Nomenclature A = mean age of air mixture during run, min (from time of closing vent) E = activation energy of permeation process, cal/g-mol G = gravimetric rate, pg’min cm, at test temp K = equilibrium constant, atm, for the dissociation reaction N2O4 s 2 NO2 = (NOa)*/N204 L = effective tube length, cm M.W. = molecular weight (46.0067 for NOn) p = ideal partial pressure of NO1 outside of permeation tube, atm Pso2 = vapor pressure of liquid NO2 inside tube at test temperature, atm P = barometric pressure, torr r = mean back pressure ratio (partial pressure of gas outside of permeation tube to vapor pressure inside) R = gas constant, 1.9872 callg-mol OK S = measured volumetric rate, pllmin (slope of plot) T = test temperature, OK ( “ C 273.16) V = volume of air mixture, ml (volume of test tube and connections) Z = compressibility factor, mean for run
+
Literature Cited Bamesberger, W. L., Adams, D. F., ENVIRON.SCI. TECHNOL. 3. 258-61 (1969). Brubaker, D.%W.,‘Kammermeyer, K. K., Ind. Eng. Cheni. 44, 1465 (1952). Elfers, L. A., Decker, C. E., Anal. Chern. 40, 1658-61 (1968). “International Critical Tables,” Vol. VII, McGraw-Hill Book Co., New York, N.Y., 1930, p 241. Jacobson, J. S., Amer. Chem. Soc. Dic. Water Air Waste Chern. Abstr. 7 (l), 232-4 (1967).
Linch, A. L., Stalzer, R . F., Lefferts, D. T., Amer. Ind. Hyg. ASS.J. 29, 79-86 (1968). O’Keeffe, A. E., Ortman, G. C., Anal. Chem. 38, 760-3 (1966). O’Keeffe, A. E., Ortman, G. C., ibid., 39, 1047 (1967). Saltzman, B. E., ENVIRON. Scr. TECHNOL. 2,22-32 (1968). Saltzman, B. E., Feldmann, C. R., O’Keeffe, A. E., ibid., 3, 1275-9 (1969). Scaringelli, F. P., Frey, S. A., Saltzman, B. E., Amer. Ind. Hj.g. ASS.J . 28, 260-6 (1967). Scaringelli, F. P., O’Keeffe, A. E., Rosenberg, E., Bell, J. P., Anal. Chem. 42, 871-6 (1970). Scaringelli, F. P., Rosenberg, E., Rehme, K . A., ENVIRON. 4, 924-9 (1970). SCI.TECHNOL. Stern, S. A., Sinclair, T. F., Gareis, P. J., Vahldieck, N. P., Mohr, P. H., Ind. Eng. Chern. 57, 49 (1965). Thomas, M. D.. Amtower. R . E.. J . Air Pollut. Contr. Ass. 16. 618-23 (i966j. Tye, R . , O’Keeffe, A. E., Feldmann, E. R., “Report on Analytical Methods Evaluation Service Studv No. 1.” Ninth Cbnference o n Air Pollution and Industrial ’Hygiene Studies, Pasadena, Calif., February 1968. Verhoek, F. H., Daniels, F., J. Amer. Chem. Soc. 53, 1250 (193 1). Waack, R., Alex, N. H., Frisch, H. L., Stannett, V., Szwarc, M., Ind. Eng. Chem. 47,2524 (1955). Receiced for reciew Sept. 14, 1970. Accepted March 8, 1971. This work was supported in part bj, The Center for the Stud), oj the Hurnan Encironriient, under US. Public Health Sercice grant ES00159, and in part bj, the National Air Pollution Control Administration under research grant AP00812. Presented before Dicision o f Water, Air and Waste Chemistry; 160th National Meeting, ACS; Chicago, Ill., Sept. 14, 1970.
Effects of Hydrogen Fluoride on Production and Organic Reserves of Bean Seed Merrill R . Pack College of Engineering Research Division, Washington State University, Pullman, Wash. 991 63
w The response of bean fruiting to H F gas was investigated in a series of experiments in growth chambers. No response was found when plants were fumigated at 4.5 to 8.0 pg (F)/m3 for 7 to 14 days during o r near flowering. Bean plants exposed from seeding to harvest to as little as 2.1 pg (F)l’m3 produced fewer fruit and (or) fewer seed per fruit than control plants. In lower HF treatments and in one experiment at 2.2 pg (F)lm3, no effects were evident. Where fruiting was affected, the mature seed had a somewhat faded, shriveled appearance, weighed less, and had a markedly lower starch content than seed of control plants. There were no definite differences in reducing sugars. total sugars, protein, or ether extract. The effects o n bean fruiting were independent of visible injury to the foliage.
