Non-linear behavior of root and stem diameter changes in monopodial orchid

Precision agriculture aims to maximize yield with optimum resources. Vast majority of natural systems are acknowledged as complex and non-linear. However, prior to formulation of precise models, linearity tests are performed to validate plant behavior. This study has presented proof that the water uptake system in monopodial orchid is indeed non-linear. The change in physical growth of root and stem due to temperature and relative humidity factors are observed. The work focused on Ascocenda Fuchs Harvest Moon x (V. Chaophraya x Boots) orchid hybrid. Three complementary methods are presented: linearity tests through 1) regression fitting; 2) scatter plots; and 3) cross-correlation function tests. Root diameter, stem diameter, temperature, and relative humidity are logged at 15 minutes interval for a duration of 71 days. The polynomial equations derived for root diameter and stem diameter changes attained strong regression coefficients. The non-linear behavior is further confirmed by the scatter plots where no linear associations are present between the independent and dependent variables. Subsequently, the cross-correlation function tests conducted on temperature-root diameter, temperature-stem diameter, relative humidity-root diameter, and relative humidity-stem diameter combinations also revealed weak correlation. Despite using different techniques, the behavior of physical changes has been consistently proven to be non-linear.

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Hidrološki odnosi susjednih krških izvora

10.31534/doct.043.kada ◽

2017 ◽

Author(s):

◽

Ana Kadić

Keyword(s):

Correlation Function ◽

Relative Humidity ◽

Correlation Analysis ◽

Output Signal ◽

Partial Correlation ◽

Cross Correlation ◽

Control Signal ◽

Cross Correlation Function ◽

Partial Correlation Analysis ◽

Karst Springs

The objective of this work is the study of two adjacent karst springs Jadro and Žrnovnica in Croatia. This work focuses on the effects of temperature, relative humidity, rainfall and discharges on the behaviour and relations of two adjacent karst springs. Partial correlation analysis implies that the impact of the control signal on the cross-correlation function between the input and output signal can be detected from the correlation coefficient between the input signal and control signal and from the cross-correlation function between the control signal and output signal. The groundwater recharge depends on the process of evapotranspiration and rainfall, so air temperature, relative humidity and rainfall control the spatial and temporal distribution of this process. The major contribution of the paper relies on the utilization of simple correlation and fist-order partial correlation analysis to characterize the functioning and relations of two adjacent karst springs in a dry and wet hydrological year by using hourly data. It has been confirmed that in the case of adjacent karst springs the discharge of each spring has effect on the rainfall-discharge correlation of the other spring. The demonstrated approach represents an improvement in investigating the relations of adjacent karst springs in dry and wet periods, and can be applied on any adjacent karst springs.

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