Licenciatavhandling Uppsala : Sveriges lantbruksuniversitet, 2009.

Most tomato cultivars used for commercial food production are imported into South Africa. Optimal growing conditions for these specific cultivars need to be determined, as wrong cultivar choices can lead to great financial losses. Lack of information on selecting well-performing cultivars may lead to lower yield or unacceptable fruit quality. Information on the performance of tomato cultivars under South African conditions, utilizing plastic tunnels or shadenet structures under soilless cultivation is still very limited. Soilless cultivation of vegetables is becoming a preferable over in-soil cultivation due to the improved yield and quality of produce, efficient water and nutrients usage by the crop; furthermore, the grower can regulate nutrient solution, electrical conductivity and pH of the nutrient solution. To identify the optimal system for growing tomatoes hydroponically, the performance of four tomato cultivars (‘FA593’, ‘Miramar’, ‘FiveOFive’ and ‘Malory’) under different growing conditions was evaluated: directly planted in soil under 40% shadenet with drip irrigation, a closed hydroponic system under 40% shadenet, an open bag system under 40% shadenet, or an open-bag system in a temperature controlled as well as a non-temperature controlled tunnel. The study revealed that ‘Miramar’ performed better than the other cultivars in all production systems, with the exception of soil cultivation where there were no differences amongst the four cultivars. Fruit cracking was found to be directly correlated with fruit size, as the large-sized cultivars ‘Malory’ and ‘FA593’ were more susceptible than the other two cultivars. Plants grown under shadenet were prone to fruit cracking and raincheck as well as early blight. Higher yields were obtained when plants were produced in the open bag system under temperature controlled conditions and in the closed system under shadenet. Growing tomatoes in the non-temperature controlled tunnel resulted in high incidences of fruit cracking, poor yield and pre-mature fruit ripening probably due to high and fluctuating temperatures under such conditions. The average marketable yield was 88% and 59% of the total yield in the temperature controlled and non-temperature controlled tunnels, respectively. A further experiment was carried out to improve yield and quality of tunnel tomatoes using beneficial micro-organisms, i.e., arbuscular mycorrhiza fungi (AMF) at different nutrient concentrations. Tomato seedlings were treated with Mycoroot™ containing four mycorrhiza species (Glomus etunicatum, Paraglomus occultum, Glomus clarum and Glomus mossea) at transplanting and subsequently transferred to either a temperature controlled or a non-temperature controlled tunnel under the recommended (100%) or reduced (75 and 50%) nutrient concentrations. Sawdust was used as a growing medium in this experiment. Application of AMF neither enhanced plant growth, yield, nor fruit mineral nutrient concentrations; although fruit Mn and Zn concentrations in the temperature controlled tunnel increased significantly following AMF application. Plants grown in the non-temperature controlled tunnel had significantly poorer plant growth, and lower yield and lower fruit mineral concentrations, compared with fruit from plants in the temperature controlled tunnel. Tomato plants in the non-temperature controlled tunnel had higher levels of micro-elements in leaf tissue, compared with those in the temperature controlled tunnel. The highest yields were obtained from plants fertigated with 75% of the recommended nutrient concentration, as compared with the 100 and 50% nutrient concentrations. When coir was subsequently used as the growing medium, Mycoroot™ applied at seeding and transplanting did not enhance mycorrhizal colonization or fruit quality. Growing tomatoes under reduced nutrient supply reduced the total soluble solids in the juice of the fruit, but improved total and marketable yield, as well as the number of marketable fruit. This effect was more substantial in the temperature controlled than in the non-temperature controlled tunnel. Fruit firmness and leaf chlorophyll concentrations were significantly higher in plants grown in the temperature controlled tunnel. Growing tomatoes in sawdust improved the leaf Mn and Ca concentration over that of tomato plants grown in coir. Mycorrhizal colonisation did not have a beneficial effect on tomato yield and quality. The study indicated that cultivar selection was important in obtaining the highest yield and quality of tomato using the closed hydroponic system under shadenet and the open bag hydroponic system in the temperature controlled tunnel. Temperature controlled tunnels with a pad–and-fan cooling system are still an effective way of cooling the tunnel environment which resulted in high yield and high quality of tomatoes with a higher fruit mineral content than that obtained under non-temperature controlled conditions where only natural ventilation is relied on. Results also demonstrated that mycorrhizal colonization in soilless condition has limited beneficial effects in allowing for better nutrient uptake and thereby for improved yield and quality of tomatoes. Further studies, including different media, nutrient composition and concentrations, need to be carried out to investigate the possible causes of AMF failure to improve yield, despite good AMF root colonization. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.

