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Theodore M. Dejong - One of the best experts on this subject based on the ideXlab platform.
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Phenotyping vigour control capacity of new peach Rootstocks by xylem vessel analysis
Scientia Horticulturae, 2011Co-Authors: Sergio Tombesi, Ali A. Almehdi, Theodore M. DejongAbstract:Abstract In peach, xylem anatomical characteristics have been shown to be related to vigour of selected Rootstocks. The goal of this research was to determine if xylem characteristics of a new set of Rootstocks that exhibit a range of size-controlling potential and have a different genetic background from previously examined material would also exhibit similar differences in xylem characteristics. If so, then anatomical analysis of xylem may be a useful means of predicting the vigour control capacity of selected peach rootstock genotypes. Samples of xylem tissue were taken from roots, trunks and shoots of four new Rootstocks that were derived from a genetic cross between ‘Harrow Blood’ and ‘Okinawa’ peaches and compared with tissue from ‘Nemaguard’, a vigorous control. Xylem samples were sectioned and analysed by optical microscope. The number and dimensions of vessels in recently developed xylem of each rootstock were measured and compared. The more dwarfing Rootstocks had fewer large vessels and more small vessels than the more vigorous Rootstocks. Weighted mean vessel diameter (Wm) and calculated hydraulic conductance ( K h ) differed among Rootstocks: more vigorous Rootstocks had higher K h and Wm than dwarfing Rootstocks. Rootstock xylem vessel dimensions varied in relation to the vigour they imparted to a common scion cultivar (‘O’Henry’). After the ‘Nemaguard’ control, ‘HBOK 50’ was the most vigorous rootstock followed by ‘HBOK 10’, ‘HBOK 32’ and ‘HBOK 27’, respectively. Thus, as was seen in previous research with a separate set of Rootstocks, the vigour-control capacity of this new series of peach Rootstocks was strongly related to their xylem hydraulic characteristics and it appears likely that it would be possible to use xylem anatomical characteristics of shoots or roots of young trees to pre-select for size-controlling potential in a rootstock development program.
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relationships between xylem vessel characteristics calculated axial hydraulic conductance and size controlling capacity of peach Rootstocks
Annals of Botany, 2010Co-Authors: Sergio Tombesi, Scott R Johnson, Theodore M. DejongAbstract:BACKGROUND AND AIMS: Previous studies indicate that the size-controlling capacity of peach Rootstocks is associated with reductions of scion water potential during mid-day that are caused by the reduced hydraulic conductance of the rootstock. Thus, shoot growth appears to be reduced by decreases in stem water potential. The aim of this study was to investigate the mechanism of reduced hydraulic conductance in size-controlling peach Rootstocks. METHODS: Anatomical measurements (diameter and frequency) of xylem vessels were determined in shoots, trunks and roots of three contrasting peach Rootstocks grown as trees, each with different size-controlling characteristics: 'Nemaguard' (vigorous), 'P30-135' (intermediate vigour) and 'K146-43' (substantially dwarfing). Based on anatomical measurements, the theoretical axial xylem conductance of each tissue type and rootstock genotype was calculated via the Poiseuille-Hagen law. KEY RESULTS: Larger vessel dimensions were found in the vigorous rootstock ('Nemaguard') than in the most dwarfing one ('K146-43') whereas vessels of 'P30-135' had intermediate dimensions. The density of vessels per xylem area in 'Nemaguard' was also less than in 'P30-135'and 'K146-43'. These characteristics resulted in different estimated hydraulic conductance among Rootstocks: 'Nemaguard' had higher theoretical values followed by 'P30-135' and 'K146-43'. CONCLUSIONS: These data indicate that phenotypic differences in xylem anatomical characteristics of rootstock genotypes appear to influence hydraulic conductance capacity directly, and therefore may be the main determinant of dwarfing in these peach Rootstocks.
