T. W ĘGRZYN
SOME ASPECTS OF THE RELATIONSHIP
BETWEEN AZOTOBACTER CHROOCOCCUM AND HERBICIDES Agricultural University of Wrocław, Poland
Herbicides have been found to exert some influence on the meta bolism of soil miezoorganisms [1, 2, 3. 4, 5, 7, 14]. Azotobacter chroo- coccum also reacts to some herbicides which affect the rate of its growth, morphology and the fixation of free nitrogen [6, 8, 12, 18].
The present paper deals with the effect of some herbicides on pro duction of biologically active auxin like substances by Azotobacter chroococcum and with the possibility of its influence on phytotoxicity o f herbicides.
METHODS
Four Azotobacter chrococcum strains Nos 24, 31, 38, 45 were isolated from the rizosphere of some cultured plants; they varied as in the colony morphology as in pigmentation intensity.
The ability of Azotobacter strains to produce biologically active substances (BAS) was determined in 7 days old cultures, incubated on Ashby medium with addition of various herbicide doses; for this purpose the chemical method after M u r o m c e w [9] and the biological pro cedure after T u r e c k a [14] were applied. The biological test consisted of cutting 10-day old bean plants and putting them into liquid bacterial culture and then into water. The length of the root sphere with growing adventitions roots, their number and growth rate indicated the intensity of BSA contained in the Azotobacter culture.
Azotobacter strains were incubated in Ashby medium with addition of 1, 10, 100 and 1000 ppm of herbicides and on the control medium without it. Additional controls were made up by water and indolilo- acetic acid in the amount of 10 jig/ml. The length of the zone with pro duction of adventitions roots was evaluated statistically [6]. The her
92 T. W ęgrzyn
bicides used were: aphalon (N-3,4-dichlorophenyl-N-methoxy-N-methyl- urea), prometryne (4,6-bisisopropyloamine-2-methylthio-l,3,5,-triazine), chlorpropham (isopropyl-N-3-chlorophenyl carbamate) in the doses of 1000, 100, 10, 1 ppm.
Changes in the herbicide phytotoxicity were studied on prometryne with bean as a test plant. Its seeds were soaked for 18-20 hours in Azotobacter culture incubated in medium containing the herbicide in the above given doses. Control tests were made with plants the seeds of which were soaked in prometryne suspension. The seeds were planted in sterile sand with addition of Knopp medium, in micropots. The ex periment lasted one month, under glasshouse conditions, at mean tem perature of 18-20°C.
RESULTS
The herbicides were found to influence the production of BSA of auxin type by Azotobacter. The changes were not invariably conditioned by the herbicide induced reduction or increase in the number of cells (Table 1); their mode of action was by no means uniform; prometryne caused an increase in the number of cells and promoted the production of auxin-like substances, whereas aphalon reduced the number of cells, with concomitant inhibitory effect on the ability to produce the sub stances. The action of chlorprophan was still more pronounced; the T a b l e 1 Effect of herbicides on the production of auxin like substances by Azotobacter hroococcum
Herbicide doses in ppm
Number of cells /in %/ in 1 ml of bacterial culture Ко. per BAS /in % / million cells 24 51 58 24 31 38 Control 100 100 100 100 100 100 Prometryne 1000 234 195 200 130 88 177 100 156 84 £35 160 116 150 10 156 94 173 106 108 110 Aphalon 1000 29 50 16 78 0 58 100 54 65 82 76 28 91 10 54 95 103 60 26 66 Chlorpropham 1000 52 75 66 13 0 0 100 51 78 80 38 0 0 10 55 88 68 51 21 54
herbicide caused diminution of cells and complete inhibition of auxin like substances. With decreasing doses of the herbicide its adverse action tended to disappear.
The biologic test coroborated the results obtained by the chemical method, as exemplified by strain No. 24 (diagram 1). The remaining strains gave similar reactions.
УШ \
-
Bacterial culture on medium with herbicideFig. 1. The influence of herbicides on the production of auxines by strain No. 24
D oses of h erb icides: 1 — 1000 ppm , 2 — 100 ppm , 3 — 10 ppm , 4 — 1 ppm , С — control (bacterial culture w ithout herbicides) ; I — m edium with herbicides, I I — bacterial culture on
m edium with herbicide
Prometryne inhibited the growth and development of bean in micro pots; affected were also the size and morphology of the leaves. In the presence of Azotobacter culture the adverse effect of prometryne was reduced (Fig. 2 and 3).
