Green Tower Research Articles

Integrating vertical farm into low-carbon high-rise building in high-density context: A design case study in Hong Kong

Today's world faces multiple challenges, including climate change, biodiversity loss, and food security. In addition, in the post-pandemic era, there is an urgent need to re-design urban habitats to reduce the epidemic's enduring impacts and reconnect citizens with healthy community activities. As a city with the top population density level in the world, Hong Kong is home to many high-rise communities. This article took the architectural design competition “Green Tower Hong Kong” as an entry point to discuss the technical feasibility and design strategies of integrating high-rise residential buildings with urban agriculture to improve urban food security, enhance on-site solar energy utilization, and develop a sustainable residential environment conducive to low-carbon living and working. The issue of how to improve the dietary structure of Hong Kong residents and reconnect them through space design was focused. Finally, taking the site of Kwun Tong Center as the case study, a resilient residential high-rise building integrated with shared gardens and greenhouses was proposed with a technical-oriented methodology and optimization framework. The final design of mixed-use buildings can provide apartments for 2500 individuals, produce 340,750 kg of vegetables with 156 % self-sufficiency, and generate electricity of 1,080,000 kWh annually. This paper examines strategies for integrating urban agriculture into high-rise residential buildings in high-density urban environments. It proposes a technology-based design optimization method, offering a reference for future explorations of low-carbon, resilient communities.

THE INFLUENCE OF CULTURAL AND ARTISTIC TRADITIONS OF CHINA ON THE IMAGE OF A RELIGIOUS BUILDING

The Buddhist temple complex of Dunhuang can be named as the oldest example of the transformation of architectural and artistic canons of foreign religions when they were transferred to the territory of China. The artistic canons of the sanctuaries, which originated in India, underwent more and more transformations as local architectural and artistic skills developed. The same can be said about the transformation of the image of an Islamic religious building in the case of mosques, for example, in Shaanxi province, which acquired the architectural and artistic image of a Chinese temple of the traditional beliefs of Taoism and Confucianism. The influence of local traditions even on the image of a Christian church, namely the German Protestant church in Qingdao, was studied. In particular, it is quite bright for the German northern national romanticism, the polychromy of the facades, which contrasts with the ascetic interior. 
 Unlike traditional Protestant churches, the Protestant church in Qingdao has an irregular plan and the entrance to it is located not from the west, as usually, but from the south (Fig. 1). The asymmetry of the church composition is emphasized by the dominant tower with a height of 39 m. 
 This object is traditionally mentioned in the same row as other objects of northern national romanticism – the Residence of the Governor of Qingdao and the Japanese Girl’s High School. First of all, let’s analyze what signs of northern national romanticism are present here: 
 – large scale;
 – an active silhouette with the presence of pseudo-Romanesque towers of different heights;
 – the presence of “torn” stone cladding;
 – lack of small details and decoration on the facades.
 Now let's define the features that are not inherent in the typical German northern national romanticism:
 – dominance of yellow tinted wall planes over planes faced with “torn” stone;
 – the introduction of bright polychromy (red tiled roofs – yellow plastered walls – planes faced with “torn” granite – green tower’s roof not in the outlines of northern national romanticism).
 An analysis of the appearance of the Protestant church in Qingdao led to the following conclusions.
 An analysis of the appearance of the Protestant church in Qingdao led to the following conclusions.
 The important role of this object in the planning structure of the settlement actually built on an empty site is evidenced by the following facts:
 – the location is close to the government district;
 – holding a competition in Berlin;
 – funding by the Qingdao Governor's Office;
 – the choice of the style of northern national romanticism. 
 However, despite the presence of some signs of northern national romanticism in its German version, the phenomenon of style transformation when transferred to Chinese soil should be noted. In particular, under the influence of the picturesque natural environment, other natural and climatic conditions and Chinese architectural and artistic traditions of bright colours, the Protestant church acquired features that are not characteristic of northern national romanticism.

