3D morphology of tomato seeds as phenotypic trait predictive of seed germination

The identification of predictive morphological traits of tomato seed quality and their germination has long been attempted using conventional radiography as a technique to observe internal seed structures and to guide the seed sorting. Many studies observed that the main obtained feature, namely the amount of internal free space, cannot be used alone to predict germination behavior. In addition, the huge variation of the internal structural abnormalities and structural damages affect germination depending on their extent and localization and their detection is not always possible by means of conventional radiography. Although the three-dimensional X-ray imaging has been increasingly common in seed science as allows much more accurate visualization of the internal seed parts, such approach has never been used to analyze tomato seeds. The aim of this work was the use of the X-ray microCT imaging for the identification of phenotypic traits of tomato seeds related to the germination capacity. A 100 seeds sample was scanned by a X-ray microtomograph and the internal and external seed traits were quantified using morpho-densitometric parameters. Then a germination test was carried out on the same seeds whose identity remained traced. The internal fragmentation degree and the Sauter mean diameter resulted as the morpho-densitometric parameters better correlated with not germinated individuals. Although such identified predictive traits are not quite rapidly detectable, a certain correlation with some two-dimensional parameters suitable for a rapid determination is expected, being the premise towards a high-throughput sorting system.