Water Stress Thresholds and Evaluation of Coefficient Ks for Perennial Ryegrass in Tropical Conditions

Terán-Chaves, César Augusto; García-Prats, Alberto; Polo-Murcia, Sonia Mercedes

doi:10.3390/w14111696

Cited by 4 publications

(3 citation statements)

References 38 publications

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“…Water deficit reduced root length. These results were consistent with those of other researchers on Quercus leucotrichophora [70], Thymus volgaris [44], and Tritipyrum lines [71]. Previous researchers have reported that root cell final lengths are smaller under water deficit [72] due to a decrease in root apical cell elongation under water stress [58].…”

Section: Discussionsupporting

confidence: 93%

The Reinforcement of Early Growth, Extract, and Oil of Silybum marianum L. by Polymer Organic Cover and Bacteria Inoculation under Water Deficit

et al. 2023

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Early growth water stress reduces the extract and fresh oil of Silybum marianum L. (S. marianum) shoots. Two experiments were conducted to reduce the effects of early growth drought. Treatments in the first experiment were organic seed cover fillers at three levels (control, vermicompost, and peat moss), hydrogel at seven levels (control, 2, 4, and 6 g hydrogelF1 per kg OSC, and 2, 4, and 6 g hydrogelA200 per kg organic seed cover), and water deficit at three levels (100, 50, and 25% of field capacity), and in the second experiment, seeds were inoculated with bacteria at four levels (control, Pseudomonas fluorescens, Pseudomonas putida, and their combination) and water deficit at four levels (100, 50, and 25% of field capacity). Our results showed that milk thistle seeds are sensitive to water deficit at the emergence stage. Covering milk thistle (S. marianum) seeds with organic seed cover increased water retention around the seeds and improved emergence percentage. Use of organic seed cover with hydrogel increased relative water content (RWC), leaf area, and shoot length, and increased extracts and oils in fresh shoots. Bacterial inoculation also improved initial growth and reduced the effect of water stress on the plant, and increased leaf number, extract, and oil. The combination of bacteria had a positive effect on initial growth and inoculation of seeds, P. fluorescens and P. putida increased relative water content (RWC), shoot height, and specific leaf area, and increased extract and oil under water deficit conditions. A comparison of the results showed that seed inoculation is a simple method without new culture medium, and improves extract and oil under water deficit conditions.

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Section: Discussionsupporting

confidence: 93%

The Reinforcement of Early Growth, Extract, and Oil of Silybum marianum L. by Polymer Organic Cover and Bacteria Inoculation under Water Deficit

et al. 2023

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“…They include canopy cover (CC), canopy growth coefficient (CGC), canopy decline coefficient (CDC), crop coefficient for transpiration at full CC, and normalized water productivity (WP*) for biomass formation. Crop water stress parameters (soil water depletion thresholds for leaf growth inhibition and stomatal conductance and for acceleration of canopy senescence) were taken from Terán-Chaves et al [41]. The crop parameters were iteratively adjusted with the help of the Independent Parameter Estimation Model (PEST) Ver.…”

Section: Crop Datamentioning

confidence: 99%

Calibration and Validation of the FAO AquaCrop Water Productivity Model for Perennial Ryegrass (Lolium perenne L.)