A
tmospheric fluorides have been suspected of affecting plant fruiting, but there has been little research to investigate the possibility. Brewer and associates (1960, 1967, 1969) consistently obtained lower yields of Washington navel orange fruit in response to fluoride treatments applied either as HF gas in the atmosphere of greenhouses or as HF or N a F 1128 Environmental Science & Technology
in solution sprayed o n trees growing outdoors. They attributed the lower yields to less photosynthetic area o n the fluoride-treated trees resulting from smaller leaf size and premature leaf drop. Studying Valencia oranges in a grove exposed to relatively high levels of airborne fluorides, Leonard and Graves (1966) found that trees enclosed in plastic greenhouses receiving unfiltered ambient air produced 21 % less fruit than trees in greenhouses receiving air filtered through calcium carbonate filters to remove fluorides. Unenclosed trees in the grove produced 78% less fruit than those in the greenhouses with filtered air. If fluoride reduces the total leaf area or injures the leaves of plants, fruit production logically may be less, simply because of reduced photosynthetic capacity of the foliage; but the author found evidence of a direct effect of fluoride o n tomato fruiting (Pack, 1966). Tomato plants exposed to HF at 6 pg (F),’m3 from 45 days after seeding till harvest produced smaller fruit than plants grown in a filtered atmosphere. The smaller fruit was partially or completely seedless, suggesting that the fluoride was interfering with some phase of fertilization or seed development. Tomato fruiting was not affected at 3 pg (F)’m3. The investigation reported here shows that the production and organic reserve composition of bean seed can be affected by growing the plants in an atmosphere containing HF.
Materials and Methods
The bean plants were grown and treated in growth chambers designed for air pollution research (Adams, 1961). The air entering the chambers was thoroughly cleaned to remove fluorides and other possible contaminants. Hydrogen fluoride was introduced by the method of Hill et al. (1959) into the airstream entering one chamber. Another chamber, in which all conditions except the HF treatment were the same, served as a control. Except for the diurnal fluctuations related t o effects of temperature on sorption and desorption of HF by the chamber surfaces. the HF treatments were maintained at fairly uniform concentrations throughout each experiment. The temperature averaged 27°C during the day and 14°C at night. Depending on the particular experiment, the day length ranged from 10 to 16 hr (Table I). The light intensity was about 1500 ft-c at bench height. One variety of field beans (red kidney), three varieties of snap beans (tendergreen, tendercrop, and pencil pod wax), and one variety of lima beans (fordhook concentrated) were used in this investigation. The tendergreen variety was most intensively studied. The plants were seeded and grown in sand culture. The pots were automatically subirrigated three times daily with nutrient solution from a separate reservoir in each chamber. The nutrient solutions used have been described previously (Pack. 1966). The standard nutrient solution contained 200 ppm calcium. In some experiments (Table I), a solution containing only 40 ppm calcium was used in an effort to increase
the response to fluoride as had been done with tomatoes. Twice a week the used solution was discarded, and fresh solution was added through the pots to flush out accumulated salts. The solution level was maintained between changes by adding distilled water to the reservoirs. Plant tissues were collected at the end of the HF fumigations or at harvest, dried in a forced draft oven at 7OoC, and ground in a Wiley mill. The samples were analyzed for fluoride by slurrying with CaO, ashing, fusing with NaOH, isolating the fluoride by perchloric acid distillation, and titrating with thorium nitrate (Remmert et al., 1953; Willard and Winter, 1933). The mature bean seed were analyzed for reducing sugars by a modified Shaffer-Somogyi procedure (Heinze and Murneek, 1940). Total sugars and starch were determined by the method of McCready et al. (1950). Protein was calculated as 6.25 times the nitrogen content determined by the Kjeldahl method, and ether extraction was used to estimate crude lipids (Association of Official Agricultural Chemists, 1945). The atmosphere of the H F fumigated chamber was sampled continuously through a fritted-glass dispersion column containing 0.01N N a O H in distilled water. The solution was changed twice daily and analyzed for fluoride by titration with thorium nitrate using alizarin indicator (Adams and Koppe, 1956). The atmosphere of the control chamber was analyzed for fluoride by drawing samples through glass-fiber filters for 2 to 4 weeks, isolating the fluoride by perchloric acid distillation, and titrating with thorium nitrate (Pack e t al., 1963).
