A non destructive method to estímate leaf area of prairie grass (<i>Bromus catharticus Vahl</i>)

El área de las láminas foliares de tas plantas es un parámetro útil en estudios fisiológicos y agronómicos. El objetivo del presente trabajo fue obtener un método no destructivo para calcular el área foliar de la cebadilla criolla mediante la m edición del ancho máximo (W) y del largo (L) de la lámina. Se emplearon hojas extraídas de plantas en distintos estados fenológicos y rebrotadas, cultivadas en macetas de 30 dm3 o en el campo. Se eligió como modelo el área del rectángulo (W.L) corregida por un coeficiente (cp = 0,7631) calculado como el promedio de los coeficientes de corrección por hoja (cp = c M'1) donde c es la relación entre el área medida (A) y el producto del ancho máximo por el largo de la lámina foliar [c = A (W .L)'1] y N es el número de láminas (N = 348). La regresión entre el área estimada (Ae) como Ae = 0,7631 W.L y el área medida de cada lámina dió una recta cuya pendiente fue de 1. El modelo fue también satisfactorio para estimar el área foliar de plantas no defoliadas o provenientes de defoliadas a fines del invierno. Ambos tratamientos fueron realizados en el campo con mayor densidad de siembra que en el diseño que dió origen al modelo.Se requerirán otros coeficientes para estimar el área foliar si las láminas difieren en su geometría de las del modelo original. Este fue el caso de las hojas provenientes de plantas rebrotadas hacia mediados o fines de la primavera y, frecuentemente, de la hoja bandera de plantas no defoliadas cuyos coeficientes fueron menores de 0,7631.Plant leaf area is a useful parameter in physiological and agronomic research The objective of the present study was to obtain a non-destructive model for estimating leaf blade areas in prairie grass plants from two easily measurables variables máximum width (W) and length (L). Leaves from plants grown in pots at different stages of maturity and non-defoliated or defoliated from a field plot were employedThe area of the rectangle (W.L) corrected by the coefficient mean cp (c p = 07 6 31 ) was the chosen modeh Coefficient cpwas the mean of the correction coefficients c (cp = c N '1) Ihat was the ratio between the measured area (A) and the product of máximum width and length of each blade [c = A (W .L)'1] and N was the number of blades (N = 348). The regression model between the estimated area (Ae = 0.7631 W.L) and the measured area of each blade provided an excellent fit to the data for non- defoliated plants. The model was succesfully validated with data sampled from non- defoliated or late winter defoliated plants in the field plot including different plant densities than those of the original model.However, different coefficients may be need calcúlale if leaf lamina geometry was different from the original model, such as leaves sampled in defoliated plants sprouted in mid or late spring and, frequently, from flag leaves clipped in non-defoliated ones.Facultad de Ciencias Agrarias y Forestale

A non destructive method to estímate leaf area of prairie grass (<i>Bromus catharticus Vahl</i>)