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growth patterns and morphology of fine roots of size controlling and invigorating peach Rootstocks
Tree Physiology, 2007Co-Authors: B Basile, Michelle L Salsman, Scott R Johnson, David R. Bryla, Carla Cirillo, Jan Marsal, Theodore M. DejongAbstract:We compared growth patterns and morphology of fine roots of size-controlling and invigorating peach (Prunus persica (L.) Batsch) Rootstocks. Peach trees were grafted on five Rootstocks: a vigorous control (Nemaguard), three intermediate vigor Rootstocks (K119-50, P30-135 and Hiawatha), and a semi-dwarfing rootstock (K146-43). Minirhizotron tubes were installed at the base of trees on each rootstock and root images captured with a minirhizotron digital camera system. Number, visible length, and diameter of new roots were recorded at fixed soil depths from April 19, 2000 to December 19, 2001. Root diameter, specific root length, root tissue density and root length density were also measured periodically for each rootstock on roots collected from in-growth cores. Rootstocks had similar seasonal patterns of new root production. Fine root production was lowest in winter and appeared to decline during the final stages of fruit growth. A rootstock with almond in its genetic background (K119-50) produced the greatest quantity of fine roots and had the greatest number of new roots below 69 cm, whereas there were no differences among the other four Rootstocks in the total number of roots produced. Rootstock K146-43 had thicker fine roots than the other Rootstocks. Independent of rootstock, fine roots produced during spring had greater specific root length than those produced later in the season. The seasonal pattern of fine root production did not appear to be associated with the previously reported effects of these dwarfing Rootstocks on shoot growth and stem water potential early in the growing season.
Sergio Tombesi - One of the best experts on this subject based on the ideXlab platform.
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Phenotyping vigour control capacity of new peach Rootstocks by xylem vessel analysis
Scientia Horticulturae, 2011Co-Authors: Sergio Tombesi, Ali A. Almehdi, Theodore M. DejongAbstract:Abstract In peach, xylem anatomical characteristics have been shown to be related to vigour of selected Rootstocks. The goal of this research was to determine if xylem characteristics of a new set of Rootstocks that exhibit a range of size-controlling potential and have a different genetic background from previously examined material would also exhibit similar differences in xylem characteristics. If so, then anatomical analysis of xylem may be a useful means of predicting the vigour control capacity of selected peach rootstock genotypes. Samples of xylem tissue were taken from roots, trunks and shoots of four new Rootstocks that were derived from a genetic cross between ‘Harrow Blood’ and ‘Okinawa’ peaches and compared with tissue from ‘Nemaguard’, a vigorous control. Xylem samples were sectioned and analysed by optical microscope. The number and dimensions of vessels in recently developed xylem of each rootstock were measured and compared. The more dwarfing Rootstocks had fewer large vessels and more small vessels than the more vigorous Rootstocks. Weighted mean vessel diameter (Wm) and calculated hydraulic conductance ( K h ) differed among Rootstocks: more vigorous Rootstocks had higher K h and Wm than dwarfing Rootstocks. Rootstock xylem vessel dimensions varied in relation to the vigour they imparted to a common scion cultivar (‘O’Henry’). After the ‘Nemaguard’ control, ‘HBOK 50’ was the most vigorous rootstock followed by ‘HBOK 10’, ‘HBOK 32’ and ‘HBOK 27’, respectively. Thus, as was seen in previous research with a separate set of Rootstocks, the vigour-control capacity of this new series of peach Rootstocks was strongly related to their xylem hydraulic characteristics and it appears likely that it would be possible to use xylem anatomical characteristics of shoots or roots of young trees to pre-select for size-controlling potential in a rootstock development program.
