Water availability is a limiting factor for the establishment and development of forest species.To understand the appropriate conditions for the initial post-transplanting phase,it is necessary to understand the speci...Water availability is a limiting factor for the establishment and development of forest species.To understand the appropriate conditions for the initial post-transplanting phase,it is necessary to understand the specific morphophysiological characteristics of the species,such as the leaf water potential and the efficiency of photosystemⅡ.We aimed to identify the influence of different water regimes on the morphophysiological aspects of young plants of two forest species(Cedrela.fissilis Vellozo and Eucalyptus saligna Sm.).Two greenhouse experiments were conducted for 28 days;one for each species.The design was completely randomized,and the treatments consisted of six different water regimes.Leaf water potential(Ψw)and chlorophyll a fluorescence were evaluated every 7 days.At the end of the experiment,morphological attributes(height,collection diameter,root volume,and dry matter)were measured and histological blades were made.The water demand of E.saligna was higher than that of C.fissilis and required greater replacement within a shorter period.The rehydration fromΨw=-2 Mpa allowed for a fast recovery of the young C.fissilis plants(Ψw=-1.5,Fv/Fm=0.796),which indicated good physiological plasticity of this species when submitted to water stress at a level that is not severe.The total dry matter allocation was different among species.Seedlings of E.saligna presented the best responses when submitted to a continuous water supply regime,while C.fissilis seedlings presented the best response under intermittent irrigation conditions.展开更多
Eucalyptus clones are selected according to productivity,wood quality,rooting capacity,and resistance to drought,frost and diseases.However,kinetic and morphological parameters that determine the absorption efficiency...Eucalyptus clones are selected according to productivity,wood quality,rooting capacity,and resistance to drought,frost and diseases.However,kinetic and morphological parameters that determine the absorption efficiency of nutrients such as nitrate(NO_(3)^(-)) and ammonium(NH_(4)^(+))are often not considered in breeding programs.The objective of this study was to evaluate the morphological,physiological and kinetic parameters of nitrogen uptake by clones of Eucalyptus saligna(32,864) and Eucalyptus grandis(GPC23).Morphological parameters in shoot and root systems,biomass and N concentrations in different organs,photosynthetic pigment concentrations,parameters of chlorophyll a fluorescence and photosynthetic rates were evaluated.Kinetic parameters,maximum absorption velocity(V_(max)),Michaelis-Menten constant(K_(m)),minimum concentration(C_(min)) and influx(I) were calculated for NO_(3)^(-)and NH_(4)^(+) in the two clones.E.granais clone was more efficient in the uptake of NO_(3)^(-)and NH_(4)^(+),and showed lower K_(m) and C_(min)values,allowing for the absorption of nitrogen at low concentrations due to the high affinity of the absorption sites of clone roots to NO_(3)^(-)and NH_(4)^(+).Higher root lengths,area and volume helped the E.grandis clone in absorption efficiency and consequently,resulted in higher root and shoot biomass.The E.saligna clone had higher K_(m) and Cmin for NO_(3)^(-)and NH_(4)^(+),indicating adaptation to environments with higher N availability.The results of NO_(3)^(-)and NH_(4)^(+) kinetic parameters indicate that they can be used in Eucalyptus clone selection and breeding programs as they can predict the ability of clones to absorb NO_(3)^(-)and NH_(4)^(+) at different concentrations.展开更多
Chemical composition of the essential oils (EOs) is dependent on the plant species and varieties, and within the same variety, from geographical region. Knowledge of the factors that determine the chemical variability...Chemical composition of the essential oils (EOs) is dependent on the plant species and varieties, and within the same variety, from geographical region. Knowledge of the factors that determine the chemical variability and yield for each species are very important in particular for commercially important species, to optimize the conditions that may affect yields and quality of essential oils. In addition to the commercial importance of the variability in yield and composition, the possible changes are also important when the essential oils and volatiles are used as chemotaxonomic tools. Therefore it is important to characterize essential oils native to Tanzania for commercial and therapeutic purpose. In the present study we investigated the variation in the yield and chemical composition of the essential oils isolated from air dried leaves of three Eucalyptus species namely Eucalyptus saligna, Eucalyptus citriodora and Eucalyptus camaldulensis collected from two different regions of Tanzania namely Morogoro and Lushoto. The steam-distilled essential oil content of E. saligna, E. citriodora and E. camaldulensis Morogoro were 0.6%(v/w), 1.68%(v/w) and 0.80%(v/w) respectively while from Lushoto are 0.30%, 1.22 and 0.36%(v/w) respectively. Using GC/MS,α-pinene (46.72%) and p-cymene (43.61%) were identified as the most abundant chemical constituents of E. saligna from Morogoro and Lushoto respectively. Citronellal (82.24% and 60.41% respectively) is the main constituents of E. citriodora from Morogoro and Lushoto respectively while p-cymene (52.59% and 64.02%) is the main constituents of E. camaldulensis.展开更多