El área de las láminas foliares de tas plantas es un parámetro útil en estudios fisiológicos y agronómicos. El objetivo del presente trabajo fue obtener un método no destructivo para calcular el área foliar de la cebadilla criolla mediante la m edición del ancho máximo (W) y del largo (L) de la lámina. Se emplearon hojas extraídas de plantas en distintos estados fenológicos y rebrotadas, cultivadas en macetas de 30 dm3 o en el campo. Se eligió como modelo el área del rectángulo (W.L) corregida por un coeficiente (cp = 0,7631) calculado como el promedio de los coeficientes de corrección por hoja (cp = c M'1) donde c es la relación entre el área medida (A) y el producto del ancho máximo por el largo de la lámina foliar [c = A (W .L)'1] y N es el número de láminas (N = 348). La regresión entre el área estimada (Ae) como Ae = 0,7631 W.L y el área medida de cada lámina dió una recta cuya pendiente fue de 1. El modelo fue también satisfactorio para estimar el área foliar de plantas no defoliadas o provenientes de defoliadas a fines del invierno. Ambos tratamientos fueron realizados en el campo con mayor densidad de siembra que en el diseño que dió origen al modelo.Se requerirán otros coeficientes para estimar el área foliar si las láminas difieren en su geometría de las del modelo original. Este fue el caso de las hojas provenientes de plantas rebrotadas hacia mediados o fines de la primavera y, frecuentemente, de la hoja bandera de plantas no defoliadas cuyos coeficientes fueron menores de 0,7631.Plant leaf area is a useful parameter in physiological and agronomic research The objective of the present study was to obtain a non-destructive model for estimating leaf blade areas in prairie grass plants from two easily measurables variables máximum width (W) and length (L). Leaves from plants grown in pots at different stages of maturity and non-defoliated or defoliated from a field plot were employedThe area of the rectangle (W.L) corrected by the coefficient mean cp (c p = 07 6 31 ) was the chosen modeh Coefficient cpwas the mean of the correction coefficients c (cp = c N '1) Ihat was the ratio between the measured area (A) and the product of máximum width and length of each blade [c = A (W .L)'1] and N was the number of blades (N = 348). The regression model between the estimated area (Ae = 0.7631 W.L) and the measured area of each blade provided an excellent fit to the data for non- defoliated plants. The model was succesfully validated with data sampled from non- defoliated or late winter defoliated plants in the field plot including different plant densities than those of the original model.However, different coefficients may be need calcúlale if leaf lamina geometry was different from the original model, such as leaves sampled in defoliated plants sprouted in mid or late spring and, frequently, from flag leaves clipped in non-defoliated ones.Facultad de Ciencias Agrarias y Forestale

Características anatômicas e fisiológicas de dois cultivares argentinos de trigo

Dois cultivares argentinos de trigo (Triticum aestivium L), Buck Cencerro (BC), com germoplasma tradicional e Buck Pucará (BP), com germoplasma mexicano, foram pesquisados para comparar as características anatômicas e fisiológicas da folha bandeira medida no espigamento (estádio E59), na antese (estádio E69) e na fase de grão aquoso completo (estádio E71). Nos dois cultivares, a taxa fotossintética foi semelhante no mesmo estágio fenológico, exceto no E71. As médias no estádio E59 foram superiores às dos estágios E69 e E71 nos dois cultivares (22,70; 18,40 e 10,40 mmol m- 2 s-1 para o BP e 23,82; 18,41 e 8,28 mmol m-2 s-1 para o BC, respectivamente). Nos três estádios, as taxas de transpiração foram maiores no BP (5,0; 5,6 e 4,89 mmol m-2 s-1) comparado ao BC (3,3; 4,4 e 2,57 mmol m-2 s-1). Consequentemente, a eficiência de uso instantâneo de água foi maior no BC, quando comparado com o BP. Não foram observadas diferenças de área foliar específica para cultivares e estádios fenológicos (área do mesófilo por unidade de massa), determinada por adsorção física de nitrogênio a baixa temperatura (78° K), registrando-se média geral de 8,9 m2 g-1. Esse valor foi semelhante a outros reportados em trabalhos prévios com T. aestivum L. e maiores que os determinados para Ligustrum lucidum Aiton, pela mesma técnica. As diferenças podem ser atribuídas à rugosidade da parede celular e as próprias dimensões da célula. Não houve correlação positiva entre área específica e taxa fotossintética para cultivares ou estádios fenológicos.Two Argentine field grown wheat cultivars (Triticum aestivum L.), Buck Cencerro (BC) with traditional germoplasm, and Buck Pucará (BP) with Mexican germoplasm, have been investigated in order to compare anatomical and physiological characteristics of the flag leaf measured in heading (stage E59), anthesis (stage E69) and kernel water ripe (stage 71). In both cultivars, photosynthetic rate was not different for the same phenological stage, except for E71. Averages in stage E59 were higher than stages E69 and E71 for both cultivars (22.70, 18.40 and 10.40 μmol m-2 s-1 for BP and 23.82, 18.41 and 8.28 μmol m-2 s-1 for BC, respectively). Transpiration rates were higher in BP (5.0, 5.6 and 4.89 mmol m-2 s-1) than BC (3.3, 4.4 and 2.57 mmol m-2 s-1) for stages E59, E69 and E71, respectively. Consequently, instantaneous water use efficiencies were higher in BC than in BP. No difference between cultivars and phenological stages was observed in specific surface area (mesophyll area per unit mass) determined by physical adsorption of nitrogen at low temperature (78° K); the mean was 8.9 m2 g- 1. It was similar as values found in previous works, in others T. aestivum L. and greater than the values found for Ligustrum lucidum Aiton, by the same technique. Differences could be attributed to the roughness of the cell wall and the dimensions of the cell itself. No positive correlation between specific surface and photosynthetic rate was observed neither for cultivars nor for phenological stages.Facultad de Ciencias Agrarias y Forestale

