oceurretl in the grasses (R'P = 6-7",,; MS = 15-9",,; ..... in: .-Juronoiny 9 (iui. In C. A. iilaik), pp. .''47 .S6.S. .-Xmeruan. Sotifty oi Agronomy, Madison, Wisconsin.
Phytol.
(1989), 112, 205 214
Infectivity and effectivity of indigenous vesicular-arbuscular mycorrhizal fungi from contiguous soils in southwestern Wyoming, USA BY T , W, llENKEL, W, K, SMITH* AND AI, CHRISTENSKN Departntctit of Botany, iJnijrrsity of Wyontiiig, Laramie, IVyonu'ng, S2()7J^ USA {Received 12 February I9HH ; accept ed 8 Mai eh 1989)
M A 1( "i'
In
a grccnliouse
concentration,
cxperiincnt,
antl clrought
t h e tlegrec
rcs|ionsf
of n i t V c t i \ i t \
in .Ifiropyniit
\esicular-arbusciilar
(\'.\) mycorrhizal
elexational ^ladicnt
in t h e \ c i i c . s a j j e b r i i s h - s t e p | i c
sintthii
as well R\clb.
as effects
on slioot
were compared
fungi. A s s e m b l a g e s weri' colleeted ol s o u t h w e . s t e r n
hioniass,
plidsphoriis
t o r s p r c i c s a s s e m b l a g e s of
I r o m d i s s i m i l a r soils across a 55 m
\ \ \omint,'. Collection
site.s a m i s o i l s
were
d e s i f ^ n a t e d a s r i d ^ e t o p ( R ' l ' ) , m i d s l o p e ( M S ) , a n d b a s e ( l i ) . AH a s s e m b l a g e s ol m y e o r r h i z a l I'unni w e r e t e s t e d i n t h e n p a r e n t s o i l s a s w e l l a s t h e o l h e r t w o s o i l s . I n t l u ' p h o s p h o r u s ( l ' ) - d e H c i e n t ( 1 0 111,1; k g ' ) KV s o i l , t h e intli(.,H'nous m y c o r r h i z a l tunK'i j i r o d t i c e d s i K n i l u a n t l y g r e a t e r c o n c e n t r a t i o n s ot P m t h e s h o o t ot t h e h o s t ( 0 . ^ . ^ 5 " , , ) t h a n tliil t h e tf uu nn gg ii if ii oo m t h e li s i t e (()-25()",,). I n t h e n o n - m y e o r r h i z a l p l a n t s t h e c- .o. n. . c- ^e .n. t. .r a. .tni w o nn IM of 1' in t h e s h o o t w a s m m e n s u e ^ o \ i . ^ o , j . i n m e i l o i i - m \ v «'i • n ' - " ' i I m (n^. s i i o o i w a s (( )) 11 SS 55 "", , . T ' Tbh e R RT T tt u n g i a lls o g e n e r a tle d d tt b b e hh igghheess tt ll ee vv ee ll ss of of ii nn tt ee ce ttiiooini , pp ll uu ss gg rr ee aa tt ee ss tt aa r br u bs c ul l e a n dd v e s i ell e the
p r o d u c t i o n in b o t b t h e R T a n d M S s o i l s . T h e li soil h a d t h e h i g h e s t a v a i l a b l e 1' e o n t e n t ( 5 1 m g k g ' ) a n d m e a n s h o o t P c o n c e n t r a t i o n s w e r e n o t s i g n i f i c a n t l y d i l f e r e i i t a m o n g p l a n t s of t h e d i H e r e n t t r e a t m e n t s g r o w n in t h i s s o i l . I n t e e t i v i t y w a s a l s o r e d t i e e d in t h e H s o i l . T h i s r e d u e t i o n m m y e o r r h i z a l a c t i v i t y w a s a t t r i b u t e d t o t b e h i g h - P a s a i l a h i h t y in t b e H s o i l . A l t l i o v i g b s h o o t d r y w e i g b t w a s e i t h e r u n a f l e e t e d o r p o s s i b l y r e d u c e d h y m y c o r r h i z a s in all s o i l s , s t o m a t a l r e s p o n s e t o d r o u g h t w a s n o t a l f e e t e d b y n n e o r r h i z a s m a n \ - o t t h e s o i l s . 'I'lie g r e a t e r elTeeti\ e n e s s of t h e R ' l " m o e u l u m for i n e i e a s i n g l> c o n c e n t r a t i o n in t h e s h o o t of . /. smithii as t b e g r e a t e r m l e e t i v i t y of t b i s i n o e u l u m , m a y i n d i c a t e a d a p t a t i o n
w h e n g r o w n in t h e R T s o i l , a s w e l l
m tbese myeorrhizal
tungi
to l o w - P
soil
c o n d i t i o n s . T h e r e l a t i v e l y low i n f e e t n i t y a n d e i f e e t i v i t y of t h e li l u n g i m t h e R T soil a l s o s u g g e s t s t h a t t l i e s e i u n g i ma>' b e l e s s a t l a p t e d t o l o w - P soil e o n d i t i o n s . T l u i s , d i l i e r e n e e s in i n t e c t i x i t y a n d e l l e c t u i t N - m a y o e e u r
among
n a t i v e V . \ m y e o r r h i z a l f u n g i w h e n t h e p a r e n t s o i l s a r e d i s s i m i l a r yet e o n t i g u o t i s . Key
words:
Indigenotis
V.X t n y c o r r b i / . a l
fungi,
pbosphorus-detieient
soil,
miectivity,
cHeetivity,
edapliic
speciheity.