Evaluation of the Existence of a New Race of Bremia lactucae on Lettuce

Lettuce is one of the most consumed leafy vegetables in Turkey. The production of lettuce has been to get difficult due to infestation of cultivation areas with Bremia lactucae. This pathogen is genetically very variable. Pathogenic variation of B. lactucae has not been studied yet in Turkey. The objective of this study was to monitore the races of B. lactucae in the two geographic regions of Turkey. During the lettuce growing season in May and October 2018, totally 72 diseased leaf samples containing B. lactucae sporangia were collected from the fields of Bartın and Ankara provinces. From these samples 6 isolates were obtained. After a multiplication procedure, in which the susceptible lettuce cultivar 'Green Towers' was used, the B. lactucae sporangia were inoculated in differentiating lettuce cultivars. The response of the lettuce seedlings to pathogen was evaluated on the 7, 11 and 14 days after inoculation. The qualitative method was used for the assessment of infected seedlings. Sextet codes of Ankara and Bartın isolates were found as 44-00-01 and 13-03-04 respectively. The sextet codes of Turkish isolates did not match any of the present 37 races of B. lactucae. This result suggests that our isolates may be new races or pathotypes.

Influence of Salinity Stress on Color Parameters, Leaf Pigmentation, Polyphenol and Flavonoid Contents, and Antioxidant Activity of Amaranthus lividus Leafy Vegetables.

This is the first attempt to evaluate the impact of four salinity levels on the color parameters, pigments, polyphenols, flavonoids, and antioxidant capacities of four promising A. lividus genotypes. The color parameters, such as the yellowness/blueness (b*) and the chroma (C*); the antioxidant components, such as the polyphenols and flavonoids; and the antioxidant capacities of the leaves were remarkably increased by 39, 1, 5, 10 and 43%, respectively, at 50 mM of NaCl, and by 55, 5, 60, 34, 58 and 82%, respectively, at 100 mM NaCl concentrations. The green tower and SA6 genotypes were identified as tolerant varieties. The total phenolic content (TPC) and the total flavonoid content (TFC) played vital roles in scavenging reactive oxygen species (ROS), and they would be beneficial for the human diet and would serve as good antioxidants for the prevention of aging, and they are also essential to human health. A correlation study revealed the strong antioxidant capacities of the pigments and antioxidant components that were studied. It was revealed that A. lividus could tolerate a certain level of salinity stress without compromising the antioxidant quality of the final product. Taken together, our results suggest that A. lividus could be a promising alternative crop for farmers, especially in saline-prone areas in the tropical and subtropical regions.

Development and Implementation of an IoT-Enabled Optimal and Predictive Lighting Control Strategy in Greenhouses.

Global population growth has increased food production challenges and pushed agricultural systems to deploy the Internet of Things (IoT) instead of using conventional approaches. Controlling the environmental parameters, including light, in greenhouses increases the crop yield; nonetheless, the electricity cost of supplemental lighting can be high, and hence, the importance of applying cost-effective lighting methods arises. In this research paper, a new optimal supplemental lighting approach was developed and implemented in a research greenhouse by adopting IoT technology. The proposed approach minimizes electricity cost by leveraging a Markov-based sunlight prediction, plant light needs, and a variable electricity price profile. Two experimental studies were conducted inside a greenhouse with “Green Towers” lettuce (Lactuca sativa) during winter and spring in Athens, GA, USA. The experimental results showed that compared to a heuristic method that provides light to reach a predetermined threshold at each time step, our strategy reduced the cost by 4.16% and 33.85% during the winter and spring study, respectively. A paired t-test was performed on the growth parameter measurements; it was determined that the two methods did not have different results in terms of growth. In conclusion, the proposed lighting approach reduced electricity cost while maintaining crop growth.

Phenotypic characterization and inheritance of enzymatic browning on cut surfaces of stems and leaf ribs of romaine lettuce

