O objetivo deste trabalho foi avaliar a capacidade de plantas jovens de mogno-africano (Khaya ivorensis) em recuperar seu status hídrico e trocas gasosas após período de deficit hídrico. Plantas com aproximadamente 315 dias, irrigadas (controle) e não irrigadas, foram avaliadas aos 14 dias da suspensão da irrigação e após um, três e sete dias da retomada da irrigação (reidratação). No dia 14, o potencial hídrico foliar de antemanhã (Ψam) das plantas estressadas foi reduzido a -2,66 MPa. Com a restrição hídrica, foram observadas reduções significativas no conteúdo relativo de água na antemanhã (redução de 32%), na taxa de assimilação líquida de CO2 (90%), na condutância estomática (95%), na transpiração (93%) e na razão entre concentração intercelular e ambiental de CO2 (37%). Durante a reidratação, o status hídrico das plantas estressadas foi restabelecido após três dias. As trocas gasosas também se restabeleceram, mas de forma mais lenta que o status hídrico. Sob deficit hídrico, a concentração de prolina aumentou e a de carboidratos solúveis totais diminuiu. Plantas jovens de mogno-africano são tolerantes ao deficit hídrico moderado.
The present work proposed an evaluation of the physiological performance, yield and chemical profile of the essential oil obtained from leaves and roots of Eryngium foetidum L. (Apiaceae) cultivated using different fertilizer sources. The other gas exchange and chlorophyll a fluorescence parameter was not different, suggested that the photosystem II was not affected by the different fertilizer sources. Highest essential oil yield was obtained in leaf samples cultivated with the mineral fertilizer (0.18 %) and control conditions (0.22%), while it was obtained by mineral fertilization in the case of root samples (0.22%). The principal component analysis -PCA and hierarchical cluster analysis -HCA showed two groups: the first was formed by roots (OrgR, MinR and ConR), characterized by the constituents 2,3
The hypothesis that application of exogenous glycine betaine (GB EX ) may attenuate the effects of mild water deficit in leaf gas exchange and lipid peroxidation in Carapa guianensis was examined. For this reason, 110-d old plants were sprayed with 0, 25, and 50 mM GB EX and then subjected to two watering regimes. In the first, irrigation was continuously performed to maintain the soil near to field capacity (watered plants). In the second, irrigation was withheld and water deficit resulted from progressive evapotranspiration (water-stressed plants). Treatment comparisons were assessed when predawn leaflet water potential (Ψ pd ) of stressed plants reached -1.28 ± 0.34 MPa. Regardless of the watering regime, significant (P<0.05) increases in foliar glycine betaine (GB Leaf ) concentration were observed in response to increasing GB EX ; however, such increases were more expressive in stressed plants. The net photosynthetic rate, stomatal conductance to water vapor, and intercellular to ambient CO 2 concentration ratio were significantly lower in water-stressed plants independently of GB EX concentration sprayed on leaves. The application of 25 and 50 mM GB EX caused significant (P<0.05) increases in ascorbate peroxidase (APX) activity in stressed plants, while significant (P<0.05) increases in catalase activity was observed just in the stressed plants treated with 50 mM GB EX . Malondialdehyde concentrations did not differ between watered and stressed plants regardless of GB EX concentration. In conclusion, C. guianensis was able to incorporate GB EX through their leaves and the resulting increases in GB Leaf attenuated lipid peroxidation in stressed plants through positive modulation of APX and CAT activities.
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