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relationships between xylem vessel characteristics calculated axial hydraulic conductance and size controlling capacity of peach Rootstocks
Annals of Botany, 2010Co-Authors: Sergio Tombesi, Scott R Johnson, Theodore M. DejongAbstract:BACKGROUND AND AIMS: Previous studies indicate that the size-controlling capacity of peach Rootstocks is associated with reductions of scion water potential during mid-day that are caused by the reduced hydraulic conductance of the rootstock. Thus, shoot growth appears to be reduced by decreases in stem water potential. The aim of this study was to investigate the mechanism of reduced hydraulic conductance in size-controlling peach Rootstocks. METHODS: Anatomical measurements (diameter and frequency) of xylem vessels were determined in shoots, trunks and roots of three contrasting peach Rootstocks grown as trees, each with different size-controlling characteristics: 'Nemaguard' (vigorous), 'P30-135' (intermediate vigour) and 'K146-43' (substantially dwarfing). Based on anatomical measurements, the theoretical axial xylem conductance of each tissue type and rootstock genotype was calculated via the Poiseuille-Hagen law. KEY RESULTS: Larger vessel dimensions were found in the vigorous rootstock ('Nemaguard') than in the most dwarfing one ('K146-43') whereas vessels of 'P30-135' had intermediate dimensions. The density of vessels per xylem area in 'Nemaguard' was also less than in 'P30-135'and 'K146-43'. These characteristics resulted in different estimated hydraulic conductance among Rootstocks: 'Nemaguard' had higher theoretical values followed by 'P30-135' and 'K146-43'. CONCLUSIONS: These data indicate that phenotypic differences in xylem anatomical characteristics of rootstock genotypes appear to influence hydraulic conductance capacity directly, and therefore may be the main determinant of dwarfing in these peach Rootstocks.
D A Baker - One of the best experts on this subject based on the ideXlab platform.
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identification and quantitation by gc ms of zeatin and zeatin riboside in xylem sap from rootstock and scion of grafted apple trees
Plant Growth Regulation, 1999Co-Authors: J S Kamboj, P Blake S Ast, J D Quinlan, D A BakerAbstract:Zeatin and zeatin riboside were identified by full-scan gas chromatography-mass spectrometry (GC-MS) in xylem sap of clonal apple Rootstocks (M.27, M.9 and MM.106). These Rootstocks exhibit a wide range of control over tree size when grafted to a common scion. The concentrations of zeatin and zeatin riboside were measured by GC-MS selected ion monitoring (SIM) in shoot xylem sap and root pressure exudate obtained from these Rootstocks and from trees of ‘Fiesta’ scion grafted onto the Rootstocks. Zeatin was the predominant cytokinin in xylem sap from the dwarfing Rootstocks, M.27 and M.9, while zeatin riboside was the predominant cytokinin in xylem sap from the more invigorating rootstock MM.106. Cytokinin concentrations (ng ml−1) in root pressure exudate and shoot xylem sap, (i.e. from above the graft union in composite trees), increased with increasing vigour of the rootstock, irrespective of whether the plants were non-grafted Rootstocks, or were composite plants of ‘Fiesta’ scion grafted onto the Rootstocks. Cytokinin content (ng shoot−1) of shoot sap differed with rootstock; the more invigorating (MM.106) had greater amounts of cytokinins than the more dwarfing (M.9 and M.27) Rootstocks. These results are discussed in relation to possible influences of roots on the growth of shoots via cytokinin supplies in the xylem sap.
J S Kamboj - One of the best experts on this subject based on the ideXlab platform.
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identification and quantitation by gc ms of zeatin and zeatin riboside in xylem sap from rootstock and scion of grafted apple trees
Plant Growth Regulation, 1999Co-Authors: J S Kamboj, P Blake S Ast, J D Quinlan, D A BakerAbstract:Zeatin and zeatin riboside were identified by full-scan gas chromatography-mass spectrometry (GC-MS) in xylem sap of clonal apple Rootstocks (M.27, M.9 and MM.106). These Rootstocks exhibit a wide range of control over tree size when grafted to a common scion. The concentrations of zeatin and zeatin riboside were measured by GC-MS selected ion monitoring (SIM) in shoot xylem sap and root pressure exudate obtained from these Rootstocks and from trees of ‘Fiesta’ scion grafted onto the Rootstocks. Zeatin was the predominant cytokinin in xylem sap from the dwarfing Rootstocks, M.27 and M.9, while zeatin riboside was the predominant cytokinin in xylem sap from the more invigorating rootstock MM.106. Cytokinin concentrations (ng ml−1) in root pressure exudate and shoot xylem sap, (i.e. from above the graft union in composite trees), increased with increasing vigour of the rootstock, irrespective of whether the plants were non-grafted Rootstocks, or were composite plants of ‘Fiesta’ scion grafted onto the Rootstocks. Cytokinin content (ng shoot−1) of shoot sap differed with rootstock; the more invigorating (MM.106) had greater amounts of cytokinins than the more dwarfing (M.9 and M.27) Rootstocks. These results are discussed in relation to possible influences of roots on the growth of shoots via cytokinin supplies in the xylem sap.
