The biochemistry underpinning industrial seed technology and mechanical processing of sugar beet

Abstract

Main conclusionSeed-processing technologies such as polishing and washing enhance crop seed quality by limited removal of the outer layers and by leaching. Combined, this removes chemical compounds that inhibit germination.AbstractIndustrial processing to deliver high-quality commercial seed includes removing chemical inhibitors of germination, and is essential to produce fresh sprouts, achieve vigorous crop establishment, and high yield potential in the field. Sugar beet (Beta vulgaris subsp. vulgaris var. altissima Doell.), the main sugar source of the temperate agricultural zone, routinely undergoes several processing steps during seed production to improve germination performance and seedling growth. Germination assays and seedling phenotyping was carried out on unprocessed, and processed (polished and washed) sugar beet fruits. Pericarp-derived solutes, known to inhibit germination, were tested in germination assays and their osmolality and conductivity assessed (ions). Abscisic acid (ABA) and ABA metabolites were quantified in both the true seed and pericarp tissue using UPLC-ESI(+)-MS/MS. Physical changes in the pericarp structures were assessed using scanning electron microscopy (SEM). We found that polishing and washing of the sugar beet fruits both had a positive effect on germination performance and seedling phenotype, and when combined, this positive effect was stronger. The mechanical action of polishing removed the outer pericarp (fruit coat) tissue (parenchyma), leaving the inner tissue (sclerenchyma) unaltered, as revealed by SEM. Polishing as well as washing removed germination inhibitors from the pericarp, specifically, ABA, ABA metabolites, and ions. Understanding the biochemistry underpinning the effectiveness of these processing treatments is key to driving further innovations in commercial seed quality.

The effects of high oxygen partial pressure on vegetable Allium seeds with a short shelf-life

“…Any one of the features of abnormality would result in a seedling being classified as abnormal as such a seedling would not produce a commercially viable ('usable') plant. Testing for abnormality is commonly practiced throughout the seed industry (Ignatz et al 2019). The maximal germination percentage (G max ) was calculated from the maximum number of seeds that germinated as a proportion of the total number of seeds and analysed using a generalised linear model with binomial errors using R version 3.6.0 (R Core Team 2019).…”

Impact of sugar beet seed priming using the SMP method on the properties of the pericarp

“…A comparison of average pericarp water diffusivity of the raw fruit (0.00134 cm 2 d − 1 ) from 48 Polish sugar beet lines stock [27] and the diffusivity of pericarp commercial variety Janosik (0.10-0.15 cm 2 d − 1 ) clearly indicates the importance of reproduction seeds in Po Valley (Italy) and proper seed treatment in form of polishing, washing, grading and priming. Similarly, Ignatz et al [14] confirm that the combined polishing and washing treatment resulting in significant improvements of the germinations performance due to a combined removal of mechanical and inhibitor constraints.…”

“…A sugar beet fruit is composed of a hard pericarp, whose mass varies from 70 to 80% [22,33] of the raw fruit. Inside the pericarp, there is a kidney-shaped botanical seed [2,8,13,14,19]. The beet pericarp can restrict the water and oxygen uptake of an enclosed seed [8,13,18,25,27,30,31,34].…”

“…On the opposite side of the operculum, there is a place where the fruit attaches to the shoot, which is called the basal pore. The basal pore is probably the most important place for water to flow to the seed [2,8,14,25]. The structure of the pericarp, the size of the basal pore and its degree of tissue filling are genetically determined by the maternal genotype.…”

“…In addition to the inorganic compounds of osmotic character in the pericarp, many organic compounds have been identified: vanillic acid, p-oxybenzoic acid, ferulic acid, coumarin acid, chlorogenic acid, ABA, rutin and protocatechuic acid [10,13,14,30,31] Interestingly, levels of several endogenous plant growth regulators, which were shown to influence the germination or early root growth, greatly differed between the pericarp and the true seed. Consequently, the pericarp is assumed to play an important role during the germination and seedling growth of sugar beet [1].…”