Allelopathy Involving Microorganisms - ACS Publications - American

Chapter 5

Allelopathy Involving Microorganisms Case Histories from the United Kingdom J. M. Lynch

Downloaded by UNIV OF NEW ENGLAND on February 11, 2017 | http://pubs.acs.org Publication Date: January 8, 1987 | doi: 10.1021/bk-1987-0330.ch005

Glasshouse Crops Research Institute, Littlehampton, West Sussex, BN17 6LP, United Kingdom Plant residues can provide substrates for the production of phytotoxic metabolites by soil microorganisms but they can also support the growth of pathogens and other deleterious micro-organisms. This is illustrated by reference to the problems of establishing crops drilled in the presence of straw residues and of decaying weed and grass residues that have been previously killed with herbicides. Short-chain acids accumulate,under anoxic conditions, which favor fermentative metabolism of bacteria. Such phytotoxins may damage the plant directly or predispose plants to infection by pathogens. However, plant residues may also be used as substrates for beneficial micro-organisms to produce plant nutrients, soil conditioners, and plant protection chemicals. There is scope to promote the beneficial microbial effects against the harmful by soil management and by inoculation. M i c r o - o r g a n i s m s produce a v a s t range o f m e t a b o l i t e s t h a t c a n p o t e n t i a l l y i n f l u e n c e p l a n t growth (_1/ 2, 3). T h i s a c t i o n c a n be positive or negative. Pathogens produce a n e g a t i v e e f f e c t b y p r o d u c i n g s p e c i f i c m e t a b o l i t e s o r enzymes. B e n e f i c i a l organisms may a c t d i r e c t l y on the p l a n t by p r o d u c i n g c h e m i c a l s t h a t s t i m u l a t e p l a n t growth o r enhance the uptake o f n u t r i e n t s . Indirect effects o f b e n e f i c i a l organisms i n c l u d e the s u p p r e s s i o n o f harmful organisms and the improvement o f s o i l s t r u c t u r e . T h i s d i v e r s e range o f m i c r o b i a l a c t i v i t i e s f a l l s w i t h i n the phenomenon o f a l l e l o p a t h y a s d e f i n e d by R i c e ( 4 ) . The d e s c r i p t i o n o f t h i s phenomenon i s u s e f u l / b u t the p r o c e s s e s c a n a l s o be d e s c r i b e d under t h e heading o f plant/microbe i n t e r a c t i o n s . Whereas a wide range o f p o t e n t i a l a l l e l o p a t h i c a g e n t s h a s been i d e n t i f i e d from s o i l m i c r o - o r g a n i s m s / i t has seldom been p r o v e n t h a t they a r e o f true e c o l o g i c a l s i g n i f i c a n c e . The minimum n e c e s s a r y c r i t e r i o n f o r t h i s i s t h a t the p r o d u c t s h o u l d o c c u r i n the form and

0097-6156/87/0330-0044$06.00/0 © 1987 A m e r i c a n C h e m i c a l Society

Waller; Allelochemicals: Role in Agriculture and Forestry ACS Symposium Series; American Chemical Society: Washington, DC, 1987.