I N T R O D t i C I ' IO N
In the pasf two deciulcs thcte has been increasing intetest in the potential clifletences among \ esiciilararbuscLilar (V,A) m \ conlii/.al I'utigi iti ihcir inlccti\ity a n d sytnbiotic elVoftivetiess, atid whether edaphic conditions ina\' inflticticc this \artattoti. DifTcrcnccs in infectixc capaliilitx' and itiHucnccs oti host plant ph\'si' (elTccti\-it>) of V.A mycofrhizal futig;i ha\x' been experimentally in\ estimated at tbe interspL'ciinc, itittaspccilic, and cotiimiinify (i.e. s p e cies assembla^'e) levels, Intersiiecil'ic \-afiation in infectivity (Wilson, 1984«,/;; .Abbott & Robson, To whom correspontk'
.should h-
ulilr
1985) and cHectixity, e.^. inHuence of \ ' A tnycott-hizal iungi on host plant biomass prodtiction (Mosse, 1972/); S c h u b e r t & H a y m a n , 1986), p h o s phorus content (Powell, 1975; Sanders et al., 1977), atid water relations (Alleti iv Hoosalis, 1983) has been detiionstrated u n d e r tiiatiy edaphtc cotulitions, using various host plants. Similar intraspecilic diHe-renccs have also been shown (Daniels & DulT, 1978; CJildon &'I'inker, 1983; Pond, M e n ^ e & jarrell, 1984; Stahl & Stnith, 1984). In addition, variation in both intectixity and erteeti\ity has been tlemoiistrated betweeti introduced species atid the tncligetious assembhtf^'es of \',-\ my corrhi/.al futigi present in the native soil (Mosse, 1972c;,/), 1977; Powell, 1 9 7 7 ^ ; Abbott & Robson, 1981), Several of these studies
206
r. W. Ilenkel, W. K. Smith and M. (Uiristensen
have demotistrated diHererit levels of mfeetivtty and efiectivity among VA tnycorrhizal fung;i wheti compared m sotls wtth dtflertng abtottc charactertsttcs, such as pi I atid available phosphorus (Mosse, I972(';, /)). These sttidies have itidicated ati apparent setisitivity of VA tnycorrhizal futigi to the sotl eii\ trotiment that may itiHuence both llieir capacity lor itilection as well as the physiological response ol the host. 'I'he above studies ha\e emphasized comparisotTS of individual species or isolates ot mycorrhizal fungi. Comparisons of \ariatioti iti ttifecttvtty and eilectivity atnotig assetnblages ol lndtgetious species are limited atid, iti getieral, have contrasted iLtngal cotntiuitiities only Irotn wtdely sepatated locales (Lambert, Cole & Raker, 1980; (Jraham, Lindermati & Menge, 1982; Ijodtl, Krikun & Haas, 1983; Kucey & Diab, 1984). 'Phe present study compared infecti\ ities aiitl degree ol host inHuence ol V!\ tnycorrhizal futigi from cotitiguotis sotls over a stiiallscale ele\atiotial gradietit. It was hypothesized that when tested iti tts sotl ol origiti, a gueti assemblage of \'A mycorrhizal fungi would be both more infective and elTectixe oti a host plant thati would ftingal assetnblages frotn contiguous native soils. 'Phe objecttves ol the stutiy were: (1) to characterize the spore-producitig assemblages of V.'\ tnycorrhizal futigi Irotii soils collected along a hillside elevatiotial gradient with characteristic clianges in soil concittiotis irom ridgctoii to base, and (2) to determine the tU'gree of infectioti aticl the relative elTect of each assemblage of ftitigi, when growti iti soil from each collet'tion stte, oti shoot tlry weight, phosphortis coticetitratioti, and drought res]iotise of the host platit .If^rtipyrntt siittllttt Rydh.
