

Together the function of the two hormones would appear to complement each other very well in terms of overall growth, yet within the SAM they appear to mix about as well as oil and water. Cells that respond to auxin often don’t respond to cytokinin, and vice versa. Why this should be so is not well understood, but studies of root vasculature development suggest that their mutual exclusion is actually used to generate spontaneous patterns that help guide plant development. In callus tissue, the two hormones are often found to have response patterns arranged in a polka-dot like arrays, where each hormone “dot” is surrounded by a circular field belonging to the other. The SAM is organized around a single such dot, where cytokinin responses occur in the RM, and auxin responses occur in the PZ which often occur in discrete foci corresponding to new lateral organs. The CZ cells in contrast, do not appear to be sensitive to either hormone, but instead express both auxin and cytokinin biosynthesis genes . The production of cytokinin in the L1 and L2 is also consistent with the distribution of bioactive cytokinin concentrations observed with immunological techniques and with GFP reporter systems. This suggests a stable arrangement of three mutual exclusion zones within the SAM, which closely correspond to the known CZ, PZ, and RM tissues. Root apical meristems in contrast, appear to be based on the reciprocal arrangement, as roots have an auxin response dot in the middle surrounded by cytokinin responses in the overarching root cap, concentrated in the root cap columella cells.Another potential communication system that has been extensively studied involves a potential feedback loop between the CZ and RM cells, thought to be carried out by WUS and CLV3. WUS is a homeodomain transcription factor produced exclusively within the RM, but is capable of moving 2-5 cell diameters away from its center of origin.

WUS has also been shown to activate transcription of CLAVATA3 in the overlying CZ cells by directly binding to the CLV3 promoter. CLV3 in turn, is thought to be a small secreted oligopeptide that is modified with a few arabinose sugars. The mature glycoprotein then travels through the apoplast to reach leucine-rich receptor kinases in the RM, such as CLV1 or BARELY ANY MERISTEM1, thereby triggering a signaling cascade that ultimately suppresses WUS transcription. Many of the intermediate biochemical steps however, have not yet been fully identified, which makes it difficult to fully reject the feedback loop null hypothesis. There is also evidence of a more complex set of feedback loops, as WUS has been found to regulate components of the cytokinin signal transduction pathway , and exogenous cytokinin are able to stimulate WUS transcription. Altered cytokinin signalling pathways have also been shown to affect CLV3 expression patterns. WUSCHEL-LIKE HOMEOBOX5 , which is closely related to WUS, is known to participate in auxin pathways within the root, while the generation of SAMs from callus or root tissue has repeatedly been shown to require a pre-incubation on auxin rich media, where it may actually stimulate auxin transport . Micro RNA molecules may also be involved, as a variant of AUXIN RESPONSE FACTOR 10 that was resistant to miR160a was able to increase WUS and CLV3 expression patterns. Clearly, there is a lot going on. To help clarify how such cross-talk contributes to SAM structure, the research presented in this dissertation explores two closely related subjects. The first is the regulation of CLV3, which was studied by resolving the promoter structure of this gene in chapter 3. The results suggest that CLV3 is regulated in part by auxin responses,square pot while activation and/or repression is likely to be controlled complicated set of cis-motifs in the 3’ enhancer region. The presence of these 3’ motifs in a known transposon also suggests a novel origin of the WUS/CLV3 feedback loop. Chapter 4 meanwhile, explores the possibility that WUS and cytokinin responses form a second feedback loop necessary for SAM structure. This was done by narrowing down the possible cellular and biochemical routes by which cytokinin could affect WUS transcription, translation, and protein movement. The results however, suggest that the two pathways are atlargely independent of each other, though cytokinin responses may increase WUS stability in the RM. Unexpectedly, the data also found that the absence of cytokinin responses in the CZ is a critical part of SAM structure. The cytokinin response-free cells were also found to have an enhanced protein degradation mechanism, which may help shape the WUS protein gradient. Interestingly, WUS proteins were found to be rapidly degraded following auxin treatments, suggesting a model in which the SAM structure is defined by cytokinin-induced stability in the RM, and auxin-induced protein degradation in the surrounding CZ and PZ cells.The WUS-CLV3 feedback loop has long been an attractive model to explain how SAM structure is maintained in a dynamically changing cellular environment. Simply by combining activation of CLV3 with the repression of WUS, computer simulations have repeatedly shown that this is sufficient to maintain constant population of cells with CZ and RM identity. However, despite the simplicity of this model, the molecular mechanisms that carry out the feedback loop have instead revealed a number of potential complications. On the forward path for example, WUS is known to be a bi-functional transcription factor, activating and repressing several hundred different target genes.

Currently it is not currently known exactly how WUS switches from activator to repressor, but it has been shown to directly bind to DNA motifs in AGAMOUS and CLV3 regulatory regions, where it activates their transcription. Additional binding sites on repressed targets such as KANADI1, YABBY3, ASYMMETRIC LEAVES2 have also been identifie. Complicating this model of is the observation that CLV3 activation requires both WUS and SHOOTMERISTEMLESS in leaf tissues, suggesting that the presence of WUS alone is not sufficient. In addition WUS has also found to directly interact with the GRAS domain transcription factor HAMl, as well as the potent transcriptional repressor TOPLESS. TPL itself further has been shown to assemble a protein complex with Sin3 ASSOCIATED PROTEIN and HISTONE DEACETYLASE 19 [49, 50], suggesting a potential link between WUS and chromatin modification. In order to discriminate between the two models, this study began by attempting to identify the cis-regulatory environment around the CLV3 locus. The CLV3 expression pattern was firstcarefully recorded with a GFP reporter, which in contrast to previously published RNA in-situ’s, found layer-specific differences in CLV3 transcriptional output. The regulatory regions of CLV3 were then annotated by mapping predicted transcription factor binding sites and computationally significant cis-motifs, which were further resolved with phylogenetic footprinting. This analysis found that CLV3 has a very simple 5’ promoter, containing an auxin responsive element, suggestive of ubiquitous expression. The 3’ enhancer in contrast, contained at least 3 large cis-regulatory modules, two of which were found within a naturally occurring transposon, while the 3rd included several known WUS binding sites. On the basis of promoter deletion experiments, all three cis-regulatory modules were found to be required for CLV3 activation. The existence of the transposon in turn, has several implications for the evolution of the WUS-CLV3 feedback loop and Brassicaceae plant anatomy. Previous reports of the CLV3 expression pattern have consistently found it localized to the apex of the SAM, where it is often used as an indicator of CZ cell identity. Within this region, the expression pattern is somewhat variable, as previous RNA in-situ revealed a narrow inverted cone-shape, while GFP and GUS reporters often produce more indistinct rounded shape 3-4 cell layers deep. In contrast, the present study found a slightly more complex pattern when viewed as a longitudinal section. In perfectly centered sections, the pCLV3:mGFP5-ER reporter often appears in an inverted cone shape, but the expression zone is noticeably broader than the previous RNA in-situ results . As the section plane is displaced from the central axis and becomes more tangential, a conspicuous gap is frequently visible, where the L2 cells have less fluorescence than those immediately above and below. This suggests a bi-partite expression pattern where a flat, circular domain occurs specifically in the L1, and a second spherical domain occurs underneath in the L3 cells . In order to identify the CLV3 regulatory structure, this work began by annotating all known regulatory motifs on an 8kb genomic sequence centered on At2g27250.