Development of a Continuous Leaf Monitoring System to Predict Plant Water Status

2017 ◽  
Vol 60 (5) ◽  
pp. 1445-1455 ◽  
Author(s):  
Rajveer S. Dhillon ◽  
Shrini K. Upadhaya ◽  
Francisco Rojo ◽  
Jed Roach ◽  
Robert W. Coates ◽  
...  
Keyword(s):  
Water Stress ◽  
Data Collection ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Leaf Temperature ◽  
Plant Water Status ◽  
Mesh Network ◽  
Plant Water ◽  
Plant Water Stress ◽  
Precision Irrigation

Abstract. There is increased demand for irrigation scheduling tools that support effective use of the limited supply of irrigation water. An efficient precision irrigation system requires water to be delivered based on crop needs by measuring or estimating plant water stress. Leaf temperature is a good indicator of water stress. In this study, a system was developed to monitor leaf temperature and microclimatic environmental variables to predict plant water stress. This system, called the leaf monitor, monitored plant water status by continuously measuring leaf temperature, air temperature, relative humidity, ambient light, and wind conditions in the vicinity of a shaded leaf. The system also included a leaf holder, a solar radiation diffuser dome, and a wind barrier for improved performance of the unit. Controlled wind speed and consistent light conditions were created around the leaf to reduce the effect of nuisance variables on leaf temperature. The leaf monitor was incorporated into a mesh network of wireless nodes for sensor data collection and remote valve control. The system was evaluated for remote data collection in commercial orchards. Experiments were conducted during the 2013 and 2014 growing seasons in walnut () and almond () orchards. The system was found to be reliable and capable of providing real-time visualization of the data remotely, with minimal technical problems. Leaf monitor data were used to develop modified crop water stress index (MCWSI) values for quantifying plant water stress levels. Keywords: Almonds, CWSI, Infrared sensor, Irrigation scheduling, Leaf temperature, Nut crops, Plant water stress, Precision irrigation, Stem water potential, Walnuts, Wireless mesh network.

Single hyperspectral bands are highly sensitive to water stress in adult mandarin trees

2021 ◽  
Author(s):  
Pablo Berríos ◽  
Abdelmalek Temnani ◽  
Susana Zapata ◽  
Manuel Forcén ◽  
Sandra Martínez-Pedreño ◽  
...  
Keyword(s):  
Water Stress ◽  
Water Deficit ◽  
Phase Ii ◽  
Irrigation Water ◽  
Water Status ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Phase Iii ◽  
Plant Water ◽  
Severe Water Stress

<p>Mandarin is one of the most important Citrus cultivated in Spain and the sustainability of the crop is subject to a constant pressure for water resources among the productive sectors and to a high climatic demand conditions and low rainfall (about 250 mm per year). The availability of irrigation water in the Murcia Region is generally close to 3,500 m<sup>3</sup> per ha and year, so it is only possible to satisfy 50 - 60% of the late mandarin ETc, which requires about 5,500 m<sup>3</sup> per ha. For this reason, it is necessary to provide tools to farmers in order to control the water applied in each phenological phase without promoting levels of severe water stress to the crop that negatively affect the sustainability of farms located in semi-arid conditions. Stem water potential (SWP) is a plant water status indicator very sensitive to water deficit, although its measurement is manual, discontinuous and on a small-scale.  In this way, indicators measured on a larger scale are necessary to achieve integrating the water status of the crop throughout the farm. Thus, the aim of this study was to determine the sensitivity to water deficit of different hyperspectral single bands (HSB) and their relationship with the midday SWP in mandarin trees submitted to severe water stress in different phenological phases. Four different irrigation treatments were assessed: i) a control (CTL), irrigated at 100% of the ETc throughout the growing season to satisfy plant water requirements and three water stress treatments that were irrigated at 60% of ETc throughout the season – corresponding to the real irrigation water availability – except  during: ii) the end of phase I and beginning of phase II (IS IIa), iii) the first half of phase II (IS IIb) and iv) phase III of fruit growth (IS III), which irrigation was withheld until values of -1.8 MPa of SWP or a water stress integral of 60 MPa day<sup>-1</sup>. When these threshold values were reached, the spectral reflectance values were measured between 350 and 2500 nm using a leaf level spectroradiometer to 20 mature and sunny leaves on 4 trees per treatment. Twenty-four HVI and HSB were calculated and a linear correlation was made between each of them with SWP, where the ρ940 and ρ1250 nm single bands reflectance presented r-Pearson values of -0.78** and -0.83***, respectively. Two linear regression curves fitting were made: SWP (MPa) = -11.05 ∙ ρ940 + 7.8014 (R<sup>2</sup> =0.61) and SWP (MPa) = -13.043 ∙ ρ1250 + 8.9757 (R<sup>2</sup> =0.69). These relationships were obtained with three different fruit diameters (35, 50 and 65 mm) and in a range between -0.7 and -1.6 MPa of SWP. Results obtained show the possibility of using these single bands in the detection of water stress in adult mandarin trees, and thus propose a sustainable and efficient irrigation scheduling by means of unmanned aerial vehicles equipped with sensors to carry out an automated control of the plant water status and with a suitable temporal and spatial scale to apply precision irrigation.</p>