Enzymatic browning is a major postharvest quality defect of romaine lettuce (Lactuca sativa L.). This study provides the first analysis of the relationship between the browning of leaf ribs and stems across twelve lettuce genotypes (ten cultivars, a breeding line, and a plant introduction). While all samples showed a progressive increase in browning index (BI) and decline in lightness (L*) and hue (h°) during 5 °C storage, differences in the rate of browning development were observed among genotypes. The most intensive browning was observed mainly around the vascular bundles dispersed along the rim area of the stems. Browning on the cut surfaces of the stems was correlated with browning on the cut leaf ribs, with Pearson correlation coefficients of 0.886 for BI, 0.891 for L* and 0.866 for h°. These results showed that the degree of browning in leaf ribs can be predicted by the browning degree of the stems. High genetic similarity was found among four cultivars with limited browning (Darkland, Parris Island Cos, Green Towers, and Hearts Delight) and also between cultivars with severe browning (King Henry and Tall Guzmaine). The highest broad-sense heritability (H2) in both trials (July and November 2018) was 0.88 and 0.92 for stem and rib browning, respectively. The method based on stem browning can be used to simplify postharvest phenotypic evaluation of lettuce and to decipher the genetics of browning to accelerate the breeding of browning-resistant cultivars.

Photosynthetic Physiology of Blue, Green, and Red Light: Light Intensity Effects and Underlying Mechanisms.

Red and blue light are traditionally believed to have a higher quantum yield of CO2 assimilation (QY, moles of CO2 assimilated per mole of photons) than green light, because green light is absorbed less efficiently. However, because of its lower absorptance, green light can penetrate deeper and excite chlorophyll deeper in leaves. We hypothesized that, at high photosynthetic photon flux density (PPFD), green light may achieve higher QY and net CO2 assimilation rate (An) than red or blue light, because of its more uniform absorption throughtout leaves. To test the interactive effects of PPFD and light spectrum on photosynthesis, we measured leaf An of “Green Tower” lettuce (Lactuca sativa) under red, blue, and green light, and combinations of those at PPFDs from 30 to 1,300 μmol⋅m–2⋅s–1. The electron transport rates (J) and the maximum Rubisco carboxylation rate (Vc,max) at low (200 μmol⋅m–2⋅s–1) and high PPFD (1,000 μmol⋅m–2⋅s–1) were estimated from photosynthetic CO2 response curves. Both QYm,inc (maximum QY on incident PPFD basis) and J at low PPFD were higher under red light than under blue and green light. Factoring in light absorption, QYm,abs (the maximum QY on absorbed PPFD basis) under green and red light were both higher than under blue light, indicating that the low QYm,inc under green light was due to lower absorptance, while absorbed blue photons were used inherently least efficiently. At high PPFD, the QYinc [gross CO2 assimilation (Ag)/incident PPFD] and J under red and green light were similar, and higher than under blue light, confirming our hypothesis. Vc,max may not limit photosynthesis at a PPFD of 200 μmol m–2 s–1 and was largely unaffected by light spectrum at 1,000 μmol⋅m–2⋅s–1. Ag and J under different spectra were positively correlated, suggesting that the interactive effect between light spectrum and PPFD on photosynthesis was due to effects on J. No interaction between the three colors of light was detected. In summary, at low PPFD, green light had the lowest photosynthetic efficiency because of its low absorptance. Contrary, at high PPFD, QYinc under green light was among the highest, likely resulting from more uniform distribution of green light in leaves.

Evaluation of Yield, Marketability, and Nitrate Levels of Lettuce Cultivars Produced in Southern Louisiana

Forty-five cultivars of lettuce (Lactuca sativa) were field-grown using best management practices at the Louisiana State University Agricultural Center (LSU AgCenter) Botanic Gardens in Baton Rouge during the Fall 2011 and Fall 2012 seasons. Recommended cultivars were selected for commercial production in Louisiana based on fresh weight and lettuce size (width and height). Nitrate (NO3–) concentration was analyzed for each cultivar, as lettuces are known to accumulate and concentrate NO3–, and were then compared with the U.S. Environmental Protection Agency’s (EPA) oral reference dose (RfD—the EPA’s maximum acceptable oral dose of a toxic substance) of 1.6 mg NO3-nitrogen (N) per kilogram body weight per day. Recommended butterhead cultivars were Caliente and Harmony (21.6 and 13.9 ppm NO3–, respectively); recommended green-leaf cultivars were Salad Bowl and Tango (10.6 and 4.6 ppm NO3–, respectively); recommended red-leaf cultivars were Red Salad Bowl, Red Sails, and New Red Fire (15.2, 15.4, and 24.0 ppm NO3–, respectively). The only recommended romaine cultivar was Green Towers (11.2 ppm NO3–), and recommended crisphead cultivars included Raider and Ithaca (17.6 and 14.9 ppm NO3–, respectively). Of the highest yielding cultivars, New Red Fire accumulated the greatest NO3– concentration: 24.0 ppm in both years 1 and 2. The NO3– concentration is less than the levels of concern for both men and women 20 to 74 years old, 3.9% of the RfD for men and 4.59% of the RfD for women.