Características anatômicas e fisiológicas de dois cultivares argentinos de trigo

Dois cultivares argentinos de trigo (Triticum aestivium L), Buck Cencerro (BC), com germoplasma tradicional e Buck Pucará (BP), com germoplasma mexicano, foram pesquisados para comparar as características anatômicas e fisiológicas da folha bandeira medida no espigamento (estádio E59), na antese (estádio E69) e na fase de grão aquoso completo (estádio E71). Nos dois cultivares, a taxa fotossintética foi semelhante no mesmo estágio fenológico, exceto no E71. As médias no estádio E59 foram superiores às dos estágios E69 e E71 nos dois cultivares (22,70; 18,40 e 10,40 mmol m- 2 s-1 para o BP e 23,82; 18,41 e 8,28 mmol m-2 s-1 para o BC, respectivamente). Nos três estádios, as taxas de transpiração foram maiores no BP (5,0; 5,6 e 4,89 mmol m-2 s-1) comparado ao BC (3,3; 4,4 e 2,57 mmol m-2 s-1). Consequentemente, a eficiência de uso instantâneo de água foi maior no BC, quando comparado com o BP. Não foram observadas diferenças de área foliar específica para cultivares e estádios fenológicos (área do mesófilo por unidade de massa), determinada por adsorção física de nitrogênio a baixa temperatura (78° K), registrando-se média geral de 8,9 m2 g-1. Esse valor foi semelhante a outros reportados em trabalhos prévios com T. aestivum L. e maiores que os determinados para Ligustrum lucidum Aiton, pela mesma técnica. As diferenças podem ser atribuídas à rugosidade da parede celular e as próprias dimensões da célula. Não houve correlação positiva entre área específica e taxa fotossintética para cultivares ou estádios fenológicos.Two Argentine field grown wheat cultivars (Triticum aestivum L.), Buck Cencerro (BC) with traditional germoplasm, and Buck Pucará (BP) with Mexican germoplasm, have been investigated in order to compare anatomical and physiological characteristics of the flag leaf measured in heading (stage E59), anthesis (stage E69) and kernel water ripe (stage 71). In both cultivars, photosynthetic rate was not different for the same phenological stage, except for E71. Averages in stage E59 were higher than stages E69 and E71 for both cultivars (22.70, 18.40 and 10.40 μmol m-2 s-1 for BP and 23.82, 18.41 and 8.28 μmol m-2 s-1 for BC, respectively). Transpiration rates were higher in BP (5.0, 5.6 and 4.89 mmol m-2 s-1) than BC (3.3, 4.4 and 2.57 mmol m-2 s-1) for stages E59, E69 and E71, respectively. Consequently, instantaneous water use efficiencies were higher in BC than in BP. No difference between cultivars and phenological stages was observed in specific surface area (mesophyll area per unit mass) determined by physical adsorption of nitrogen at low temperature (78° K); the mean was 8.9 m2 g- 1. It was similar as values found in previous works, in others T. aestivum L. and greater than the values found for Ligustrum lucidum Aiton, by the same technique. Differences could be attributed to the roughness of the cell wall and the dimensions of the cell itself. No positive correlation between specific surface and photosynthetic rate was observed neither for cultivars nor for phenological stages.Facultad de Ciencias Agrarias y Forestale

Internal leaf surface of ten wheat cultivars and its relationship with photosynthesis

