Breeding for postharvest performance in chrysanthemum by selection against storage-induced degreening of disk florets Geert van Geest a,b,c, *, Aike Post b , Paul Arens c , Richard G.F. Visser c , Uulke van Meeteren a a Horticulture & Product Physiology, Department of Plant Sciences, Wageningen University, P.O. box 16, 6700 AA, Wageningen, The Netherlands b Deliflor Chrysanten B.V., Korte Kruisweg 163, 2676 BS, Maasdijk, The Netherlands c Wageningen UR Plant Breeding, Wageningen University and Research Centre, P.O. Box 386, 6708 PB, Wageningen, The Netherlands A R T I C L E I N F O Article history: Received 14 June 2016 Received in revised form 9 September 2016 Accepted 11 September 2016 Available online 15 October 2016 Keywords: Breeding Chrysanthemum Vase life Carbohydrate Phenotyping A B S T R A C T Breeding for postharvest performance in ornamentals is challenging, since many different deteriorative processes determine vase life. In order to improve postharvest performance by breeding, selection should take place on these processes separately. To define processes that are important for chrysanthemum postharvest performance, vase life was assessed after two weeks of cold storage in a set of 44 chrysanthemum cultivars. Since disk floret degreening was the most frequent reason for ending vase life, we further investigated this trait in a large biparental population (n = 381). To quantify disk floret degreening in this large number of genotypes, we developed a high-throughput phenotyping method. The method consists of the quantification of loss of green color as expressed by an increase of intensity of red divided by the intensity of green (R/G) in dark-held detached capitula. R/G increases when disk florets lose green color. The increase in R/G correlated significantly with the number of days until disk floret degreening occurred during vase life. This was the case for the 44-cultivar cultivar panel (Pearson’s correlation coefficient (r) of 0.70; p < 0.0001) as well as in a subset of the biparental pulation (n = 145; r = 0.67; p < 0.0001). R/G increase segregated in a quantitative manner in the full biparental population, and had a moderately high heritability of 0.73. Carbohydrate content after harvest was measured in a smaller subset of the biparental population (n = 55). The R/G increase correlated with carbohydrate content (r=-0.56; p < 0.0001). Since carbohydrate content did not explain all variation in degreening sensitivity, we discuss different possible mechanisms to cope with carbohydrate starvation and avoid degreening. In conclusion, disk floret degreening is an important postharvest trait in chrysanthemum, and it is related to carbohydrate starvation. The quantitative segregation suggests involvement of multiple alleles, probably at multiple loci. The moderately high heritability makes it a suitable trait for QTL mapping, which we will commence in the near future. ã 2016 Elsevier B.V. All rights reserved. 1. Introduction In many crop plants, and specifically ornamental crops, breeding for postharvest quality is challenging. A reason for this, is that vase life and shelf life terminating symptoms vary within a crop (Fanourakis et al., 2013; Ferrante et al., 2015; Rico et al., 2007) implying that many different unrelated processes can explain genotypic variation. In addition, a wide range of pre- and postharvest environmental variation can interact with the time to occurrence and severity of these symptoms (Fanourakis et al., 2013). The interaction between genotype and environment is therefore an important factor to take into account while investigating postharvest performance. Breeding aims to maximize the number of favourable alleles in a certain germplasm or genotype. Timing of occurrence and extent of different postharvest-related deteriorative processes is generally encoded by a broad set of alleles and loci (Carvalho et al., 2015; Moreno et al., 2008; Zhang et al., 2007). This large variation strongly impairs the development of breeding tools that allow estimation of the phenotype from a genotype. The overall postharvest performance of a certain crop should therefore be divided in specific parameters that can be measured reliably and are potentially encoded by a limited set of alleles. Genotypic improvement should take place at the level of these parameters. * Corresponding author at: Horticulture & Product Physiology, Department of Plant Sciences, Wageningen University, P.O. box 16, 6700 AA, Wageningen, The Netherlands. E-mail addresses: geert.vangeest@wur.nl, geert.vangeest@gmail.com (G. van Geest). http://dx.doi.org/10.1016/j.postharvbio.2016.09.003 0925-5214/ã 2016 Elsevier B.V. All rights reserved. Postharvest Biology and Technology 124 (2017) 45–53 Contents lists available at ScienceDirect Postharvest Biology and Technology journal homepa ge: www.elsev ier.com/locate/postharvbio