Assessing the potential use of two portable chlorophyll meters in diagnosing the nutritional status of plants

Afonso, Sandra; Arrobas, Margarida; Ferreira, I.Q.; Rodrigues, M. Ângelo

doi:10.1080/01904167.2017.1385798

Cited by 14 publications

(11 citation statements)

References 27 publications

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“…These variations in tissue nutrient concentrations were probably the result of dilution and concentration effects, which have been well-known for a long time [34], and/or antagonism and synergism in plant nutrient uptake [35]. SPAD and NDVI usually provide a good indication of the greenness of the leaves and general plant health [36,37]. In this study, however, only NDVI values were associated with the most productive plots.…”

Section: Discussionmentioning

confidence: 60%

Response of Hops to Algae-Based and Nutrient-Rich Foliar Sprays

2021

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Over recent years, some hopyards of northeast Portugal have presented poorly developed plants and reduced productivity. In this study, an attempt was made to improve the homogeneity of hop fields and restore their productivity by using plant biostimulants as foliar sprays. The experimental apparatus included four field trials carried out in four plots of different plant vigour, as evaluated by farmers over previous years (weak, fair, good and very good). The experiments were arranged as a factorial of foliar treatment (two plant biostimulants containing extracts of seaweed algae and an untreated control) and year (2017 and 2018). The plot and the year influenced greatly almost all the measured variables related to tissue nutrient concentration and crop performance. In the control plots, cone dry matter (DM) yield varied from 83.3 to 394.4 g plant−1 from the weak to the very good plots. In 2018, cone DM yield was significantly higher than in 2017. The use of foliar sprays influenced less the elemental composition of plant tissue than the plot or the year. The use of foliar sprays only increased significantly crop yield in the plot of weak plant vigour. The foliar treatments did not increase α- and β-acid concentration in the cones; in the control treatment of the most productive plot, the values were, respectively, 11.2 and 3.9%. Although seaweed extracts tend to help plants cope with several abiotic and biotic stresses, they showed to be effective in mitigating the stress that is affecting these plants, which probably is poor soil drainage caused by the flooding irrigation system, only under conditions of severe stress.

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Section: Discussionmentioning

confidence: 60%

Response of Hops to Algae-Based and Nutrient-Rich Foliar Sprays

2021

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“…Red-edge spectral reflectance is associated with higher sampling resolution as it is relatively easily affected (strongly controlled) by chlorophyll concentration change compared to the red spectral reflectance [ 39 ]. In addition, NDVI data distributions show saturation towards higher reading values [ 47 ], and this can decrease the model performance.…”

Section: Discussionmentioning

confidence: 99%

“…Shafian et al [ 46 ] evaluated the performance of an Unmanned Aerial Systems-based remote sensing system for quantification of crop growth parameters of sorghum LAI, fractional vegetation cover (fc) and yield. In their work to assess the potential use of portable SPAD-502 and the FieldScout CM 1000 NDVI meters in diagnosing the nutritional status of plants, Afonso et al [ 47 ] concluded that although both devices showed good reproducibility, the FieldScout NDVI readings showed a marked saturation curve with the leaf nitrogen concentration, and was thus considered not suited for reliable use as nitrogen nutritional status index. Using RapidEye images and in situ data from alfa-alfa, barley, maize and winter wheat, Xie et al [ 39 ] proposed three improved indices combining reflectance both in the red and red-edge spectral regions into the NDVI, the modified simple ratio index (MSR), and the green chlorophyll index formula for LAI retrieval.…”

Section: Introductionmentioning

confidence: 99%

Machine learning models based on remote and proximal sensing as potential methods for in-season biomass yields prediction in commercial sorghum fields