Longer Photoperiods with the Same Daily Light Integral Increase Daily Electron Transport through Photosystem II in Lettuce.

Controlled environment crop production recommendations often use the daily light integral (DLI) to quantify the light requirements of specific crops. Sole-source electric lighting, used in plant factories, and supplemental electric lighting, used in greenhouses, may be required to attain a specific DLI. Electric lighting is wasteful if not provided in a way that promotes efficient photochemistry. The quantum yield of photosystem II (ΦPSII), the fraction of absorbed light used for photochemistry, decreases with increasing photosynthetic photon flux density (PPFD). Thus, we hypothesized that the daily photochemical integral (DPI), the total electron transport through photosystem II (PSII) integrated over 24 h, would increase if the same DLI was provided at a lower PPFD over a longer photoperiod. To test this, ΦPSII and the electron transport rate (ETR) of lettuce (Lactuca sativa ‘Green Towers’) were measured in a growth chamber at DLIs of 15 and 20 mol m−2 d−1 over photoperiods ranging from 7 to 22 h. This resulted in PPFDs of 189 to 794 μmol m−2 s−1. The ΦPSII decreased from 0.67 to 0.28 and ETR increased from 55 to 99 μmol m−2 s−1 as PPFD increased from 189 to 794 μmol m−2 s−1. The DPI increased linearly as the photoperiod increased, but the magnitude of this response depended on DLI. With a 7-h photoperiod, the DPI was ≈2.7 mol m−2 d−1, regardless of DLI. However, with a 22-h photoperiod, the DPI was 4.54 mol m−2 d−1 with a DLI of 15 mol m−2 d−1 and 5.78 mol m−2 d−1 with a DLI of 20 mol m−2 d−1. Our hypothesis that DPI can be increased by providing the same DLI over longer photoperiods was confirmed.

Selection of Heat Tolerant Lettuce (Lactuca sativa L.) Cultivars Grown in Deep Water Culture and Their Marketability

Lettuce is a cool season vegetable often produced in greenhouses and other protective structures to meet market demands. Greenhouses are being increasingly adopted in warm climate zones where excessive heat often leads to physiological disorders of lettuce, such as tipburn and premature bolting. Greenhouse lettuce growers in warm climates need cultivar recommendations that can help improve production without ignoring marketability. In the current study, eighteen lettuce cultivars were grown in deep water culture and evaluated for growth, bolting, and tipburn in a greenhouse in Auburn, AL, starting on 30 June and 19 August 2016. Based on the severity of bolting and tipburn, nine cultivars were then selected and evaluated on 17 November 2016 for sensory attributes and marketability by 50 untrained consumer panelists. Cultivars ‘Adriana’, ‘Aerostar’, ‘Monte Carlo’, ‘Nevada’, ‘Parris Island’, ‘Salvius’, ‘Skyphos’, and ‘Sparx’ were selected as having higher heat tolerance than cultivars ‘Bambi’, ‘Buttercrunch’ ‘Coastal Star’, ‘Flashy Trout Back’, ‘Green Forest’, ‘Green Towers’, ‘Jericho’, ‘Magenta’, and ‘Truchas’. Higher crispness, lower bitterness, higher overall texture, and higher overall flavor each correlated to higher marketability, regardless of cultivar, but the strongest predictor of marketability was overall flavor. Overall flavor and overall texture were more strongly correlated to marketability than bitterness and crispness, respectively, suggesting that broader sensory categories may better capture human sensory perceptions of lettuce than narrower categories. Cultivars ‘Aerostar’, ‘Monte Carlo’, ‘Nevada’, ‘Parris Island’, ‘Rex’, ‘Salvius’, and ‘Sparx’ performed well in a hot greenhouse and were preferred by consumers. This step-wise experiment could be an adaptable tool for determining highest performing cultivars under any given production constraint, without ignoring marketability.

