Almeida, Domingos P. F.

Carvalho, D.R.A

Carvalho, Susana M.P.

Fanourakis, D.

Gitonga, V.

Heusden, A.W. van

Heuvelink, E.

English

Repositório Institucional da Universidade Católica Portuguesa

Breeding cut roses for better keeping quality: first stepsD. Fanourakis1, D.R.A Carvalho2, V. Gitonga3, A.W. van Heusden3, D.P.F. Almeida2,E. Heuvelink1, Susana M.P. Carvalho1,21 Wageningen University – Plant Sciences Department, Horticultural Supply Chains group (The Netherlands) 2 Portuguese Catholic University – College of Biotechnology (Portugal)3 Wageningen University – Plant Sciences Department, Laboratory of Plant Breeding (The Netherlands)Introduction Production of high keeping quality plants is of utmost importance: Increased competition in the ornamental horticultural sector Key factor for consumers’ satisfaction Water stress is the major post-harvest quality problem  shorter vase life End of vase (at flower auction): 52% water stress• Bent-neck• Leaf and flower wilting• Leaf drying 33% Botrytis 15% natural senescence(source: Van Meeteren, pers. comm)How can we influence vase life of cut roses? Most research has been focused on post-harvest conditions   (e.g. preservative solutions)Environment during cultivationGenotypePotential Vase Lifee.g.12 daysproblem is already therePost-harvest handlingActualVase Lifee.g. 7 days Potential vase life = maximum vase life Objectives Screen a segregating tretraploid (K5) rose population for stomatal responses to leaf desiccation Analyse the variation existing in the gene pool for: stomatal responses to leaf desiccation cuticular transpiration Vase-life evaluationContribute to fasten the selection criteria and procedures for breeding for cultivars with longer vase life (better control of water loss)M&M: Cut rose population screening (Expt. 1) 110 genotypes & 2 parents Population created for studing resistence to powdery mildew Shows segregation for many morphological traits Greenhouse cultivation Response to leaf desiccation n = 12 terminal leaflets per genotype Detached and re-hydrated during 1 hr in light Desiccation in test room (RH: 50±3 %, T: 21°C, 50 µmol m-2 s-1) RWC after 4 hours desiccation100*Dry WeighthtFresh Weig SaturatedDry WeighthtFresh WeigWCRM&M: Cut rose population screening – cont.010203040506070800 20 40 60 80 100GenotypeRWC 4h (%)Expt.1: Population screening Large genotypic variation in response to leaf desiccation RWC 4h desiccation ranged 7-62% (parents: 20, 51% RWC)Low responsivenessModerate responsivenessHigh responsivenessExpt.2: Variation in the stomatal responsiveness (SR) Representative genotypes from each group (12 & 2 parents) Leaf desiccation (n = 12 per genotype) Transpiration rate during 4 hours (gravimetrically)0.00.40.81.21.62.00 40 80 120 160 200 240Time (min)Transpiration rate (mmolm-2s-1 )0.00.40.81.21.62.0020406080100RWC (%)Transpiration rate (mmolm-2s-1 )low SRmoderate SRhigh SR Initial transpiration rate (10min) is only slightly related to stomatal responsiveness Final transpiration rate (4h) is an irrelevant trait, since it corresponds to very different leaf hydration levels (RWC)Variation in the stomatal responsiveness (SR) – cont.0.00.40.81.21.62.00 20 40 60 80Transpiration rate 10 min (mmolm-2s-1 )RWC 4h (%)0.00.40.81.21.62.00 20 40 60 80Transpiration rate 4h (mmolm-2s-1 )RWC 4h (%)low SRmoderate SRhigh SRR2=0.61R2=0.040.00.40.81.21.62.00 20 40 60 80Transpiration rate at 60% RWC  (mmolm-2s-1 )RWC 4h (%)low SRmoderate SRhigh SR010203040506070800 20 40 60 80Stabilization RWC (%)RWC 4h (%) Speed of stomatal closure is strongly related to stomatal responsiveness (RWC stabilization high > moderate > low)  Degree of stomatal closure at certain leaf hydration level (RWC) is strongly related to stomatal responsiveness (high > moderate > low) Variation in the stomatal responsiveness (SR) – cont.R2=0.99 R2=0.90 8 genotypes (4+4) & 2 parents n = 12 per genotype  Sealing lower leaf  surface with wax and polyethylene sheet Desiccation in test room (RH: 50±3 %, T: 21°C, 2,5 µmol m-2 s-1)Expt. 3 – Variation in the cuticular transpirationHypostomatous leavesCuticular permeability (G): no screening value Similar range of G in contrasting genotypes  Cuticular contribution to total water loss is minimal0.00.40.81.21.62.0020406080100RWC (%)Transpiration rate (mmolm-2s-1 )low SRmoderate SRhigh SRExpt. 3 – Vase-life evaluation 6 genotypes (3+3) n = 8 stems/genotype (normalized length & leaf area) Harvest at stage 2 (VBN, 2001) Standard solution(0.7mM CaCl2, 1.5mM NaHCO3, 5µM CuSO4) RH: 50 %, T: 20°C, 10-12 µmol m-2s-1 (12h/d) End of vase life according to VBN criteria (2001)Importance of stomatal responsiveness on vase life Low stomatal responsiveness (SR) Shorter  vase-life (8 days ± 0.5 / 15 days ± 3.1) limited by the high water loss rates048121620240 20 40 60 80Vase life (days)RWC 4h (%)0.00.20.40.60.81.00 20 40 60 80Transpiration rate (mmol m-2 s-1)RWC 4h (%)low SRhigh SR0123450 20 40 60 80Flower stageRWC 4h (%)low SRhigh SRStomatal responsiveness & Flower opening Low stomatal responsiveness  hampered flower opening (end vase life without reaching stage 5)1 2 3                    4 5Conclusions Large variation present in the gene pool for stomatal responsiveness  many possibilities for breeding for better control of water loss Key traits: speed & degree of stomatal closure(i.e. stomatal physiology) Cuticular permeability is not a relevant traitConclusions RWC after 4h of leaf desiccation proved to be a quick and relible screening method suitable for large-scale screening of rose genotypes for stomatal responses to water stress Genotypes with lower RWC at 4h desiccation (i.e. lower stomatal responsiveness):  Shorter vase life flower opening is hamperedMuito obrigada!!!Thank you for your attention!Why relative water content (RWC) after 4h desiccation?100*Dry WeighthtFresh Weig SaturatedDry WeighthtFresh WeigWCR0.00.40.81.21.60 40 80 120 160 200 240Time (min)Transpiration rate (mmolm-2s-1 )0.00.40.81.21.6020406080100RWC (%)Transpiration rate (mmolm-2s-1 ) Previous work has shown that RWC is a good indicator of the control of water loss High RH○ Low RH

Breeding cut roses for better keeping quality: first steps

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Breeding cut roses for better keeping quality: first steps

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