Distribution of Foliar-applied Boron Measured by Spark-source Mass Spectrometry and Laser-probe Mass Spectrography

Abstract

The distribution of foliar-applied boron (I1'Bjboric acid) in radish (Raphanus sativus L.) was studied using for analysis of the stable isotopes a technique allowing a high sensitivity: spark-source mass spectrometry.Boron was recovered in the nontreated aerial parts and in the roots; however, the greatest fraction was in the treated leaf. It was possible with a laser-probe mass spectrograph to show that boron was not superficialy located in the treated area but was present in tissues at all levels of depth considered.Many investigations on the uptake and the translocation of nutrients applied to leaves have been carried out with the help of radioactive isotopes (2); however, for elements such as boron, the lack of a convenient radioactive isotope makes similar studies very difficult. Here, two novel techniques are used to determine the distribution of foliar-applied boron; (a) in intact plants by mea-surement of the isotopic ratio "B/'0B using a highly sensitive technique, spark-source MS; and (b) in the tissues ofboron-treated leaves, with a microanalytical method that we have recently developed using the laser-probe mass spectrograph (4). The example of boron is considered because this micronutrient is applied frequently by foliar spraying, particularly when the soil is potentially capable of fixing large amounts of this element (7). The redistribution of boron after foliar application has already been studied by Thellier (6, 10) with the help of an enriched stable isotope and a nuclear reaction (n,a). MATERIALS AND METHODS EXPERIMENTAL PROCEDUREThe experiments were performed on radish (Raphanus sativus L. cv. 18 days). The plants were grown in a greenhouse on a sandsphagnum peat moss mixture (1:2, v/v) supplied with a complete commercial fertilizer and micronutrients. When they were 31 days old, 20 mm H3B03 with Tween 20 (0.1% v/v) was applied to the middle of the lamina of one of the pair of first leaves at a temperature of 25 C and a RH of 70%o.The distribution of boron in the entire plants was determined with plants receiving 2 droplets each of 20 Al boric acid enriched with°B (90.5 ± 0.2 atom %). The localization of boron in the treated part was studied with leaves receiving 3 contiguous droplets each of 2 Al of nonenriched boric acid. In the latter case, a small volume of liquid was applied in order to have a limited and well-defined treated area. With both methods of boron application, the treated leaf was sectioned 24 h after the foliar application and was washed rapidly twice for a total of 60 s in 1 liter distilled H20, and then the different parts, including the treated leaf, hypocotyl, and epicotyl, were freeze-dried.The samples for microanalysis were cut immediately after the washing from the treated leaves to include the area initially in contact with the droplets. They were rapidly immersed in isopentane cooled with liquid N2, then freeze-dried in an apparatus VirTis (model 10-OlOTD) and preserved in a desiccator until analysis. SPARK-SOURCEThe preparation of plant samples and analyses ...

Health and Environmental Effects Document on Geothermal Energy -- 1982 update

“…146 Although this value has a g r e a t deal of uncertainty associated with it for crops other than radishes, t h e ratio of absorption to deposition of boron has been measured directly only in this instance and for our purposes we assume that this value is t h e most representative. The concentration of boron in t h e leaves of crops as a result of root uptake was calculated f o r e a c h crop.…”

“…145 This reduction in chlorophyll would reduce photosynthetic activity in t h e leaves considerably, which eventually would cause plant mortality and corresponding yield reductions. Data in more recent reports, which address t h e redistribution of boron in plants after follar application, reveal t h a t t h e 140, 146 In greatest proportion of t h e boron absorbed through t h e leaf remains in t h e leaf. t h e leaf, boron is probably present as borate polysaccharide complexes, which are believed to b e responsible for preventing any substantial translocation of t h e element from t h e leaf .…”

Retranslocation of boron in broccoli and lupin during early reproductive growth

“…For the next 14 or 21 days, experimental plants were sup-The stable isotopes '"B and "B have been used to moni-plied with 95.5% ^°B-enriched boric acid (Cambridge Isotor the short-distance transport of B (Thellier et al 1979, tope Laboratories, Wobum, MA, USA) at either the same Chamel et al 1981, Jimenez et al 1988) and the move-concentration supplied previously or at the 0.05 mg B 1"m ent of foliar-applied B (Hanson 1991, Brown et al concentration. For the next 14 or 21 days, experimental plants were sup-The stable isotopes '"B and "B have been used to moni-plied with 95.5% ^°B-enriched boric acid (Cambridge Isotor the short-distance transport of B (Thellier et al 1979, tope Laboratories, Wobum, MA, USA) at either the same Chamel et al 1981, Jimenez et al 1988) and the move-concentration supplied previously or at the 0.05 mg B 1"m ent of foliar-applied B (Hanson 1991, Brown et al concentration.…”

ULTRASTRUCTURE AND ANALYSIS, BY LASER PROBE MASS SPECTROGRAPHY, OF THE MINERAL COMPOSITION OF THE VESICLES OF TRIFOLIUM PRA TENSE ENDOMYCORRHIZAS

“…The principle of the apparatus previously described (Chamel et al, 1981)iŝ ummarized: a light pulse of 10^ to 10^ W is focused on a precisely determine" point on the specimen to be analysed. The target tissue undergoes a sudden ri^^ different chemical elements and their isotopes.…”

“…The data so obtained on mineral composition of the fungus might help to determine its growth requirements and define the substances necessary to development in controlled conditions. The laser probe mass spectrography is a technique of microanalysis already successfully used in plant biology for the analysis of bulk samples (Paris et al, 1978;Chamel and Eloy, 1980;Chamel, Andreani and Eloy, 1981). This technique has not previously been applied in the study of mycorrhizas.…”