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Involving

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c o n c e n t r a t i o n that i n f l u e n c e p l a n t growth. To demonstrate t h i s u s u a l l y i n v o l v e s v e r y m i l d e x t r a c t i o n p r o c e d u r e s because/ f o r example/ even m i l d a c i d s o r a l k a l i s can d e p o l y m e r i z e l i g n i n t o y i e l d p h e n o l s t h a t would o t h e r w i s e be i n e r t because i n the p o l y m e r i c state. A n o t h e r f a c t o r r a r e l y c o n s i d e r e d i s the zone o f the r o o t system s u b j e c t e d t o the m i c r o b i a l m e t a b o l i t e . I t i s l i k e l y t h a t the m e t a b o l i t e s w i l l o n l y be formed i n p a r t i c u l a r r e g i o n s o f the s o i l where t h e r e a r e s u i t a b l e s u b s t r a t e s f o r p r o d u c e r m i c r o - o r g a n i s m s and i t i s u n l i k e l y t h a t the e n t i r e r o o t system w i l l come under the influence of a metabolite. F o r example/ a c e t i c a c i d i s a common m i c r o b i a l f e r m e n t a t i o n p r o d u c t o f c e l l u l o s e and i s p h y t o t o x i c (j>/ 6). However/ i n ^ t r e a t i n g a s i n g l e r o o t t i p w i t h a s m a l l c o n c e n t r a t i o n (5 mol m )/ r o o t and s h o o t growth were s t i m u l a t e d . This was n o t o b s e r v e d when a g r e a t e r number o f t i p s were t r e a t e d o r g r e a t e r c o n c e n t r a t i o n s o f the a c i d were used ( T a b l e I ) . Lengths o f r o o t s were more s e n s i t i v e than t i p s t o i n h i b i t o r y c o n c e n t r a t i o n s o f the a c i d . Compensatory growth i n non t r e a t e d r o o t s c o u l d o c c u r i n response t o t r e a t m e n t o f o t h e r p a r t s o f the r o o t s y s t e m .

Table

I.

Response o f B a r l e y Root E l o n g a t i o n t o Treatment w i t h 10 mol m

Region

treated

2 cm t i p 2 cm t i p 2 cm s e c t i o n 2 cm s e c t i o n Control*

No. o f roots treated

1 3 1 3 _

Acetic Acid

Mean l e n g t h o f non-treated root + s.e.m.

11.6 15.8 16.5 17.5 11.2

Mean l e n g t h o f treated root + s.e.m.

8.2 9.1 12.9 7.4 12.4

+ 1.7 + 0.2 + 0.5 + 1.3 + 0.7

+ + + + +

1.1 0.6 2.6 0.8 0.7

* Means o f p l a n t s where e i t h e r one o r t h r e e t i p s o r l e n g t h s were t r e a t e d w i t h p l a n t c u l t u r e s o l u t i o n o r where no r o o t s were t r e a t e d . Source: The New

Reproduced w i t h p e r m i s s i o n from K e f . Phytologist.

7.

Copyright

1982

Whereas a l i p h a t i c a c i d s can produce permanent s h o o t and t i l l e r damage/ when the a c i d s a r e removed from the growth medium/ r o o t growth can be promoted (8)/ presumably by compensatory a c t i o n . Q u i t e commonly m i c r o - o r g a n i s m s and t h e i r p r o d u c t s a r e b i o assayed together. When l e a v e s o f Anthoxanthum odoraturn were decomposed a e r o b i c a l l y the t o t a l s u s p e n s i o n c o n t a i n e d g r o w t h i n h i b i t o r y m i c r o - o r g a n i s m s b u t no c e l l - f r e e p h y t o t o x i c m e t a b o l i t e s (Table I I ) . By c o n t r a s t wheat straw degraded a n a e r o b i c a l l y y i e l d e d p h y t o t o x i c m e t a b o l i t e s b u t no g r o w t h - i n h i b i t i n g m i c r o - o r g a n i s m s .


46

ALLELOCHEMICALS: ROLE IN AGRICULTURE A N D FORESTRY T a b l e I I . E f f e c t o f M i c r o - o r g a n i s m s and T h e i r M e t a b o l i t e s Formed D u r i n g 14 Days D e c o m p o s i t i o n o f P l a n t R e s i d u e s on Longest Root L e n g t h (mm) o f B a r l e y S e e d l i n g s

Control (distilled water)


Residue

Micro organisms

Total suspension Filtrate

Anthoxanthum l e a v e s / a e r o b i c

75

79

74

59*

Wheat s t r a w / a n a e r o b i c

84

35***

37***

7

Significantly different

r e s u l t s i n d i c a t e d by * * *

Source: Reproduced w i t h p e r m i s s i o n from R e f . M a r t i n u s N i j h o f f Β. V .

