Roberto Alves Braga

Plant tissue culture enables the controlled evaluation of plant responses under in vitro conditions, whereas biospeckle laser analysis (BSL) provides a non-invasive approach for assessing dynamic responses in living tissues. However, its application in plant tissue culture requires methodological standardization, particularly in the selection of the illuminated region. This study aimed to standardize BSL acquisition in in vitro grown A. obesum seedlings by comparing the basal, middle, and tip root regions under two contrasting culture medium conditions. Biospeckle responses were quantified using the Absolute Value of the Differences (AVD) index and graphical AVD (GAVD). A significant culture medium × root region interaction was detected for AVD. In MS medium, the basal region showed the highest AVD values, followed by the middle and tip regions, whereas no significant differences among root regions were observed in the medium without mineral salts. The mean root AVD was positively correlated with dry mass, leaf number, fresh mass, leaf length, leaf width, and root length, indicating an association with seedling performance. These findings support the basal region as a suitable candidate for standardized BSL acquisition in A. obesum under the evaluated conditions and demonstrate that root-region selection should be considered during the methodological optimization.

The biospeckle laser (BSL) technique is recognized as a sensitive method for detecting biological activity and has been successfully applied for seed vigor testing. Given these achievements, whether the integration of BSL into automated systems can provide complementary information on the seed imbibition process remains limited. Addressing this gap represents a significant challenge with strong potential for technological innovation. This study presents an automated laser-optical system designed to monitor the imbibition process of multiple seeds over time using a mechanized carousel. The developed apparatus integrates all necessary components for the illumination and image acquisition of eight seeds across programmable time intervals, controlled by an industrial-grade programmable controller. Validation using maize seeds (Zea mays L.) over a 36-h period confirmed the system’s reliability. BSL indices enabled the characterization of internal biological activity throughout imbibition, revealing dynamic processes that remained undetected in previous discrete-time analyses. These results highlight the potential of the proposed system for more comprehensive and continuous seed monitoring. The successful automated laser-optical system with relative humidity control opens great potential in seeds research and daily industrial analysis. The test of the proposed system in other seeds is the next challenge, regarding the thick and colored coats. The design of larger carousels is a possible step forward, which will demand studies of the limits linked to the illumination and image acquisition time performed in each seed.

Optics and image analysis technologies support modern agriculture, providing detailed insights into crop health, soil conditions, and environmental factors at both the macro and micro scales

Seeds are a fundamental input in food production programs, as well as in the restoration and conservation of ecosystems. Consequently, their physiological potential, specifically vigor, has become a key parameter for evaluating germination capacity and seedling establishment. Biospeckle Laser (BSL) technology has been increasingly used in seed vigor studies as a complement of the traditional tests. The objective of this work was to evaluate the graphical outcomes provided by the BSL in seed vigor analysis. Seeds from commercial species (maize, soybean and common bean) and native forest species (purple trumpet tree and yellow poinciana) were analyzed. Seeds were illuminated by a 632 nm laser at zero and four hours of imbibition, and the speckle images were assembled and analyzed using four graphical outcomes: the Generalized Differences (GD), the Graphical Average Value of the Differences (GraphAVD), the graphical Inertia Moment (GraphIM), and the Fujii method. The graphical outcomes represent the activity maps of the seeds, and the results presented a different response provided by the Fujii method in comparison with the other methods. The graphical analysis GD, GraphAVD, and GraphIM proved suitable for assessing seed vigor after four hours of imbibition. Among these, the GraphAVD highlighted the ability to simultaneously detect regions from low to high biological activity including the areas with medium activity. Additionally, it was possible to distinguish the viable from the non-viable purple trumpet tree seeds.

Seed vigor testing traditionally requires large sample sizes and extended durations. The biospeckle laser (BSL) technique offers a faster, image-based alternative for seed analysis though the standardization of set protocols. This study evaluated the efficiency of local and global BSL analyses in bean seeds (Phaseolus vulgaris L.). Two groups of seeds (872 in total) were classified into high- and low-vigor seeds using the emergence test over 800 samples. The BSL test was then applied to 72 seeds (36 per group), analyzing biological activity locally (vascular and embryonic areas) and globally (whole image). BSL analysis detected significant differences between the groups (p < 0.05). Among the methods, the local analysis of the embryonic axis was most effective (F = 44.252, p = 0.000), showing a clearer distinction than the global analysis (F = 19.484, p = 0.000). The vascular area analysis did not yield significant results. These findings highlight the efficiency of the local BSL analysis at the embryonic axis for vigor tests compared to the global analysis. However, it was observed that the selected point in the local analysis affects the reliability of the vigor test. It was a relevant step toward standardization demanding additional tests in other species and varieties.

