Correlations between germination capacity and selected physical properties of perennial ryegrass cv. Maja seeds

Perennial ryegrass is one of the most valuable pasture grasses. The species is recommended for sodding various types of land in Poland due to its fast growth and the ability to produce large numbers of vegetative shoots. Seedling emergence and biomass yield are largely determined by seed quality. This study analyzes the correlations between the basic physical properties of seeds of perennial ryegrass cv. Maja and their germination capacity. The basic dimensions (length, width and thickness) and mass of each of the 150 seeds were determined, and their arithmetic mean diameter, geometric mean diameter, aspect ratio, sphericity index and density were calculated. The seeds were germinated for 14 days, and the results were recorded daily, which enabled to determine germination time for each seed. The relationships between the evaluated parameters were determined by the Student’s t-test for independent samples and correlation analysis. The analyzed physical properties of seeds had no significant effect on the germination rate index. Germinated and non-germinated seeds differed significantly in width, length and arithmetic mean diameter, but they should not be sorted based on their plumpness to improve the quality of seed material because it could lead to a high loss of viable seeds

Design concept and parameters of a conical bar separator

The process of adapting a screen separator to seeds of a given species and variety requires a corresponding set of replaceable screens. Screen replacement is a time-consuming process. Screens are often selected from the available size range, therefore, cleaning and separation processes are not always optimized. This study proposes a design concept of a new device for cleaning and separating seeds, which features a conical bar screen that rotates around its own axis. The screen has grooves whose width is smallest at the beginning of the screen and increases along the screen surface. Seeds can be sorted into various size fractions by changing the position of collecting buckets under the screen. The functional parameters of the separating device were designed based on a review of publications describing the size of the most popular agricultural seeds. The basic geometrical relationships in the proposed conical bar screen were described. The geometrical parameters of the screen were selected on the assumption that the radius at which bars are fixed to the screen can range from 200 mm to 400 mm and that bar diameter can range from 5 mm to 10 mm. Two variants of the device were proposed as a replacement for one universal separating screen. The first variant will be used to sort small seeds, including seeds of small-seeded legumes, seeds of major cereal species and medium-sized seeds with dimensions similar to cereal seeds, whereas the second variant will be applied to separate large seeds, including seeds of large-seeded legumes and plumper seeds from the medium-size fraction. The width of grooves at the beginning and end of the screen should equal 1 mm and 5 mm in the first variant and 2.5 mm and 13 mm in the second variant, respectively

Assessment of cereal seed shape with the use of sphericity factors

Shape is one of the key discriminating factors in seeds. It plays a major role in seed cleaning and sorting, and it influences the bulk behavior of seeds. The shape of seeds can be described with the use of sphericity factors. In this study, the thickness, width, length and mass of principal cereal seeds (wheat, rye, barley, oats and triticale) were determined. The geometric parameters of seeds were used to calculate five sphericity factors for each seed type. The results of measurements and calculations were processed statistically by analysis of variance, correlation analysis and linear regression analysis. In the group of the analyzed cereal seeds, the lowest values were noted for sphericity factor K5 in the range of 0.046 to 0.275, and the highest values - for sphericity factor K3 in the range of 0.359 to 0.650. The shape of cereal seeds was mostly highly correlated with: thickness in barley seeds, width in wheat seeds, width and thickness in rye and triticale seeds, and length in oat seeds. All of the analyzed sphericity factors can be used interchangeably to describe the shape of cereal seeds, and the relationships between those factors can be described with linear equations

Basic physical properties of Norway spruce (Picea abies (L.) Karst.) seeds

The range of variations in a given separation parameter and its relationships with other attributes have to be determined for designing seed cleaning and sorting processes. In this study, those relationships were determined for five batches of Norway spruce seeds supplied by a seed extraction plant in Jedwabno. The seeds were harvested from seed stands in northern Poland. The terminal velocity, length, width, thickness and mass of every seed were determined. The results were used to calculate the geometric mean diameter, aspect ratio, sphericity index and density of the evaluated seeds. Those parameters were compared by analysis of variance and linear correlation analysis. Similarities in the average values of all physical properties were noted only between seeds harvested in the same seed zone, from tree stands occupying the same habitat type. The analyzed seeds can be effectively separated into mass fractions with the use of traditional sorting devices such as pneumatic separators, mesh sieves with longitudinal or round openings, cylindrical graders, winnowing machines and pneumatic sieves, in order to achieve more uniform seedling emergence when each seed fraction is sown separately