Terán-Chaves

García-Prats

Polo-Murcia

2022

Water

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Crop models that can accurately estimate yield and final biomass have been used for major herbaceous crops and to a lesser extent in forage systems. The AquaCrop version 7.0 contains new modules that have been introduced to simulate the growth and production of perennial herbaceous forage crops. Simulated forage yields as a function of water consumption provide valuable information that allows farmers to make decisions for adapting to both climate variability and change. The study aimed to calibrate and validate the AquaCrop model for perennial ryegrass (Lolium perenne L.) in the high tropics of Colombia (South America). The experiments were conducted during two consecutive seasons, in which perennial ryegrass meadows were subjected to two irrigation regimes: full irrigation and no irrigation. The model was evaluated using precision, accuracy, and simulation error indices. The overall performance of AquaCrop in simulating canopy cover, biomass and soil water content showed a good match between measured and simulated data. The calibration results indicated an acceptable measurement of simulated canopy cover (CC) (R2 = 0.95, d-index = 0.41, RMSE = 9.4%, NRMSE = 12.2%, and FE = −21.72). The model satisfactorily simulated cumulative dry mass (R2 = 0.95, d-index = 0.98, RMSE = 2. 63 t ha−1, NRMSE = 11.8%, and FE = 0.94). Though the biomass values obtained in the end-of-season cuts were underestimated by the model, soil water content was simulated with reasonable accuracy (R2 = 0.82, d-index = 0.84, RMSE = 6.10 mm, NRMSE = 4.80%, and FE = 0.32). During validation, CC simulations were good, except under water deficit conditions, where model performance was poor (R2 = 0.42, d-index = 0.01, RMSE = 40.60%, NRMSE = 40.90%, and FE = −25.71); biomass and soil water content simulations were reasonably good. The above results confirmed AquaCrop’s (v 7.0) suitability for simulating responses to water for perennial ryegrass. A single crop file was developed for managing a full season and can be confidently applied to direct future research to improve the understanding of the necessary processes and interactions for the development of perennial herbaceous forage crops.

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“…K cb values from this technique were used to estimate the reduction of transpiration as the water stress term K s (Trout and DeJonge, 2021). Formulations to calculate K s include a linear reduction in transpiration as deficit exceeds the Readily Available Water (RAW) as suggested by FAO-56 (Allen et al, 1998), but more recently an exponential decay function was used, e.g., as defined by Aq-uaCrop (Steduto et al, 2009) and reinforced by other studies (Trout and DeJonge, 2021;Terán-Chaves et al, 2022).…”

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confidence: 99%

Diurnal Trends of Maize Canopy Cover Under Water Stress

DeJonge,

Zhang,

Cummins

et al. 2024

Journal of Natural Resources and Agricultural Ecosystems

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Highlights RGB trail cams above maize crop collected images every 15 minutes, day and night, to monitor leaf curl. Fractional canopy cover (fc,%) was constant for full irrigation but reduced during the day for limited irrigation. Techniques were developed to estimate reductions in water use (i.e., evapotranspiration) using images of fc. Measurements of fc prior to wilting represent transpiration demand (Kcb ), and reductions of fc represent stress (Ks ). Abstract. By differentiating green and non-green pixels of RGB images of crop canopy, the fractional canopy cover (fc,%) can be estimated and subsequently used to estimate crop transpiration demand (e.g., Kcb, basal crop coefficient, following FAO-56 methodology). While unstressed maize crops maintain consistent fc through the day, leaves of heat or water stressed crops will curl, thereby reducing the instantaneous fc and the associated transpiration. This paper reports the effects of diurnal leaf curl and subsequent fc reduction on full and limited water treatments of irrigated maize through nadir images obtained every 15 minutes. Results suggest that fc images obtained in the early morning (fcNS) are typically representative of a non-stressed condition and can be used to estimate Kcb. Reduction of fc throughout the day (i.e., fc/fcNS) was compared to water stress coefficient Ks obtained from neutron probe and TDR measurement and showed that fc/fcNS from hours 11 a.m. to 2 p.m. had a high correlation (R2 = 0.773), indicating that mid-day fractional canopy cover reduction could be used as a proxy for Ks. This method creates new opportunities for estimating crop water stress during vegetative growth but also highlights potentially unknown challenges regarding lower resolution remote sensing during the same growth stages. Keywords: Basal crop coefficient, Canopy cover, Crop coefficient, Evapotranspiration, Stomatal conductance, Stress crop coefficient, Transpiration, Water stress.

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Water Stress Thresholds and Evaluation of Coefficient Ks for Perennial Ryegrass in Tropical Conditions

Cited by 4 publications

References 38 publications

The Reinforcement of Early Growth, Extract, and Oil of Silybum marianum L. by Polymer Organic Cover and Bacteria Inoculation under Water Deficit

The Reinforcement of Early Growth, Extract, and Oil of Silybum marianum L. by Polymer Organic Cover and Bacteria Inoculation under Water Deficit

Calibration and Validation of the FAO AquaCrop Water Productivity Model for Perennial Ryegrass (Lolium perenne L.)

Diurnal Trends of Maize Canopy Cover Under Water Stress

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