Scott R Johnson - One of the best experts on this subject based on the ideXlab platform.
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relationships between xylem vessel characteristics calculated axial hydraulic conductance and size controlling capacity of peach Rootstocks
Annals of Botany, 2010Co-Authors: Sergio Tombesi, Scott R Johnson, Theodore M. DejongAbstract:BACKGROUND AND AIMS: Previous studies indicate that the size-controlling capacity of peach Rootstocks is associated with reductions of scion water potential during mid-day that are caused by the reduced hydraulic conductance of the rootstock. Thus, shoot growth appears to be reduced by decreases in stem water potential. The aim of this study was to investigate the mechanism of reduced hydraulic conductance in size-controlling peach Rootstocks. METHODS: Anatomical measurements (diameter and frequency) of xylem vessels were determined in shoots, trunks and roots of three contrasting peach Rootstocks grown as trees, each with different size-controlling characteristics: 'Nemaguard' (vigorous), 'P30-135' (intermediate vigour) and 'K146-43' (substantially dwarfing). Based on anatomical measurements, the theoretical axial xylem conductance of each tissue type and rootstock genotype was calculated via the Poiseuille-Hagen law. KEY RESULTS: Larger vessel dimensions were found in the vigorous rootstock ('Nemaguard') than in the most dwarfing one ('K146-43') whereas vessels of 'P30-135' had intermediate dimensions. The density of vessels per xylem area in 'Nemaguard' was also less than in 'P30-135'and 'K146-43'. These characteristics resulted in different estimated hydraulic conductance among Rootstocks: 'Nemaguard' had higher theoretical values followed by 'P30-135' and 'K146-43'. CONCLUSIONS: These data indicate that phenotypic differences in xylem anatomical characteristics of rootstock genotypes appear to influence hydraulic conductance capacity directly, and therefore may be the main determinant of dwarfing in these peach Rootstocks.
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growth patterns and morphology of fine roots of size controlling and invigorating peach Rootstocks
Tree Physiology, 2007Co-Authors: B Basile, Michelle L Salsman, Scott R Johnson, David R. Bryla, Carla Cirillo, Jan Marsal, Theodore M. DejongAbstract:We compared growth patterns and morphology of fine roots of size-controlling and invigorating peach (Prunus persica (L.) Batsch) Rootstocks. Peach trees were grafted on five Rootstocks: a vigorous control (Nemaguard), three intermediate vigor Rootstocks (K119-50, P30-135 and Hiawatha), and a semi-dwarfing rootstock (K146-43). Minirhizotron tubes were installed at the base of trees on each rootstock and root images captured with a minirhizotron digital camera system. Number, visible length, and diameter of new roots were recorded at fixed soil depths from April 19, 2000 to December 19, 2001. Root diameter, specific root length, root tissue density and root length density were also measured periodically for each rootstock on roots collected from in-growth cores. Rootstocks had similar seasonal patterns of new root production. Fine root production was lowest in winter and appeared to decline during the final stages of fruit growth. A rootstock with almond in its genetic background (K119-50) produced the greatest quantity of fine roots and had the greatest number of new roots below 69 cm, whereas there were no differences among the other four Rootstocks in the total number of roots produced. Rootstock K146-43 had thicker fine roots than the other Rootstocks. Independent of rootstock, fine roots produced during spring had greater specific root length than those produced later in the season. The seasonal pattern of fine root production did not appear to be associated with the previously reported effects of these dwarfing Rootstocks on shoot growth and stem water potential early in the growing season.
