Identifying Differential Tissue Response in Grape (Vitis riparia) During Induction of Endodormancy Using Nuclear Magnetic Resonance Imaging
Physiological and biophysical changes were monitored during shoot maturation and bud endodormancy induction in grape ( Vitis riparia Michx.) under controlled environments. Growth, dry weight (DW), periderm development, bud endodormancy, and nuclear magnetic resonance imaging (MRI) T 2 relaxation tim...
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Veröffentlicht in: | Journal of the American Society for Horticultural Science 2001-11, Vol.126 (6), p.681-688 |
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Sprache: | eng |
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Zusammenfassung: | Physiological and biophysical changes were monitored during shoot maturation and bud endodormancy induction in grape (
Vitis riparia
Michx.) under controlled environments. Growth, dry weight (DW), periderm development, bud endodormancy, and nuclear magnetic resonance imaging (MRI) T
2
relaxation times were monitored at 2, 4, or 6 weeks of long-photoperiod [long day (LD), 15 h, endodormancy inhibition] or short-photoperiod [short day (SD), 8 h, endodormancy induction] treatments at 15/9 h day/night thermoperiod of 25/20 ± 3 °C. Shoots on LD plants grew throughout the entire study period, although the rate of growth decreased slightly during the 6th week. Shoot growth slowed significantly after 2 weeks of SD, was minimal by the 4th week of SD and most of the shoot tip meristems had abscised after 6 weeks of SD. Endodormancy was induced after 4 weeks of SD. DW of the stem and buds increased with increasing duration of LD and SD. While bud DW increased more under SD than LD, stem DW increased more under LD than SD. T
2
relaxation times were calculated from images of transverse sections of the grape node. There was a slight decrease in the T
2
times in the node tissues with increased duration of LD treatment, whereas SD induced a significant decrease in T
2
times during endodormancy induction. T
2
values for the node decreased after 4 weeks of SD, coinciding with endodormancy induction. Separation of node tissues into bud, leaf gap, and the remainder of the stem and analysis of the proportion of short and long T
2
times within those tissues indicated differential tissue response. A greater proportion of short T
2
times were observed in the 2-week SD leaf gap tissue than in the LD and the proportion of short T
2
times continued to increase with subsequent SD treatment. Bud and all other stem tissues had a greater proportion of short T
2
times after 4 weeks of SD, coinciding with bud endodormancy induction. The proportion of short and long T
2
times in a tissue was a better indicator of endodormancy than the averaged T
2
time for the tissue. Thus, MRI allows nondestructive identification of differential tissue response to photoperiod treatments and makes it possible to separate normal vegetative maturation responses from endodormancy induction. |
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ISSN: | 0003-1062 2327-9788 |
DOI: | 10.21273/jashs.126.6.681 |