Genotypic and Phenotypic Differences in Fresh Weight Partitioning of Cut
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Acta Physiologiae Plantarum (2020) 42:48 https://doi.org/10.1007/s11738-020-03044-w ORIGINAL ARTICLE Genotypic and phenotypic diferences in fresh weight partitioning of cut rose stems: implications for water loss Dimitrios Fanourakis1 · Dimitris Bouranis2 · Georgios Tsaniklidis3 · Abdolhossein Rezaei Nejad4 · Carl‑Otto Ottosen5 · Ernst J. Woltering6,7 Received: 20 July 2019 / Revised: 27 November 2019 / Accepted: 18 March 2020 © Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków 2020 Abstract In vase life studies, cut fower fresh weight is often recorded, but mass distribution is not. Here, we addressed the variation in mass distribution among the diferent cut fower organs, and assessed its role in water relations. In the frst part of the study, excised leaves, fower, and stem were exposed to desiccation. Water loss (per fresh mass) of both fower and stem was low, relatively constant over time and comparable between the three studied cultivars. Instead, water loss (per fresh mass) of leaves was initially much higher, and decreased upon desiccation due to stomatal closure. Leaves had the greatest contribu- tion to cut fower water loss, while this contribution was diferent among the tested cultivars. Similar fndings were obtained following evaluation of the contribution of leaves, stem, and fower to cut fower transpirational water loss under conditions where water supply was not limiting. A strong correlation between the leaf weight loss in the desiccation experiment and the length of vase life was found. Low evaporative demand during vase life evaluation increased vase life, and alleviated vase life diferences between cultivars. Instead, high evaporative demand during evaluation shortened vase life, and increased the noted diferences in vase life between cultivars. In the second part of the study, fresh weight partitioning was assessed within and among cut rose cultivars. Among eight cultivars, same weight fowering stems may have over 11% diference in leaf weight. In conclusion, cultivar diferences in transpirational water loss between cut fowers of the same weight may be attributed to variations in both stomatal characteristics and mass partitioning to the leaves. Keywords Transpiration · Mass allocation · Vase life Abbreviations Introduction RH Relative air humidity VPD Vapor pressure defcit Long keeping quality is a very important factor determining consumers’ satisfaction and thus choice (Fanourakis et al. 2015b; Onozaki 2018). A basic requirement for a long keeping quality is a positive water balance (i.e., water uptake > water Communicated by P. Wojtaszek. loss; Fanourakis et al. 2013b; In et al. 2016). A yet unexplored strategy to improve cut fower longevity could be to select gen- Electronic supplementary material The online version of this article (https ://doi.org/10.1007/s1173 8-020-03044 -w) contains otypes with a reduced rate of water loss (Giday et al. 2013b; supplementary material, which is available to authorized users. * Dimitrios Fanourakis 4 Department of Horticultural Sciences, Faculty of Agriculture, [email protected] Lorestan University, P.O. Box 465, Khorramabad, Iran 5 Department of Food Science, Aarhus University, 1 Giannakakis SA, Export Fruits and Vegetables, Tympaki, Kirstinebjergvej 10, 5792 Årslev, Denmark Greece 6 Wageningen Food & Biobased Research, Bornse Weilanden 2 Plant Physiology and Morphology Laboratory, Crop Science 9, 6708 WG Wageningen, The Netherlands Department, Agricultural University of Athens, Athens, Greece 7 Horticulture & Product Physiology, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, 3 Institute of Olive Tree, Subtropical Plants and Viticulture, The Netherlands Hellenic Agricultural Organization ‘Demeter’ (NAGREF), P.O. Box 2228, 71003 Heraklio, Greece Vol.:(0123456789)1 3 48 Page 2 of 10 Acta Physiologiae Plantarum (2020) 42:48 Carvalho et al. 2015). Until now, this discussion mostly cent- in a multispan plastic greenhouse. Two harvests were con- ers around a better closure of the stomatal pores on the leaf ducted (6 and 20 July, 2015), supplying material for the two surface (Fanourakis et al. 2016b; Woltering and Paillart 2018). respective experiments. In the frst harvest, three cultivars However, cut fower water loss is not one-dimensional. The were tested (Bordeaux, Lenny, and Testarossa). These three mechanism of leaf stomatal closure is crucial (Fanourakis et al. cultivars were selected based on preliminary measurements, 2019a, b) albeit not a unique parameter that infuences the cut showing similar fresh mass partitioning to the leaves. In the fower water loss trait, while other attributes such as biomass second experiment, fve more cultivars (Avalanche, Gladi- allocation to the leaves should also be taken into consideration ator, Jumilia, Sorbet avalanche, and Talea) were included, (Giday et al. 2014). A research gap currently exists on how thus making eight ones in total. Twenty days prior to each variable biomass allocation to the leaves is among as well as harvest (corresponding to the growth period), climate within cut rose cultivars, which evidently afects the relation- parameters were automatically recorded. Preceding the frst ship between leaf and cut fower water loss. harvest, mean air temperature was 22.3 ± 0.4 °C, and prior to Leaf water loss is often employed to make assumptions the second harvest it was 23.7 ± 0.7 °C. Relative air humidity regarding the whole cut fower transpiration (Woltering and (RH) averaged 53 ± 6% in either period, resulting in vapor Paillart 2018; Fanourakis et al. 2019b). However, leaf water pressure defcits (VPDs) of 1.27 ± 0.16 kPa (experiment 1) loss responses may not always correlate to the whole cut fower and 1.38 ± 0.18 kPa (experiment 2). Based on the proxim- transpiration, especially under several specifc storage scenar- ity of the two harvest dates and the comparable evaporative ios that are nevertheless not uncommon during the postharvest demand during the two growth periods, it is safe to attribute life of the fowers. For instance, although most gas exchange the noted phenotypic diferences to the genotype (thus limit- indeed occurs through leaf stomata when they are open (Car- ing its interaction with the growth environment). penter and Rasmussen 1974; Mayak et al. 1974), transpira- In either experiment, harvested shoots had a length of tion rate through the stem and the fower bud may potentially approximately 0.7 m and a fower bud with a cylindrical become increasingly important for cut fower water loss when shape and pointed tip. Replicate shoots were collected from stomata are closed (e.g., during the dark period of vase life, or diferent plants. Cut fowers were collected in the morning upon water defcit). Further research is thus required to quan- (08:00–10:00 h), and immediately placed in buckets with tify the impact of leaf transpiration on total cut fower water aqueous sodium hypochlorite solution (1%, v/v). The stems loss under diferent stomatal closure states. Moreover, stem were transferred to the laboratory in these buckets at the and fower bud transpiration data have not been previously day of harvest and using refrigerated transport (2 °C). Upon recorded in diferent rose cultivars, and therefore, their poten- arrival, the leaves on the lower 0.15 m of the shoot were tial contribution to the cultivar diferences in cut fower water stripped. Cut fowers were stored overnight in buckets with loss remains elusive. Such divergences that directly afect the water-containing sodium hypochlorite (1%, v/v), at 2 °C and cut fower water balance during the postharvest life can be darkness. critical for the quality and marketability of the cut fowers. To prevent bacterial growth, which would cause vascular The aims of the current study are: (1) to quantify the con- blockage leading to low water uptake, sodium hypochlorite tribution of the stem, the leaves and the fower bud to total cut was added in the water, where the cut fowers were placed fower water loss under diferent stomatal closure states (i.e., throughout handling and evaluation (Fanourakis et al. under both ample water supply, and upon water defcit), and 2016b). (2) to evaluate variation in mass distribution among and within At the end of each experiment, leaf area (using ImageJ; cultivars. The examination of the results obtained by these two Koubouris et al. 2018), number of leaves, stem and pedi- objectives combined are expected to provide not only a better cel length, top (below the pedicel) and bottom (above insight into cultivar diferences in transpirational water loss, the cut point) stem diameter together with pedicel diam- which in many cases underlie variation in vase life (Spinarova eter (assessed midway its length) were evaluated in all cut and Hendriks 2007; Fanourakis et al. 2012, 2016b), but also fowers. to facilitate the scaling of water loss data from organ level to processes occurring to whole cut fower level. Contribution of stem, leaves, and fower bud to cut fower water loss upon water defcit (experiment 1) Materials and methods Cultivar diferences in the contribution of each individ- ual part involved in cut fower transpirational water loss Plant material and growth conditions were investigated in the course of desiccation. The fully hydrated cut fowers were taken from the refrigerated stor- Cut roses were obtained from a commercial grower age (2 °C and darkness) and placed into the test room, (Polioudakis G., Rethymno, Greece). Plants were grown where they were kept for