Dissertation (Ph.D.)--Auburn University, 2008. / Abstract. Includes bibliographic references.

Made available in DSpace on 2014-06-11T19:30:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-08-31Bitstream added on 2014-06-13T20:40:16Z : No. of bitstreams: 1 vitericabezas_wp_me_botfca.pdf: 276987 bytes, checksum: fefb989fa21883ab05774fb93da9941f (MD5) / A produção de mudas da espécie Eucalyptus grandis x Eucalyptus urophylla tem crescido muito nos últimos anos no Brasil, devido a sua boa adaptação nos diferentes solos e regiões, possuindo comportamentos diferentes quanto à exigência nutricional em diferentes tipos de substrato que o mercado oferece. O conhecimento desses comportamentos trará benefícios econômicos e diminuição dos impactos ambientais causados pelo uso excessivo de fertilizantes. Neste trabalho buscou-se avaliar o efeito de doses de fósforo em três tipos de substratos na produção de mudas de Eucalyptus grandis x Eucalyptus urophylla. O experimento foi inteiramente casualizado em fatorial 3x4, utilizando 3 substratos e 4 doses de fósforo na base, totalizando 12 tratamentos distribuídos em 4 parcelas com 25 plantas. O adubo usado na fertilização de base foi o superfosfato simples e as doses foram de 0, 160, 320 e 480 g por m3 de substrato. Os substratos utilizados foram: Carolina Soil® a base de turfa, vermiculita e casca de arroz carbonizada; substrato Mecplant® a base de casca de pinus e vermiculita e substrato a base de fibra de coco e vermiculita. As avaliações do experimento constituíram-se de análise química do substrato e características morfológicas das mudas: altura da parte aérea, diâmetro do coleto, massas secas da parte aérea e radicular e qualidade de raiz. Em função dos resultados obtidos pode-se inferir que para o substrato Carolina Soil® a dose que apresentou mudas com maior desenvolvimento foi a de 320 g m-3. Para o substrato fibra de coco + vermiculita foi a de 160 g m-3 e para o substrato a Mecplant® tanto na dose zero quanto na de 480 g m-3 apresentaram resultados semelhantes, indicando a não necessidade de aplicação de P na adubação de base neste substrato. Os três substratos produziram mudas semelhantes e dentro do padrão de qualidade adequado / The production of cuttings of the species Eucalyptus grandis x Eucalyptus urophylla has grown significantly in recent years in Brazil due to its good adaptation to different types of soil and region, having different behaviors a far as its nutritional demands on the different kinds of substrate offered by the market. Knowledge of these behaviors will bring economic benefit and a diminishing of the environmental impact caused by the excessive use of fertilizers. This investigation sought to validate the effect of doses of phosphorus on three types of substrate in the production of cuttings of Eucalyptus grandis x Eucalyptus urophylla. The experiment was entirely done on 3x4 factorial, using 3 substrates of 4 doses of phosphorous on the base, totaling 12 applications distributed among 4 parcels with 25 plants each. The fertilizer used for the base was a simple superphosphate and the doses were 0, 160, 320 and 480 g per m3 of substrate. The substrates used were: truffle based Carolina Soil®, vermiculite and carbonized rice shells, vermiculite and pinus shell based Mecplant® and coconut fiber and vermiculite substrate. Evaluations in the experiment include chemical analysis of the substrate and morphological characteristics of the cuttings: height of the airborne area, stalk diameter, dry spots on the airborne area and root and overall quality of the root. From the obtained results, it’s possible to infer that for the Carolina Soil® substrate, the dosage that showed the best growth was 320 g m3. For the coconut + vermiculite substrate the best results came with 160 g m-3 and for the Mecplant® substrate, both the zero dose and the 480 g m3 showed similar results, indicating that there isn’t a need for the application of P on the fertilizing of the base of this substrate. The three substrates will produce similar cuttings and within an adequate pattern of quality

Orientador: Magali Ribeiro da Silva / Coorientador: Iraê Amaral Guerrini / Banca: Hélio Grassi Filho / Banca: Gisela Ferreira / Resumo: A produção de mudas da espécie Eucalyptus grandis x Eucalyptus urophylla tem crescido muito nos últimos anos no Brasil, devido a sua boa adaptação nos diferentes solos e regiões, possuindo comportamentos diferentes quanto à exigência nutricional em diferentes tipos de substrato que o mercado oferece. O conhecimento desses comportamentos trará benefícios econômicos e diminuição dos impactos ambientais causados pelo uso excessivo de fertilizantes. Neste trabalho buscou-se avaliar o efeito de doses de fósforo em três tipos de substratos na produção de mudas de Eucalyptus grandis x Eucalyptus urophylla. O experimento foi inteiramente casualizado em fatorial 3x4, utilizando 