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Báo cáo lâm nghiệp: " The use of ultrasonic detectors for water stress determination in fruit trees"

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Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài: The use of ultrasonic detectors for water stress determination in fruit trees...

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The use of ultrasonic detectors for water stress determination in fruit trees 2 Higgs 3 Bergamini A. K.H. H.G.Jones 1 Institute of Horticultural RResearch, Wellesbourne, Warwick, U.K., tural esearch, W .K., urne, 2 Institute of Horticultural Research, East Malling, Maidstone, U.K., and 3 Istituto Sperimentale per la Frutticoltura, Trento, Italy converted into 5 V pulses and recorded on Introduction were logger. AE production of 3 apple a counter or cultivars (Cox’s Orange Pippin, Golden Deli- cious and /t?20/3) on 2 rootstocks (M.9 and conductance in In drought, the hydraulic M.25) were compared in a glasshouse drought tree stems can be reduced by embolisms experiment from 8-10 October 1987. 24 potted that occur within xylem vessels and tra- trees were transferred from a sandbed on 4 cheids. There is good circumstantial evi- October and waiter was withheld from 2 of each rootstock/cultivar combination. Three days later, dence that these cavitation events can be water was withheld from one more tree from detected acoustically, either at low fre- each combination, the remainder of the trees quency, i.e., 0.2-2 kHz (Milburn and John- being retained as well-watered controls. Two son, 1966) or high frequency, i.e., 0.1-1.0 ultrasound transducers were attached to stems of pairs of trees to record counts over 5 min MHz (Tyree and Dixon, 1983) It is impor- periods. Each transducer was mounted onto the tant to know at what stage cavitations xylem tissue of the rootstock stem (covered occur and whether there are inherent dif- with petroleum jelly) about 10 cm below the ferences between varieties or species. As graft union. Leaf water potential ( down to -4 , VI a tool to investigate cavitation events, we MPa) and conductance to water vapor (g were ) i monitored concurrently with AE. have used ultrasound detectors, since they are able to operate in a noisy envi- ronment or in field conditions without background interference. Results Results presented for the 3 cultivars are Materials and Methods in Fig. 1. There was a clear separately rootstock effect with the count rate for M.9 being up to Ei times that for M.25, de- design based on that by Sand- Using a circuit pending upon y. The threshold of y!i at ford and Grace (1984), acoustic emissions (AE)
a data logger recording at 30 min using intervals. Two ’ were used: A120/3 on trees M.25 and Cox on M.9. The pattern of V, vs AE was similar to that in the previous experiment. It was evident from the time courses that a marked diurnal pattern existed where ,AE followed radiation (PAR) levels approximately, except in some in- stances when !4E increased, or continued, which AEs started was different for the during the night (Fig. 2). various rootstock/cultivar combinations (Table I). The cultivar effect was not so marked, Discussion and Conclusion there was a tendency for fewer although AE to be produced at any yfl for A120/3 on M.25 when compared with the other culti- These results indicate that the response to vars on the same rootstock. On no occa- applied drought in apple trees produced sion did AE for well-watered controls AE in a dwarfing rootstock more exceed 2 per 5 min and were usually zero. (M.9) than in at vigorous one (M.25) for a There was some evidence with individual given y Also there was a threshold of y, q. plants that AE decreased after prolonged below which A,E start to occur. This was stress. different for the 2 rootstocks. Other evi- dence suggests that embolised vessels In a separate experiment, AE were are not easily refilled (Milburn, 1979; monitored diurnally (along with radiation)
Jones and Pena, 1986) and so a cumula- Bot. apple (Malus x domestica Borkh.). J. Exp. 37, 1245-1254 tive reduction in hydraulic conductivity Milburn J.A. (1979) In: Water Flow in Plants. could occur. Work is continuing in order to Longman, London evaluate the technique for assessing plant Milburn J.A. & Johnson R.P.C. (1966) The responses to drought in the field and as a conduction of sap. 11. Detection of vibrations means of measuring physiological water produced by sap cavitations in Ricinus stem. stress. Planta 69, 43-52 Sandford A.P. & Grace J. (1985) The measure- ment and interpretation of ultrasound from woody stems. J. Exp. Bot 36, 298-311 1 References M.T. & Dixon M.A. (1983) Cavitation Tyree Thuja occidentalis L.? Ultrasonic events in Jones H.G. & Pena J. (1986) Relationships be- acoustic emissions from the sapwood can be tween water stress and ultrasound emission in measured. Plant Physiol. 72, 1094-1099

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