Straw

9·

6

Ρ < .001; * Ρ ^ N

Copyright

.05

1984

Residues

In the d i r e c t d r i l l i n g ( n o - t i l l s e e d i n g ) p r a c t i c e i n the U n i t e d Kingdom/ s t r a w r e s i d u e s from the p r e c e d i n g c r o p a r e u s u a l l y b u r n t because poor c r o p e s t a b l i s h m e n t and y i e l d s c a n r e s u l t / p a r t i c u l a r l y on heavy s o i l s i n wet y e a r s ( 1 0 ) . S i m i l a r problems can o c c u r i n the c o n s e r v a t i o n t i l l a g e systems o f the P a c i f i c Northwest ( L . F . E l l i o t t and H . - H . Cheng/ t h i s v o l u m e ) . The o l d e r a g r i c u l t u r a l t e x t b o o k s i n d i c a t e t h a t t h i s i s due t o the s t r a w h a v i n g a h i g h C : N r a t i o ( c . 100:1) compared w i t h the decomposer m i c r o - o r g a n i s m s ( c . 5:1) and t h a t Ν o t h e r w i s e a v a i l a b l e to p l a n t s i s immobilized i n t o m i c r o b i a l biomass. It i s quite easy t o demonstrate t h i s e f f e c t i n p o t experiments/ where s e e d l i n g s show o b v i o u s s i g n s o f Ν d e f i c i e n c y i n the p r e s e n c e o f s t r a w . However/ i t i s l i k e l y t h a t i n the f u l l c r o p p i n g season the i m m o b i l i z e d Ν w i l l s u b s e q u e n t l y become a v a i l a b l e t o the c r o p / a l t h o u g h l i t t l e f i r m e x p e r i m e n t a l e v i d e n c e has been o b t a i n e d t o s u p p o r t t h i s h y p o t h e s i s . Indeed Ν i m m o b i l i z e d i n m i c r o b i a l biomass d u r i n g w i n t e r c o u l d p r e v e n t w i n t e r l e a c h i n g and t h e r e f o r e s t r a w c o u l d even be b e n e f i c i a l t o the Ν c y c l e . C e r t a i n l y e x t e n s i v e t r i a l s i n the UK show t h a t a p p l i c a t i o n o f seedbed Ν has l i t t l e o r no b e n e f i c i a l e f f e c t on c r o p p r o d u c t i v i t y compared w i t h normal a p p l i c a t i o n t i m e s . There i s a need f o r f u r t h e r s t u d i e s on t h i s t o p i c . One model l a b o r a t o r y s t u d y has demonstrated t h a t the N - i m m o b i l i z a t i o n p o t e n t i a l i s g r e a t l y r e d u c e d when f e r t i l i z e r Ν i s p l a c e d s e v e r a l c e n t i m e t r e s below the s o i l s u r f a c e ( 1 1 ) . The Ν t i e - u p i s much s m a l l e r when r e s i d u e s a r e l e f t on the s o i l s u r f a c e a s opposed t o b e i n g mixed i n the s o i l . In the USA some e v i d e n c e (12) has been r e p o r t e d f o r Pythium s p p . i n c r e a s i n g a s a consequence o f d i r e c t - d r i l l i n g i n t o s t r a w b u t i n the UK l i t t l e e v i d e n c e has been r e p o r t e d a s y e t f o r pathogens b u i l d i n g - u p on straw/ a l t h o u g h t h i s i s l i k e l y t o v a r y g r e a t l y between l o c a t i o n s and c o n d i t i o n s . Straw i s a f a v o r a b l e s u b s t r a t e f o r p a t h o g e n i c Fusarium s p p . and Pythium s p p . Growth-inhibitory b a c t e r i a may a l s o be a p a r t o f the problem ( L . F . E l l i o t t and H . - H . Cheng, t h i s v o l u m e ) .