Table I. Summary of Treatments and Tissue Fluoride Concentrations for All Bean Experiments of pla nt _ tissue, ~ F content ~_ _ _ppm _ ~_- - _ _ Days Av H F Da> Leaflets Stems. uetioles Fruit Nutrient length. exposed concii, When . sollib hr to HF p g (F)/m3 exposedc Control HF Control HF control HF 160d 12 7 2.4d S 4.8 A 3.2 0.3 0.1 4.4d 120d 0.2 0.7d 12 7 S 5.3 E 1.1 2.0d 0 270 12 7 S 8.0 B 0.2 0 0 2.7 26 9 1.2 S 8.0 BE 180 12 12 0.6 0.3 0.6d S 12 14 0.3d 7.8 BE 330 20 0.7 2.5 0.2 L 7 3.ld 4.5 BE 52d 3.3d 12 2.0 3.0 2.1 L 69 39 33 12 1.7 3.5 0.9 5.4 C 880 L 8.3 70 2.2 C 260 11 1.o 0.7 0 4.2 L 260 70 2.2 C 10 11 0.3 1.5 13 0 L 340 21 70 24 2.2 C 0 11 1.o 0.5 L 21 70 19 2.2 C 11 220 0.3 0 0.3 L 70 11 710 29 25 6.6 C 0 0 0.3 70 L 29 0 11 6.6 C 0 700 46 0.3 L 70 710 47 26 0 11 6.6 C 0 0 L 70 34 11 540 31 6.6 C 1. o 0 0 L 70 11 1670 66 59 13.9 C 1.4 2.4 3.6 L 70 11 49 80 1220 1.8 2.2 2.4 13.9 C S 13 82 28d 1.5 4.5 10.5 C Oe 13d'e 690 L 14 92 30 4.5 20e 9.1 C 0.8 0.5. 775 S 16 84 140 14 3.0 14. 2.1 C 0.5 Oe S 10 92 4.0 0.60 C 0. 4.0. 54 1.5 3.0 S 16 74 0.58 C 0. 3.5 49 2.5 3.6. 0.9 ~~
Bean variety" RK RK RK PP W
TC FCL
TG RK TG TC PPW
RK TG TC PPW
RK TG
TG TG TG TG TG
~~~
~
R K , red kidney; PPW, pencil g o d w a x ; TC, tendercrop; TG tendergreen; FCL, fordhook concentrated lima. S, standard nutrient solution containing 200 p p m C a ; L, low Ca nutrient solution containing 40 p p m Ca. A, c!irectly after flowering; E, during early flowering; B, directly before flowering; BE, beginning before flowering a n d extending into early flowering; c, continuously, f r o m seeding to harvest. Sainples for F analysis collected some time after H F treatment, when plants were harvested. All other F analyses of fumigated plants apply t o samples collected a t end of H F treatment. e Mature seed only.
