Caracterização morfofisiológica de cultivares de sorgo sacarino em estresse hídrico

• Ano de defesa: 2011
• Autor(a) principal: Moreira, Luciano Rezende
• Orientador(a): Miranda, Glauco Vieira
• Banca de defesa: Oliveira, Lucimar Rodrigues de , Souza, Moacil Alves de , Ogliari, Juares , Berger, Paulo Geraldo
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Doutorado em Fitotecnia
• Departamento: Plantas daninhas, Alelopatia, Herbicidas e Resíduos; Fisiologia de culturas; Manejo pós-colheita de
• País: BR
• Palavras-chave em Português: Estresse de seca; WinRhizo; Sorgo sacarino
• Palavras-chave em Inglês: Drought stress; WinRhizo; Saccharine sorghum
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA
• Link de acesso: http://locus.ufv.br/handle/123456789/1173

The sorghum [Sorghum bicolor (L.) Moench] is a species from which the diversity center is located on northern Africa and presents high efficiency in using water. The sweet sorghum is used as raw material for bioenergy (ethanol), and it is a good alternative in relation to the use of the sugarcane and also as option for the microdistilleries located in areas with low pluviometric index due to its high juice production in those conditions. The tolerance of this species to the drought can be due to both morphologic and physiologic characters of either root system and aerial part of the plant. So, this study was carried out to characterize the morphologic, physiologic and agronomic aspects related to the plant and to the crop as well as to identify the genotypes of the sweet sorghum that are adapted to hydric deficit conditions. Four experiments were accomplished during the period from July 2009 and March 2011 in the Universidade Federal de Viçosa (UFV). The entirely randomized experimental design was used and the sorghum cultivars were Rio, Ramada, BRS 501 and BRS 506. In the first experiment, the morphological parameters of those four genotypes were evaluated for tolerance to the drought stress. The experiment was set up under greenhouse conditions and the vases with soil contained the plots. It was possible to analyze, to characterize and to quantify the sorghum roots with more reliability, mainly for precocious evaluation of the root system, by using the analytical system of digital images WinRhizo. In this experiment, no morphological variations that would explain the difference among genotypes were verified. In the second experiment also set up under greenhouse conditions and the vases fulfilled with soil , it was aimed to establish the ideal water depth available in the soil to characterize the water deficit. This water deficit was used to characterize the cultivars that are tolerant to drought. At the initial development phase of the BRS 501 cv., the irrigation effects on the root conformation were evaluated. It was concluded the growth of the plants to be sensible to the decrease of water in the soil, as being strongly affected by low water availability. The methodology showed to be viable for the other experiments from which the purpose was to discriminate the sorghum cultivars that are tolerant to drought. In this sequence, the third experiment was carried out to characterize the sweet sorghum cultivars for their physiological characteristics at different irrigation levels tested in the previous experiment. The water availability caused no alterations in the perspiration of the cultivars Ramada and BRS 501, but it affected the cultivars Rio and BRS 506 that presented a positive response to the increased irrigation. Similar result occurred with photosynthesis, in which the different levels of water availability positively affected only the cultivars Rio and BRS 506. With the increased irrigation, there was an increment in the stoma conductance of the cultivars under evaluation. The results concerning to fluorescence of the chlorophyll showed superiority of the cultivars BRS 506, Rio and Ramada. Finally, the last experiment discriminated the sweet sorghum cultivars through evaluation of the morphological characteristics, aerial part and root system at four irrigation levels. The increase of the irrigation altered the morphological aspects of either roots and aerial part among cultivars in several characters under evaluation. The use of the digital image analysis technique showed to be a promising tool for studies of the sorghum roots, since it allows to discriminate the morphological attributes at precocious phase of the crop.