Study of a Non-destructive Method for Estimating the Leaf Area Index in Vegetable Crops Using Digital Images

One estimate of a crop's ability to capture light energy is the leaf area index (LAI), which is defined as the proportion of leaf area per unit of land area. Direct methods of estimation involve determining the LAI in a significant area of cultivation and individually measuring the leaf surface, which is often tedious. The objective of this study was to develop a cheap and simple method for determining LAI based on the percentage of groundcover (PGC) measured in two vegetable crops with notable differences in leaf type and plant architecture using digital images obtained with a commercial camera and applying open-source software. The PGC values obtained from digital image analysis in cauliflower and tomato crops and the measurements of LAI obtained by destructive sampling (measured with a planimeter) allowed us to obtain a relationship between two variables (r2 > 0.88). In all cases, the extinction coefficients were obtained from comparisons of LAI and PGC with values ranging between 0.75 and 0.85 for processing tomato and 0.60 and 0.70 for cauliflower. The method used allows non-destructive estimations of LAI that are comparable with other more expensive indirect methods that require a skilled operator.

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Adjusting Ceptometer Data to Improve Leaf Area Index Measurements

Agronomy ◽

10.3390/agronomy9120866 ◽

2019 ◽

Vol 9 (12) ◽

pp. 866 ◽

Cited By ~ 4

Author(s):

Klára Pokovai ◽

Nándor Fodor

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Measurement Techniques ◽

Well Being ◽

Average Error ◽

Light Conditions ◽

Simple Method ◽

Area Index ◽

Expert Opinions ◽

Optimal Illumination

Leaf Area Index (LAI) is an important plant parameter for both farmers and plant scientists to monitor and/or model the growth and the well-being of plants. Since direct LAI measurement techniques are relatively laborious and time-consuming, various indirect methods have been developed and widely used since the early 1990s. The LP-80 ceptometer uses a linear array of PAR (photosynthetically active radiation) sensors for non-destructive LAI measurements that is backed by 15 years of research. Despite this, considerable discrepancy can be found between the expert opinions regarding the optimal illumination conditions recommended for the measurement. The sensitivity of ceptometer-based LAI values to PAR was investigated, and a simple method was devised to correct raw ceptometer data collected under non-ideal light conditions. Inadequate light conditions (PAR < 1700 µmol m−2 s−1) could cause an underestimation of LAI. Using the corrected LAI values, the ceptometer data showed a significantly better fit (higher R2, smaller mean average error and closer to zero mean signed error values) to the destructive LAI data for both wheat and maize. With the help of the correction equations, the use of the LP-80 ceptometer could be extended to days when light conditions are not ideal.

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A PROPOSED METHODOLOGY FOR THE CORRECTION OF THE LEAF AREA INDEX MEASURED WITH A CEPTOMETER FOR PINUS AND EUCALYPTUS FORESTS

Revista Árvore ◽

10.1590/0100-67622016000500008 ◽

2016 ◽

Vol 40 (5) ◽

pp. 845-854 ◽

Cited By ~ 2

Author(s):

Domingos Mendes Lopes ◽

Nigel Walford ◽

Helder Viana ◽

Carlos Roberto Sette Junior

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Correction Factor ◽

Basal Area ◽

Allometric Equations ◽

Nutrient Cycle ◽

Area Index ◽

Physiological Processes ◽

The Difference ◽

Non Destructive

ABSTRACT Leaf area index (LAI) is an important parameter controlling many biological and physiological processes associated with vegetation on the Earth's surface, such as photosynthesis, respiration, transpiration, carbon and nutrient cycle and rainfall interception. LAI can be measured indirectly by sunfleck ceptometers in an easy and non-destructive way but this practical methodology tends to underestimated when measured by these instruments. Trying to correct this underestimation, some previous studies heave proposed the multiplication of the observed LAI value by a constant correction factor. The assumption of this work is LAI obtained from the allometric equations are not so problematic and can be used as a reference LAI to develop a new methodology to correct the ceptometer one. This new methodology indicates that the bias (the difference between the ceptometer and the reference LAI) is estimated as a function of the basal area per unit ground area and that bias is summed to the measured value. This study has proved that while the measured Pinus LAI needs a correction, there is no need for that correction for the Eucalyptus LAI. However, even for this last specie the proposed methodology gives closer estimations to the real LAI values.

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Productivity of Vegetable Crops in a Region of High Solar Input. IV. Field Chamber Measurements on French Beans (Phaseolus vulgaris L.) And Cabbages (Brassica oleracea L.)