3 substratos e 4 doses de fósforo na base, totalizando 12 tratamentos distribuídos em 4 parcelas com 25 plantas. O adubo usado na fertilização de base foi o superfosfato simples e as doses foram de 0, 160, 320 e 480 g por m3 de substrato. Os substratos utilizados foram: Carolina Soil® a base de turfa, vermiculita e casca de arroz carbonizada; substrato Mecplant® a base de casca de pinus e vermiculita e substrato a base de fibra de coco e vermiculita. As avaliações do experimento constituíram-se de análise química do substrato e características morfológicas das mudas: altura da parte aérea, diâmetro do coleto, massas secas da parte aérea e radicular e qualidade de raiz. Em função dos resultados obtidos pode-se inferir que para o substrato Carolina Soil® a dose que apresentou mudas com maior desenvolvimento foi a de 320 g m-3. Para o substrato fibra de coco + vermiculita foi a de 160 g m-3 e para o substrato a Mecplant® tanto na dose zero quanto na de 480 g m-3 apresentaram resultados semelhantes, indicando a não necessidade de aplicação de P na adubação de base neste substrato. Os três substratos produziram mudas semelhantes e dentro do padrão de qualidade adequado / Abstract: The production of cuttings of the species Eucalyptus grandis x Eucalyptus urophylla has grown significantly in recent years in Brazil due to its good adaptation to different types of soil and region, having different behaviors a far as its nutritional demands on the different kinds of substrate offered by the market. Knowledge of these behaviors will bring economic benefit and a diminishing of the environmental impact caused by the excessive use of fertilizers. This investigation sought to validate the effect of doses of phosphorus on three types of substrate in the production of cuttings of Eucalyptus grandis x Eucalyptus urophylla. The experiment was entirely done on 3x4 factorial, using 3 substrates of 4 doses of phosphorous on the base, totaling 12 applications distributed among 4 parcels with 25 plants each. The fertilizer used for the base was a simple superphosphate and the doses were 0, 160, 320 and 480 g per m3 of substrate. The substrates used were: truffle based Carolina Soil®, vermiculite and carbonized rice shells, vermiculite and pinus shell based Mecplant® and coconut fiber and vermiculite substrate. Evaluations in the experiment include chemical analysis of the substrate and morphological characteristics of the cuttings: height of the airborne area, stalk diameter, dry spots on the airborne area and root and overall quality of the root. From the obtained results, it's possible to infer that for the Carolina Soil® substrate, the dosage that showed the best growth was 320 g m3. For the coconut + vermiculite substrate the best results came with 160 g m-3 and for the Mecplant® substrate, both the zero dose and the 480 g m3 showed similar results, indicating that there isn't a need for the application of P on the fertilizing of the base of this substrate. The three substrates will produce similar cuttings and within an adequate pattern of quality / Mestre

Please read the abstract in the section 00front of this document. / Dissertation (MSc (Plant Production))--University of Pretoria, 2004. / Plant Production and Soil Science / unrestricted

ABSTRACT A Comparative Study of Three Growing Media and Four Plant Groups Under Extensive Green Roof Conditions in San Luis Obispo, California Todd A. Nelson Green roof growing media and plant species are critical factors when deciding on the best materials for a project. Growing media must be chosen in accordance with load bearing capacities of structures and water requirements of the plant material. Plant species must be able to thrive in the climate of the green roof and withstand a green roof’s harsh environment. The objectives of this research were: (1) to determine which of three extensive green roof growing media support the most growth of Sedum, a proven extensive green roof plant genus; and (2) to determine which of four plant groups provides the most media coverage under extensive green roof conditions. Sedum growing in a granular growing media blend with higher organic matter and larger particles provided more coverage than Sedum growing in a medium with smaller particles with lower organic matter and an experimental foam medium. Sedges covered the soil faster than Sedum, grasses, and Mediterranean species. These results will help green roof designers and landscape architects anticipate the plant growth rates during the first 36 weeks of new projects and choose more effective growing media blends. They can also observe the growth patterns of the plant groups to choose plant material that will achieve the functional objectives of a green roof more efficiently. These results are applicable to green roofs designed for moderate California coastal climates and regions with similar weather conditions.

