TY - JOUR

T1 - Mature sweet cherries have low turgor

AU - Knoche, Moritz

AU - Grimm, Eckhard

AU - Schlegel, Henrik Jürgen

PY - 2014/1/1

Y1 - 2014/1/1

N2 - The pressure inside a mature sweet cherry (Prunus avium L.) fruit is thought to be an important factor in rain cracking. However, to our knowledge, this pressure has never been quantified directly. The objectives of this study are to quantify: 1) the cell turgor (ψcellP) in fruit using a cell pressure probe (CPP) and a vapor pressure osmometer (VPO); and 2) the tissue pressure in a fruit (ψfruitP) using both a fruit pressure probe (FPP) and a compression-plate technique (CP). The value of YcellP in mesocarp cells of mature sweet cherry fruit averaged 28.1 kPa in 'Samba' and 17.5 kPa in 'Sam' at depths below the fruit surface between 200 and 400 mm. A ψcellP (range 38 to 64 kPa for different cultivars) calculated from the tissue water potential (Ytissue = -2968 to -4035 kPa) and the osmotic potential (ψfruitP) (ψfruitP = -3020 to -4116 kPa) of excised mesocarp discs as determined by VPO was of the same order of magnitude as that by CPP. Similar low ψfruitP values were obtained by FPP (range 8.0 to 11.8 kPa across cultivars). The ψfruitP were consistently lower than the YcellP values measured by CPP or by VPO. The ψfruitP value in the mesocarp increased slightly with increasing depth below the surface. However, ψfruitP was always negligible (e.g., 'Samba' ψfruitP = 10 kPa) compared with either ψfruitP ('Samba' ψfruitP = -2395 kPa) or calculated water potential (ψfruit) ('Samba' ψfruit = -2385 kPa). When subjecting intact fruit to CP, linear relationships were obtained between the forces applied and the resulting aplanation areas. The ψfruitP values obtained by CP (range in sweet cherry 18.4 to 36.1 kPa) were somewhat larger than the ψfruitP values obtained by FPP (range in sweet cherry 8.0 to 11.8 kPa). Incubating fruit for up to 7.5 h in deionized water or for up to 96 h in air enclosed above dry silica gel had no measurable effects on ψfruitP. The low ψcellP and the low ψfruitP values are not unique to sweet cherry. Values of the same order of magnitude were obtained also in mature sour cherry (Prunus cerasus L.), european plum (Prunus domestica L.), grape (Vitis vinifera L.), gooseberry (Ribes uva-crispa L.), red currant (Ribes rubrum L.), black currant (Ribes nigrum L.), blueberry (Vaccinium corymbosum L.), and tomato (Solanum lycopersicum L.). Possible explanations for the very low values of ψcellP and ψfruitP are discussed.

AB - The pressure inside a mature sweet cherry (Prunus avium L.) fruit is thought to be an important factor in rain cracking. However, to our knowledge, this pressure has never been quantified directly. The objectives of this study are to quantify: 1) the cell turgor (ψcellP) in fruit using a cell pressure probe (CPP) and a vapor pressure osmometer (VPO); and 2) the tissue pressure in a fruit (ψfruitP) using both a fruit pressure probe (FPP) and a compression-plate technique (CP). The value of YcellP in mesocarp cells of mature sweet cherry fruit averaged 28.1 kPa in 'Samba' and 17.5 kPa in 'Sam' at depths below the fruit surface between 200 and 400 mm. A ψcellP (range 38 to 64 kPa for different cultivars) calculated from the tissue water potential (Ytissue = -2968 to -4035 kPa) and the osmotic potential (ψfruitP) (ψfruitP = -3020 to -4116 kPa) of excised mesocarp discs as determined by VPO was of the same order of magnitude as that by CPP. Similar low ψfruitP values were obtained by FPP (range 8.0 to 11.8 kPa across cultivars). The ψfruitP were consistently lower than the YcellP values measured by CPP or by VPO. The ψfruitP value in the mesocarp increased slightly with increasing depth below the surface. However, ψfruitP was always negligible (e.g., 'Samba' ψfruitP = 10 kPa) compared with either ψfruitP ('Samba' ψfruitP = -2395 kPa) or calculated water potential (ψfruit) ('Samba' ψfruit = -2385 kPa). When subjecting intact fruit to CP, linear relationships were obtained between the forces applied and the resulting aplanation areas. The ψfruitP values obtained by CP (range in sweet cherry 18.4 to 36.1 kPa) were somewhat larger than the ψfruitP values obtained by FPP (range in sweet cherry 8.0 to 11.8 kPa). Incubating fruit for up to 7.5 h in deionized water or for up to 96 h in air enclosed above dry silica gel had no measurable effects on ψfruitP. The low ψcellP and the low ψfruitP values are not unique to sweet cherry. Values of the same order of magnitude were obtained also in mature sour cherry (Prunus cerasus L.), european plum (Prunus domestica L.), grape (Vitis vinifera L.), gooseberry (Ribes uva-crispa L.), red currant (Ribes rubrum L.), black currant (Ribes nigrum L.), blueberry (Vaccinium corymbosum L.), and tomato (Solanum lycopersicum L.). Possible explanations for the very low values of ψcellP and ψfruitP are discussed.

KW - Cracking

KW - Exocarp

KW - Osmotic potential

KW - Pressure

KW - Prunus avium

KW - Strain

KW - Transpiration

KW - Water potential

KW - Water uptake

UR - http://www.scopus.com/inward/record.url?scp=84892570002&partnerID=8YFLogxK

U2 - 10.21273/jashs.139.1.3

DO - 10.21273/jashs.139.1.3

M3 - Article

AN - SCOPUS:84892570002

VL - 139

SP - 3

EP - 12

JO - Journal of the American Society for Horticultural Science

JF - Journal of the American Society for Horticultural Science

SN - 0003-1062

IS - 1

ER -