基金supported by the Council for Scientific and Technological Development(CNPq)the Coordination for the Improvement of Education Personnel(CAPES)。
文摘Water availability is a limiting factor for the establishment and development of forest species.To understand the appropriate conditions for the initial post-transplanting phase,it is necessary to understand the specific morphophysiological characteristics of the species,such as the leaf water potential and the efficiency of photosystemⅡ.We aimed to identify the influence of different water regimes on the morphophysiological aspects of young plants of two forest species(Cedrela.fissilis Vellozo and Eucalyptus saligna Sm.).Two greenhouse experiments were conducted for 28 days;one for each species.The design was completely randomized,and the treatments consisted of six different water regimes.Leaf water potential(Ψw)and chlorophyll a fluorescence were evaluated every 7 days.At the end of the experiment,morphological attributes(height,collection diameter,root volume,and dry matter)were measured and histological blades were made.The water demand of E.saligna was higher than that of C.fissilis and required greater replacement within a shorter period.The rehydration fromΨw=-2 Mpa allowed for a fast recovery of the young C.fissilis plants(Ψw=-1.5,Fv/Fm=0.796),which indicated good physiological plasticity of this species when submitted to water stress at a level that is not severe.The total dry matter allocation was different among species.Seedlings of E.saligna presented the best responses when submitted to a continuous water supply regime,while C.fissilis seedlings presented the best response under intermittent irrigation conditions.
基金funded partly by the Conselho Nacional de Desenvolvimento Científico and Tecnológico(CNPq)。
文摘Eucalyptus clones are selected according to productivity,wood quality,rooting capacity,and resistance to drought,frost and diseases.However,kinetic and morphological parameters that determine the absorption efficiency of nutrients such as nitrate(NO_(3)^(-)) and ammonium(NH_(4)^(+))are often not considered in breeding programs.The objective of this study was to evaluate the morphological,physiological and kinetic parameters of nitrogen uptake by clones of Eucalyptus saligna(32,864) and Eucalyptus grandis(GPC23).Morphological parameters in shoot and root systems,biomass and N concentrations in different organs,photosynthetic pigment concentrations,parameters of chlorophyll a fluorescence and photosynthetic rates were evaluated.Kinetic parameters,maximum absorption velocity(V_(max)),Michaelis-Menten constant(K_(m)),minimum concentration(C_(min)) and influx(I) were calculated for NO_(3)^(-)and NH_(4)^(+) in the two clones.E.granais clone was more efficient in the uptake of NO_(3)^(-)and NH_(4)^(+),and showed lower K_(m) and C_(min)values,allowing for the absorption of nitrogen at low concentrations due to the high affinity of the absorption sites of clone roots to NO_(3)^(-)and NH_(4)^(+).Higher root lengths,area and volume helped the E.grandis clone in absorption efficiency and consequently,resulted in higher root and shoot biomass.The E.saligna clone had higher K_(m) and Cmin for NO_(3)^(-)and NH_(4)^(+),indicating adaptation to environments with higher N availability.The results of NO_(3)^(-)and NH_(4)^(+) kinetic parameters indicate that they can be used in Eucalyptus clone selection and breeding programs as they can predict the ability of clones to absorb NO_(3)^(-)and NH_(4)^(+) at different concentrations.
文摘Chemical composition of the essential oils (EOs) is dependent on the plant species and varieties, and within the same variety, from geographical region. Knowledge of the factors that determine the chemical variability and yield for each species are very important in particular for commercially important species, to optimize the conditions that may affect yields and quality of essential oils. In addition to the commercial importance of the variability in yield and composition, the possible changes are also important when the essential oils and volatiles are used as chemotaxonomic tools. Therefore it is important to characterize essential oils native to Tanzania for commercial and therapeutic purpose. In the present study we investigated the variation in the yield and chemical composition of the essential oils isolated from air dried leaves of three Eucalyptus species namely Eucalyptus saligna, Eucalyptus citriodora and Eucalyptus camaldulensis collected from two different regions of Tanzania namely Morogoro and Lushoto. The steam-distilled essential oil content of E. saligna, E. citriodora and E. camaldulensis Morogoro were 0.6%(v/w), 1.68%(v/w) and 0.80%(v/w) respectively while from Lushoto are 0.30%, 1.22 and 0.36%(v/w) respectively. Using GC/MS,α-pinene (46.72%) and p-cymene (43.61%) were identified as the most abundant chemical constituents of E. saligna from Morogoro and Lushoto respectively. Citronellal (82.24% and 60.41% respectively) is the main constituents of E. citriodora from Morogoro and Lushoto respectively while p-cymene (52.59% and 64.02%) is the main constituents of E. camaldulensis.