\ t i n r i o D.s A N D
M Ari:i-! 1A i.s
Stttiiy sites
The stttdy area was located at the western edge of an extetisne Artemtsut grassland that is characteristic of the intermotintain Red Desert regton ol Wyotnitig (hat. 41° 43' N, Lotig. 1 10° 38' W). 'Phe region, part of tile Wyotnitig ()\ erthrust Belt, has a base el e vat ton ol 2100 tn and has been ch;iracterized hy nitich faultnig and folditig of the upper rock strata, wliteh has resulted iti north-south ritlges. Mean atititial precipitatioti is tiear 23 em atid occtirs prttnarily as wititer snow, while mean tnontlily temperatures range from — ] 1 °C in January to 17 °C in July. Hoth precipttaftoti and temperature are tnarkedly seasotial and Negefation of the area is that ol a colci desert (VlacMahon, 1979). Three study siti's were established oti a htll imtnecliatcK' west ol the Ketnmerer Coal .Vline operated by the Ptttsbttrg and Midway t'oal Mining t'otnpatiy, located approximately 8 km southwest ol Kemmerer, Wyotntng, USA ('I'2O, R117W, S9). They were: (1) ridgetop (R'P); (2) east-facing
midslope (MS), and (3) base (B). A \ertical distatice of approxitnately 55 m atid a walkttig dtstatice ol approximately 300 m separated the R'P atid B sites. All three sites had undisturbed vegetation oi
the Arteinisici-Af>ropyrtift
sagebrush-steppe
type
(Kuchler, 1964). Small-scale diderenees iti growth form atid platit detisity amotig the sttes rellected the spatial atid microclitnattc vartatton prevtottsly tioted for the area (.-\llen & MacMahon, 1985). Soil and vefj^etation santplitti; Soil atid vegetation were satnpled alotig the slope gradient in May 1985. .At each site, a 100 tn (N' S) X 50 m (1-^ VV) c|uadrat was delimited and divided by 10 ratidotnly arratiged I". W tratisects, .Along the tratisects, a total of 10 20 soil satnples per site were taketi, each cotitaitiitig ajiproxitnately 500 g fresh weight of soil. Soil samples, taken at depths of 10 15 cm using ati ethanol-sterilized trowel, were eollected for atialysis of V.A myeorrhizal i'ungi atid abiotic characteristics. Bulk sotl samples were also collected for later experimental studies iti the greenhotise. Soil samples were returned to the lal) and maintained for two weeks at 5 °C.' belore analysis. Vegetattve co\ er was estitnated alotig each tratisect Lisitig percetit canopy coxerage for herbaceous platits atid low-lymg ( < 10 cm m height) shrubs (Daubentnire, 1959), and the line intercejit method for larger shrubs (.Mueller-Dombois 8: I':ilenberg, 1974).
Soil phystctil ititd citenttcal analyses Soil te.xttire was determined by the Bouyoucos hydrotneter tnethod (Day, 1965) atid pll was tneasured (or saturated soil pastes using a glass electrode (McLean, 1982). l'",leetrical coticiuctix ity of filtrate from each saturated paste was tin-asured with a tlirect indicating bridge, and organic matter content was determined using the Walkley-Blaek wetoxidatioti tnethod ((irewlitig & Pcech, 1960). Bicarbotiate-extraetable P was determitied colorimetrieally (Olseti & Sotnmers, 1982), total N was determined as total l\ieldalil tiitrogeti (Bretntier & Mulvaney, 1982), and N().,-N of soil extracts was coloritnetrically detertnined by the chromotropic acid method (Sims & Jackson, 1971). Nutnbers of samples ior pi I, electrical conductivity, organic matter, bicarbonate-extraetable P, and N ( ) . , - \ ranged from 10 20 per site while only two replicates per site were analyzed for soil textttre atid total N.