Volume 5, Number 11, November 1971
1129
_
Experimental Six preliminary experiments were conducted in an attempt t o determine if there is a particular stage of reproduction at which bean fruiting is especially sensitive to HF. Four varieties of beans were fumigated with HF for 7 to 14 days at various times relative t o flowering. The atmospheric fluoride concentrations averaged 4.5 to 8.0 pg (F)/m3 during these fumigations. The plants were maintained in a control chamber before and after treatment. They were grown in 1-qt polyethylene pots, with three plants per pot and eight pots per treatment. All flowers were tagged with the date of anthesis. When the seed had reached about maximum size, the plants were harvested. The flowers producing fruit, the condition of the fruit, the number of seed per fruit, and the relationship of each of these factors to the fumigation and flowering dates were determined. The short-term fumigations failed to affect fruiting, so an exploratory experiment was conducted with tendergreen beans to evaluate their response to continuous HF treatment. The plants were grown from seeding to harvest (10 weeks) in an atmosphere containing HF at an average concentration of 5.4 pg (F)im3. They were grown in 1-gal stoneware pots, with four plants per pot and eight pots per treatment. After the preceding experiment showed effects of HF o n bean fruiting, three experiments were conducted to evaluate more critically the response of beans to continuous HF fumigation. Plants were exposed to HF from seeding to harvest at concentrations averaging 2.2, 6.6, and 13.9 pg (F)/m3, respectively, in the three experiments. Red kidney, tendergreen, tendercrop, and pencil pod wax bean varieties were used at the two lowest HF levels. Red kidney and tendergreen varieties were used in the highest HF treatment. The plants in these and all subsequent experiments were grown six to a pot in I-gal stoneware pots. I n each atmospheric treatment, there were six pots of each bean variety in the first two experiments [2.2 and 6.6 pg (F),’m3] and 10 pots of each variety in the third experiment [13.9 pg (F)/m3]. To obtain maximum use of the fumigation facilities available for this investigation, each of the preceding experiments was terminated when most of the bean seed had reached approximately maximum size rather than letting them completely mature. I n a subsequent experiment, conducted for other purposes than to evaluate fruiting, some seed matured completely o n tendergreen bean plants exposed continuously to HF from seeding to harvest at an average concentration of 10.5 pg (F)/m3. These mature seed showed apparent effects of HF that had not been evident in the preceding experiments. Four additional experiments were then conducted in which sqed were grown to full maturity o n tendergreen bean plants exposed from seeding to harvest to HF a t concentrations averaging 9.1, 2.1, 0.60, and 0.58 pg (F)/m3, respectively. Six pots of six plants per pot were grown in each treatment of each experiment. Results
The HF treatments and the fluoride content of plant samples from the various experiments are summarized in Table I. The fluoride concentration in the control chamber atmosphere was consistently less than 0.01 Fg (F)/m3. The bean leaflets accumulated appreciable fluoride in the HF treatment of each experiment, especially under continuous fumigation at the highest H F concentrations. The stems, petioles, and fruit were considerably lower in fluoride, and there were only negligible amounts in all control plant parts. No evidence was found that bean flowering, fruiting, or 1130 Environmental Science & Technology
Table 11. Growth and Fruiting of Tendergreen Beans as Affected by Continuous Exposure to HF at 5.4 pg (F)/m3 Yield per pot Control HF Green wt of leaves and stems, g 163 185. Dry wt of leaves and stems, g 21 . o 24.4b Green wt of fruit, g 161 138. Dry wt of fruit, g 33.0 24.3. No. of fruit 24 0 19.1. Dry wt per fruit, g 1.37 1.26 a
Significantly different from control a t 1 % level. Significantly different from control a t 5 % level.
seed production was affected by any of the short-term (7- t o 14-day) HF fumigations. The red kidney variety was treated before, during, and after flowering, when it was assumed the likelihood of an effect was greatest. The only apparent effect of the short-term HF treatments on the bean plants was a mild, light green, interveinal chlorosis of the young leaves. This symptom developed to some degree in each of these experiments. I n the first continuous fumigation experiment with tendergreen beans, the number, and consequently the total weight, of fruit in the HF treatment was lower than in the control treatment by a highly significant amount (Table 11). This reduction in fruiting was accompanied by an increase in the weight of leaves and stems. The tendency toward lower dry weight per fruit in the H F treatment suggests the possibility of a n inhibition of seed development, but the difference was not statistically significant. A mild interveinal chlorosis developed on the leaves in the HF treatment. Results of the experiments with continuous HF fumigations at 2.2, 