scholarly journals A model of environmental limitations on production of Agave americana L. grown as a biofuel crop in semi-arid regions

2018 ◽  
Vol 70 (22) ◽  
pp. 6549-6559 ◽  
Author(s):  
Nicholas A Niechayev ◽  
Alexander M Jones ◽  
David M Rosenthal ◽  
Sarah C Davis
Keyword(s):  
Photosynthetically Active Radiation ◽  
Arid Regions ◽  
Physiological Responses ◽  
Field Conditions ◽  
Radiation Temperature ◽  
Biofuel Crop ◽  
Active Radiation ◽  
Agave Americana ◽  
Semi Arid

Physiological responses to variation in photosynthetically active radiation, temperature, and water can be used to predict the growth of Agave americana L. in field conditions.

Effect of season on thermoregulatory responses and energy expenditure of goats on semi-arid range in India

2002 ◽  
Vol 139 (1) ◽  
pp. 87-93 ◽  
Author(s):  
A. K. SHINDE ◽  
RAGHAVENDRA BHATTA ◽  
S. K. SANKHYAN ◽  
D. L. VERMA
Keyword(s):  
Heart Rate ◽  
Heat Stress ◽  
Solar Radiation ◽  
Energy Expenditure ◽  
Arid Regions ◽  
Physiological Responses ◽  
Face Mask ◽  
Mean Value ◽  
The Mean ◽  
Semi Arid

A study of the physiological responses and energy expenditure of goats was carried out from June 1999 to May 2000 by conducting two experiments: one on bucks maintained on stall feeding in autumn 1999 (Expt 1) followed by year-round grazing on native ranges over three seasons: monsoon, winter and summer (Expt 2). Physiological responses and energy expenditure (EE) measurements of housed and grazing goats were recorded at 06.00 h and 14.00 h for 5 consecutive days in each season. Goats were fixed with a face mask and meteorological balloon for collection of expired air and measurement of EE. Respiration rate (RR) at 06.00 h was similar in all seasons (14 respiration/min) except in the monsoon, where a significantly (P<0.05) higher value (26 respiration/min) was recorded. At 14.00 h, RR was higher in monsoon and summer (81 and 91 respiration/min) than in winter (52 respiration/min). Irrespective of the season, heart rate (HR) was higher at 14.00 h (86 beat/min) than at 06.00 h (64 beat/min). The rise of rectal temperature (RT) from morning (06.00 h) to peak daily temperature (14.00 h) was 0.9 °C in housed goats in autumn and 1.0, 2.1 and 2.0 °C in grazing goats during monsoon, winter and summer, respectively. The mean value was 1.7 °C. Skin temperature (ST) was lowest in winter (30.1 °C) and highest at 14.00 h in summer (40.3 °C). Energy expenditure of goats at 06.00 h was 32.7 W in winter and significantly (P<0.05) increased to 52.0 W in summer and 107.8 W in monsoon. At 14.00 h, EE was 140.2 W in winter and increased to 389.0 W and 391.3 W respectively in monsoon and summer. It is concluded that monsoon and summer are both stressful seasons in semi-arid regions. Animals should be protected from direct solar radiation during the hottest hours of the day to ameliorate the effect of heat stress.

scholarly journals Drivers of inter-annual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

2009 ◽  
Vol 6 (2) ◽  
pp. 251-266 ◽  
Author(s):  
S. A. Archibald ◽  
A. Kirton ◽  
M. R. van der Merwe ◽  
R. J. Scholes ◽  
C. A. Williams ◽  
...  
Keyword(s):  
South Africa ◽  
Eddy Covariance ◽  
Photosynthetically Active Radiation ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Ann Model ◽  
Rainfall Events ◽  
Active Radiation ◽  
Annual Variability ◽  
Semi Arid