Habyarimana

Baloch

2021

PLoS ONE

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Crop yield monitoring demonstrated the potential to improve agricultural productivity through improved crop breeding, farm management and commodity planning. Remote and proximal sensing offer the possibility to cut crop monitoring costs traditionally associated with surveys and censuses. Fraction of absorbed photosynthetically active radiation (fAPAR), chlorophyll concentration (CI) and normalized difference vegetation (NDVI) indices were used in crop monitoring, but their comparative performances in sorghum monitoring is lacking. This work aimed therefore at closing this gap by evaluating the performance of machine learning modelling of in-season sorghum biomass yields based on Sentinel-2-derived fAPAR and simpler high-throughput optical handheld meters-derived NDVI and CI calculated from sorghum plants reflectance. Bayesian ridge regression showed good cross-validated performance, and high reliability (R2 = 35%) and low bias (mean absolute prediction error, MAPE = 0.4%) during the validation step. Hand-held optical meter-derived CI and Sentinel-2-derived fAPAR showed comparable effects on machine learning performance, but CI outperformed NDVI and was therefore considered as a good alternative to Sentinel-2’s fAPAR. The best times to sample the vegetation indices were the months of June (second half) and July. The results obtained in this work will serve several purposes including improvements in plant breeding, farming management and sorghum biomass yield forecasting at extension services and policy making levels.

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“…Studies on many crops have observed an enhanced radiation interception to be directly related to improved uptake of soil N when soil moisture was not limiting (Andersen, Heidmann, & Plauborg, ; Oppong Danso et al, ; Zhou, Plauborg, Thomsen, & Andersen, ). Although we did not determine crop N uptake in the present study, the LCC is usually taken as a surrogate measure of the N content of crops due to the linear relation between the two (Afonso, Arrobas, Ferreira, & Rodrigues, ; Muchecheti, Madakadze, & Soundy, ). In line with this, the LCC in our study was significantly and linearly related to both TDMY and IPAR in both years with R 2 of 0.7 and 0.8 in 2017 and 0.5 and 0.8 in 2018 (Table ).…”

Section: Discussionmentioning

confidence: 99%

Effect of rice straw biochar and irrigation on growth, dry matter yield and radiation‐use efficiency of maize grown on an Acrisol in Ghana

Danso

Yakubu

Arthur

et al. 2019

J Agronomy Crop Science

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In order to determine whether the current low productivity associated with rainfed cultivation on degraded soils in Ghana can be improved by biochar amendment and irrigation, field experiments with maize were conducted over two seasons in 2017 and 2018. Rice straw biochar at rates of 0 t/ha (B0), 15 t/ha (B15) and 30 t/ha (B30) was combined with irrigation regimes of full irrigation (I100), deficit irrigation (I60) and no irrigation (I0). The I100 treatment was irrigated to field capacity every 3–4 days according to time domain reflectometry measurements while the I60 treatment received 60% of the irrigation amount given to I100 but with the same irrigation frequency. The I0 treatment was not irrigated. In both seasons, the B30 treatment recorded the highest total dry matter yield (TDMY), intercepted photosynthetically active radiation (IPAR) and radiation‐use efficiency (RUE) and these were significantly (p ≤ .05) higher than B0 except for RUE in 2017. Irrigation regimes did not significantly affect TDMY, IPAR and RUE in 2017 but compared to I100, I0 significantly reduced TDMY, IPAR and RUE in the relatively dryer 2018 season. Measured ratio vegetation indices differentiated biochar treatments earlier in the 2018 season than during 2017 and increase of leaf chlorophyll content indices with biochar rate in both seasons indicated that biochar amendment improved nitrogen uptake. Our study demonstrated that rice straw biochar is capable of increasing TDMY, IPAR and RUE of maize grown on degraded soils in Ghana. The study further showed that TDMY, IPAR and RUE of deficit irrigated maize for two seasons were similar to the counterpart fully irrigated maize and may be a viable water management option for farmers in Ghana to save irrigation water resources.

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Assessing the potential use of two portable chlorophyll meters in diagnosing the nutritional status of plants

Cited by 14 publications

References 27 publications

Response of Hops to Algae-Based and Nutrient-Rich Foliar Sprays

Response of Hops to Algae-Based and Nutrient-Rich Foliar Sprays

Machine learning models based on remote and proximal sensing as potential methods for in-season biomass yields prediction in commercial sorghum fields

Effect of rice straw biochar and irrigation on growth, dry matter yield and radiation‐use efficiency of maize grown on an Acrisol in Ghana

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