6.6, and 13.9 pg (F)/m3 are summarized in Table 111. Under the lowest H F treatment, no significant effects on fruiting were found with any of the four bean varieties tested, and the foliage showed no injury symptoms or growth differences. The 6.6 pg (F)/m3 treatment caused a light yellowgreen, chlorotic interveinal mottling, predominantly o n the young leaves. A highly significant reduction in the number of seed per fruit of the tendergreen beans and a significant reduction in the number of fruit of the pencil pod wax variety also were found under this H F treatment. The latter difference was reflected in a reduction in the total dry weight of fruit. At 13.9 pg (F)/m3 the interveinal chlorosis was more prevalent and severe than in the other experiments, but some degree of green color remained in practically all tissues. Highly significant reductions in the number of seed per fruit of both bean varieties tested and a significantly smaller number of fruit of the red kidney variety were obtained under this HF treatment. These differences were reflected in reduced fruit weights. The weight of leaves plus stems of the tendergreen beans was again higher in the HF treatment than in the control. No difference in flowering was found between the control and HF-treated plants in any of these experiments. At the stage of maximum seed size when the foregoing experiments were terminated, the fruit and seed in the HF and control treatments appeared generally similar. An exception was that in the experiments with high, continuous H F treatments, where fruiting was affected, the seed of the control plants frequently showed evidence of being more mature at harvest than those in the HF treatments. When the seed in the H F treatments were still entirely green, some of
those in the control treatments had acquired appreciable red to purple color. The pods on the control plants also started t o turn yellow sooner. The tendergreen bean seed that were grown to full maturity under continuous exposure t o HF a t 9.1 and 10.5 pg (F)/m3 tended to be shriveled and distorted, and the black coloration often was a faded blue-black. In comparison, the seed from control plants were generally larger and well rounded and had a glossy black color. The abnormalities were more pronounced in the seed produced at 9.1 pg (F)/m3 than in those produced at 10.5 pg (F)/m3, possibly because the response to fluoride was accentuated by the low level of calcium nutrition of the plants grown at 9.1 pg (F)/m3. Some of the seed produced at 2.1 pg (F)'m3 also showed the shriveling and faded coloration but to a lesser degree than the seed produced in the higher H F treatments. The seed produced at 0.58 and 0.60 pg (F)/m3 were indistinguishable from comparable control seed. Seed production was not measured for the plants grown a t 10.5 pg (F)/m3. The production data for the other experi-
ments in which the seed were grown to full maturity are given in Table IV. The HF treatments caused no significant differences in the number of fruit produced in any of these experiments. There were fewer seed per fruit in the H F treatments at 2.1 and 9.1 p g (F)/m3, but n o differences occurred at the two lowest HF concentrations. The rest of the data in Table IV were obtained from the total combined seed from each treatment and is not amenable to statistical analysis. The average weights per seed were appreciably less in the 9.1 and 10.5 pg (F)/m3 treatments than for the comparable controls, reflecting the shriveling mentioned previously. There were no manifest differences in average seed weight between the H F and control treatments of the other experiments. The usual chlorotic symptoms developed on the leaves at 9.1 and 10.5 pg (F)/m3, but n o leaf symptoms were evident in the three lowest HF treatments. Of the organic food reserves determined in the mature bean seed, the one that was quite obviously affected by HF was starch. There were pronounced reductions in starch under each of the three highest HF treatments. This probably
Table 111. Growth and Fruiting (Yield per Pot) of Four Varieties of Beans Exposed Continuously from Seeding to Harvest a t Three Different Concentrations of HF Red kidney ~- -~Tendergreen___ Control HF Control HF
2.2 pg (F),'m3 Green wt of leaves and stems, g Dry wt of leaves and stems, g Green wt of fruit, g Dry wt of fruit, g No. of fruit No. of seed per fruit 6.6 pg (F)/m3 Green wt of leaves and stems, g Dry wt of leaves and stems, g Green wt of fruit, g Dry wt of fruit, g No. of fruit No. of seed per fruit 13.9 pg (F)/m3 Green wt of leaves and stems, g Dry wt of leaves and stems, g Green wt of fruit, g Dry wt of fruit, g No. of' fruit No. of seed per fruit a
Significantly different from control at 1 Significantly different from control at 5
Tendercrop Control HF
Pencil pod wax -~ Control HF
153 21.5 113 18.5 13.5 2.96
154 21.4 116 20.3 14.2 3.24
206 27.1 203 38.1 22.7 4.34
189 22.6 161 31.4 20.0 4.12
88.5 10.6 68.1 7.3 10.7 3.38
88.8 11.2 72.3 7.6 11.8 3.28
150 21.2 115 18.9 15.2 4.24
153 22.0 135 20.6 16.5 4.24
139 19.5 102 18.9 12.7 2.82
136 18.5 89.2 16.0 11.5 2.83
186 24.6 165 33.2 22.0 4.13
213 29.8 143 24.8 21.2 3.20.
