Computer-aided digital image analysis of seedling size and growth rate for assessing seed vigour in Impatiens

Vigour was measured using computer-aided analysis of digital images in six seed lots of Impatiens that differed in vigour but retained greater than 86% standard germination. Seed lots that differed in initial seed vigour were selected based on the commercially used Ball Vigour Index and vigour independently assessed using saturated salts accelerated aging tests. Digital images were captured from seeds germinated in Petri dishes placed on a flat-bed scanner. Seedling growth was measured daily for four days following initial radicle protrusion using commercially available root length calculating software. Seedling size and growth rate generally ranked seed lots from high to low vigour in a similar way compared to the Ball Vigour Index and saturated salts accelerated aging tests. The exception was that seed lot #2 was identified as the highest vigour seed lot using seedling growth parameters rather than seed lot #1. However, high and low vigour seed lots were identified as well with seedling growth measurements compared to the other two vigour tests used to evaluate Impatiens seed lots. Additionally, two vigour indices were calculated for seedling length using standard deviation as a measure of population uniformity. Both indices showed less ability to statistically separate seed lots compared to growth measurements alone. The current study showed that computer-aided analysis of digital images could be used successfully to rank seed lot vigour in Impatiens based on seedling length.