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A l l the present evidence p o i n t s t o p h y t o t o x i c s t e a m - v o l a t i l e f a t t y a c i d s / p a r t i c u l a r l y a c e t i c , b e i n g a major m i c r o b i o l o g i c a l f a c t o r r e s p o n s i b l e f o r t h e c r o p damage, and t h e c o n d i t i o n s o f e c o l o g i c a l s i g n i f i c a n c e r e f e r r e d t o e a r l i e r have been s a t i s f i e d . However, the t o x i n i s produced o n l y i n the s t r a w t i s s u e and i t s c o n c e n t r a t i o n d e c l i n e s e x p o n e n t i a l l y w i t h d i s t a n c e from t h e s t r a w (13). A c o r r e l a t i o n o f s o i l a c e t i c a c i d content with p h y t o t o x i c i t y i s therefore n e i t h e r expected n o r found.


Weed R e s i d u e s When dense i n f e s t a t i o n s o f weeds a r e k i l l e d w i t h h e r b i c i d e s , a s i t u a t i o n a n a l o g o u s t o the s t r a w problem c a n o c c u r because a l a r g e amount o f r e a d i l y d e g r a d a b l e s u b s t r a t e becomes a v a i l a b l e t o t h e saprophytic microbial population of s o i l . With h e r b i c i d e s t h a t a r e t r a n s l o c a t e d , such a s g l y p h o s a t e , t h e r e i s a chance t h a t t h e h e r b i c i d e i t s e l f would be r e l e a s e d t o the s o i l , b u t t h i s has n o t been found t o be the case ( 1 4 ) . C e r t a i n l y p h y t o t o x i c a c e t i c , p r o p i o n i c and b u t y r i c a c i d s c a n be produced from t h e couch (quack) grass rhizome. However c r o p damage i s u s u a l l y o b s e r v e d i n d r y (50% water s a t u r a t i o n ) s o i l s and t h i s c o u l d be r e p e a t e d i n g l a s s h o u s e t r i a l s (15). Thus i t appeared u n l i k e l y t h a t t h e n e c e s s a r y a n a e r o b i c c o n d i t i o n s f o r b a c t e r i a l f e r m e n t a t i v e metabolism would n o r m a l l y exist. Dry s o i l s f a v o r the development o f the pathogen Fusarium culmorum (16) and l a r g e p o p u l a t i o n s o f t h i s fungus have been found on decomposing rhizomes o f the weed. However, even under d r y c o n d i t i o n s s m a l l c o n c e n t r a t i o n s o f the o r g a n i c a c i d c a n form and u n l e s s the pathogen p o p u l a t i o n i s v e r y l a r g e the a c i d a p p e a r s t o p r o v i d e a compounding s t r e s s on the h o s t p l a n t ( T a b l e I I I ) .

Table I I I .

E f f e c t o f 5 mM A c e t i c A c i d and Fusarium culmorum on t h e Growth o f B a r l e y S e e d l i n g s

Mean l e n g t h o f f i r s t t h r e e l e a v e s (mm) 12 days a f t e r g e r m i n a t i o n Inoculum d e n s i t y (spores/ml)

7 10

0

S e e d l i n g s t r e a t e d w i t h 5 mM a c e t i c a c i d No a c i d t r e a t m e n t Results with d i f f e r e n t (P < 0.05)

b 120 140

a

letters are significantly

c 98Γ 118

Ζ 10

D

cd 89, 114

~7~ 10°

cd 83 , 78

different

N

Source: Reproduced w i t h p e r m i s s i o n from R e f . Blackwell S c i e n t i f i c Publications Ltd.

17.

