Studies on the daily course of carbon exchange in alfalfa plants

1972 ◽  
Vol 50 (6) ◽  
pp. 1377-1383 ◽  
Author(s):  
C. J. Pearson ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Medicago Sativa ◽  
Dark Period ◽  
Day Length ◽  
Carbon Dioxide Exchange ◽  
Carbon Exchange ◽  
Diurnal Pattern ◽  
Carbon Dioxide Output ◽  
Maximum Value ◽  
Medicago Sativa L

The diurnal pattern of carbon dioxide exchange is described for plants of cultivars Vernal and Moapa alfalfa (Medicago sativa L.) grown at day/night temperatures of 30/25C and 20/15C, an irradiance of 25 nanoEinsteins cm−2 s−1 (400–700 nm), and a day length of 15.5 h. The net carbon dioxide intake (NCI) of the tops reached 90% of its maximum value after 4–5 h of illumination at 20/15C, but after only 1–2 h at 30/25C; by contrast, NCI of the tops declined after 11–14 h from the start of the photoperiod at 20/15C and after 8.5–10.5 h at 30/25C. Net carbon dioxide output (NCO) of the tops increased throughout the dark period at 20/15C, but remained constant at 30/25C. NCO of the roots remained constant throughout the photoperiod at 20/15C, and increased linearly for 4–8 h at 30/25C. Similarly, NCO of the roots remained constant throughout the dark period at 20/15C, but changed with time (decreased) at 30/25C.

scholarly journals Role of Potassium in Carbon Dioxide Assimilation in Medicago sativa L

1979 ◽  
Vol 63 (5) ◽  
pp. 878-881 ◽  
Author(s):  
Timothy R. Peoples ◽  
David W. Koch
Keyword(s):  
Carbon Dioxide ◽  
Medicago Sativa ◽  
Carbon Dioxide Assimilation ◽  
Medicago Sativa L

Quantative inheritance in Lucerne, Medicago sativa L. I. Inheritance and selection for winter yield

1957 ◽  
Vol 8 (6) ◽  
pp. 635 ◽  
Author(s):  
FHW Morley ◽  
H Daday ◽  
JW Peak
Keyword(s):  
Medicago Sativa ◽  
Growth Rates ◽  
Combining Ability ◽  
Low Temperatures ◽  
Day Length ◽  
Winter Dormancy ◽  
Published Evidence ◽  
Medicago Sativa L ◽  
Temperature Interaction ◽  
Summer Growth

Spaced plants of lucerne, Medicago sativa L., derived from 10 strains and 44 F1's, grown in the field at Canberra, exhibited discontinuous variation in winter growth. Some were completely dormant, others grew at over 40 per cent. of their summer rate. Strains differed with respect to combining ability for growth rates, both in summer and in winter, but differences between strains in combining ability were much more evident in minter than in summer. The correlation between winter and summer growth rates was markedly affected by differences in winter dormancy. Thus the Canadian Creeping-rooted strain, which had the highest combining ability for summer growth, was among the poorest for winter growth. Within strains or crosses, winter and summer growth rates were strongly correlated (r = 0.77), presumably because genotypes within such lines were relatively homogeneous with respect to winter dormancy. The Hairy Peruvian strain, and to a lesser extent Hunter River, Provence, and an Australian selection, showed high combining ability for winter growth. In other experiments winter dormancy was broken by either increased temperatures (heated glass-house) or by supplementing the natural day length with low-intensity artificial light. These treatment effects were supplementary without interaction. In one set of material a highly significant genotype (clone) X temperature interaction, and the absence of a genotype X day length interaction, indicated that genetic differences in dormancy could be determined largely by the response to low temperatures. For the present neither short days nor low temperatures alone seem sufficient to distinguish between winter-active and winter-dormant genotypes. The growth rates of some genotypes in winter provide encouragement for the introduction, selection, and management for increased winter production of lucerne and other species. The behaviour of the strains in the field, and published evidence on this and other species with a temperate-subtropical distribution, indicates that genes for winter activity are most likely to be found in the warmer parts of the distribution.