Photochemical Characterization of Greenhouse-grown Lettuce (Lactuca sativa L. ‘Green Towers’) with Applications for Supplemental Lighting Control

Plant light use efficiency decreases as light intensity is increased, and a better understanding of crop-specific light responses can contribute to the development of more energy-efficient supplemental lighting control strategies for greenhouses. In this study, diurnal chlorophyll fluorescence monitoring was used to characterize the photochemical responses of ‘Green Towers’ lettuce (Lactuca sativa L.) to photosynthetic photon flux density (PPFD) and daily light integral (DLI) in a greenhouse during a production cycle. Plants were monitored continuously for 35 days, with chlorophyll fluorescence measurements collected once every 15 minutes. Quantum yield of photosystem II (ΦPSII) decreased exponentially with PPFD, whereas electron transport rate (ETR) increased asymptotically to 121 µmol·m–2·s–1. Daily photochemical integral (DPI) is defined as the integral of ETR over a 24-hour period; DPI increased asymptotically to 3.29 mol·m–2·d–1 with increasing DLI. No effects of plant age or prior day’s DLI and a negligible effect of PPFDs 15 or 30 minutes before measurements within days were observed. Simulations were conducted using the regression equation of ETR as a function of PPFD {ETR = 121[1 – exp(–0.00277PPFD)]} to illustrate methods of increasing photochemical light use efficiency for improved supplemental lighting control strategies. For a given DLI, DPI can be increased by providing light at lower PPFDs for a longer period of time, and can be maximized by providing light with a uniform PPFD throughout the entire photoperiod. Similarly, the DLI required to achieve a given DPI is reduced using these same methods.

Growth and yield of different leaf-type lettuce cultivars grown in protected and open field cultivation

Leafy vegetable production in the Philippines is less diversified than many other countries, especially those used in salads. As a result, Filipino farmers are less familiar with production of leaf-type lettuce that is increasing in popularity with consumers. Therefore, two separate experiments were conducted simultaneously in open field and under bamboo house-type protective structures roofed with plastic to evaluate the performance and profitability of different leaf-type lettuce cultivars. Each study was carried out in randomized complete block design with five treatment cultivars and three replications. Most cultivars grown under protective structures had higher marketable yields than those grown in the open field. Despite plants grown under protective structures incurring higher production costs compared to the open field, higher marketable yields under protective structures resulted in higher net returns. Among the five cultivars, Green Span gave the highest return in the open field and Green Tower under the protective structure. Smaller lettuce cultivars produced lower yields than bigger cultivars.

Levantamento de raças do agente causador do míldio da alface no Estado de São Paulo em 2012 e 2013

RESUMO A alface é, entre as hortaliças folhosas, a mais importante economicamente para o Brasil. No inverno, com baixas temperaturas e com molhamento foliar, o míldio da alface, doença causada pelo agente etiológico Bremia lactucae, ocorre em praticamente todas as regiões de cultivo desta hortaliça, sendo considerada uma das doenças foliares mais severas da cultura. O objetivo deste trabalho foi identificar as raças de B. lactucae no ano de 2012 e 2013 que ocorreram nas principais regiões produtoras do Estado de São Paulo, como: Ribeirão Preto, Jaboticabal, Pirangi, Catanduva, São José do Rio Preto, Atibaia, Salesópolis, Biritiba Mirim, Mogi das Cruzes, Campinas, Itapira, Mogi Mirim, Cândido Mota, Presidente Prudente, Echaporã, Assis, Marília, Botucatu e Bauru. Durante o mês de julho/agosto de 2012 e 2013, coletaram-se amostras de folhas de alface com sintomas de míldio, sendo que, em cada amostra coletada, as estruturas do patógeno referiram-se a um isolado. Os esporângios foram multiplicados na cultivar suscetível Solaris, com posterior inoculação nas cultivares diferenciadoras, realizando-se as avaliações no 12º dia do aparecimento da primeira esporulação na cultivar suscetível ‘Green Tower’ (Dm-0), conforme o código “Sextet”. Em 2012, foi determinado dois novos códigos, identificando duas novas raças, SPBl:10 (63/31/02/00) e SPBl:11 (63/63/18/00). Em 2013, uma nova codificação foi determinada (63/31/18/00), à qual propôs a denominação de SPBl:12. Os genes Dm-14 e Dm-15, e os fatores de resistência FR-17, FR-18, FR-36, FR-37 e FR-38 conferem resistência a essas novas raças identificadas. Recomenda-se, portanto, em programas de melhoramento genético de alface, a utilização dos fatores FR-17, FR-18 e FR-38 como fontes de resistência para novas cultivares desenvolvidas para cultivo no Estado de São Paulo, por conferirem resistência a todas as 12 raças já identificadas.

