The Troublesome Document

An essay concerning the development of documentary photography, its relationship to political norms, conventions of realism in visual culture, and the form of the photographic book

Response of African eggplants to Fusarium spp. and identification of sources of resistance

Eggplant (Solanum spp.) production in Arumeru district and other parts of Africa is severely affected by wilting diseases of unknown etiology. Fusarium spp. characterized through morphological and sequence analysis of the translation elongation factor associated with Fusarium wilt of eggplants was used to test the response of three different eggplant species. Three Solanum spp. accessions were tested in a screen house at the seedling stage for resistance to two isolates each of Fusarium equiseti (corda) Sacc, Fusarium solani (Mart.) Sacc and Fusarium oxysporum (Schlecht). The study indicated that accessions MM 1131 (Solanum macrocapon) and N 19 (Solanum anguivi) accessions are susceptible to F. equiseti. Accession N 19 (S. anguivi) was susceptible to F. solani while both N 19 (S. anguivi) and MM 1131 (S. macrocarpon) was also susceptible to F. oxysporum f. sp. melongenae. Ninety-three accessions of cultivated and wild eggplants were subsequently evaluated in two screen house trials for resistance to Fusarium wilt. A root dip technique was used to inoculate the accessions with isolate Fs 40 (F. oxysporum f.sp. melongenae). Seventeen of the 93 accessions were found to be resistant and they belonged to Solanum macrocarpon and Solanum aethiopicum species. Accessions in S melongena were found to be the most susceptible. Eggplant accessions that showed high levels of resistance could potentially serve as valuable sources of Fusarium wilt resistance in eggplant breeding programs in Tanzania and beyond.Keywords: African eggplants, Fusarium spp. susceptibility, resistanc

Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns

[EN] Between February 2018 and April 2018, flowers were collected from eight Rosaceae species. Flowers were kept in a freezer at -20 degrees C for three freezing times (Treatment 1, two months; Treatment 2, four months; Treatment 3, six months). After extracting pollen, in vitro germination was induced in a culture medium and incubated at six different temperatures for 72 h. The percentage of pollen germination, average pollen tube length and maximum pollen tube length were measured. Pollen germination was maximum for all species between 15 degrees C and 30 degrees C. Cydonia oblonga, Malus sylvestris, Prunus avium, Prunus domestica, Prunus dulcis, Prunus persica and Pyrus communis obtained 30-52% pollen germination between 15 degrees C and 20 degrees C. Prunus cerasifera had 40% pollen germination at 30 degrees C. All species studied reached the maximum pollen tube length between 10 degrees C and 25 degrees C. Germination did not change significantly for any of the species with freezing time, but we found significant differences in the three parameters measured between treatments. The highest germination percentages were obtained in Treatment 2 (four months frozen at -20 degrees C), while the maximum pollen tube length was reached in Treatment 1 (two months frozen at -20 degrees C). According to our results, freezing time affected the germination-temperature patterns. This could indicate that studies on the effect of temperature on pollen germination should always be carried out with fresh pollen to obtain more conclusive data.This work was supported by the Asociacion Club de Variedades Vegetales Protegidas as a part of a project with the Universitat Politecnica de Valencia (UPV 20170673). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Beltrán, R.; Valls, A.; Cebrián, N.; Zornoza, C.; García-Breijo, F.; Reig Armiñana, J.; Garmendia, A.... (2019). Effect of temperature on pollen germination for several Rosaceae species: influence of freezing conservation time on germination patterns. PeerJ. 7:1-18. https://doi.org/10.7717/peerj.8195S1187Acar, I., & Kakani, V. G. (2010). The effects of temperature on in vitro pollen germination and pollen tube growth of Pistacia spp. Scientia Horticulturae, 125(4), 569-572. doi:10.1016/j.scienta.2010.04.040Boavida, L. C., & McCormick, S. (2007). TECHNICAL ADVANCE: Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana. The Plant Journal, 52(3), 570-582. doi:10.1111/j.1365-313x.2007.03248.xBrewbaker, J. L., & Kwack, B. H. (1963). THE ESSENTIAL ROLE OF CALCIUM ION IN POLLEN GERMINATION AND POLLEN TUBE GROWTH. American Journal of Botany, 50(9), 859-865. doi:10.1002/j.1537-2197.1963.tb06564.xBurke, J. J., Velten, J., & Oliver, M. J. (2004). In Vitro Analysis of Cotton Pollen Germination. Agronomy Journal, 96(2), 359-368. doi:10.2134/agronj2004.3590Castède, S., Campoy, J. A., García, J. Q., Dantec, L., Lafargue, M., Barreneche, T., … Dirlewanger, E. (2014). Genetic determinism of phenological traits highly affected by climate change in Prunus avium: flowering date dissected into chilling and heat requirements. New Phytologist, 202(2), 703-715. doi:10.1111/nph.12658Cerovlć, R., & Ružić, D. (1992). Pollen tube growth in sour cherry (Prunus cerasusL.) at different temperatures. Journal of Horticultural Science, 67(3), 333-340. doi:10.1080/00221589.1992.11516256Egea, J., Burgos, L., Zoroa, N., & Egea, L. (1992). Influence of temperature on thein vitrogermination of pollen of apricot(Prunus armeniaca, L.). Journal of Horticultural Science, 67(2), 247-250. doi:10.1080/00221589.1992.11516244Fan, L.-M. (2001). In vitro Arabidopsis pollen germination and characterization of the inward potassium currents in Arabidopsis pollen grain protoplasts. Journal of Experimental Botany, 52(361), 1603-1614. doi:10.1093/jexbot/52.361.1603Feij�, J. A., Malh�, R., & Obermeyer, G. (1995). Ion dynamics and its possible role during in vitro pollen germination and tube growth. Protoplasma, 187(1-4), 155-167. doi:10.1007/bf01280244Goldwin, G. K., & Webster, A. D. (1983). The cumulative effects of hormone mixtures containing GA3, DPU plus NOXA, NAA or 2,4,5-TP on the cropping and flowering of sweet cherry cultivars,Prunus aviumL. Journal of Horticultural Science, 58(4), 505-516. doi:10.1080/00221589.1983.11515149Hebbar, K. B., Rose, H. M., Nair, A. R., Kannan, S., Niral, V., Arivalagan, M., … Vara Prasad, P. V. (2018). Differences in in vitro pollen germination and pollen tube growth of coconut (Cocos nucifera L.) cultivars in response to high temperature stress. Environmental and Experimental Botany, 153, 35-44. doi:10.1016/j.envexpbot.2018.04.014Hedhly, A., Hormaza, J. I., & Herrero, M. (2004). Effect of temperature on pollen tube kinetics and dynamics in sweet cherry,Prunus avium(Rosaceae). American Journal of Botany, 91(4), 558-564. doi:10.3732/ajb.91.4.558Hedhly, A., Hormaza, J. I., & Herrero, M. (2005). The Effect of Temperature on Pollen Germination, Pollen Tube Growth, and Stigmatic Receptivity in Peach. Plant Biology, 7(5), 476-483. doi:10.1055/s-2005-865850Hegedűs, A., & Halász, J. (2006). Self-incompatibility in plums (Prunus salicina Lindl., Prunus cerasifera Ehrh. and Prunus domestica L.). A minireview. International Journal of Horticultural Science, 12(2). doi:10.31421/ijhs/12/2/646Hegedűs, A., Lénárt, J., & Halász, J. (2012). Sexual incompatibility in Rosaceae fruit tree species: molecular interactions and evolutionary dynamics. Biologia plantarum, 56(2), 201-209. doi:10.1007/s10535-012-0077-3Heide, O. M., & Prestrud, A. K. (2005). Low temperature, but not photoperiod, controls growth cessation and dormancy induction and release in apple and pear. Tree Physiology, 25(1), 109-114. doi:10.1093/treephys/25.1.109Iglesias, A., Garrote, L., Quiroga, S., & Moneo, M. (2011). A regional comparison of the effects of climate change on agricultural crops in Europe. Climatic Change, 112(1), 29-46. doi:10.1007/s10584-011-0338-8KAKANI, V. G., PRASAD, P. V. V., CRAUFURD, P. Q., & WHEELER, T. R. (2002). Response of in vitro pollen germination and pollen tube growth of groundnut (Arachis hypogaea L.) genotypes to temperature. Plant, Cell & Environment, 25(12), 1651-1661. doi:10.1046/j.1365-3040.2002.00943.xKAKANI, V. G., REDDY, K. R., KOTI, S., WALLACE, T. P., PRASAD, P. V. V., REDDY, V. R., & ZHAO, D. (2005). Differences in in vitro Pollen Germination and Pollen Tube Growth of Cotton Cultivars in Response to High Temperature. Annals of Botany, 96(1), 59-67. doi:10.1093/aob/mci149Mesejo, C., Martínez-Fuentes, A., Reig, C., Rivas, F., & Agustí, M. (2006). The inhibitory effect of CuSO4 on Citrus pollen germination and pollen tube growth and its application for the production of seedless fruit. Plant Science, 170(1), 37-43. doi:10.1016/j.plantsci.2005.07.023Pham, V. T., Herrero, M., & Hormaza, J. I. (2015). Effect of temperature on pollen germination and pollen tube growth in longan ( Dimocarpus longan Lour.). Scientia Horticulturae, 197, 470-475. doi:10.1016/j.scienta.2015.10.007Reddy, K. R., & Kakani, V. G. (2007). Screening Capsicum species of different origins for high temperature tolerance by in vitro pollen germination and pollen tube length. Scientia Horticulturae, 112(2), 130-135. doi:10.1016/j.scienta.2006.12.014Rosell, P., Herrero, M., & Galán Saúco, V. (1999). Pollen germination of cherimoya (Annona cherimola Mill.). Scientia Horticulturae, 81(3), 251-265. doi:10.1016/s0304-4238(99)00012-6Sanzol, J., & Herrero, M. (2001). The «effective pollination period» in fruit trees. Scientia Horticulturae, 90(1-2), 1-17. doi:10.1016/s0304-4238(00)00252-1Saxe, H., Cannell, M. G. R., Johnsen, Ø., Ryan, M. G., & Vourlitis, G. (2001). Tree and forest functioning in response to global warming. New Phytologist, 149(3), 369-399. doi:10.1046/j.1469-8137.2001.00057.xSedgley, M. (1977). The Effect of Temperature on Floral Behaviour, Pollen Tube Growth and Fruit Set in the Avocado. Journal of Horticultural Science, 52(1), 135-141. doi:10.1080/00221589.1977.11514739Silva, G. J., Souza, T. M., Barbieri, R. L., & Costa de Oliveira, A. (2014). Origin, Domestication, and Dispersing of Pear (Pyrusspp.). Advances in Agriculture, 2014, 1-8. doi:10.1155/2014/541097Sorkheh, K., Azimkhani, R., Mehri, N., Chaleshtori, M. H., Halász, J., Ercisli, S., & Koubouris, G. C. (2018). Interactive effects of temperature and genotype on almond ( Prunus dulcis L.) pollen germination and tube length. Scientia Horticulturae, 227, 162-168. doi:10.1016/j.scienta.2017.09.037Sorkheh, K., Shiran, B., Rouhi, V., & Khodambashi, M. (2011). Influence of temperature on the in vitro pollen germination and pollen tube growth of various native Iranian almonds (Prunus L. spp.) species. Trees, 25(5), 809-822. doi:10.1007/s00468-011-0557-7Sorkheh, K., Shiran, B., Rouhi, V., Khodambashi, M., Wolukau, J. N., & Ercisli, S. (2011). Response of in vitro pollen germination and pollen tube growth of almond (Prunus dulcis Mill.) to temperature, polyamines and polyamine synthesis inhibitor. Biochemical Systematics and Ecology, 39(4-6), 749-757. doi:10.1016/j.bse.2011.06.015Stern, R. A., Goldway, M., Zisovich, A. H., Shafir, S., & Dag, A. (2004). Sequential introduction of honeybee colonies increases cross-pollination, fruit-set and yield of ‘Spadona’ pear (Pyrus communisL.). 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Indeterminacy : Thoughts on Time, the Image, and Race(ism)