Copyright

American Chemical Society Library 1155 16th St, N.W. Washington, D.C 20038


1982

ALLELOCHEMICALS: ROLE IN AGRICULTURE A N D FORESTRY

48

Permanent N e u t r a l

Grassland

I t c a n be d i f f i c u l t t o e s t a b l i s h new g r a s s e s i n t o permanent g r a s s land. T h i s may be an example o f a l l e l o p a t h y and the r e a s o n why some s p e c i e s dominate o l d g r a s s l a n d . Newman (18) p r e p a r e d a r e v i e w on whether a l l e l o p a t h y i s e c o l o g i c a l a d a p t a t i o n o r a c c i d e n t . His r e s e a r c h team a t B r i s t o l U n i v e r s i t y i n v e s t i g a t e d a l l e l o p a t h y w i t h i n permanent g r a s s l a n d u s i n g p o t e x p e r i m e n t s w i t h ' d o n o r or ' t r e a t m e n t and ' r e c e i v e r ' o r ' t e s t ' s p e c i e s o f d i f f e r e n t g r a s s e s (19/ 20/ 21/ 22/ 2 3 ) . These s t u d i e s showed/ f o r example, t h a t the decomposing r o o t s o f Rumex a c e t o s a had the g r e a t e s t i n h i b i t i n g e f f e c t on f o u r s p e c i e s ( T a b l e I V ) . When the n u t r i e n t c o n t e n t o f Loiiurn perenne a s ' t e s t ' s p e c i e s was a n a l y z e d / R^ a c e t o s a r e s i d u e s gave r i s e t o a s i m i l a r Ρ c o n t e n t i n the t e s t s p e c i e s a s the P - d e f i c i e n t s o i l a l o n e ; t h e r e was no s u c h e f f e c t on Ν c o n t e n t ( T a b l e V). They c o n c l u d e d t h a t the a l l e l o p a t h y a c t e d by the r e s i d u e s o f the t r e a t m e n t s p e c i e s f a i l i n g t o make Ρ a v a i l a b l e t o the t e s t s p e c i e s / an e f f e c t which was g r e a t e s t i n wet s o i l . 1


1

T a b l e IV. Dry Weights (mg) o f Shoots o f ' T e s t ' P l a n t s o f G r a s s l a n d S p e c i e s Grown on S o i l s C o n t a i n i n g the Decomposing Roots o f 'Treatment' Species

'Test'

'Treatment'

species

Anthoxanthum odoratum (Ao) L o l i u m perenne (Lp) Plantago l a n c e o l a t a (Pi) Rumex a c e t o s a (Ra) Nil

species

Ao

Lp

Pi

61b 155a 199a 47b 44b

122a 180a 216a 38b 62b

215a 456a 326a 18c 77b

Ra

174a 73ab 41c 17c 103ab

V a l u e s n o t s h a r i n g the same s m a l l l e t t e r s i n each column d i f f e r s i g n i f i c a n t l y (P < 0.05) Source: The New

Reproduced w i t h p e r m i s s i o n from R e f . Phytologist.

24.

Copyright


1981

5.

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Table V. N i t r o g e n and Phosphorus i n Shoots o f ' T e s t Plants Grown on S o i l s C o n t a i n i n g the Decomposing Roots o f T r e a t m e n t Species 1

1

1

L o l i u m perenne


•Treatment

1

N%

species

P%

0.217a 0.195a 0.201a 0.140b 0.157b

2.95ab 2.19c 2.39bc 2.51bc 3.22a

Anthoxanthum odoratum L o l i u m perenne Plantago l a n c e o l a t a Rumex a c e t o s a Nil (wet)

V a l u e s n o t s h a r i n g the same s m a l l l e t t e r s i n e a c h column s i g n i f i c a n t l y (P < 0.05) Source: Reproduced w i t h p e r m i s s i o n from R e f . Blackwell S c i e n t i f i c Publications Ltd.

23.

differ

Copyright

1979

In p a r a l l e l s t u d i e s i t was demonstrated t h a t the r h i z o s p h e r e p o p u l a t i o n s of g r a s s l a n d s p e c i e s c o u l d a f f e c t each other/ there b e i n g a l a r g e i n c r e a s e i n f u n g a l biomass ( T a b l e V I ) . The s i g n i f i c a n c e of t h i s observation i s s t i l l unclear. There have been r e l a t i v e l y few q u a n t i t a t i v e s t u d i e s o f m i c r o - o r g a n i s m s on p l a n t r o o t s i n m o n o c u l t u r e l e t a l o n e i n mixed s t a n d s . Such a p p r o a c h e s s h o u l d prove u s e f u l i n a s s e s s i n g the p o t e n t i a l magnitude o f microbial metabolic processes i n a l l e l o p a t h i c i n t e r a c t i o n s .