Se determinaron experimentalmente la superficie específica (área interna foliar) y la tasa fotosintética máxima de diez cultivares de Tríticum aestivum L. con el fin de establecer la interacción entre estos parámetros. Se encontraron diferencias signi­ficativas entre los cultivares en la tasa fotosintética y superficie específica individual­mente. No se encontró correlación entre el área interna foliar y la fotosíntesis, pro­bablemente debido a la influencia de otros factores no tenidos en cuenta en este trabajo. Los valores de superficie específica, medidos por adsorción de nitrógeno, variaron entre 2,24 y 8,19m2 g-1, lo que dio como resultado relaciones de superficie interna a externa foliar mayores que las determinadas por los métodos geométricos convencionales. Se atribuyen estas diferencias a la rugosidad de la pared celular, no detectada por la microscopía óptica utilizada por los métodos geométricos y sí por medio de la adsorción física de gases.Internal leaf surface (ILS), measured by N physical adsorption of N2, máximum CO2 exchange rate and its relationships were determined m ten wheat cultivars growing in the field. Differences were found in internal leaf surface and máximum CO2 exchange rate amongs cultivars, but no relationshíp between these two factors were found The ILS valúes varied between 2,24 and 8,19m2 g-1 which were higher than those determined by conventional geometric methods. This can be attributed to the rugosity of the cellular wall, which can not be detected using geometric methods, but can be determined by physical adsorption of gases.Facultad de Ciencias Agrarias y Forestale

Internal leaf surface of ten wheat cultivars and its relationship with photosynthesis

Se determinaron experimentalmente la superficie específica (área interna foliar) y la tasa fotosintética máxima de diez cultivares de Tríticum aestivum L. con el fin de establecer la interacción entre estos parámetros. Se encontraron diferencias signi­ficativas entre los cultivares en la tasa fotosintética y superficie específica individual­mente. No se encontró correlación entre el área interna foliar y la fotosíntesis, pro­bablemente debido a la influencia de otros factores no tenidos en cuenta en este trabajo. Los valores de superficie específica, medidos por adsorción de nitrógeno, variaron entre 2,24 y 8,19m2 g-1, lo que dio como resultado relaciones de superficie interna a externa foliar mayores que las determinadas por los métodos geométricos convencionales. Se atribuyen estas diferencias a la rugosidad de la pared celular, no detectada por la microscopía óptica utilizada por los métodos geométricos y sí por medio de la adsorción física de gases.Internal leaf surface (ILS), measured by N physical adsorption of N2, máximum CO2 exchange rate and its relationships were determined m ten wheat cultivars growing in the field. Differences were found in internal leaf surface and máximum CO2 exchange rate amongs cultivars, but no relationshíp between these two factors were found The ILS valúes varied between 2,24 and 8,19m2 g-1 which were higher than those determined by conventional geometric methods. This can be attributed to the rugosity of the cellular wall, which can not be detected using geometric methods, but can be determined by physical adsorption of gases.Facultad de Ciencias Agrarias y Forestale

Response to Chilling of Zea mays, Tripsacum dactyloides and their Hybrid

Maize (Zea mays ssp. mays) and eastern gamagrass (Tripsacum dactyloides) are known for their susceptibility to chilling injuries. Their hybrid (Z. mays × T. dactyloides) showed higher tolerance to low temperatures (−2 °C) in the field than its parents. Exposure to 5 °C for 2 or 3 d reduced the variable to maximal chlorophyll fluorescence ratio (FV/FM), an indicator of the maximum photochemical efficiency of the photosystem 2, and the variable to minimal fluorescence ratio (FV/F0) more in maize and eastern gamagrass than in hybrid plants. Chlorophyll contents for rewarming plants (25 °C for 3 d) were lower than before chilling in both parents while values for hybrid plants were similar. Electrolyte leakage was higher in chilled than control plants but it did not show significant differences among genotypes. Our data suggest that hybrid plants have higher capacity to recover from chilling injury in controlled conditions than their parents.Facultad de Ciencias Agrarias y Forestale