Plant Water Stress Detection Using Leaf Temperature and Microclimatic Information

2011 ◽  
Author(s):  
Vasu Udompetaikul ◽  
Shrini K Upadhyaya ◽  
David C Slaughter ◽  
Bruce D Lampinen ◽  
Ken A Shackel
Keyword(s):  
Water Stress ◽  
Leaf Temperature ◽  
Plant Water ◽  
Stress Detection ◽  
Plant Water Stress

scholarly journals Precision irrigation in Almonds based on plant water status

2018 ◽  
Vol 2 (1) ◽  
pp. 113-116 ◽  
Author(s):  
Erin Kizer ◽  
Channing Ko-Madden ◽  
Kelley Drechsler ◽  
Julie Meyers ◽  
Chunxia Jiang ◽  
...  
Keyword(s):  
Water Status ◽  
Plant Water Status ◽  
Plant Water ◽  
Precision Irrigation

scholarly journals Dependence of CWSI-Based Plant Water Stress Estimation with Diurnal Acquisition Times in a Nectarine Orchard

2021 ◽  
Vol 13 (14) ◽  
pp. 2775
Author(s):  
Suyoung Park ◽  
Dongryeol Ryu ◽  
Sigfredo Fuentes ◽  
Hoam Chung ◽  
Mark O’Connell ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Stress ◽  
Data Acquisition ◽  
Irrigation Scheduling ◽  
Physiological Parameters ◽  
Acquisition Time ◽  
Plant Water ◽  
Crop Water ◽  
Crop Water Stress Index ◽  
Plant Water Stress

Unmanned aerial vehicle (UAV) remote sensing has become a readily usable tool for agricultural water management with high temporal and spatial resolutions. UAV-borne thermography can monitor crop water status near real-time, which enables precise irrigation scheduling based on an accurate decision-making strategy. The crop water stress index (CWSI) is a widely adopted indicator of plant water stress for irrigation management practices; however, dependence of its efficacy on data acquisition time during the daytime is yet to be investigated rigorously. In this paper, plant water stress captured by a series of UAV remote sensing campaigns at different times of the day (9h, 12h and 15h) in a nectarine orchard were analyzed to examine the diurnal behavior of plant water stress represented by the CWSI against measured plant physiological parameters. CWSI values were derived using a probability modelling, named ‘Adaptive CWSI’, proposed by our earlier research. The plant physiological parameters, such as stem water potential (ψstem) and stomatal conductance (gs), were measured on plants for validation concurrently with the flights under different irrigation regimes (0, 20, 40 and 100 % of ETc). Estimated diurnal CWSIs were compared with plant-based parameters at different data acquisition times of the day. Results showed a strong relationship between ψstem measurements and the CWSIs at midday (12 h) with a high coefficient of determination (R2 = 0.83). Diurnal CWSIs showed a significant R2 to gs over different levels of irrigation at three different times of the day with R2 = 0.92 (9h), 0.77 (12h) and 0.86 (15h), respectively. The adaptive CWSI method used showed a robust capability to estimate plant water stress levels even with the small range of changes presented in the morning. Results of this work indicate that CWSI values collected by UAV-borne thermography between mid-morning and mid-afternoon can be used to map plant water stress with a consistent efficacy. This has important implications for extending the time-window of UAV-borne thermography (and subsequent areal coverage) for accurate plant water stress mapping beyond midday.

Soil Moisture as Predictor of Plant Water Status

2021 ◽  
Vol 47 (3) ◽  
pp. 110-115
Author(s):  
Johannes Hertzler ◽  
Steffen Rust
Keyword(s):  
Water Potential ◽  
Soil Water ◽  
Water Status ◽  
Soil Water Potential ◽  
Irrigation Scheduling ◽  
Plant Water Status ◽  
Plant Water ◽  
Estimation Errors ◽  
Plant Available Water ◽  
The Relationship

Soil water potential can be used as a proxy for plant available water in irrigation scheduling. This study investigated the relationship between soil water potential and plant water status of pines (Pinus sylvestris L.) planted into two different substrates. Predawn leaf water potential as a well-established measure of the plant water status and soil water potential correlated very well. However, estimating the plant water status from individual sensor readings is subject to significant estimation errors. Furthermore, it was shown that heterogeneous soil/root ball combinations can lead to critical effects on the soil water balance, and that sensors installed outside of the root balls cannot estimate the plant water status without site-specific calibration.

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