Abstract. Inter-annual variability in primary production and ecosystem respiration was explored using eddy-covariance data at a semi-arid savanna site in the Kruger Park, South Africa. New methods of extrapolating night-time respiration to the entire day and filling gaps in eddy-covariance data in semi-arid systems were developed. Net ecosystem exchange (NEE) in these systems occurs as pulses associated with rainfall events, a pattern not well-represented in current standard gap-filling procedures developed primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN) model incorporating these features predicted measured fluxes accurately (MAE 0.42 gC/m2/day), and was able to represent the seasonal patterns of photosynthesis and respiration at the site. The amount of green leaf area (indexed using satellite-derived estimates of fractional interception of photosynthetically active radiation fAPAR), and the timing and magnitude of rainfall events, were the two most important predictors used in the ANN model. These drivers were also identified by multiple linear regressions (MLR), with strong interactive effects. The annual integral of the filled NEE data was found to range from −138 to +155 g C/m2/y over the 5 year eddy covariance measurement period. When applied to a 25 year time series of meteorological data, the ANN model predicts an annual mean NEE of 75(±105) g C/m2/y. The main correlates of this inter-annual variability were found to be variation in the amount of absorbed photosynthetically active radiation (APAR), length of the growing season, and number of days in the year when moisture was available in the soil.

scholarly journals Drivers of interannual variability in Net Ecosystem Exchange in a semi-arid savanna ecosystem, South Africa

2008 ◽  
Vol 5 (4) ◽  
pp. 3221-3266 ◽  
Author(s):  
S. Archibald ◽  
A. Kirton ◽  
M. van der Merwe ◽  
R. J. Scholes ◽  
C. A. Williams ◽  
...  
Keyword(s):  
South Africa ◽  
Eddy Covariance ◽  
Photosynthetically Active Radiation ◽  
Ecosystem Respiration ◽  
Net Ecosystem Exchange ◽  
Ann Model ◽  
Rainfall Events ◽  
Active Radiation ◽  
Annual Variability ◽  
Semi Arid

Abstract. Inter-annual variability in primary production and ecosystem respiration was explored using eddy-covariance data at a semi-arid savanna site in the Kruger Park, South Africa. New methods of extrapolating night-time respiration to the entire day and filling gaps in eddy-covariance data in semi-arid systems were developed. Net ecosystem exchange (NEE) in these systems occurs as pulses associated with rainfall events, a pattern not well-represented in current standard gap-filling procedures developed primarily for temperate flux sites. They furthermore do not take into account the decrease in respiration at high soil temperatures. An artificial neural network (ANN) model incorporating these features predicted measured fluxes accurately (MAE 0.42 g C/m2/day), and was able to represent the seasonal patterns of photosynthesis and respiration at the site. The amount of green leaf area (indexed using satellite-derived estimates of fractional interception of photosynthetically active radiation fAPAR), and the timing and magnitude of rainfall events, were the two most important predictors used in the ANN model. These drivers were also identified by multiple linear models (MLR), with strong interactive effects. The annual integral of the filled NEE data was found to range from −138 to +155 g C/m2/y over the 5 year eddy covariance measurement period. When applied to a 25 year time series of meteorological data, the ANN model predicts an annual mean NEE of 75 (±105) g C/m2/y. The main correlates of this inter-annual variability were found to be variation in the amount of absorbed photosynthetically active radiation (APAR), length of the growing season, and number of days in the year when moisture was available in the soil.

scholarly journals Type of Trellis Affects Radiation Absorption and Must Composition but not Yield of `Petite Sirah' Grapes

HortScience ◽  
1992 ◽  
Vol 27 (1) ◽  
pp. 20-22 ◽  
Author(s):  
T.H. Morsil ◽  
A.D. Matthias ◽  
J.L. Stroehlein
Keyword(s):  
Vitis Vinifera ◽  
Photosynthetically Active Radiation ◽  
Total Dissolved Solids ◽  
Radiation Absorption ◽  
Alcohol Content ◽  
Dissolved Solids ◽  
Active Radiation ◽  
Fruit Composition ◽  
Arid Conditions ◽  
Semi Arid

The effects of trellising on absorption of photosynthetically active radiation (PAR, 400- to 700-nm wavelength) by foliage and fruits, on fruit composition, and yield were studied in 1988 under semi-arid conditions using field-grown Vitis vinifera L. `Petite Sirah' grapevines in a mature vineyard. A vertical inclination was obtained by attaching shoots to a vertically arranged three-wire trellis; 60° shoot inclination from horizontal was obtained by attaching shoots to a “V-type” Tatura trellis; a standard two-wire trellis (control) was used in which shoots attached to the upper wire were permitted to orient downward to the vineyard floor. PAR absorption by foliage during mid-morning to mid-afternoon periods was highest in the standard trellis and lowest in the Tatura trellis. PAR available for absorption by fruits was lowest in the standard trellis and highest in the Tatura trellis. Analysis of fruit composition at harvest revealed that total dissolved solids (°Brix) was significantly higher for berries from the Tatura trellis than for the vertical trellis or the control. The Tatura trellis resulted in the highest alcohol content of wine. Per-vine yields did not differ significantly among the three trellis systems.

