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URI permanente desta comunidadehttps://thoth.dti.ufv.br/handle/123456789/3352
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Item Anatomic and physiological modifications in seedlings of Coffea arabica cultivar Siriema under drought conditions(Editora UFLA, 2014-01) Melo, Emanuelle Ferreira; Fernandes-Brum, Christiane Noronha; Pereira, Fabrício José; Castro, Evaristo Mauro de; Chalfun-Júnior, AntonioDue to the weather changes prognostic for the coming years, the understanding of water deficit and physiological responses of plants to drought becomes an important requirement in order to develop technologies such as mechanisms to assist plants to cope with longer drought periods, which will be essential to maintenance of Brazilian and worldwide production. This study aimed to evaluate ecophysiological and anatomical aspects as well as the nitrate reductase activity in Siriema coffee seedlings subjected to four treatments: Daily irrigated, non-irrigated, re-irrigated 24 hours and re-irrigated 48 hours after different stress periods. Non-irrigation promoted a reduction in leaf water potential being accented from the ninth day of evaluation onwards. Re-irrigation promoted a partial recovery of the plant water potential. Non-irrigated plants showed an increase in stomatal resistance and reduction of transpiration and nitrate reductase activity. In the roots, there was a decrease in nitrate reductase activity under water stress. Leaf anatomical modifications were significant only for the adaxial surface epidermis and palisade parenchyma thickness, this latter characteristic being higher in control plants. Stomatal density and polar and equatorial diameter ratios showed the highest values in plants under water stress. In the roots, differences only in the cortex thickness being bigger in the non-irrigated treatment could be observed. Therefore, Siriema coffee plants under water stress show physiological, biochemical and anatomical modifications that contribute to the tolerance of this genotype to these conditions.Item Modifications in the metabolism of carbohydrates in (Coffea arabica L. cv. siriema) seedlings under drought conditions(Editora UFLA, 2013-04) Brum, Christiane Noronha Fernandes; Melo, Emanuelle Ferreira; Barquero, Luis Orlando Barboza; Alves, José Donizeti; Chalfun-Júnior, AntonioUnderstanding what mechanisms are involved in drought response in coffee plants will generate relevant information to assist breeding and/or genetic engineering to obtain new commercial varieties with drought tolerance. This research aimed at studying the effects of drought on leaf water potential, carbohydrate concentrations, and sucrose synthase and invertase activity in coffee seedlings (Coffea arabica Siriema), originating from a natural cross between C. racemosa and C. arabica Blue Mountain (Carvalho et al., 2008). Seedlings were grown in a greenhouse under non-irrigated and daily irrigated conditions. Plants were evaluated every three days until they reached the permanent wilting point or, at most. 30 days after withholding water. In addition, plants under different drought conditions (as of 30 days) were irrigated and evaluated 24 and 48 hours after water application. The non-irrigated treatment prompted a significant reduction in leaf water potential, whereas re-irrigation promoted partial recovery of plant water potential. There was a significant increase in the levels of total soluble sugars and reducing sugars, both in the leaves and roots of the non-irrigated plants. The re-irrigated plants behaved like the non-irrigated plants; however, lower levels of sugars were detected in these samples. The leaves and roots of the non- irrigated plants also showed a significant reduction in starch levels. The activity of sucrose synthase and invertase, neutral and acid enzymes, increased as a result of water stress.