Search Results (7)

The automated grading of Scots pine seeds in the near-infrared wavelength region (NIR grading) is a starting point for further actions, such as coating and priming. This reduces the time and financial costs and increases the accuracy of seed viability classification compared to invasive techniques. The NIR-based wave reflected from each pine seed must be detected and processed with sufficient accuracy. To focus the reflected beam, we used fiber-optic Bragg grating, a Bragg mirror, and diffraction grating. For each focusing option based on the DOE matrix, one experiment of 20 runs (n = 20) and three replicas (m = 3) in each run was conducted. In each replica, we used 100 conditioned and 100 non-conditioned seeds (N_C + N_NC = 200) selected randomly from five samples weighing 50 g from a seedlot weighing 1 kg extracted from cones collected from a natural tree stand. Three experiments were conducted on the NIR grading of Scots pine seeds using an optoelectronic device. An adequate DOE regression model of the grading efficiency function was obtained. The functions included the following arguments: angle of incidence of the optical beam, NIR wavelength reflected from the seed, and height of the seed pipeline. The influence of the inclination angle of the light source relative to the plane of pine seed movement on the grading quality prevails over other factors. The NIR grading of Scots pine seeds allows the separation of seeds according to the viability index, which is important, since dead petrified seeds (possibly up to 25%) may occur in the seed batch, which cannot be eliminated by either seed size or mass. The peak of NIR grading is achieved by combining the average grader engineering parameters: 968–973 nm for the wavelength and 44–46 degrees for the inclination angle of the reflected beam at a seed pipe size of 0.18–0.23 m. Full article

The development of mobile optoelectronic graders for separating viable seeds by spectrometric properties with high detection accuracy represents a very relevant direction of development for seed handling operations. Here, the main parameters of the radiation source and receiver for detecting a single seed in the diagnostic system of a mobile grader were modeled based on the principles of technical optics using Scots pine (Pinus sylvestris L.) seeds as a case study. Among the pine seeds in the seed batch, there are fossilized and empty seeds that are exactly the same in geometric and gravitational parameters as live seeds. For their separation from the seed batch, data from spectrometric studies in the near-infrared (980 nm) region can be used. To substantiate the parameters of the light source, a geometric optical model of optical beam formation was considered, while the energy model of optical beam formation was considered to substantiate the parameters of the light detector. The results of this study show that the signal value depended on the orientation of a single seed relative to the recording window. The beam angle from the radiation source should be within 45 degrees. The difference between the optical streams should be 50 microns, which made it possible to clearly detect the signal at a standard noise level of 15 microns and signal-to-noise detection accuracy ratio of 56.3 dB. This study expands theoretical knowledge in the field of the spectrometric properties of a single seed, considering the cases of its orientation relative to the optical beam, which affected the effective area of detection of the seed. The obtained data on the location of the main elements of the diagnostic system will speed up the design of mobile optoelectronic graders, and the development of a contemporary protocol for improving Scots pine seed quality. Full article

Discrete feeding of forest seeds is an urgent task for accurate detection of seeds during grading and reducing the seeding rate. The study used Pinus sylvestris L. seeds from cones collected in a natural stand of the Lisinsky educational-and-experimental forestry farm, Leningrad region, Russia, in 2017. Well-known methods for determining the properties of bulk materials were used; the results were processed by mathematical statistics using the MS Excel program. The physical and mechanical properties of uncalibrated seeds as a bulk material were determined. The angle of repose of Pinus sylvestris L. seeds, determined using a hollow cylinder by calculation, is 24.92°. The angle of repose of Pinus sylvestris L. seeds, determined using a hollow cylinder and a goniometer, is 32.7°. The significant discrepancy (~8°) in the values obtained by these methods is explained by the seeds shape. The flowability of Pinus sylvestris L. seeds corresponds to an excellent (free) category. The study will enable correct seed treatment protocols for sustainable forest management. However, some questions remained unresolved: how to orient a single seed in the right direction? How does seed-size calibration affect the angle of repose? Full article

Research Highlights: There is a problem of forest seeds quality assessment and grading afield in minimal costs. The grading quality of each seed coat color class is determined by the degree of its separation with a mobile optoelectronic grader. Background and Objectives: Traditionally, pine seeds are graded in size, but this can lead to a loss of genetic diversity. Seed coat color is individual for each forest seed and is caused to a low error in identifying the genetic features of seedling obtained from it. The principle on which the mobile optoelectronic grader operates is based on the optical signal detection reflected from the single seed. The grader can operate in scientific (spectral band analysis) mode and production (spectral feature grading) mode. When operating in production mode, it is important to determine the optimal engineering parameters of the grader that provide the maximum value of the separation degree of seed-color classes. For this purpose, a run of experiments was conducted on the forest seeds separation using a mobile optoelectronic grader and regression models of the output from factors were obtained. Materials and Methods: Scots pine (Pinus sylvestris L.) seed samples were obtained from cones of the 2019 harvest collected in a natural stand. The study is based on the Design of Experiments theory (DOE) using the Microsoft Excel platform. In each of three replications of each run from the experiment matrix, a mixture of 100 seeds of light, dark and light-dark fraction (n = 300) was used. Results: Interpretation of the obtained regression model of seed separation in the visible wavelength range (650–715 nm) shows that the maximum influence on the output—separation degree—is exerted by the angle of incidence of the detecting optical beam. Next in terms of the influence power on the output are paired interactions: combinations of the wavelength with the angle of incidence and the wavelength with the grader’s seed pipe height. The minimum effect on the output is the wavelength of the detecting optical beam. Conclusions: The use of a mobile optoelectronic grader will eliminate the cost of transporting seeds to and from forest seed centers. To achieve a value of 0.97–1.0 separation degree of Scots pine seeds colored fractions, it is necessary to provide the following optimal engineering parameters of the mobile optoelectronic grader: the wavelength of optical radiation is 700 nm, the angle of incidence of the detecting optical beam is 45° and the grader’s seed pipe height is 0.2 m. Full article