Experimental Field Study of Green Tower Setup

A Green Tower for setup a pilot experiment consists of the solar collector and the tower was built. The temperature distribution of the Green Tower was measured and analyzed. The data of the highest experimental temperature inside the Green Tower collector’s reached was 52oC at 1300 hours at solar irradiation received of 623W/m2 respectively, with the ambient temperature at 31 oC. The Green Tower that used solar thermal power and utilizing a combination of solar air collector using the principal of solar oven and central updraft tube to generate a solar induced convective flow, which drives pressure to develop artificial wind. This paper presents the experimental field study and practical experience of the Green Tower. The discussion on temperature distribution and also updraft wind of the Green Tower is described and then the results from the designing, building and experimental are presented. The results and suggestions for the future reference will also be discussed.

Comparison of Shoe-surface Tractions on Various Playing Surfaces in Futsal

Futsal is a small version of football, which is played in over 100 countries. The smaller pitch of futsal causes players to perform multiple activities in several times such as sprinting, walking, running, jumping, cutting and so on. Consequently, the risks of non-contact injuries are increasing. One of the factors can influence the risks is a shoe-surface traction. The Current research is aimed at comparing the traction between futsal shoe and four different playing surfaces. In the first part of the experimental test, cutting maneuver as a critical activity was performed by former Bayern Munich Player, Mr. Timo Heinze. A force plate and two high speed cameras were prepared to collect forces (Fx,Fy and FZ) and angles during cutting maneuver. In the second part, a device, traction tester was considered in order to simulate the certain activity, which was reconciled with the force and angle of the subject. Accordingly, the traction between futsal shoe (Joma Top Flex 301 Sala) and four samples (Snap Sport (Shock Tower), Descol (Pulastic Outdoor), Green Tower and Snap Sport (Bounce Back)) were measured. The activity classified into two traction phases, translation and rotation. T-test results show that there are significant differences between translational traction (TT) and rotational traction (TR) in three samples (Snap Sport Bounce Back, Green tower and Descol) . They are 0.0019, 0.0001, 0.012 respectively (P-value<0.05). The mean of three trials of tractions determined that greater translational tractions (Phase1) are associated lower rotational traction (Phase 2). To avoid foot fixation and ACL injuries in phase 2, a greater rate of TR than TT is necessary. The Snap Sport (Bounce Back) showed the higher level of translational coefficient (0.2007) and a safe range of rotational coefficient (0.0647). It was considered as an appropriate playing surface among other samples.

First Report of White Mold Caused by Sclerotinia minor on Mexican Sunflower in California.