Table VI. B a c t e r i a l Cover and Fungal Mycelium Length on Root S u r f a c e s o f L o l i u m perenne (Lp) and P l a n t a g o l a n c e o l a t a (Pi)

B a c t e r i a l cover (%)

Separate Together

Lp

Pi

4.3 6.3

5.6 5.8

Fungi (mm mm" )

Mean p l a n t w e i g h t (g)

2

Lp

Pi

Lp

Pi

0.7 2.1

1.8 2.9

0.71 1.01

0.69 0.69

S o u r c e : Reproduced w i t h p e r m i s s i o n from R e f . Macmillan Journals L t d .

19·

Copyright

1974

Reseeding O l d G r a s s l a n d When g r a s s l a n d becomes u n p r o d u c t i v e because o f p o o r s p e c i e s c o m p o s i t i o n / the o l d sward c a n be k i l l e d o f f w i t h h e r b i c i d e and new g r a s s e s r e s e e d e d by d i r e c t - d r i l l i n g i n t o the t r e a t e d s w a r d . This


ALLELOCHEMICALS: ROLE IN AGRICULTURE A N D FORESTRY

50


p r e s e n t s a s i t u a t i o n o f m i c r o b i a l d e c o m p o s i t i o n which i s a n a l o g o u s t o the d e c o m p o s i t i o n o f s t r a w and weed r e s i d u e s . Shoots o f a range o f g r a s s s p e c i e s were t o x i c t o o t h e r g r a s s e s and c l o v e r when decomposed a n a e r o b i c a l l y ( T a b l e V I I ) . The photot o x i c i t y seemed t o be caused by o r g a n i c a c i d s and was l e s s a f t e r 20 days o f d e c o m p o s i t i o n than a f t e r 1 0 . F e s t u c a r u b r a , A g r o s t i s s t o l o n i f e r a / and A l o p e c u r u s p r a t e n s i s r e s i d u e s were the most t o x i c ; which t o an e x t e n t i s c o n s i s t e n t w i t h f i e l d o b s e r v a t i o n s t h a t r e s i d u e s o f the former two s p e c i e s a r e p a r t i c u l a r l y d i f f i c u l t t o seed i n t o . When the s h o o t s were decomposed a e r o b i c a l l y , some were t o x i c a f t e r 10 days b u t t h i s t o x i c i t y d i s a p p e a r e d a f t e r 20 days when some r e s i d u e s c o u l d s t i m u l a t e p l a n t growth ( T a b l e VII).

T a b l e VII.

E f f e c t o f S o l u t i o n s Produced a f t e r 10 Days D e c o m p o s i t i o n o f P l a n t R e s i d u e s on Root E x t e n s i o n

Root e x t e n s i o n o f

Residue

Alopecurus myosuroides

Fr

Hi

Lp

test species

Poa annua

Pt

(mm)

Trifolium repens

(a) Aerobic Agrostis stolonifera Alopecurus p r a t e n s i s Anthoxanthum odoraturn Festuca rubra (Fr) H o l c u s l a n a t u s (Hi) L o l i u m perenne (Lp) Poa t r i v i a l i s (Pt) Control

13 13 13 13 13 11 11 11

7 6 7 11 6 6 6 6

11 10 10 10 9 10 11 11

28 35 25 28 25 24 26 30

8 9 10 10 9 10 11 8

4 5 6 7 3 6 7 5

38 42 34 30 32 24 32 46

(b) Anaerobic Agrostis stolonifera Alopecurus p r a t e n s i s Anthoxanthum odoratum Festuca rubra (Fr) Holcus l a n a t u s ( H i ) L o l i u m perenne (Lp) Poa t r i v i a l i s (Pt) Control

0 0 15 0 15 6 11 10

0 5 7 0 9 8 4 7

3 0 14 4 21 10 7 10

9 3 25 5 36 26 16 32

5 0 10 0 12 10 7 10

0 0 6 0 11 7 3 5

2 0 33 0 37 22 21 48

C o n t r o l c o n t a i n e d s o i l and water o n l y Source: The New

Reproduced w i t h p e r m i s s i o n from R e f . Phytologist.