The influence of nitrification on the “soil” solution of container media has not been documented. The investigation of this influence is justified since the ionic form of N in a soil solution has a significant influence on plant tissue nutrient content and growth. Three genera of woody plants were grown in one-liter containers filled with pine bark, treated with and without a nitrification inhibitor and fertilized with 210 ml of a 100 ppm NH₄-N solution. Without the inhibitor and over time, “soil” solution NH₄-N concentrations and pH decreased and NO₃-N concentrations increased. “Soil” solution and tissue cation concentrations were generally greater without the inhibitor. In a second experiment, pine bark in one-liter containers was treated with either 0, 3 or 6 kg lime m⁻³. “Soil” solution data and NO₃-N accumulation rate (NAR) data showed an earlier nitrification of NH₄-N at the 6 kg lime compared to the 3 kg lime treatment whereas NO₃-N was not found at the 0 kg lime treatment. In a 3rd experiment, pine bark in one-liter containers was treated with 210 ml of either 25, 100 or 200 ppm NH₄-N. Over time “soil” solution NO₃-N concentrations were greatest and pH values were lowest at the 200 ppm N treatment. The NAR of the 25 ppm N treatment was less than the 100 and 200 ppm N treatment which were not different. The lack of correspondence between the “soil” solution NO₃-N data and the NAR data for the 100 and 200 ppm N treatments was explained on the basis of NH₄-N supply. In a 4th experiment, pine bark in one-liter containers were subjected to either 10°, 20°, 30° or 40° C for 24 days. “Soil” solution NH₄-N concentrations decreased over time at 10°, 20° and 30°. “Soil” solution NH₄-N and NO₃-N concentrations at 40° were considerably higher and lower, respectively, than at other temperatures. Over time the general order of NAR was: 20° = 30° > 10° > 40°. Results of these experiments indicate that nitrification is an important consideration in the nutrition of container-grown plants. / Ph. D.

Peat extraction for horticultural production poses a threat to wetland ecosystems. The rapid growth rate of the horticulture industry has prompted an ongoing search for sustainable alternative growth media components to replace peat. The alternative components need to provide properties (physical and chemical) similar to or better than peat and provide conditions that will enhance ideal growth and yield of potted plants. Potted Dendranthema x grandiflorum is one of the most important pot plants cultivated worldwide in the floriculture industry. There is a global research effort to replace peat with a sustainable alternative growth media for potted plants; however, so far, no study has been conducted in South Africa that used similar treatments on potted Dendranthema x grandiflorum. The aim of this study was to determine a suitable alternative growth media to replace peat as a growth media for cultivation of potted D. x grandiflorum. A greenhouse experiment was conducted at the University of South Africa’s Horticulture centre in Florida, Johannesburg for 89 days. Eight growth media (100 % peat (T1) (control), 100 % bagasse (T2), 50:50 % v/v bagasse:peat (T3), 75:25 % v/v bagasse:peat (T4), 25:75 % v/v bagasse:peat (T5), composted bagasse (T6), Coir (T7), and pine bark (T8)) as treatments and one hybrid (Mount® Runca) of D. x grandiflorum were arranged in a randomized complete block design with four replicates. In this study, nutrient uptake, chlorophyll content, growth, and yield parameters were measured for potted D. x grandiflorum grown in all eight growth media. The results show that treatments had different chemical and physical properties compared to peat. The pH of 100 % bagasse and coir were within the ideal range recommended for growth media. The EC results indicated that after the experiment, other treatments were within the defined range except for composted