"In a series of written exchanges, David Campany and Stanley Wolukau-Wanambwa consider the options for photography in resisting the oppressive orthodoxies of racial capital, conservative history, and neoliberal visual culture. How does the essential indeterminacy of photography square with the need to work out alternative practices? How is visibility achieved beyond the consensual categories of the mass media and the commodification of art? What models are there for the making and reception of photographic books and exhibitions that might cultivate an active spectatorship beyond boutique consumerism? These urgent questions and more are discussed in a spirit of speculation and possibility, in the light of signal events that have shaped the recent past." -- Back cover of document

Effect of various concentrations of Aloe vera coating on postharvest quality and shelf life of mango (Mangifera indica L.) fruits Var. ‘Ngowe’

Mango (Mangifera indica L.) is a popular and economically important tropical fruit throughout the world due to its excellent nutritional composition, eating and visual qualities. However, the fruit is highly perishable and as a result high post-harvest losses continue to be reported especially in Africa. In order to address this problem, four concentrations of Aloe vera (AG) (0, 25, 50 and 75%) and chitosan (1%) were tested at two temperature levels (room temperature and 13°C) to determine their effect on the postharvest life of mango (var.’ngowe’). The experimental design was a 5 by 2 factorial experiment embedded in a complete randomized design with three replications. Data were recorded on weight loss, pH and total soluble solids (TSS) among others. The results show that at both temperatures 50 and 75% aloe concentrations significantly increased the shelf life evidenced by reduced percentage weight loss. Fruit firmness and total soluble solids concentration and pH were also maintained for longer periods in these treatments. Findings of this study demonstrate the potential of using A. vera gel at 50% as a coating for improved postharvest shelf life and maintaining quality of mango fruits hence reduced postharvest losses.Keywords: Aloe vera gel, postharvest shelf life, mango fruit qualityAfrican Journal of Biotechnology, Vol 13(31) 3724-372

Leaf nutritional levels in peach and nectarine grown in subtropical climate

The study evaluated the leaf nutritional levels of peach and nectarine trees under subtropical climate in order to improve the fertilization practices. The experiment was carried out in São Paulo state University, Botucatu, São Paulo State, Brazil. The experimental design consisted of subdivided plots, in which plots corresponded to cultivars and subplots to the leaf sample periods. The evaluated peach cultivars were: Marli, Turmalina, Precocinho, Jubileu, Cascata 968, Cascata 848, CP 951C, CP 9553CYN, and Tropic Beauty, and that of nectarine was 'Sun Blaze'. The sample periods were: after harvest, plants in vegetative period; dormancy; beginning of flowering and fruiting (standard sample). Results indicated significant variations in the levels of N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn for the sampling period and in N, Ca, Mg, S, B, Fe and Mn levels for the cultivars