24.

Copyright

1981

Even though t o x i n s c o u l d a t l e a s t i n p a r t be i n v o l v e d , F u s a r i u m culmorum a g a i n seemed t o be r e s p o n s i b l e f o r the damage ^25). Whereas the f u n g i c i d e s carbendazim and d r a z o x o l o n were e f f e c t i v e i n c o n t r o l l i n g the d i s e a s e , c a l c i u m p e r o x i d e was a l s o e f f e c t i v e (26). T h i s compound had the added advantage o f r e l e a s i n g a l k a l i t o


5.

LYNCH

Allelopathy

Involving

51

Microorganisms

n e u t r a l i s e o r g a n i c a c i d t o x i n s and oxygen t o m i n i m i z e o r g a n i c formation (27).


C o n c l u s i o n : The Scope f o r S o i l

acid

Biotechnology

The p o t e n t i a l o f m a n i p u l a t i n g s o i l m i c r o - o r g a n i s m s / e s p e c i a l l y f o r the u t i l i z a t i o n o f c r o p r e s i d u e s , has been o u t l i n e d ( 2 8 ) . F o r example, a c c e l e r a t i n g s t r a w breakdown c a n reduce the "time p e r i o d i n which o r g a n i c a c i d t o x i n s a r e produced ( 2 9 ) . By i n o c u l a t i n g s t r a w w i t h a c o n s o r t i u m o f a c e l l u l o l y t i c fungus and a n a n a e r o b i c N ^ f i x i n g b a c t e r i u m i n the l a b o r a t o r y , s t r a w breakdown has been a c c e l e r a t e d and the r e s u l t i n g r e s i d u e i s e n r i c h e d i n Ν ( T a b l e V I I I ) . In o t h e r s i m i l a r a s s o c i a t i o n s the c e l l u l o l y t i c fungus has b i o c o n t r o l p o t e n t i a l a g a i n s t r o o t d i s e a s e , and a s s o c i a t e d p o l y s a c c h a r i d e p r o d u c i n g b a c t e r i a c a n a s s i s t w i t h the s t a b i l i z a t i o n o f s o i l s t r u c t u r e (211). I f such approaches c o u l d be c a r r i e d t o p r a c t i c e i n the f i e l d , a new e r a o f m a n i p u l a t i v e a l l e l o p a t h y would emerge. This presents a great challenge f o r s o i l biotechnologists but w i l l c e r t a i n l y n o t be r e a l i s e d u n t i l the e c o l o g i c a l a s p e c t s o f a l l e l o pathy a r e c l e a r l y understood.

Table V I I I .

D e c o m p o s i t i o n o f N o n - S t e r i l e Straw C o n t a i n e d i n G l a s s Columns a t 25°C f o r 8 Weeks

Ν gain

Treatment

Non-inoculated Pénicillium corylophilum + C l o s t r i d i u m butyricum

Decomposition r a t e c o n s t a n t , k (d~ )

Per g straw lost

(mg)

Per g original straw

0.0096

8.8

2.8

0.0139

11.5

5.0

Source: Reproduced w i t h p e r m i s s i o n from R e f . 30. Society f o r General Microbiology.

Copyright

1983

Acknowledgments The comments o f Dr L . F . E l l i o t t and Dr E . I . Newman a r e much appreciated. P e r m i s s i o n s t o p u b l i s h d a t a i n the t a b l e s i s a s f o l l o w s : The New P h y t o l o g i s t T r u s t ( T a b l e s I , IV and V I I ) , M a r t i n u s N i j h o f f (Table I I ) , Blackwell S c i e n t i f i c P u b l i c a t i o n s (Tables I I I and V ) , M a c m i l l a n J o u r n a l s ( T a b l e VI) and S o c i e t y f o r G e n e r a l M i c r o b i o l o g y (Table V I I I ) .