bagasse due to high concentration of soluble salts. The BD of control and composted bagasse were similar and may have resulted in the low root response. The concentration of total N was high in the shoots of plants cultivated in 100 % peat with a subsequent increased fresh and dry shoots weight. The highest significant chlorophyll content was present in plants cultivated in composted bagasse, which contained high total N and, Fe and Zn concentrations in shoots. Taken together, the results showed that composted bagasse was the best alternative to replace peat for cultivation of potted D. x grandiflorum. / Turfonttrekking vir tuinboukundige produksie hou ʼn bedreiging vir moerasland-ekostelsels in. Die vinnige groeitempo van die tuinboubedryf het gelei tot ʼn voortdurende soektog na volhoubare groeimediakomponente om turf te vervang. Die alternatiewe komponente moet (fisiese en chemiese) eienskappe kan bied wat soortgelyk aan, of beter as dié van turf is, en moet toestande gee wat die ideale groei en opbrengs van potplante verbeter. Potplant- Dendranthema x grandiflorum is een van die belangrikste potplante wêreldwyd wat in die blomboerderybedryf aangeplant word. Daar word wêreldwyd navorsing gedoen om turf met ʼn volhoubare groeimedium vir potplante te vervang; sover is daar egter nog nie in Suid-Afrika ʼn studie gedoen wat soortgelyke behandelings vir potplante- Dendranthema x grandiflorum gebruik nie. Die doel van hierdie studie was om ʼn gepaste alternatiewe groeimedium te bepaal om turf as ʼn groeimedium te vervang vir die aanplanting van D. x grandiflorum-potplante. ʼn Kweekhuis-eksperiment is by die Universiteit van Suid-Afrika se Tuinbousentrum in Florida, Johannesburg uitgevoer vir 89 dae. Agt groeimedia (100% turf (T1) (beheer), 100% bagasse (T2), 50:50% v/v bagasse:turf (T3), 75:25% v/v bagasse:turf (T4), 25:75 % v/v bagasse:turf (T5), bagasse wat tot kompos verwerk is (T6), klapperhaar (T7), en dennebas (T8)) as behandelings en een hibried (Mount® Runca) van D. x grandiflorum is in ʼn verewekansigde, volledige blokontwerp met vier repliserings gerangskik. In hierdie studie is voedingstofopname-, chlorofilinhoud-, groei- en opbrengs-parameters gemeet vir potgroei van D. x grandiflorum in al agt groeimedia. Die resultate toon dat die behandelings verskillende chemiese en fisiese eienskappe in vergelyking met turf het. Die pH van 100% bagasse en klapperhaar val binne die ideale reikwydte wat vir groeimedia aanbeveel word. Volgens die EG (elektriese geleiding)-resultate was ander behandelings binne die gedefinieerde reikwydte – behalwe vir bagasse wat tot kompos verwerk is – vanweë die hoë konsentrasie oplosbare soute. Die BD van beheer en bagasse wat tot kompos verwerk is, was soortgelyk en kon die lae wortelrespons veroorsaak het. Die konsentrasie totale N was hoog in die lote van plante wat in 100% turf aangeplant is, met ʼn gevolglike verhoging in die gewig van vars en droë lote. Die hoogste beduidende chlorofilinhoud was teenwoordig in plante wat gekweek is in bagasse wat tot kompos verwerk is, en wat hoë totale konsentrasies van N, Fe en Zn in die lote bevat het. Alles in ag genome het die resultate getoon dat bagasse wat tot kompos verwerk is, die beste alternatief is om turf te vervang in die kweking van D. x grandiflorum in potte. / Go ntsha borubu mo kumong ya mokgwa wa temo go na le matshosetsi mo matshelong a diphologolo le ditlhare tsa lefatshe le le kolobileng. Kelo ya kgodiso e e bonako ya intaseteri ya matshelo a diphologolo le ditlhare e susumetsa patlo e e tswelelang ya dikarolo tsa mekgwa ya kgodiso ya thefosano e e tswelelang ya go emela go ntsha borubu. Dikarolo tse dingwe di tlhoka go neela dipharologantsho (sebopego le khemikale) tse di tshwanang le kgotsa botoka mo go ntsheng borubu le go neela mabaka a a ka tsholetsang kgodiso e e ikaeletsweng, mme ya ntsha dijalo tse di ka fa dipitseng. Dendranthema x grandiflorum e e ka