Coniferous seeds as an integral part of Forest Reproductive Material (FRM) are a fairly valuable product that is transported by trade operations over long distances. Seed quality determines the rate of reforestation. Improving quality indicators and increasing the competitiveness of forest seeds is one of the promising directions of a few country’s forestry development strategy and an opportunity to integrate into global reforestation initiatives. Based on the direct interaction of biophysical studies of seed spectrometric parameters, implementation of their genotype in different environmental conditions, biometric studies of seedling growth and development and genetic conditioning of these components, it is possible to develop and test a comprehensive concept for obtaining FRM with high quality indicators. What practical application can be expected? First, it is possible to study genetic variability among the seeds of the studied species, using molecular DNA markers. This would help obtain a comprehensive and categorical classification of samples that illustrates the genetic similarity and relationship structure relative to the desired characteristics of seedlings and seeds with high viability rates. Genetic and spectrometric data could be further combined to build a consensus tree of genetic similarity. Second, algorithms could be developed for integrating these parameters in the FRM-Library database to synchronize the quality indicators of forest reproduction material, with information processing devices of optoelectronic graders and phenoseeders. Third, methods and algorithms could be developed for optimal selection of technology for coniferous seeds grading of different breeding values. These would be developed based on data extracted from the FRM-Library database for the production of forest reproductive material, considering various goals and frontier methods of contemporary forest landscape restoration. Full article

Forest owners will be able to solve the problem of protecting small forest seeds from mechanical and atmospheric influences during aerial sowing, as well as the problem of manufacturing capsules in the field, saving financial, time and material resources. The process of creating a capsule by freezing the seed in a water-saturated dispersed system—immersion freezing—allows you to organize the technological properties of forest seeds depending on the initial requirements. In most cases, the quality of the seed capsule is determined by the thermophysical and mechanical properties of the components. The technological process of obtaining seed capsules for aerial seeding and the choice of freezing modes is based on a priori mathematical modeling of heat-and-mass transfer processes. The main purpose of the study is to predict the duration of the seed freezing process in a capsule with a water-saturated dispersed medium, depending on the external temperature conditions, the geometric parameters of the capsule and the seed. The cooling agent is carbon dioxide. The research is based on the use of numerical modeling methods on the platform COMSOL Multiphysics. A mathematical model is proposed that allows us to obtain the dynamics of the distribution of temperature and moisture content fields in the dispersed system and seed depending on a complex of geometric and thermophysical factors. The time of immersion freezing of the capsule with the common pine seed for the conditions considered should be in the range of 150 to 250 s. Full article

Research Highlights: Forest owners will be able to solve the problem of testing and selection of viable forest seeds on location and save financial, time, and material resources. The possibility of integrating non-destructive quality control and separation functions in a single portable apparatus is extremely promising. The speed of the contemporary optoelectronic grader is limited by the speed of the slowest component—the mechanical system. Background and Objectives: The technological process of forest seed establishment and design of optoelectronic graders is based on a priori mathematical modeling of structural characteristics, taking into account these criteria. Known models of industrial photoseparators are expensive and have a high energy and material consumption not applicable in the field. Laboratory seed analyzers are characterized by a long time exposure, and the overall size and level of climatic performance do not allow them to be used in the field. Consequently, for small amounts of seed treatment, it is necessary to orient the seeds one by one and ensure clear and rapid coordinated actions of optoelectronic and mechanical systems. The main goal of this research is to increase the efficiency of grading forest seeds by patterning the speed of the mobile device. We will answer the following questions. What are effective geometric parameters for the seed pipe? What factors affect the speed of a single seed’s movement? Materials and Methods: This study is based on mathematical modeling, taking into account the basic principles of mechanics, using MatLab software. Results: A mechanical model of a single Scots pine seed’s motion in different zones of the seed pipe is designed, taking into account air resistance. The effective height of the seed pipe, taking into account the response time of optoelectronic grader systems, is determined. Conclusions: The time and speed of single seed movement through grader systems depends on the seed pipe’s height and radius of curvature. Other things being equal, through the use of the same optical scheme with a microprocessor to solve various problems, the compactness of the photodetector scheme allows, if necessary, to upgrade the grader to solve research problems and for use in forestry. Full article