Effects of temperature on the photosynthesis–irradiance response curves of newly matured leaves of alfalfa

1977 ◽  
Vol 55 (8) ◽  
pp. 872-879 ◽  
Author(s):  
S. B. Ku ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Stomatal Resistance ◽  
Carbon Dioxide Exchange ◽  
Response Curves ◽  
Oxygen Inhibition ◽  
Thermal Environments ◽  
Growth Regime ◽  
Medicago Sativa L ◽  
Effects Of Temperature ◽  
Mesophyll Resistance

Various carbon dioxide exchange characteristics are described for two alfalfa (Medicago sativa L.) genotypes (AT 171 and CC 120) grown at 20:15 °C and 30:25 °C day:night temperatures and 53 nE cm−2 s−1 irradiance (400–700 nm). Growth at 30:25 °C as compared with 20:15 °C resulted in lower net carbon dioxide exchange rates (NCE) for both genotypes when analyzed at 20 °C, but did not cause any sizeable change for CC 120 at 30 °C. Oxygen inhibition of photosynthesis increased with irradiance to 48 nE cm−2 s−1 but either declined or remained constant with further increase in irradiance. Oxygen inhibition was higher at 30 °C than at 20 °C and was not consistently influenced by growth temperature. However, the ratio of oxygen inhibition to carbon dioxide exchange rate in air containing 1% oxygen and the mesophyll resistance were greater with AT 171 grown at 30:25 °C than at 20:15 °C, particularly at high irradiances. NCE measured at 20 °C instead of 30 °C for plants grown at 30:25 °C was reduced to a much more marked extent with CC 120 than with AT 171; this difference was paralleled by a more marked increase in stomatal resistance length (rSL) for CC 120.rSL decreased with an increase in irradiance, was generally higher at 20 °C than at 30 °C, and did not differ between growth temperatures when measured at an irradiance of 116 nE cm−2 s−1 and a temperature equal to the day temperature of the growth regime. The results are discussed in relation to factors responsible for adaptability to different thermal environments.

scholarly journals A Daylight Climate Chamber for Testing Greenhouse Climate Control Strategies and Calculating Canopy Carbon Dioxide Exchange

2006 ◽  
Vol 16 (2) ◽  
pp. 191-198 ◽  
Author(s):  
Lise T. Jensen ◽  
Jesper M. Aaslyng ◽  
Eva Rosenqvist
Keyword(s):  
Carbon Dioxide ◽  
Air Temperature ◽  
Control Strategies ◽  
Day Length ◽  
Small Scale ◽  
Carbon Dioxide Exchange ◽  
Climate Control ◽  
Climate Chamber ◽  
Greenhouse Climate ◽  
Greenhouse Climate Control

A daylight climate chamber was designed with the aim of testing new greenhouse climate control strategies on a small scale. Precise control and measure ment of the chamber climate and long-term measurement of canopy carbon dioxide (CO2) exchan ge was possible. The software was capable of simulating a climate computer used in a full-scale greenhouse. The parameters controlled were air temperature, CO2 concentration, irradiance, air flow, and irrigation. The chamber was equipped with a range of sensors measuring the climate in the air of the chamber and in the plant canopy. A chamber perfor mance experiment with chrysanthemum (Chrysanthemum grandiflorum `Coral Charm') plants grown in perlite was carried out over the course of 3 weeks. Five air temperature treatments at a day length of 13 hours were carried out, all with the same 24-hour mean temperature of 20 °C, but different day temperatures (18.0 to 25.1 °C) and night temperatures (14.0 to 22.4 °C). Rate of canopy CO2 exchange in the chambers was calculated. In the range of day temperatures used, rates of canopy photosynthesis were almost equal. The results showed that leaf area and plant dry weight after 3 weeks were not significantly different among temperature treatments, which is promising for further investigations of how climate control can be used to decrease energy consumption in greenhouse production.

Effects of pretreatment temperature on carbon dioxide exchange in alfalfa

1972 ◽  
Vol 50 (9) ◽  
pp. 1925-1930 ◽  
Author(s):  
C. J. Pearson ◽  
L. A. Hunt
Keyword(s):  
Carbon Dioxide ◽  
Temperature Response ◽  
Day Length ◽  
Carbon Dioxide Exchange ◽  
Response Curves ◽  
Free Atmosphere ◽  
Pretreatment Temperature ◽  
Higher Temperature ◽  
Increasing Temperature ◽  
The Relationship