Relations between specific leaf surface and gas exchanges in Triticum genotypes

Se determinaron experimentalmente la superficie específica (área superficial por unidad de masa), la tasa fotosintética aparente máxima y la conductancia al vapor de agua de la hoja bandera de cuatro cultivares de Triticum aestivum, uno de Triticum spelta y otro de Triticum dicoccum, cultivados en invernáculo, con la finalidad de establecer la interacción entre estos parámetros, en condiciones de riego normal y de estrés hídrico. Los valores de superficie específica, medidos por adsorción de nitrógeno (temperatura 77,3 K), variaron entre 2,9 y 6,0 m2 g-1 lo que dio como resultado valores de superficie interna foliar mayores que los determinados por los métodos geométricos convencionales basados en microscopía óptica. Se atribuyeron estas diferencias a la capacidad de la técnica empleada para poner en evidencia una superficie interna extremadamente rugosa a nivel molecular, resultante de la intrincada estructura de la pared celular a través de la cual se realiza el intercambio gaseoso. La tasa fotosintética medida varió entre 5,0 y 29,3 µmol CO2 m-2 s-1 , mientras que la conductancia al vapor de agua varió entre 74,3 y 457,3 mmol H2 O m-2 s-1 Se encontraron diferencias significativas entre algunos cultivares para la superficie específica, la tasa fotosintética y la conductancia al vapor de agua, en los diferentes tratamientos. También se encontró correlación positiva entre la tasa fotosintética y la conductancia al vapor de agua. No se encontró correlación alguna entre el área interna foliar y la fotosíntesis o la conductancia foliar.Specific surface (surface area per gram of material), photosynthetic rate and water vapor conductance of the flag leaf of four Triticum aestivum, one Triticum spelta and one Triticum dicoccum cultivars, grown in a greenhouse, were studied in order to establish the correlation among them in normal watered condition and under drought stress. The specific surface values obtained in our experiments by physical adsorption of nitrogen (temperature 77.3 K), ranged from 2.9 to 6.0 m2 g-1 and were higher than values obtained by conventional geometric methods based on optical microscopy. Differences were attributed to the ability of the technique to measure the roughness of the cellular wall of the mesophyll cells through which gas exchange take place. The measure of photosynthetic rate ranged from 5.0 to 29.3 µmol CO2 m-2 s-1 , and the water vapor conductance ranged between 74.3 and 457.3 mmol H2 O m-2 s-1. Significative statistical differences were found among cultivars in specific surface, photosynthetic rate and water vapor conductance, for both treatments. Although, a positive correlation was found among photosynthetic rate and water vapor conductance, no correlation was found between specific surface and photosynthetic rate or water vapor conductance.Facultad de Ciencias Agrarias y Forestale

Relations between specific leaf surface and gas exchanges in Triticum genotypes

Se determinaron experimentalmente la superficie específica (área superficial por unidad de masa), la tasa fotosintética aparente máxima y la conductancia al vapor de agua de la hoja bandera de cuatro cultivares de Triticum aestivum, uno de Triticum spelta y otro de Triticum dicoccum, cultivados en invernáculo, con la finalidad de establecer la interacción entre estos parámetros, en condiciones de riego normal y de estrés hídrico. Los valores de superficie específica, medidos por adsorción de nitrógeno (temperatura 77,3 K), variaron entre 2,9 y 6,0 m2 g-1 lo que dio como resultado valores de superficie interna foliar mayores que los determinados por los métodos geométricos convencionales basados en microscopía óptica. Se atribuyeron estas diferencias a la capacidad de la técnica empleada para poner en evidencia una superficie interna extremadamente rugosa a nivel molecular, resultante de la intrincada estructura de la pared celular a través de la cual se realiza el intercambio gaseoso. La tasa fotosintética medida varió entre 5,0 y 29,3 µmol CO2 m-2 s-1 , mientras que la conductancia al vapor de agua varió entre 74,3 y 457,3 mmol H2 O m-2 s-1 Se encontraron diferencias significativas entre algunos cultivares para la superficie específica, la tasa fotosintética y la conductancia al vapor de agua, en los diferentes tratamientos. También se encontró correlación positiva entre la tasa fotosintética y la conductancia al vapor de agua. No se encontró correlación alguna entre el área interna foliar y la fotosíntesis o la conductancia foliar.Specific surface (surface area per gram of material), photosynthetic rate and water vapor conductance of the flag leaf of four Triticum aestivum, one Triticum spelta and one Triticum dicoccum cultivars, grown in a greenhouse, were studied in order to establish the correlation among them in normal watered condition and under drought stress. The specific surface values obtained in our experiments by physical adsorption of nitrogen (temperature 77.3 K), ranged from 2.9 to 6.0 m2 g-1 and were higher than values obtained by conventional geometric methods based on optical microscopy. Differences were attributed to the ability of the technique to measure the roughness of the cellular wall of the mesophyll cells through which gas exchange take place. The measure of photosynthetic rate ranged from 5.0 to 29.3 µmol CO2 m-2 s-1 , and the water vapor conductance ranged between 74.3 and 457.3 mmol H2 O m-2 s-1. Significative statistical differences were found among cultivars in specific surface, photosynthetic rate and water vapor conductance, for both treatments. Although, a positive correlation was found among photosynthetic rate and water vapor conductance, no correlation was found between specific surface and photosynthetic rate or water vapor conductance.Facultad de Ciencias Agrarias y Forestale

