scholarly journals Estimation of Productivity in Dryland Mediterranean Pastures: Long-Term Field Tests to Calibration and Validation of the Grassmaster II Probe

2020 ◽  
Vol 2 (2) ◽  
pp. 240-255
Author(s):  
João Serrano ◽  
Shakib Shahidian ◽  
Francisco Moral ◽  
Fernando Carvajal-Ramirez ◽  
José Marques da Silva
Keyword(s):  
Field Tests ◽  
Correlation Coefficients ◽  
Growth Cycle ◽  
Great Effort ◽  
Long Term Study ◽  
Sampling Points ◽  
Capacitance Probe ◽  
Favorable Period ◽  
Pasture Productivity

The estimation of pasture productivity is of great interest for the management of animal grazing. The standard method of assessing pasture mass requires great effort and expense to collect enough samples to accurately represent a pasture. This work presents the results of a long-term study to calibrate a Grassmaster II capacitance probe to estimate pasture productivity in two phases: (i) the calibration phase (2007–2018), which included measurements in 1411 sampling points in three parcels; and (ii) the validation phase (2019), which included measurements in 216 sampling points in eight parcels. A regression analysis was performed between the capacitance (CMR) measured by the probe and values of pasture green matter and dry matter (respectively, GM and DM, in kg ha−1). The results showed significant correlations between GM and CMR and between DM and CMR, especially in the early stages of pasture growth cycle. The analysis of the data grouped by classes of pasture moisture content (PMC) shows higher correlation coefficients for PMC content >80% (r = 0.775; p < 0.01; RMSE = 4806 kg ha−1 and CVRMSE = 28.1% for GM; r = 0.750; p < 0.01; RMSE = 763 kg ha−1 and CVRMSE = 29.7% for DM), with a clear tendency for the accuracy to decrease when the pasture vegetative cycle advances and, consequently, the PMC decreases. The validation of calibration equations when PMC > 80% showed a good approximation between GM or DM measured and GM or DM predicted (r = 0.959; p < 0.01; RMSE = 3191 kg ha−1; CVRMSE = 23.6% for GM; r = 0.953; p <0.01; RMSE = 647 kg ha−1 and CVRMSE = 27.3% for DM). It can be concluded that (i) the capacitance probe is an expedient tool that can enable the farm manager to estimate pasture productivity with acceptable accuracy and support the decision-making process in the management of dryland pastures; (ii) the more favorable period for the use of this probe in dryland pastures in a Mediterranean climate, such as the Portuguese Alentejo, coincides with the end of winter and beginning of spring (February–March), corresponding to PMC > 80%.

scholarly journals Sodium Handling and Interaction in Numerous Organs

2020 ◽  
Vol 33 (8) ◽  
pp. 687-694 ◽  
Author(s):  
Shintaro Minegishi ◽  
Friedrich C Luft ◽  
Jens Titze ◽  
Kento Kitada
Keyword(s):  
Salt Content ◽  
The Body ◽  
Sodium Balance ◽  
Plasma Sodium ◽  
Great Effort ◽  
Salt Balance ◽  
Long Term Study ◽  
Salt Excretion ◽  
Sodium Handling

Abstract Salt (NaCl) is a prerequisite for life. Excessive intake of salt, however, is said to increase disease risk, including hypertension, arteriosclerosis, heart failure, renal disease, stroke, and cancer. Therefore, considerable research has been expended on the mechanism of sodium handling based on the current concepts of sodium balance. The studies have necessarily relied on relatively short-term experiments and focused on extremes of salt intake in humans. Ultra-long-term salt balance has received far less attention. We performed long-term salt balance studies at intakes of 6, 9, and 12 g/day and found that although the kidney remains the long-term excretory gate, tissue and plasma sodium concentrations are not necessarily the same and that urinary salt excretion does not necessarily reflect total-body salt content. We found that to excrete salt, the body makes a great effort to conserve water, resulting in a natriuretic-ureotelic principle of salt excretion. Of note, renal sodium handling is characterized by osmolyte excretion with anti-parallel water reabsorption, a state-of-affairs that is achieved through the interaction of multiple organs. In this review, we discuss novel sodium and water balance concepts in reference to our ultra-long-term study. An important key to understanding body sodium metabolism is to focus on water conservation, a biological principle to protect from dehydration, since excess dietary salt excretion into the urine predisposes to renal water loss because of natriuresis. We believe that our research direction is relevant not only to salt balance but also to cardiovascular regulatory mechanisms.

Early family selection in jack pine

1990 ◽  
Vol 20 (3) ◽  
pp. 285-291 ◽  
Author(s):  
K. K. Carter ◽  
G. W. Adams ◽  
M. S. Greenwood ◽  
P. Nitschke
Keyword(s):  
Field Tests ◽  
Growth Cycle ◽  
Jack Pine ◽  
Family Selection ◽  
Growth Cycles ◽  
Accelerate Growth ◽  
Second Growth ◽  
Natural Photoperiod ◽  
Early Family

Twenty open-pollinated families of jack pine (Pinusbanksiana Lamb.) were grown for 16 to 21 months in two different greenhouse regimes, one providing an extended growing season with natural photoperiod and one employing control of temperature and photoperiod to accelerate growth cycles. Height measurements during and at the end of greenhouse growth were compared with height of 7-year-old seedlings of the same families growing in field tests. For both greenhouse regimes, height at the end of the second growth cycle was positively correlated with 7-year field height. Greenhouse measurements correctly classified the majority of families into upper and lower groups based on field heights. Early family selection in jack pine appears to have applications in long-term breeding strategies.

Quinapril for Sclerosis Failed in Long-Term Study

2007 ◽  
Vol 38 (6) ◽  
pp. 14
Author(s):  
DAMIAN MCNAMARA
Keyword(s):  
Term Study ◽  
Long Term Study

Theoretical and Methodological Problems of a 10-Year Follow-Up Program Evaluation Study

2002 ◽  
Vol 18 (3) ◽  
pp. 229-241 ◽  
Author(s):  
Kurt A. Heller ◽  
Ralph Reimann
Keyword(s):  
Program Evaluation ◽  
Evaluation Studies ◽  
Evaluation Study ◽  
Control Groups ◽  
Cross Sectional ◽  
Long Term Study ◽  
Partial Inclusion ◽  
Methodological Problems

Summary In this paper, conceptual and methodological problems of school program evaluation are discussed. The data were collected in conjunction with a 10 year cross-sectional/longitudinal investigation with partial inclusion of control groups. The experiences and conclusions resulting from this long-term study are revealing not only from the vantage point of the scientific evaluation of new scholastic models, but are also valuable for program evaluation studies in general, particularly in the field of gifted education.

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