fa dipitseng ke thefosano nngwe ya dijalo tsa ka fa dipitseng tse di botlhokwa thata tse di jadilweng mo lefatsheng ka bophara mo intasetering ya mokgwa wa temo ya dithunya. Go na le boiteko jwa patlisiso ya bogotlhe ya go emela go ntsha borubu ka mokgwa wa kgodiso wa thefosano o mongwe o o tswelelang wa dijalo tsa ka fa dipitseng; le gale, go le kalo, ga go na thuto e e setseng e dirilwe mo Aforikaborwa e e dirisang ditshwaro tse di tshwanang mo go Dendranthema x grandiflorum e e mo dipitseng. Maikaelelo a thuto eno e ne e le go tlhomamisa mekgwa ya grandiflorum e e mo dipitseng. Maikaelelo a thuto eno e ne e le go tlhomamisa mekgwa ya kgodiso ya thefosano e mengwe e e tshwanelang go emela go ntsha borubu jaaka mekgwa ya kgodiso ya go jala D. x grandiflorum ka mo dipitseng. Tekelelo ya ntlo e tala e ne ya dirwa kwa lefelong la Mokgwa wa matshelo a diphologolo le ditlhare ya Yunibesiti ya Aforikaborwa kwa Florida, Johannesburg mo matsatsing a le 89. Mekgwa ya kgodiso e merobedi (100 % ya go ntsha borubu (T1) (taolo), 100 % bagasse (T2), 50:50 % v/v bagasse: go ntsha borubu (T3), 75:25 % v/v bagasse: go ntsha borubu (T4), 25:75 % v/v bagasse: go ntsha borubu (T5), bagasse e e bodisitsweng (T6), Coir (T7), le kutu ya phaene (T8)) jaaka ditshwaro le lotswakwa lo lo longwe (Mount® Runca) ya D. x grandiflorum di ne di beilwe ka moakanyetso wa boloko e e feletseng ka kakaretso ka ditshwano di le nne. Mo thutong eno, go tsaya kotlo, diteng tsa setalafatsi, kgodiso le diparametara tse di ntshitsweng di ne tsa lekanyediwa mo go D. x grandiflorum e e mo dipitseng e e jadilweng mo mekgweng ya dikgodiso tse di robedi tse tsotlhe. Dipheto di bontsha gore ditshwaro di na le dikarolo tsa dikhemikale le dibopego tse di farologaneng fa di tshwantshanngwa le go ntsha borubu. Bagasse ya pH ya 100 % le coir di ne di le magareng ga paka ya botlhokwa ya kgodiso e e atlenegisitsweng mo mekgweng ya kgodiso. Dipheto tsa EC di bontsha gore morago ga tekelelo, ditshwaro tse dingwe di ne di le magareng ga paka e e tlhalositsweng kwa ntle ga bagasse e e bodisitsweng kwa kokoanong e e kwa godimo ya matswai a a tlhaolositsweng. BD ya taolo le bagasse e e bodisitsweng, mme go ka bo go dirile gore go nne le tsibogelo ya medi e e kwa tlase. Kokoano ya N yotlhe e ne e le kwa godimo mo matlhogeding a dijalo tse di jadilweng ka go ntsha borubu jwa 100 % ka koketso e e latelang ya bokete jwa matlhogedi a mantshwa le a a omileng. Diteng tsa setalafatsi se se botlhokwa se se kwa godimodimo di ne di le teng mo dijalong tse di jadilweng ka bagasse e e bodisitsweng, e e nang le kokoano ya bogotlhe jo bo kwa godimo jwa N, Fe le Zn mo matlhogeding. Di tserwe mmogo, dipheto di bontsha gore bagasse e e bodileng jaaka sengwe se se gaisang go emela go ntsha borubu mo jalong ya D. x grandiflorum ka mo dipitseng. / School of Environmental Sciences / M. Sc. (Ornamental Horticulture)

The development of a plant growth chamber capable of sustaining plant growth over multiple generations is a necessary step towards the attainment of a Controlled Ecological Life Support System (CELSS). The studies herein examine the effects of aeration abilities and rates on plants grown in three model nutrient delivery systems during germination and over the life-cycle of the plant. These studies are the first time a porous tube nutrient delivery system was compared to another active nutrient mist delivery system. During germination an indicator of hypoxic stress, alcohol dehydrogenase (ADH) activity, was measured and was more affected by aeration rate than mode of nutrient delivery. Over the life-cycle of the plant, however, plants grown in the porous tube system had the least ADH activity and the highest levels of shoot (leaf + stem), root and leaf biomass. None of the plants in any system, however, produced viable seed. This study highlights the need to optimize aeration capabilities in the root zone of enclosed chambers.