92.0 11.6 78 4 9.8 12.5 3.35
109 15.9 101 11.5 17.5 2.94
175 23.7 147 25.8 22.8 3.78
137 20.6 lOlb 16.76 14.8b 3.82
149 19.2 126 27.2 16.2 2.79
125 17.0 80.0. 12.6. 12. l b 2,20fi
140 18.9 106 23.2 19.4 3.10
1970 28,s. 90.4 14.0. 19.1 1.95.
zlevel. level.
Table IV. Fruit and Seed Production and Food Reserve Content of Mature Bean Seed as Affected by Continuous Exposure of the Plants to H F 10.5f i g (F)/m3~. Control HF
Total no. of fruit No. of seed per fruit Av wt per seed, mg Reducing sugars, mg!seed Total sugars, mg,/seed Starch, mglseed Protein, mg'seed Ether extract, mg'seed a
323 7.8 12.0 113 62.7 3.7
211 5.3 12.4 44.7 52.1 2.9
9.1 pg (F)/m3 Control HF
~~~~
169 4.5 280 4.6 10.4 95 5 55.7 2.8
g (F)/m3 ~2.1 pL ~ Control HF
154 166 3.4~ 4.6 184 248 4.4 5.2 10.3 13.0 28.3 92.5 47.5 40 4 2.3 2.9
170 3.7a 226 6.1 11.4 40.7 42.3 2.8
_ 0.60 _pg (F)/m3
Control
HF
163 4.3 276 2.6 13.8 102 54.1 3.3
152 4.6 284 1.5 14.8 99.4 59.9 3.5
0.58 pg (F)/m3 -Control HF
187 4.3 265 1.5 14.6 106 42.9 3.2
202 4.6 305 1.8 18.6 104 54.0 4.2
Significantly different from control at 1 % level. Volume 5, Number 11, November 1971
1131
accounts for the shriveling and smaller size of the seed in these treatments. The data are expressed in milligrams per seed in Table IV to show the net differences in the individual organic reserves. Although starch was the only component determined that showed clear-cut differences associated with the H F treatments, there was a tendency for all of the reserves to be slightly lower in the seed produced in the two highest treatments.
Discussion
Beans were selected for evaluation of the effects of H F on seed development because previous tests had suggested they undergo such effects and because their plant size, large seed, and short life cycle make them convenient test plants for such a n investigation. Beans are only moderately sensitive to H F , however, so it was necessary to use some fairly high HF treatments to characterize the responses encountered. Hopefully, the results obtained are indicative of responses of plants in general and will provide a useful basis for investigation of effects of HF o n seed development in other plants. Work now in progress indicates that some plants-e.g., corn, soybeans, and strawberries-show similar effects under lower HF treatments. Effects of atmospheric fluorides o n bean fruiting or seed development per se may be of limited practical importance. Continuous exposure of plants to HF at 5.4 yg (F)/m3 or higher, under which fruiting of the tendergreen variety of beans was consistently affected, probably constitutes unrealistically severe treatment, as is evident from the very high fluoride concentrations that accumulated in the leaves. Yet, bean fruiting was not greatly affected even under the most severe H F treatments. Continuous treatment with about 2 pg (F)/m3, which reduced the number of seed per pod and the starch content of the seed in one experiment, is also fairly severe; but it probably is within the range of the average gaseous fluoride concentrations that may be encountered in the near vicinity of some fluoride-emitting industries. The fluoride concentrations that averaged about 0.6 pg (F)/m3 were much more typical of those that might be found over fairly large areas around some fluoride-emitting industries, but no effects o n the beans were found under these treatments. Although there was no response of bean fruiting t o the short-term fumigations, there undoubtedly is a stage of reproduction during which the sensitivity of fruiting to fluoride is maximum. The effects of HF o n fruiting presumably depend on the concentration of dissolved or active fluoride in the sensitive tissues during that critical stage. This in turn depends on both the concentrations of HF to which the tissues have been exposed and the length of the exposures. For although some fluoride may be inactivated within plant tissue and some may be lost from the tissue after once being absorbed (Leone et al., 1956; Jacobson et al., 1966), fluoride intrinsically is a n accumulative phytotoxicant. Therefore, to produce the same effects with short-term HF treatments as were obtained in the long-term fumigations, appreciably higher H F concentrations probably would be required. However, there is need for a critical evaluation of the response of plants to short-term exposure at high HF concentrations in comparison to long-term exposure at low concentrations. The reductions in the number of seed per bean fruit support the evidence previously found with tomatoes that the influence of HF on fruiting is related to effects on fertilization o r seed development. The reductions in the number of fruit 1132 Environmental Science & Technologj