We assume that the reaction of the plants to the herbicide and bacterial culture is a result of their concurrent action. In this case the interaction was as follows; prometryne was inhibiting and Azotobacter stimulating the growth of the plant. The promoting effect of Azotobacter on the plant is determined by production of growth regulating auxin and gibberelin like substances [10, 13, 17]. Prometryne did not inhibit but even promoted the production of the substances. Eventually, the stimulating effect of bacterial metabolites was stronger than the in hibiting one of prometryne. Consequently, the resultant of the concurrent action of both factors proved to be favourable for the plant.
Fig. 2. The effect of prometryne on the growth of bean
a — prom etryne, b — pro m etry n e+ cu ltu re of A z o t o b a c t e r c h r o o c o c c u m strain N o. 38; doses of
pro m etry n e: 1 — 1000 ppm , 2 — 100 ppm , 3 — 10 ppm. 4 — l ppm
Fig. 3. The effect of prometryne on the leaves of bean
a — prom etryne 100 ppm , b — culture of A z o t o b a c t c r c h r o o c o c c u m strain N o. 75, с —
prom etryne 100 p p m 4-culture o f A z o t o b a c t e r
96 T. W ęgrzyn
CONCLUSIONS
It is possible to influence the phytotoxicity of herbicides through the action o f microorganisms, which was substantiated by the expe riment with Azotobacter chroococcum.
REFERENCES
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poi. 18, 1969, 11.
[3] B a l i c k a N., K o s i n k i e w i c z B., W ę g r z y n T.: Acta microb. poi. 2, 1970, 547.
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[6] D u d à J., P ę d z i w i I k F.: Acta microb. pol. 1, 1952, 193. [7] K r ę ż e l Z., L e s z c z y ń s k a D., Ż u k o w s k a Z.: page 99. [8] L e n h a r d G. S.: African J. Agr. Seien 2, 1957, 487.
[9] M u r o m c e ł G. S., P i e ń k ó w L. A .: Gibereling Edit. PWRiL, Warszawa 1964, 62. [10] M i s z u s t i n E. N., M a r e n k o W. G.: 5, 1965, 863. [11] R a n k o w W. , J e l o n k o w E., S y r l e k o w P., W a l e w B.: Agrobiołogija 3, 1966, 115. [12] R u b i e ń c z y k L. J.: Mikrobiol. 4, 1958, 503. [13] S o b i e s z c z a ń s k i J. : page 79.
[14] T u r e c k a R. Ch.: The physiology of root formation by graft and growth regulators (russ.). Edit. Acad. Sc. USSR, Moskwa 1961, 29.
[15] U l i ń s k a M.: Technika obliczeń przy opracowywaniu wyników doświadczeń rolniczych. PWRiL, Warszawa 1957, 25.
[16] V a n c u r a V.: Natüre 192, 1961, 479. [17] W ę g r z y n T. Acta microb. pol. 3, 1971, 131.
T. W Ę G R Z Y N
NIEKTÓRE A SP E K TY W ZAJEMNEGO O D D ZIA Ł Y W A N IA
A Z OTOBACTER CHROOCOCCUM I HERBICYDÓW
Akademia Rolnicza we Wrocławiu
S t r e s z c z e n i e
Pod wpływem herbicydów zmieniała się intensywność wytwarzania substancji biologicznie aktywnych przez wybrane szczepy Azotobacter chroococcum. Efekt ten zależał od rodzajs^herbicydu i jego dawki.
Stwierdzono, że Azotobacter chroococcum obniżył fitotoksyczne działanie pro- metrynu na roślinę testową.
Т. В Е Н Г Ж И Н НЕКОТОРЫЕ АСПЕКТЫ ВЗАИМОДЕЙСТВИЯ A ZOTOBACTER CHROOCOCCUM И ГЕРБИЦИДОВ Сельскохозяйственная академия во Вроцлаве Р е з ю м е Под влиянием гербицидов изменялась интенсивность образования биоло гически активных веществ со стороны выбранных штаммов Azotobacter chroo- соссит. Это явление было обусловлено видом и дозой гербицида. Установлено, что Azotobacter chroococcum снижал фитотоксическое дей ствие прометрина на тестовые растения.