52

ALLELOCHEMICALS: ROLE IN AGRICULTURE AND FORESTRY

Literature Cited 1. 2. 3. 4.


5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31.

Lynch, J.M. CRC Crit. Rev. Microbiol. 1976, 5, 67-107. Lynch, J.M. In "Soil Organic Matter and Biological Activity"; Vaughan, D.; Malcolm, R.E., Eds.; Martinus Nijhoff: The Hague, 1985; pp. 151-74. McCalla, T.M.: Norstadt, F.A. Agric. Ehviron. 1974, 1, 153-74. Rice, E.L. "Allelopathy"; Academic: Orlando, 1984, 2nd edition. Lynch, J.M. J . Appl. Bact. 1977, 42, 81-7. lang, C.S.; Waiss, A.C. J . Chem. Ecol. 1978, 4, 225-32. Gussin, E.J.; Lynch, J.M. New Phytol. 1982, 92, 345-8. Cochran, V.L.; Bikfasy, D.; Elliott, L.F.; Rapendick, R.I. Plant Soil 1983, 74, 369-77. Chapman, S.J.; Lynch, J.M. Plant Soil 1984, 74, 457-9. Lynch, J.M.; Ellis, F.B.; Harper, S.H.T.; Christian, D.G. Agric. Environ. 1980, 5, 321-8. Cochran, V.L.; Elliott, L.F.; Bapendick, R.I. Soil Sci. Soc. Amer. S. 1980, 44, 978-82. Cook, R.J.; Sitton, J.W.; Waldher, J.T. Plant Disease 1980, 64, 102-3. Lynch, J.M.; Gunn, K.B.; Ranting, L.M. Plant Soil 1980, 56, 93-8. Penn, D.J.; Lynch, J.M. New Phytol. 1982, 90, 51-5. Penn, D.J.; Lynch, J.M. J . Appl. Ecol. 1981, 18, 669-74. Papendick, R.J.; Cook, R.J. Phytopathology 1974, 64, 358-63. Penn, D.J.; Lynch, J.M. Plant Pathol. 1982, 31, 39-43. Newman, E.I. "Biochemical Aspects of Animal and Plant CoEvolution"; Barbourne, J.B., Ed.; Academic: London, 1978, pp. 327-42. Christie, P.; Newman, E.I.; Campbell, R. Nature (Lond.) 1974, 250, 570-1. Newman, E.I.; Rovira, A.D. J . Ecol. 1975, 63, 727-37. Newman, E.I.; Miller, M.H. J . Ecol. 1977, 65, 399-411. Newbery, D.McC.; Newman, E.I. Oecologia (Berl.) 1978, 33, 361-80. Newbery, D.McC. J . Appl. Ecol. 1979, 16, 613-22. Gussin, E.J.; Lynch, J.M. New Phytol. 1981, 89, 449-57. Gussin, E.J.; Lynch, J.M. J . Gen. Microbiol. 1983, 129, 271-5. Gussin, E.J.; Lynch, J.M. Trans. Brit. Mycol. Soc. 1983, 81, 426-9. Lynch, J.M.; Harper, S.H.T.; Sladdin, M. Curr. Microbiol. 1981, 5, 27-30. Lynch, J.M. "Soil Biotechnology. Microbiological Factors in Crop Productivity", Blackwell Scientific Publications: Oxford, 1983. Lynch, J.M.; Elliott, L.F. Soil Biol. Biochem. 1983, 15, 221-2. Lynch, J.M.; Harper, S.H.T. J . Gen. Microbiol. 1983, 129, 251-3. Lynch, J.M.; Harper, S.H.T. Phil. Trans. R. Soc. Lond. 1985, B310, 221-6.

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June

20,1986


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