Chlorophyll-fluorescence sorting can improve Capsicum pepper-seed quality

Uşak and Ankara, Turkey and Wageningen, The Netherlands--In the interests of improving the quality and uniformity of Capsicum pepper-seed crops, Researchers from the University of Uşak, the University of Ankara, and the Wageningen UR Greenhouse Horticulture have turned to chlorophyll-fluorescence-based laser sorting to separate seeds produced by peppers of different maturity.¹

According to the researchers, Capsicum (Capsicum annuum L.) peppers' habit of nonsynchronous seed production means that pepper fruits that are produced from different flowering times mature at different periods, thus resulting in different-quality seeds. Pepper seed lots may consist of a mixture of less mature and fully mature seeds as a result of differences in flowering times, say the researchers, adding that this wide variation in a single lot can reduce overall seed quality. Less mature seeds germinate more slowly and produce smaller seedlings, whereas mature seeds emerge faster and produce larger seedlings. This variation in seed maturity ultimately results in variations in plant growth and development.

To separate out less-mature seeds to enhance the overall quality of pepper-seed lots, the researchers used chlorophyll fluorescence, which has been used successfully to detect and sort other types of seeds. The nondestructive technique uses lasers and narrowband optical filters to help detect chlorophyll in the seed coat to measure the resulting fluorescence and link it with the quality of the seeds.

The researchers evaluated four different Capsicum cultivars at four fruit harvest dates: orange (immature), bright red (half-mature), dark red (mature), and dark red and soft (overmature). Seeds were either sorted or nonsorted after harvesting, and standard laboratory germination, seedling emergence, and controlled deterioration tests were conducted. Results showed that chlorophyll fluorescence-sorting significantly increased laboratory germination, seedling emergence, and seed vigor. The scientists found that maximum improvements were obtained from seeds harvested from half-mature and mature stages.

"While previous studies evaluated seed quality solely based on laboratory germination tests conducted under optimum germination conditions, our work tested the effect of chlorophyll-fluorescence sorting not only on laboratory germination, but also on emergence and physiological aging as indicators of seed vigor," says corresponding author Burcu Begüm Kenanoglu.

REFERENCE:

1. Burcu Begüm Kenanoglu et al., HortScience, Vol. 48, No. 8, p. 965, August 2013.