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Theodore M. Dejong - One of the best experts on this subject based on the ideXlab platform.
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Interactions between Rootstock, inter-stem and scion xylem vessel characteristics of peach trees growing on Rootstocks with contrasting size-controlling characteristics
AoB PLANTS, 2010Co-Authors: Sergio Tombesi, R. Scott Johnson, Kevin R. Day, Theodore M. DejongAbstract:Background and aims The primary physiological mechanism influencing tree vigour in size-controlling Rootstocks of peach has been related to the hydraulic conductance of the Rootstock. Differences in Rootstock hydraulic conductance are a function of Rootstock xylem vessel characteristics. The present research examined whether the vigour and xylem vessel characteristics of the Rootstock influence the xylem characteristics of the scion. We tested whether using a size-controlling Rootstock genotype as an inter-stem influences the xylem vessel characteristics of either the Rootstock below the inter-stem or the scion above it and vice versa. Methodology Anatomical measurements (diameter and frequency) of xylem vessels were determined above and below the graft unions of the trunks of peach trees with differing scion/Rootstock combinations. The three peach Rootstocks were ‘Nemaguard’ (vigorous), ‘P30-135’ (intermediate vigour) and ‘K146-43’ (dwarfing). The vigorous scion cultivar was ‘O’Henry’. The inter-stem experiment involved trees with ‘Nemaguard’ (vigorous) as the Rootstock, ‘K146-43’ (dwarfing) as the inter-stem and ‘O’Henry’ as the scion. Based on anatomical measurements, we calculated the theoretical axial xylem conductance of each stem piece and Rootstock genotype with the Hagen – Poiseuille law. Principal results Xylem vessel dimensions of Rootstocks varied in conjunction with tree vigour. Scion xylem vessel dimensions of different scion/Rootstock combinations were only marginally affected by Rootstock genotype. The inter-stem sections from the dwarfing genotype (‘K146-43’) had narrower vessels and a lower calculated hydraulic conductance than the xylem from either the vigorous Rootstock below (‘Nemaguard’) or the scion above (‘O’Henry’). Conclusions Rootstock genotype only marginally affected scion xylem vessel characteristics. Thus the xylem vessel characteristics of the dwarfing Rootstock genotypes appear to influence tree growth directly rather than through an effect on the xylem characteristics of the scion. A dwarfing Rootstock genotype used as an inter-stem appeared to work as a physical restriction to water movement, reducing potential xylem flow and conductance of the whole tree.
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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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Interactions between Rootstock, inter-stem and scion xylem vessel characteristics of peach trees growing on Rootstocks with contrasting size-controlling characteristics
AoB PLANTS, 2010Co-Authors: Sergio Tombesi, R. Scott Johnson, Kevin R. Day, Theodore M. DejongAbstract:Background and aims The primary physiological mechanism influencing tree vigour in size-controlling Rootstocks of peach has been related to the hydraulic conductance of the Rootstock. Differences in Rootstock hydraulic conductance are a function of Rootstock xylem vessel characteristics. The present research examined whether the vigour and xylem vessel characteristics of the Rootstock influence the xylem characteristics of the scion. We tested whether using a size-controlling Rootstock genotype as an inter-stem influences the xylem vessel characteristics of either the Rootstock below the inter-stem or the scion above it and vice versa. Methodology Anatomical measurements (diameter and frequency) of xylem vessels were determined above and below the graft unions of the trunks of peach trees with differing scion/Rootstock combinations. The three peach Rootstocks were ‘Nemaguard’ (vigorous), ‘P30-135’ (intermediate vigour) and ‘K146-43’ (dwarfing). The vigorous scion cultivar was ‘O’Henry’. The inter-stem experiment involved trees with ‘Nemaguard’ (vigorous) as the Rootstock, ‘K146-43’ (dwarfing) as the inter-stem and ‘O’Henry’ as the scion. Based on anatomical measurements, we calculated the theoretical axial xylem conductance of each stem piece and Rootstock genotype with the Hagen – Poiseuille law. Principal results Xylem vessel dimensions of Rootstocks varied in conjunction with tree vigour. Scion xylem vessel dimensions of different scion/Rootstock combinations were only marginally affected by Rootstock genotype. The inter-stem sections from the dwarfing genotype (‘K146-43’) had narrower vessels and a lower calculated hydraulic conductance than the xylem from either the vigorous Rootstock below (‘Nemaguard’) or the scion above (‘O’Henry’). Conclusions Rootstock genotype only marginally affected scion xylem vessel characteristics. Thus the xylem vessel characteristics of the dwarfing Rootstock genotypes appear to influence tree growth directly rather than through an effect on the xylem characteristics of the scion. A dwarfing Rootstock genotype used as an inter-stem appeared to work as a physical restriction to water movement, reducing potential xylem flow and conductance of the whole tree.