Mexican sunflower (Tithonia rotundifolia) is a plant in the Asteraceae that is grown commercially as a cutflower commodity and also as a beneficial insectary plant. In June 2012 in coastal California (Santa Cruz County), several fields of organic lettuce (Lactuca sativa) were interplanted with direct-seeded rows of Mexican sunflower (cv. Torch) in order to attract beneficial insects. When approximately 2 to 3 weeks from harvest, lettuce plants began to wilt and collapse. Lettuce crowns were decayed and covered with white mycelium and small (0.5 to 3 mm diameter), irregularly shaped, black sclerotia. These plants were confirmed to have lettuce drop disease caused by Sclerotinia minor (2). In addition, Mexican sunflower plants began to wilt and eventually died. Initial symptoms on crowns and bases of the main stems in contact with soil consisted of a light tan discoloration. These discolored areas turned darker brown, became necrotic, and later were covered with white mycelium and sclerotia that were identical to those found on lettuce. Symptomatic sunflower stems were surface disinfested and small pieces from the margins of necrotic areas were placed into petri plates containing acidified potato dextrose agar. Resulting fungal colonies were white, produced profuse numbers (approx. 39 sclerotia/cm2) of small black sclerotia, and were identified as S. minor. Six-week-old Mexican sunflower plants grown in a peat moss-based rooting medium in 5-cm square pots were used to test the pathogenicity of four isolates. Isolates were grown on cubed and autoclaved potato pieces and resulting sclerotia were recovered and dried (1). For each isolate, 12 plants for each of three cultivars (cvs. Fiesta del Sol, Torch, and Yellow Torch) were inoculated by placing 3 to 5 sclerotia 1 cm below the soil level and adjacent to the plant crowns/stem bases. Sterile sand was placed next to crowns of the control plants. Plants were maintained in a greenhouse at 22 to 24°C. Symptom development was rapid and after 6 to 7 days, inoculated Tithonia plants exhibited brown necrosis at inoculated areas. After 10 days, Tithonia crowns were decayed and plants wilted. S. minor was reisolated from selected necrotic crown and stem tissues. Diseased plants that were not used for reisolations later supported the growth of the characteristic white mycelium and black sclerotia. There were no significant differences between the Tithonia cultivars, and overall disease incidence ranged from 74 to 100%. Non-inoculated plants were asymptomatic. The experiment was repeated and results were similar. In addition, the sclerotia of the four Tithonia isolates were similarly inoculated onto sets of 12 romaine lettuce plants (cv. Green Towers). After 5 to 6 days, all plants developed lettuce drop disease and the pathogen was reisolated. To my knowledge, this is the first report of Mexican sunflower as a host of S. minor. These findings indicate that Mexican sunflower and lettuce are susceptible to the same lettuce drop pathogen, and that this beneficial insectary plant could increase soilborne inoculum of S. minor. Growers should therefore be aware of the host status of beneficial insectary and other plants interplanted with crops.

Monitoramento de raças de Bremia lactucae em 2010 e 2011 no Estado de São Paulo

A alface é uma das mais importantes hortaliças folhosas cultivadas no Brasil. Porém, com a intensificação da produção, a dificuldade em se cultivar essa hortaliça tem aumentado principalmente pela infestação das áreas de produção pelo fitopatógeno Bremia lactucae Regel, agente causador do míldio, uma das principais doenças da alface. O objetivo deste trabalho foi identificar raças de Bremia lactucae nos anos de 2010 e 2011 nos principais municípios produtores de alface do Estado de São Paulo. Para isso, coletaram-se folhas com esporângios de B. lactucae em municípios produtores de alface, sendo que cada amostra foi considerada um isolado, totalizando 56 e 96 nos anos de 2010 e 2011, respectivamente. Os esporângios coletados foram multiplicados na cultivar suscetível Solaris, com posterior inoculação nas cultivares diferenciadoras, realizando-se as avaliações no mesmo dia do aparecimento da primeira esporulação na cultivar suscetível 'Green Tower' (DM 0). No ano de 2010, identificou-se um novo código de B. lactucae em alface (63/31/03/00), correspondente a uma nova raça na qual se propôs a denominação de SPBl:07. No ano de 2011, outros dois códigos de B. lactucae foram identificados (31/63/51/00 e 31/63/9/00), aos quais se propôs as denominações de SPBl:08 e SPBl:09, respectivamente.

SM09A and SM09B: Romaine Lettuce Breeding Lines Resistant to Dieback and with Improved Shelf Life

SM09A and SM09B are F8 romaine breeding lines of lettuce resistant to the dieback disease (caused by Tomato bushy stunt virus and Lettuce necrotic stunt virus) and with good shelf life. SM09B was selected from a cross between 'Darkland' and PI 491224, whereas SM09A was developed from 'Green Towers' × ('Darkland' × PI 491224). Resistance to the disease in both breeding lines is derived from PI 491224, a primitive romain-type lettuce that is highly perishable when processed for salad. In replicated field trials, the 2 breeding lines showed complete resistance to dieback. Field observations (in California, USA) were confirmed through the analysis of molecular markers closely linked to the dieback resistance gene Tvr1. Testing of salad-cut lettuce in modified atmosphere packaging indicated slower decay in the 2 breeding lines compared with other dieback-resistant romaines. Morphological and horticultural characteristics of the 2 breeding lines are given.

