Recently, considerable attention has been placed upon exploiting the negative-feedback effect in accelerating the quenching time of the avalanche current in passively quenched single-photon avalanche-diode (SPAD) circuits. Reducing the quenching time results in a reduction in the total charge generated in the SPAD, thereby reducing the number of trapped carries; this, in turn, can lead to impro...

ABSTRACT- The evaluation of leaf area and leaf nutritional value is important for crop growth modeling and estimations of its performance. The purpose of this study was to use image processing techniques to develop an economical method to ease the assessment of nutrient status and leaf area (LA) of plants and to compare the outcomes of this method with linear models. Leaf area and leaf chloroph...

In situ optical meters are widely used to estimate leaf chlorophyll concentration, but non-uniform chlorophyll distribution causes the opticalmeasurement to vary widely among species for the same chlorophyllconcentration. Over 30 studies have sought to quantify the in situ/in vitro (optical/absolute) relationship, but neither chlorophyll extraction normeasurement techniques for ...

The generally established protocol for leaf measurement with proximal optical sensors is to use the most recently fully expanded leaf. However, differences in nitrogen (N) status of lower and upper leaves could possibly be used enhance sensor measurement. Normalized indices that consider both have been proposed improve assessment crop N yield estimation. This study evaluated whether normalized ...

Relative chlorophyll content (SPAD) is an important index for characterizing the nitrogen nutrient status of plants. Continuous, rapid, nondestructive, and accurate estimation SPAD values in wheat after heading stage can positively impact subsequent fertilization management strategies, which regulate grain filling yield quality formation. In this study, leaf relative spring was conducted at exp...

The effects of root zone temperature (RZT) and flooding on physiology and growth of Annona glabra L. (pond apple) and A. muricata L. (soursop) were investigated. Trees planted in containers were exposed to RZTs of 5, 10, 20, 25 or 35 degrees C in controlled root temperature chambers. Trees at each RZT were either non-flooded (control) or continuously flooded. There were four replications over t...

In order to detect leaf chlorophyll level nondestructively and instantly, VIS/NIR reflection spectroscopy technique was examined. In the test, 70 leaf samples were collected for model calibration and another 50 for model verification. Each leaf sample was optically measured by USB4000, a modular spectrometer. By the observation of spectral curves, the spectral range between 650nm and 750nm was ...

Acala cotton (Gossypium hirsutum, var. Maxxa) was planted into a split-plot factorial design field trial on the Shafter Research and Extension Center, Shafter, CA. The two main treatments were optimum irrigation (Io) and stressed irrigation (Is) containing five levels of soil nitrogen availability (-100, -50, optimum, +50, and +100 lbs N/ac). The objective of this field trial was to determine i...