Anatomical and physiological characteristics of two argentine wheat cultivars Características anatômicas e fisiológicas de dois cultivares argentinos de trigo

Two Argentine field grown wheat cultivars (Triticum aestivum L.), Buck Cencerro (BC) with traditional germoplasm, and Buck Pucará (BP) with Mexican germoplasm, have been investigated in order to compare anatomical and physiological characteristics of the flag leaf measured in heading (stage E59), anthesis (stage E69) and kernel water ripe (stage 71). In both cultivars, photosynthetic rate was not different for the same phenological stage, except for E71. Averages in stage E59 were higher than stages E69 and E71 for both cultivars (22.70, 18.40 and 10.40 µmol m-2 s-1 for BP and 23.82, 18.41 and 8.28 µmol m-2 s-1 for BC, respectively). Transpiration rates were higher in BP (5.0, 5.6 and 4.89 mmol m-2 s-1) than BC (3.3, 4.4 and 2.57 mmol m-2 s-1) for stages E59, E69 and E71, respectively. Consequently, instantaneous water use efficiencies were higher in BC than in BP. No difference between cultivars and phenological stages was observed in specific surface area (mesophyll area per unit mass) determined by physical adsorption of nitrogen at low temperature (78&deg; K); the mean was 8.9 m² g-1. It was similar as values found in previous works, in others T. aestivum L. and greater than the values found for Ligustrum lucidum Aiton, by the same technique. Differences could be attributed to the roughness of the cell wall and the dimensions of the cell itself. No positive correlation between specific surface and photosynthetic rate was observed neither for cultivars nor for phenological stages.<br>Dois cultivares argentinos de trigo (Triticum aestivium L), Buck Cencerro (BC), com germoplasma tradicional e Buck Pucará (BP), com germoplasma mexicano, foram pesquisados para comparar as características anatômicas e fisiológicas da folha bandeira medida no espigamento (estádio E59), na antese (estádio E69) e na fase de grão aquoso completo (estádio E71). Nos dois cultivares, a taxa fotossintética foi semelhante no mesmo estágio fenológico, exceto no E71. As médias no estádio E59 foram superiores às dos estágios E69 e E71 nos dois cultivares (22,70; 18,40 e 10,40 µmol m-2 s-1 para o BP e 23,82; 18,41 e 8,28 µmol m-2 s-1 para o BC, respectivamente). Nos três estádios, as taxas de transpiração foram maiores no BP (5,0; 5,6 e 4,89 mmol m-2 s-1) comparado ao BC (3,3; 4,4 e 2,57 mmol m-2 s-1). Consequentemente, a eficiência de uso instantâneo de água foi maior no BC, quando comparado com o BP. Não foram observadas diferenças de área foliar específica para cultivares e estádios fenológicos (área do mesófilo por unidade de massa), determinada por adsorção física de nitrogênio a baixa temperatura (78&deg; K), registrando-se média geral de 8,9 m² g-1. Esse valor foi semelhante a outros reportados em trabalhos prévios com T. aestivum L. e maiores que os determinados para Ligustrum lucidum Aiton, pela mesma técnica. As diferenças podem ser atribuídas à rugosidade da parede celular e as próprias dimensões da célula. Não houve correlação positiva entre área específica e taxa fotossintética para cultivares ou estádios fenológicos