Analysts of VA mycorrhizal fiin^t Spores of VA tnycorrhizal futigi were extraeted frotn teti 25 g (air-dried wt.) soil replicates from each site using a modification of the tlillerential water-sucrose centrii\igation tnethod of Alleti el til. (1979). 'Phis
Infc'Ctnitx
j \ A
invcorrhizdl
207
from
m e t h o d is tlie most effectixc at extractinjj; spores from natixc soils in this rejjion (laiison & Allen, 1986). Follow inji; sucrose eentriluj^alion and \ a c uum-liltration of the s u p e r n a t a n t oxer a 22 //m nxlon m e s h , t h e isolated sjiores were washed into a I'etri dish with distilled water, examined u n d e r a d i s seetinfi microseope, catef^orizetl, and counted. I'.ach spore type was identilied, where possible, usiiiu; c u r r e n t taxonomie guides ( ( j e r d e m a n n ti Traiiiie, 1974; Hall & Fish, 1979; T r a p p e , 1982). T h e sjiore t\'pes isolated Irom each site weix' characterizetl in t e r m s of their absolute densities, ielati\e tlensities, and trei|uencies ot oecui renee (Stahl & C hristensen, 1982). Spores appearing;; empty of c \ t o p l a s m were not includetl in this (_]uantitati\ e characterization. Percent similarities were calculated lor all c o m b i n a tions ol the three lun^al e o m m u m t i e s (Whittaker, 1975).
VA mycorrhizal inoculum NM
RT
MS
RT
RT/NM
RT/RT
RT/MS
RT/B
•^ MS
MS/NM
MS/RT
MS/MS
MS/B
B/NM
B/RT
B/MS
B/B
CD
Fig. 1. SeeciliiiKS of Ai^ropyioii siinlhii were Iran.splanu-d into unpasteun/.ed soil cores (\'.\ m\ cori-hizal inoculuni) from each research site which had heen mserled iiilo pasteurized soils Irom each of the three sites. Sites arc RT = rufuetop, MS = rnitlslope, H = hase.
plemental liuhtin^ was provided h\ six tensity, full-spectrum, metal halide lamps to a c h i e \ c a mean tiaytime photon liux detisitx (300 700 nm) of Bulk soil samples from the R'l', M S and H sites were about 8()0/nii()l m - s '. l-'or t h e first seven weeks of separately' mixed and steam pasleLirizetl lor 4 h at irrowth, each pot received 500 ml of distilled water 1 10 °C' to eliminate mycorrhi/.al lun^i. A total of 96 every third day, and 700 ml per dav thereafter. Pots plastic pots (15 cm diameliM') were lilled with ei|ual were r a n d o m h re|iositioned after each wateriiiL;. a m o u n t s (2 k)^) of pasteurized soil from the three sites (32 pots each with R T , M S ami H soils); soils in llosi resfyoiisi' to i/rou^/il stri'ss all pots were packet! to similar hulk densit\\ .M\'corrhizal inoculum was introduced h\' remoxinj; T h e response to tlroti^ht was e\ aluateti m liost plants two cylindrical cores ol soil from t^aeh pot and re- grown in the two soils most dilferent accortling to the filling each with unpasteurizeti soil '(inoculum), m soil parameters measured, R T and H. A series of four accordance with the experimental design (I'lti;. I). conseeuttve dryin.t; cycles was employed to generate Pasteuri/.etl soil ol thi' listed type was used m the sulhctent data lor comiiarison of stomatal coiuiucnon-myeorrhrzal controls. Since the R T , M S and H tancc over a range of xylem pressure potentials soils had potentialK' diHercnt inoculum potentials, tndicattve of saturated to drought stress condtttons the a m o u n t ol soil in the m o e u l u m cores was xaried (Stahl & Smith, 1984). Plants were grown for 70 d to standardize the initial spore content at approxi- tinder well-watered conditions prior to initiation of m a t e h ' 300 spores jier yniX a m o n ^ the treatments drying cycles. At the start of each drying cycle, all (20 K of R T soil, 10 ii of M S soil aiul 5 u of H soil). pots were moistened to liekl capacity antl allowed to dry for 5 d. Over the course of each tlrymg period, individual leaves ol sitnilar-sized plants from all roiidilions Iiioculdtioit, ;^ treatments tested were ratuiomK sampled on a dailv Seeds ol A. smilliii were surfaee-stcrilizctl (10",, basis for determination of stomatal conductance (g) soditim hypochlorite for l O m i n ) and germinated m and xylem pressure potential ( X P P ) (one leaf per moist, sterile sand. I'ixe