The temperature response curves for net carbon dioxide exchange are described for plants of cultivars (cvs.) Vernal and Moapa alfalfa (Medicago sativa L.) grown at day/night temperatures of 30/25C and 20/15C, an irradiance of 25 nE cm−2 s−1 (400–700 nm), and a day length of 15.5 h. Net carbon dioxide intake (NCI) of the tops decreased with increasing temperature from 20 mg dm−2 h−1 at 10C to 5 mg dm−2 h−1 at 40C. The nature of the NCI-temperature response curve was affected by pretreatment temperature, with NCI being lower at all temperatures except 10C after growth at 20/15C. Photorespiration, which reached its maximum value at a higher temperature (20–30C) than that required for maximum NCI, accounted for 22% of the gross carbon dioxide intake (net carbon dioxide exchange in an oxygen-free atmosphere) at 10C and 55% at 40C. Pretreatment affected the relationship between net carbon dioxide output (NCO) and temperature, with NCO being higher at 10C but lower at 30C after growth at 20/15C as compared to 30/25C.

Estimación de biomasa aérea de forrajes de invierno bajo riego a través de un dron

2019 ◽  
Vol 12 (4) ◽  
Author(s):  
Francisco Gavi Reyes ◽  
César Botello-Aguillón ◽  
Leonardo Tijerina-Chávez ◽  
Arturo Galvis-Spíndola ◽  
Rodrigo Roblero-Hidalgo
Keyword(s):  
Medicago Sativa ◽  
Avena Sativa ◽  
Medicago Sativa L

E Objetivo: Desarrollar un procedimiento para estimar biomasa con imágenes digitales captadas desde un dron y modelación 3D (ID-Dron-3D) aplicable en alfalfa (Medicago sativa L.) y avena forrajera (Avena sativa L.). Diseño/metodología/aproximación: Con una cámara digital acoplada al dron se obtuvieron imágenes antes de la cosecha de los cultivos, que fueron procesadas con software para luego estimar volumen de biomasa. En cada cultivo se midió altura de la planta y área cosechada, volumen aparente y real de biomasa, y peso de biomasa fresca y seca. Resultados: Con base en el análisis de regresión se obtuvieron modelos lineales a una p<0.05 para predecir: biomasa fresca en avena (R2=0.70) y alfalfa (R2 =0.47); y biomasa seca en avena (R2=0.78) y en alfalfa (R2=0.31) mediante ID-Dron-3D. Limitaciones del estudio/implicaciones: Considerando las R2 de los modelos obtenidos, los resultados en la avena forrajera fueron mejores, respecto a los detectados en alfalfa, lo cual se puede deber a la mayor variabilidad de la cobertura vegetal, ya que, en algunas unidades de muestreo, las plantas de alfalfa no cubrían completamente el suelo. Hallazgos/conclusiones: El rendimiento de biomasa fresca y seca de ambos cultivos se correlacionó significativamente con su respectivo volumen aparente estimado con imágenes digitales tomadas desde un dron y su procesamiento 3D (ID-Dron-3D).

ALFALFA (Medicago sativa L.) CULTIVADA EN CAMPECHE, MÉXICO Y SU INTEGRACIÓN LOCAL EN LA ALIMENTACIÓN DE CORDEROS EN CONFINAMIENTO

2018 ◽  
Vol 11 (9) ◽  
Author(s):  
CC. Castillo-Águilar
Keyword(s):  
Medicago Sativa ◽  
Pennisetum Purpureum ◽  
Medicago Sativa L

Se comparó el uso de diferentes dietas con base en heno de alfalfa cultivada (Medicago sativa L.) en Campeche y su relación con un concentrado comercial y pasto Taiwán (Pennisetum purpureum), T1=concentrado comercial, T2=T1+heno de alfalfa, T3=T1+pasto Taiwán, T4=heno de alfalfa. Se evaluó el comportamiento productivo y metabólico de corderos en sistema intensivo utilizando 20 corderos machos con encaste de Pelibuey, Dorper y Black Belly de 12.5±1 kg de peso vivo (PV). Se midió el consumo de materia seca total (CMS), la ganancia diaria de peso (GDP), la conversión alimenticia (CA), y la digestibilidad in situ de la materia seca (DISMS). También fueron evaluados el pH, nitrógeno amoniacal (NH3) y la concentración de ácidos grasos volátiles (AGV) en líquido ruminal. La mejor GDP en gramos por día, de 234 g (p?0.05) se obtuvo en el T2; en contraste, el T3 mostró la menor GDP. La dieta que incluyó la mezcla de heno de alfalfa y concentrado mejoró significativamente las condiciones de las variables pH, NH3 y AGV (p?0.05).

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