The dynamic laser speckle, or biospeckle laser, is a reliable technique for monitoring activity in biological and non-biological material. The applications in agriculture are related to seed analysis, fruits maturity, identification of fungi, root growing among many other. However, despite the proved reliability as a sensitive, fast and objective sensor its adoption by new users demands computational knowledge, that in some cases presents as a limitation. Following a tendency of web-based solutions devoted to the dissemination of science, this work developed an online and interactive environment for analysing the BSL datasets by means of an accessible human-machine interface (HMI) using the JavaScript language, and adopting remote computing in the graphic cards of the users’ computers. The environment was hosted by a web-site devoted to BSL and the results presented the feasibility of use developed tool in analysing all sort of BSL datasets. Particularly, in this work, the dataset of a coffee seed was analysed as an example.

Seed analysis is a cornerstone in advancing agriculture, with vigor tests playing a critical role in evaluating the physiological quality of seeds. However, monitoring seed vigor over time poses a significant challenge for the seed industry, as traditional methods are time-consuming and heavily reliant on subjective human judgment. Concerning these limitations, optical-based techniques have emerged as promising alternatives. Among them, the biological laser speckle phenomenon, rooted in optical interferometry, has proven effective in sensitively detecting and monitoring activity levels in living tissues. Known as the biospeckle laser (BSL) technique, this approach offers reliable results in assessing seed vigor. The BSL technique stands out due to its simplicity, rapid analysis, objectivity, and potential for automation, making it a valuable tool for seed analysis. This paper explores the state-of-the-art application of the BSL technique for evaluating seed vigor, highlighting successful approaches, identifying current challenges, and outlining areas for future research. It delves into the experimental setup for seed illumination and discusses the associated image processing methods. Furthermore, the paper examines the numerical and graphical outcomes, underscoring the BSL technique’s ability to carry out seed analysis by addressing the limitations of traditional methods and enhancing efficiency in the agricultural sector.

The biological activity assessment using the dynamic laser speckle (DLS) technique is recognized as a feasible methodology to analyze seeds vigor. Nevertheless, the technique presents the accessibility as a restriction to final users, and the large size of the equipment is a key limitation to allow the portability of the DLS. This work aimed to propose a reduced and portable configuration of the image capture system adopted in the DLS technique for seed analysis applications. A compacted digital camera with an embedded magnification, known by mini microscope, was tested associated with adapted diaphragm as an alternative to the traditional CCD camera, macro zoom and integrated diaphragm. The tests of the proposed adapted mini microscope, in comparison to the traditional configuration, were carried out in the monitoring of drying a paint and in the separation of high-vigor from early-aged seeds. Diaphragms with three different apertures (3, 4 and 5 mm) were evaluated. The results using the 3 mm diameter aperture presented the best performance, like in the case of the traditional CCD camera set. It was possible to follow the drying of a paint activity compared to its loss of weight and to distinguish statistically high-vigor from early-aged seeds at a significance level of 5%. The reliable results of the proposed configuration offered a compact and portable version for using the DLS in seed analysis laboratories.

The Dynamic Laser Speckle (DLS) is a photonic phenomenon transformed into a technique to monitor tiny changes in many materials, particularly in biological ones (Biospeckle Laser – BSL). Its high sensitivity is key to monitor tiny changes in the tissues that can characterise biological features in medical and in agricultural samples. This work aimed to develop an environment at the world-wide-web to share raw data of BSL and to offer access to an interactively online analysis with tutorials. The gateway designed was implemented using PHP and JavaScript tools solving the challenges of managing data (images) and online interactive use. The result was an easy-to-use environment boosting the BSL research. The early results presented thousands of accesses and of more than one hundred different users from all around the world.

Background and aim: Soil structure is an important indicator of the quality of soil, but detecting the early signs of soil degradation from soil structure is difficult. Developing precise instruments able to diagnose soil structure quickly is therefore critical to improve management practices. Here, the objective is to develop an instrument analysing the roughness of surfaces resulting from the fracture of soil cores, and to test the instrument’s ability to detect changes in soil structure cause by crop type and tillage. We have designed and constructed a 3D laser profilometer suitable for analysing standard soil cores. The 3D soil profiles were first assembled into a 3D surface using image analysis before roughness indicators could be computed. The method was tested by analysing how soil surface roughness was affected by crop varieties (barley and bean) and tillage (conventional tillage and no tillage). Results showed the method is precise and could reliably detect an influence of crop type and tillage on the roughness indicator. It was also observed that tillage reduced the difference in soil structure between the different cultures. Also, the soil in which barley grew had significantly lower roughness, irrespective of the tillage method. This could indicate that the roughness indicator is affected by biopores created by the root system. In conclusion, roughness indicators obtained from the fracture of soil cores can be easily obtained by laser profilometry and could offer a reliable method for assessing the effect of crop types and soil management on soil quality.