Germinação e crescimento do capim raiz (chloris orthonothon doell) /
Abstract:Chloris orthonothon Doell seeds were collected at Fazenda Bom Fim, in São Caetano - PE, and stored for 7 months at 15°C and 55% relative humidity in a cold chamber. During this whole period the germination rate was close to zero. To break dormancy, the seeds were immersed in concent...
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| Formato: | Dissertação |
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| Endereço do item: | https://app.bczm.ufrn.br/home/#/item/191206 |
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| Resumo: | Abstract:Chloris orthonothon Doell seeds were collected at Fazenda Bom Fim, in São Caetano - PE, and stored for 7 months at 15°C and 55% relative humidity in a cold chamber. During this whole period the germination rate was close to zero. To break dormancy, the seeds were immersed in concentrated sulphuricacid for 0, 30, 45, 60, 90, and 120 seconds. Immersion for 45 to 90 seconds resulted in 29,5% germination, with rates decreasing with the longer treatment. Seeds were also scarified by cutting their tips, opposite to rootlet emergence site, with a razor blade. Maintaining these seeds in the dark, after scarification, resulted in 40% germination while irradia ting them with red light increased germination to 75,5%. This later effect was reversed by far-red light (50,5% germination) which was reversed again by red light (92,5% germination), demonstrating that the phytochrome is envolved in the germina¬tion of Chlofil& orthonothon Doell seeds. Scarified seeds which were placed in 40°C water for 30 minutos and maintained in the dark presented germination rates of 64%, indicating that the light requirement can be substituted by a thermal shock. Chloris ortkcnotkon Doell plants were submited to 10 different clipping frequency treatments by combining clipping intervals ranging from 21 to 105 days. Plant height and number to tillers, stolons and inflorescences were deter¬mined at each clipping date. Rates of dry matter accumula¬tion were highest during the first 21 day growing period and decreased gradually in subsequent periods but in such a way that total production was not different for most treatments . The only statistically significant difference was observed between the treatment with three 21 day clipping intervals followed by one 63 day interval and the treatment with one 105 day interval followed by one 21 day interval. Inflores-cence and stolon numbers were very low, reaching a maximum of 10% of all plants, in those clipped after 105 days, probably due to the high clipping pressure. There were no differences in tiller numbers among all treatments. Protein content de¬creased gradually with longer interval while carbohydrate contents remained stable for 63 days, decreasing thereafter. |
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