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Made available in DSpace on 2021-06-25T12:17:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-01 Eucalyptus seedlings are sensitive to the interference imposed by weed community, especially during the initial growth period, which is the first year after crop establishment. Thus, this study aimed at evaluating the effect of increasing densities of Commelina benghalensis L. on the initial growth of Eucalyptus grandis Hill (ex Maiden) plants at two seasons of the year. For this, two experiments were carried out using 70 L boxes in an open and semi-controlled area: one in winter (during 90 days) and another in summer (during 120 days). Both experiments were randomized block designs with four replicates each. The treatments consisted of increasing densities of tropical spiderwort, namely: 0 (control), 4, 8, 16, 20, 28, 36, 40, 60 and 80 plants m(-2). Fifteen days after planting the tropical spiderwort seedlings, one seedling of eucalyptus was planted in the center of each box. The height, diameter, leaf area and total dry mass of eucalyptus were evaluated at the end of the experimental periods. Densities from 4 plants m(-2) negatively interfered with eucalyptus growth, reducing by 38.4% the leaf area and 35% the dry mass in winter. While in summer, we found reductions of 52.9% in the leaf area and 64.7% in the dry mass. We concluded that the density from 4 plants m(-2) interferes with the growth of eucalyptus and that the weed shows a more aggressive competitive behavior in the summer causing greater interference in the eucalyptus. Empresa Algodao, Campina Grande, Paraiba, Brazil Univ Estadual Paulista, Jaboticabal, SP, Brazil Univ Western Australia, Perth, WA, Australia Univ Estadual Paulista, Jaboticabal, SP, Brazil

Made available in DSpace on 2019-10-04T12:38:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2019-01-01. Added 1 bitstream(s) on 2021-07-15T15:23:14Z : No. of bitstreams: 1 S1980-50982019000100385.pdf: 784784 bytes, checksum: bb56192a4dc6945e108b91ae4c83b859 (MD5) Plant growth regulators and herbicides can act and modify several metabolic processes in plants. The use of sub-lethal doses of those compounds might modulate the development and growth of plants, an effect known as hormesis. Recent studies reported the stimulatory responses of sub-lethal doses of trinexapac-ethyl on the biomass accumulation and leaf area expansion of eucalypt plants. To date, there is no recommendation regarding promoting or inhibitory doses of such compounds for eucalypt production industry. Thus, this work aims to investigate the effect of trinexapac-ethyl on the establishment and initial growth of Eucalyptus urograndis seedlings. Trinexapacethyl was applied at doses varying 15 to 90 g (plus a control treatment) per hectare of active ingredient (g a.i. ha(-1)) in two application methods: spraying and root immersion. The doses of 15 g a.i. ha(-1) through spraying and the 30 g a.i. ha(-1) in root immersion resulted in a positive effect on the growth of Eucalyptus urograndis Clone GG100. Total dry biomass increased by 74.6% and 12.8%, respectively, compared to control plants. The spraying of 15 to 90 g a.i. ha(-1) of trinexapax-ethyl resulted in a stimulatory effect on the growth of eucalyptus. The doses of 15 and 30 g a.i. ha(-1) via root immersion provided a positive effect on the all evaluated characteristics of eucalyptus. The dose of 90 g a.i. resulted in an inhibitory effect on eucalyptus growth through root immersion at 35 days after the trinexapac-ethyl application. Univ Western Australia, Fac Sci, Sch Biol Sci, Plant Sci, 35 Stirling Highway, Perth, WA 6009, Australia Univ Estadual Paulista, Fac Ciencias Agr & Vet, Prod Vegetal, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Biol Aplicada Agr, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Prod Vegetal, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil Univ Estadual Paulista, Fac Ciencias Agr & Vet, Dept Biol Aplicada Agr, Via Acesso Prof Paulo Donato Castellane S-N, BR-14884900 Jaboticabal, SP, Brazil