Functional Plant Biology ◽

10.1071/pp9750461 ◽

1975 ◽

Vol 2 (4) ◽

pp. 461 ◽

Cited By ~ 8

Author(s):

PJM Sale

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Growth Rates ◽

Dark Respiration ◽

Gas Analysis ◽

Large Field ◽

Co2 Uptake ◽

Vegetable Crops ◽

Area Index ◽

French Beans

Net CO2 uptakes have been measured for crop canopies of French beans and cabbages, sown at two plant densities, using a large field assimilation chamber and a semi-closed gas-analysis system. For both species, the maximum rates of uptake were a little less than 40 mg CO2 dm-2 (ground area) h-1, and light saturation of the canopy occurred at 600-650 W m-2 (French beans) or about 800 W m-2 (cabbages). Net CO2 uptake decreased with leaf area index at values below about 5, but was relatively insensitive to temperature over the range used. Once this leaf area index was reached, the relationship between net uptake and solar radiation remained fairly constant throughout the growth period. For both species, dark respiration rates were markedly dependent on temperature, and also were lower at night than during the day when measured at the same temperature. For both French beans and cabbages, growth analyses showed the maximum growth rates to be 18-19 g dry weight m-2 (ground area) day-1. The mean growth rate from emergence to harvest for an overwintered cabbage crop was 5.5 g m-2 day-1. It is suggested that the main advantage of the region in terms of plant productivity lies in the long frost-free growing season and the ability of frost-tolerant crops to maintain fairly high growth rates throughout a mild and comparatively sunny winter.

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Development and Evaluation of a Leaf Disease Damage Extension in Cropsim-CERES Wheat

Agronomy ◽

10.3390/agronomy9030120 ◽

2019 ◽

Vol 9 (3) ◽

pp. 120 ◽

Cited By ~ 3

Author(s):

Georg Röll ◽

William Batchelor ◽

Ana Castro ◽

María Simón ◽

Simone Graeff-Hönninger

Keyword(s):

Sensitivity Analysis ◽

Leaf Area Index ◽

Leaf Area ◽

Mean Squared Error ◽

Septoria Tritici Blotch ◽

Septoria Tritici ◽

Extended Model ◽

Simple Method ◽

Area Index ◽

The Impact

Developing disease models to simulate and analyse yield losses for various pathogens is a challenge for the crop modelling community. In this study, we developed and tested a simple method to simulate septoria tritici blotch (STB) in the Cropsim-CERES Wheat model studying the impacts of damage on wheat (Triticum aestivum L.) yield. A model extension was developed by adding a pest damage module to the existing wheat model. The module simulates the impact of daily damage on photosynthesis and leaf area index. The approach was tested on a two-year dataset from Argentina with different wheat cultivars. The accuracy of the simulated yield and leaf area index (LAI) was improved to a great extent. The Root mean squared error (RMSE) values for yield (1144 kg ha−1) and LAI (1.19 m2 m−2) were reduced by half (499 kg ha−1) for yield and LAI (0.69 m2 m−2). In addition, a sensitivity analysis of different disease progress curves on leaf area index and yield was performed using a dataset from Germany. The sensitivity analysis demonstrated the ability of the model to reduce yield accurately in an exponential relationship with increasing infection levels (0–70%). The extended model is suitable for site specific simulations, coupled with for example, available remote sensing data on STB infection.

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NON-DESTRUCTIVE ESTIMATION OF LEAF AREA INDEX IN VASE-SHAPE SWEET CHERRY TREES

Acta Horticulturae ◽

10.17660/actahortic.2014.1020.30 ◽

2014 ◽

pp. 209-215

Author(s):

V. Hochmaier ◽

L. San Martino ◽

E.D. Cittadini

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Sweet Cherry ◽

Area Index ◽

Non Destructive ◽

Cherry Trees

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Estimating leaf area index of sugarcane based on multi-temporal digital images

2016 Fifth International Conference on Agro-Geoinformatics (Agro-Geoinformatics) ◽

10.1109/agro-geoinformatics.2016.7577689 ◽

2016 ◽

Cited By ~ 2

Author(s):

Dongdong Zhang ◽

Xiaodong Song ◽

Lamin R. Mansaray ◽

Zhen Zhou ◽

Kangyu Zhang ◽

...

Keyword(s):

Leaf Area Index ◽

Leaf Area ◽

Digital Images ◽

Area Index ◽

Multi Temporal

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Leaf area estimation of medium size plants using optical metrology

Revista Brasileira de Engenharia Agrícola e Ambiental ◽

10.1590/s1415-43662013000600004 ◽

2013 ◽

Vol 17 (6) ◽

pp. 595-601 ◽

Cited By ~ 3

Author(s):

Kleber M. Ribeiro ◽

Roberto A. Braga ◽

Myriane S. Scalco ◽

Graham W. Horgan

Keyword(s):

Leaf Area ◽

Direct Methods ◽

Optical Metrology ◽

Medium Size ◽

Coffee Plant ◽

Indirect Methods ◽

Area Index ◽

The Subject ◽

Non Destructive ◽

Commercial Equipment

The total leaf area (TLA) estimation is an important feature of the crops and their assessment a challenge, since the direct methods of obtaining it are destructive and time consuming. Non-destructive methods have been explored to obtain the TLA by indirect approaches, in turn creating other features, as the leaf area index. The development of non-destructive technology to access the TLA of a plant has been the subject of much research, and the optical metrology is an promising approach. In this work, some indirect methods associated with optical approaches were evaluated as an alternative to obtain the TLA of the coffee plant. Commercial equipment were used, such as a camera with a fish eye lens and lux meters, associated to the sizes of the canopies were tested and compared to another non-destructive method and with methods proposed in the literature. The association between production and the TLA estimated was also evaluated. The results showed that the commercial equipment, generally used in forestry, was not the best approach in coffee plants, and that the methods related to the size and lux values of the plants were the best alternatives to estimate the TLA of the coffee plant.

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