Dynamic relationships between field temperatures and romaine lettuce yield and head quality

Abstract Romaine lettuce (Lactuca sativa L. var. longifolia Lam.) has great potential as a winter alternative crop in coastal South Carolina. Apache (A), Darkland (D), Green Tower (GT), Green Forest (GF), Ideal Cos (IC), and Tall Guzmaine (TG) romaine lettuce cultivar transplants were planted on 9 different planting dates in Charleston, South Carolina (SC) on monthly intervals from September to April from 1998 to 2001. The objective was to determine romaine's yield and quality responses to different growing season climates. Growing season mean (GSM) minimum or maximum temperatures (temps) were determined by averaging daily min and max temps from planting date to harvest date. The growing season for the September planting date (PD) was the warmest, followed by the April PD. The coldest growing season was the December PD, followed by January and November PDs. Collectively, GSM max temps ranged from 17 to 27 °C and GSM min temps ranged from 5 to 15 °C with these planting dates. The total accumulated heat units (Base 4.5 °C) were similar for all 8 PD growing seasons. The harvest maturities were similar between: September versus April PDs; October versus March PDs; and November versus February PDs. The December PD growing season required the greatest number of days to reach harvest from transplanting followed by the January PD growing season, with every 1 °C decrease in GSM min or max temps, days to harvest increased by 5 days. GSM min temperature affected number of marketable heads produced per plot more than GSM max temps for A, D, GT and TG but not GF and IC. Individual marketable head weight, however, was unaffected by GSM min and max temps. When all cultivar data were pooled and regressed, we found that from about 3 to 6 °C GSM min temps, the number of culls produced dropped steeply, but then plateaued from about 6 to 11 °C, and then decreased rapidly from 11 to 14 °C. The major cull defect was loss due to field rots. Generally, the pooled cultivar mean indicated that with an increase in GSM min temps from 3 to 6.5 °C, the rate of field rot production accelerated, but from 6.5 to 14 °C, field rot production was much slower in contrast.

Planting Date and Romaine Lettuce Cultivar Affect Quality and Productivity

The objective of this study was to determine the best combination of planting dates (PDs) and cultivars on yield and quality for long-term production of romaine lettuce. `Green Forest' (GF), `Apache' (AP), `Darkland' (DK), `Green Tower' (GT), `Ideal Cos' (IC), and `Tall Guzmaine' (TG) were successfully grown to harvest maturity on 19 PDs from September 1998 to April 2001. Lettuce planted in September and April PDs (pooled over cultivars and year), required as little as 47 and 49 days, respectively, to reach harvest (all cultivars harvested on the same day). Lettuce planted in October, November, February, and March PDs (pooled over cultivars and year), required on average 64, 66, 75, and 67 days to reach harvest, respectively, but in the coldest PDs of December and January, 90 and 98 days, respectively, were needed to reach maturity. Of the eight PDs evaluated, marketable numbers/plot (pooled over cultivars and years) were greatest in the September PD, followed by April (–8% decrease from September PD) &gt; March (–13%) &gt; October (–17%) &gt; November (–21%) &gt; December = January = February (about –30%) and heads weighed the most in September &gt; January = February (–7% decrease from September PD) &gt; March = April (–14%) &gt; October (–21%) &gt; December (–25%) &gt; November (–31%). Cull heads/plot (pooled over cultivars and years) were greatest in April &gt; December (–5% decrease from April PD) &gt; January = February (–16%) &gt; November (–27%) &gt; October (–34%) &gt; March (–44%) &gt; September (–49%). Two out of three November PDs were lost to freezing damage and this PD should be avoided. Significant bolting occurred primarily in the September and October PDs (in 1 of 3 years) with negligible bolting in the November, December, and January PDs, but bolting recurred again in the February, March and April PDs. Marketable numbers/plot (pooled over all PDs and years) were greatest for GF &gt; GT (–7% decrease from GF) &gt; AP (–8%) &gt; IC (–9%) &gt; DK (–11%) &gt; TG (–21%). The interaction effect of cultivar × PD indicated that GF yielded the most marketable heads in 6 out of 8 PDs. The best performing cultivars by PD (pooled over years) were September and February = GF and IC; October = TG; November = AP; December, January, March, and April = GF.