Loblolly pine (Pinus taeda) and coppiced sweetgum (Liquidambar styraciflua) seedlings were grown in competition with a native weed community using soil and seed bank collected near Appomattox, Virginia. Seedlings and weeds were exposed to CO₂ (ambient and elevated) and water (water stressed and well watered) treatments for approximately one growing season in closed top chambers. Weed growth had an effect on tree growth, but the amount of variation in tree biomass explained by weed biomass was very low. It appears that the tree seedlings benefited more from available resources than the herbaceous weeds. The influence of competition with loblolly pine and elevated CO₂ did not have an influence on total weed biomass; however, it did favor C3 weed community development regardless of water availability. This suggests that weed community composition may shift toward C₃ plants in a future elevated CO₂ atmosphere. Loblolly pine height, diameter, needle, shoot and total biomass were significantly greater in the well watered treatment than the water stressed treatment. Pine root, needle, shoot and total biomass were significantly greater in the elevated treatment than the ambient treatment. While not significant, root biomass of water stressed pine seedlings was 63% greater in the elevated CO₂ treatment than the ambient treatment. There was a significant water and CO₂ interaction for pine root:shoot ratio. Under elevated CO₂, root:shoot ratio was significantly greater in the water stressed treatment than the well watered treatment. In contrast, root:shoot ratio in the ambient treatment was nearly identical under both water treatments. These results indicate that loblolly pine will respond favorably in an elevated CO₂ atmosphere, even under dry conditions. The coppiced sweetgum seedlings responded favorably to well watered conditions with significant increases in leaf area, specific leaf area, leaf, shoot and total biomass compared to water stressed conditions. Leaf, root, shoot+stump and total biomass of sweetgum significantly increased and specific leaf area decreased under elevated CO₂ compared to ambient CO₂, but differences were smaller than previous findings. This indicates that coppicing may dampen the growth response to elevated CO₂, at least in the initial growth stage after coppicing. / Master of Science

Made available in DSpace on 2015-04-11T13:56:14Z (GMT). No. of bitstreams: 1 DISSERTACAO-ODILUZA DE OLIVEIRA.pdf: 463456 bytes, checksum: 4659db769076ee8a7caffb16c2fd8abe (MD5) Previous issue date: 2010-02-26 / Fundação de Amparo à Pesquisa do Estado do Amazonas / This study aimed to determine the period of Weed on three cultivars of cowpea (Vigna unguiculata (L.) Walp) in floodplain in the State of Amazonas. The sowing of cowpea was in October 2007 in the conventional system. The experimental design was a randomized complete block with four replications, arranged in subplots. The plots consisted of eleven periods of coexistence between cowpea and weeds at 0, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days after sowing, after these periods, weeds were removed weekly.. Subplots were placed cultivars EV x 91-2E-2, IPEAN V69 e BR8 Caldeirão. The interference of weeds throughout the life cycle of cowpea reduced the final stand, the number of pods per plant, weight of 1000 grains. The yield of genotypes EV x 91-2E-2, BR8 Caldeirão, IPEAN V69, was reduced by 59,78; 68,18 and 90.18% respectively. The period before the interference was 0 to 5 days after sowing for the cultivar BR IPEAN V69 while for the cultivars BR8 Caldeirão and EV x 91-2E-2 was 6 and 7 of, respectively. / Este trabalho teve o objetivo de determinar o período de convivência das plantas daninhas com três genótipos de feijão-caupi (Vigna unguiculata (L.) Walp) em solo de várzea no Estado do Amazonas. A semeadura do feijão-caupi foi em outubro de 2007 no sistema convencional. O delineamento experimental foi o de blocos casualizados com quatro repetições, arranjados em subparcelas. As parcelas foram constituídas por onze períodos de convivência entre o feijão-caupi e as plantas daninhas de 0, 7, 14, 21, 28, 35, 42, 49, 56, 63 e 70 dias após sua semeadura, depois desses períodos, as plantas daninhas foram eliminadas semanalmente por capina. Nas subparcelas foram colocados os genótipos EV x 91-2E-2, IPEAN V69 e BR8 Caldeirão. A interferência das plantas daninhas durante todo o ciclo de vida do feijão-caupi reduziu o estande final, o número de vagens por planta, o peso de 1000 grãos. A produtividade dos genótipos EV x 91-2E-2, BR8 Caldeirão, BR IPEAN V69 foi reduzida em 59,78; 68,18 e 90,18%, respectivamente. O Período anterior a interferência foi de 0 a 5 dias após a semeadura para o cultivar IPEAN V69. Para os genótipos BR8 Caldeirão e EV x 91-2E-2 foi 0 a 6 e 7 DAS, respectivamente.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-08-15T12:16:42Z No. of bitstreams: 2 Dissertação - Janaína de Assis Silva - 2017.pdf: 1125529 bytes, checksum: db2bd96979a55f5960d44d645ef02e20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-08-15T12:17:12Z (GMT) No. of bitstreams: 2 Dissertação - Janaína de Assis Silva - 2017.pdf: 1125529 bytes, checksum: db2bd96979a55f5960d44d645ef02e20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-08-15T12:17:12Z (GMT). No. of bitstreams: 2 Dissertação - Janaína de Assis Silva - 2017.pdf: 1125529 bytes, checksum: db2bd96979a55f5960d44d645ef02e20 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-07-14 / The objective of this study was to evaluate the interference of weeds in corn crop, cultivated on two spacings, under no-tillage system, in order to determine the periods of infesting community interference. The trial was conducted at Federal University of Goiás, Regional Jataí. The experimental design was randomized blocks in a split-split plot design with three replications. The row spacings of plots were (0.45 and 0.90 m). The subplots were coexistence groups (with and without bush) and the split-split plots were seven periods of coexistence or control of the weed community (0, 10, 20, 30, 40, 60 and 120 DAE). Weed control was performed by manual weeding. The weed community was evaluated by density and floristic composition. Plant height, cob insertion height, cob diameter, cob length, number of rows per cob, number of grains per row and grain yield were evaluated. In corn plants, it was verified that there coexistence with weeds was significant difference for cob insertion height, cob length and number of rows per cob. The 0.90 m row spacing provided a longer cob length. Interference periods (PAI, PCPI, PTPI) were not possibel determined for Feroz Vip at short season under two spacings / Objetivou-se avaliar a interferência das plantas daninhas na cultura do milho, cultivado em segunda safra com dois espaçamentos, sob sistema de plantio direto, a fim de determinar os períodos de interferência da comunidade infestante sobre a cultura. A pesquisa foi conduzida na Universidade Federal de Goiás, Regional Jataí. O delineamento experimental adotado foi o de blocos ao acaso em esquema de parcelas subsubdivididas com três repetições. As parcelas foram compostas pelos espaçamentos (0,45 e 0,90 m). As subparcelas pelos grupos de convivência (Com e Sem Mato) e as subsubparcelas por sete períodos de capina manual da comunidade infestante (0, 10, 20, 30, 40, 60 e 120 DAE). A comunidade infestante foi avaliada por meio da densidade e composição florística. Avaliou-se altura de plantas, altura de inserção de espiga, diâmetro de espiga, comprimento de espiga, número de fileiras de grãos por espiga, número de grãos por fileira e produtividade de grãos. Na pesquisa foi verificado que a convivência com as plantas daninhas interferiu de forma negativa a altura de inserção de espiga e o número de fileiras por espiga. O espaçamento 0,90 m proporcionou maior comprimento de espiga. Não foi possível determinar os períodos de interferência (PAI, PTPI, PCPI) para o híbrido Feroz Vip cultivado no período de segunda safra sob dois espaçamentos.