may be due to the same mechanism, since some pods may have shriveled and abscised because no seed developed in them. The number of flowers produced was not affected by the H F treatments. The fact that higher weights of stems and leaves were flound in some H F treatments where seed production was reduced provides further evidence that the H F was affecting fruiting directly rather than just causing a reduction in the overall growth of the plants. It is significant also that the effects a t 2 yg (F)/m3 occurred in the absence of any fluoride injury symptoms on the bean foliage. The effect of some of the fluoride treatments on the starch content of the seed is particularly significant in view of the low concentrations of fluoride found in the seed. Much higher fluoride concentrations commonly accumulate in leaves with no apparent effects. i t is possible that the fluoride may have exerted its influence outside the seed by affecting the formation or translocation to the seed of some substance necessary for starch biosynthesis, but the reducing sugar analyses gave no indication of a n effect on the glucose supply. In fact, the reducing sugars consistently were slightly higher on a percentage basis in the seed where the starch content was reduced. The possibility that the lower starch content was a consequence of decreased photosynthesis in the leaves also is inconsistent with the increased vegetative growth found in some H F treatments. If starch biosynthesis in the seed was directly affected by the H F treatments, the system must be much more sensitive to fluoride than any that have been evaluated in leaves, or the leaves must have much more effective protective mechanisms against fluoride than the seed do. Acknowledgment
The technical assistance of Charles W. Sulzbach, Sara Carnahan, and Sharon Grimes is gratefully acknowledged. Literature Cited
Adams, D. F., J . Air Pollut. Contr. Ass. 11, 470-7 (1961). Adams, D. F., Koppe, R. K., Anal. Chem. 28, 116-117 (1956). Association of Official Agricultural Chemists, Washington, D.C.. “Official and Tentative Methods of Analysis,” 6th ed., pp 25-7,408 (1945). Brewer, R. F., Garber, M. J., Guillemet, F. B., Sutherland, F. H., Proc. Amer. Soc. Hort. Sci. 91, 150-6 (1967). Brewer, R. F., Sutherland, F. H., Guillemet, F. B., ENVIRON. Scr. . TECHNOL. 3. 378-81 (19691. _ ~ Brewer, R . F., Sutherland, F. H.,’Guillemet, F. B., Creveling, R. K., Proc. Amer. Soc. Hort. Sci. 76, 208-14 (1960). Heinze, P. H., Murneek, A. E., Missouri Agricultural EXperiment Station, Research Bulletin 314 (1940). Hill, A. C., Transtrum, L. G., Pack, M. R., Holloman, A,, Jr., J . Air Pollut. Contr. Ass. 9, 22-7 (1959). Jacobson, J. S., Weinstein, L. H., McCune, D. C., Hitchcock, A. E., J . Air Pollut. Contr. Ass. 16, 412-7 (1966). Leonard. C. D.. Graves. H. B.., Jr... Proc. Fla. State Hort. Soc. 79, 79-86 (1966). ’ Leone, I. A., Brennan, E., Daines, R. H., Plant Physiol. 31, 329-33 (1956). McCready, R. M., Guggolz, J., Silviera, V., Owens, H. s., Anal. Chem. 22, 1156-8 (1950). Pack, M. R., J . Air Pollut. Contr. Ass. 16, 541-4 (1966). Pack, M. R., Hill, A. C., Benedict, H. M., J . Air Pollut. Contr. A S S .13, 374-7 (1963). Remmert, L. F., Parks, T. D., Lawrence, A. M., McBurney, E. H., Anal. Chem. 25, 450-3 (1953). Willard. H. H.. Winter, 0. B., Znd. Eng. Ckem. Anal. Ed. 5, 7-10 (1933). ’ ~
~
Receiced f o r review Oct. 29, 1970. Accepted March 18, 1971. Supported in part by grant nc. AP-00341 from the Air Paflution Control Ofice, Encironmental Protection Agency.