scholarly journals Balanço de Radiação em Ecossistema de Caatinga Preservada Durante um Ano de Seca no Semiárido Pernambucano (Radiation Balance in Caatinga Ecosystem Preserved for a Year Drought in Semiarid Pernambucano)

2015 ◽  
Vol 8 (1) ◽  
pp. 041
Author(s):  
Luciana Sandra Bastos de Souza ◽  
Magna Soelma Beserra de Moura ◽  
Gilberto Chohaku Sediyama ◽  
Thieres George Freire da Silva
Keyword(s):  
Seasonal Variation ◽  
Solar Radiation ◽  
Photosynthetically Active Radiation ◽  
Climatic Conditions ◽  
Semiarid Region ◽  
Radiation Balance ◽  
Net Radiation ◽  
Active Radiation ◽  
Brazilian Semiarid ◽  
Semi Arid

O objetivo deste trabalho foi analisar as variações diárias e sazonais dos componentes do balanço de radiação e da radiação fotossinteticamente ativa para a caatinga preservada durante um ano seco no Semiárido pernambucano. O experimento foi conduzido durante o ano de 2012 em Petrolina, PE, localizado na região do Semiárido brasileiro. Para determinação dos componentes do balanço de radiação foi utilizado um saldo radiômetro modelo CNR1 instalado à 13,3 metros da superfície. Adicionalmente, analisou-se a interação entre a vegetação e a radiação por meio de sensores para o monitoramento da radiação fotossinteticamente ativa acima e em diferentes posições abaixo do dossel da caatinga. Estes dados foram utilizados no cálculo da fração da radiação fotossinteticamente ativa interceptada (fRFAi) e absorvida (fRFAa). Foi observada uma ampla variação sazonal da radiação solar global e do saldo de radiação que atingiram valores médios diários em torno de 23 MJ m-2 dia-1 e 15 MJ m-2 dia-1, respectivamente. Neste caso, observou-se que a magnitude dos valores dos componentes do balanço de radiação foi afetada principalmente em decorrência da nebulosidade e mudanças na vegetação que afetaram principalmente os níveis de emitância da superfície e sua reflexão. No que se refere às frações da radiação fotossinteticamente ativa interceptada e absorvida, observou-se que as mesmas apresentaram valores médios diários ao longo do ano bastante próximos, os quais foram iguais a 0,69 e 0,64, nesta ordem. Estes dados podem ser extremamente úteis para uma melhor compreensão da interação entre a caatinga e a atmosfera sob condições climáticas singulares, e portanto, serem utilizados na formulação de políticas climáticas.   A B S T R A C T The objective of this study was to analyze the daily and seasonal variations of the components of the radiation balance and photosynthetically active radiation for the Caatinga during a dry year in Pernambuco Semi-Arid. The experiment was conducted during the year 2012 in Petrolina, PE, located in the Brazilian semiarid region. To determine the components of the radiation balance we used a balance radiometer CNR1 model installed the 13.3 meters of surface. Additionally, we analyzed the interaction between vegetation and radiation using sensors to monitor the photosynthetically active radiation above and in different positions under the canopy of scrub. These data were used to calculate the fraction of intercepted photosynthetically active radiation (fRFAi) and absorbed (fRFAa). A wide seasonal variation of solar radiation and net radiation was observed that reached daily averages around 23 MJ m-2 d-1 and 15 MJ m-2 d-1, respectively. In this case, it was observed that the magnitude of the component values ​​of the radiation balance was mainly affected due to the cloudiness and changes in vegetation which mainly affected the levels of emittance and reflection surface. With regard to fractions of intercepted and absorbed photosynthetic active radiation, it was observed that they had daily average values ​​over the next years, which were equal to 0.69 and 0.64 in order. This data can be extremely useful for a better understanding of the interaction between the savanna and the atmosphere under natural climatic conditions. Keywords: radiation, net radiation, photosynthetically active radiation, Caatinga, dry.  

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