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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, T 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.
T M Dejong - 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, T 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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the effect of root pressurization on water relations shoot growth and leaf gas exchange of peach prunus persica trees on Rootstocks with differing growth potential and hydraulic conductance
Journal of Experimental Botany, 2006Co-Authors: Luis I Solari, T M DejongAbstract:It is well known that Rootstocks can have an effect on the vegetative growth and development of the tree; however, there has been no clear explanation about the physiological mechanism involved in this phenomenon. Evidence indicates that the Rootstock effects on tree vegetative growth may be related to hydraulic limitations of the Rootstock. The objective of these experiments was to investigate the shoot growth, water potential, and gas exchange of peach trees on different Rootstocks in response to manipulations of water relations of trees on Rootstocks that differ in root hydraulic conductance. Tree water relations were manipulated by applying different amounts of pneumatic pressure on the root system and then relative shoot extension growth rate, tree transpiration rate, leaf water potential, leaf conductance, leaf transpiration, and net CO2 exchange rate responses were measured. Root pressurization increased leaf water potential, relative shoot extension growth rate, leaf conductance, leaf transpiration, and net CO2 exchange rates of trees on both vigorous and dwarfing Rootstocks. There was a significant positive linear correlation between applied pneumatic pressure and tree transpiration rate and leaf water potential. Leaf conductance, transpiration rate, and net CO2 exchange rate as well as relative shoot extension growth rates were also positively correlated with the applied pneumatic pressure on the root system. These relationships were consistent across both vigorous and size-controlling Rootstocks, indicating that Rootstock hydraulic limitation may be directly involved in the vegetative growth control of peach trees.
Amnon Levi - One of the best experts on this subject based on the ideXlab platform.
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grafting for management of southern root knot nematode meloidogyne incognita in watermelon
Plant Disease, 2010Co-Authors: Judy A Thies, Jennifer J Ariss, Richard L Hassell, S M Olson, Chandrasekar S Kousik, Amnon LeviAbstract:ABSTRACTFour bottle gourd (Lagenaria siceraria) cultivars, one squash (Cucurbita moschata × C. maxima) hybrid, five wild watermelon (Citrullus lanatus var. citroides) germplasm lines, and one commercial wild watermelon (C. lanatus var. citroides) cultivar were evaluated as Rootstocks for cultivated watermelon (C. lanatus var. lanatus) in fields infested with the southern root-knot nematode (Meloidogyne incognita) in Charleston, SC in 2007 and 2008, and in Quincy, FL in 2008. Commercial watermelon ‘Fiesta’ (diploid seeded) and ‘Tri-X 313’ (triploid seedless) scions were grafted onto the Rootstocks in 2007 and 2008, respectively. In 2007, the plants grafted on Rootstock from the wild watermelon germplasm line RKVL 318 had significantly less (P < 0.05) root galling than nongrafted ‘Fiesta’ watermelon or plants with the squash hybrid or bottle gourd Rootstocks. In 2008, ‘Fiesta’ plants with Rootstocks from all five wild watermelon germplasm lines and the commercial watermelon Rootstock had significantly less ...
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, T 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.