d a \ s alter jrerniination, pot, three to five pots per t r e a t m e n t per daiK seedlings were transplanted into the inoeiilum cores sampling interval). C o n d u c t a n c e was first measured of eacli treatment (one seedling per core, two cores on the attaehed leaf, and then X P P was measured per pot) h\' inserting the radicle into a channel in tlie immediately after detaching the leaf. Hy the filth davcentre of the eore to a depth of approximateK' 1 cm. of each drying cvclc, plants invariably exhibited Immediately foUowmj^ transiilantation, all pots were advanced leal rolling and wilting, l^aeh pot was then watered to liekl capacity. 'I'o reintroduce n o n - watered to field capacitv' and the plants allowetl to mycorrhizal mierollora a m o n ^ the treatments, a reh\xlrate for 2 d before the next dr\-ing cvclc. T h i s 2 2 / / m filtrate was preparetl from a tnixttire ol the process was repeated until all drving cvck's were three unpasteurized soils and added in equal p r o - eompleted. A transient diffusion p o r o m e t e r (Model portions to the pots ( L i n d e r m a n & I Iendrix, 1982). LI-7()0, LiC'or Inc., Lincoln, \ l " ; ) a n d a ScholanderRanciomized pots were maintained under condi- tv'pe pressure chamber (Model 1000, P M S Instruti(jns simulating early Ljrowmjj; season m the saL;e- ments Co., Corvalhs, O R ) were used to measure g hrush-stepjie enxironment (14 h d a \ \ 20 28 "C ; 10 h and X I ' P , respectivelv. All porometer tneasurements t, 15 2 0 " C ' ; 20 30",, relative humidity). S u p - were completed following the precautions and cali-
7'. H'. lleiikel,
208
IT. K. Smith
(uid M.
Chnstenseu
brations suggcstetl iti Smith & Hollinger (1988). Pots were ratulomly repositioned loUowmg eacli pt'riod of measurcmt-nt. Shoot
(uialvsis
Alter lour m o n t h s ol growth, all pots wt'rt' harv ested, and shoots and roots were si'jiarated. Shoot dry weights were determined after o v e n - d r y i n g (60 °C for 36 h). I-'our plants (icr treatment were randomlv' sclectt'tl and green, healthy shoots were analyzed for shoot 1' concentration tising inductively coupled |-ilasma s p t x t r o m e t r v (Ilavlin & Soltanpour, 1980). ()nlv iilants grown in the soils that chllered tnost in available I' ( R T ami H) were analvzed for shoot I' coticentration.
ahsolutt' and relative tlensities of the S|-iore t\ pes (log-transtormed), shoot dry weights (arcsmc-translormed), shoot P eonccntrations, mlcction levels (arcsine-transformi'd) antl infection extents, and n u m b e r s ol a r b u s i n l e s and vesicles were compared using onc-wav' analvscs of variance followei.1 by Sehelfe tests (Zar, 1*)84). Phv siological data were linearized by a M i n i t a b c o m p u t e r p r o g r a m , antl regressions were c o m p a r e d Lising analvsis of e o varianee. In atklition, the X P P ilata were divided into three sectit)ns for each treatment withm a soil and t h e corrcsjiontling mean stomatal conductance values eomparetl atnong the t r e a t m e n t s using one way analysis of variance. I'inally, correlations b e tween infeetivitv- and efleetivitv' parameters were obtametl tising linear regression. Acceptanee levels for all statistical tests v\ere set at /' = 0-05.
\l\corrhiz(il injection Rl'Sr I.TS
I'ollow ing harv est at lour m o n t h s , root systems were Field (hitit storetl in formalm-acctic acid-cthanol until examination lor myeorrhrzal intection. Roots were p r e ' P h e t h r e e s t u t l y s i t e s tlilleretl s t r o n g l y m v a r i o u s pared aiul exatnined using the staiulard methotl of e t i a p h i e f a c t o r s . A l t h o u g h all soils w e r e n o n - s a l i n e Phillips & llavnian (1970). l'oUowing dearitig and s a n d y l o a m s (clay c o n t e n t s ; R ' P = 8 " , , , M S = 9 " , , stainnig, portions of secotitlary and tertiary root antl H = I I " , , ) , m e a n soil n u t r i e n t c o n c e n t r a t i o n s , systems from each pot were CLII into I cm segments. t)rganic m a t t e r , and m o i s t u r e e o n t e n t s generally I'llty 1 cm segments were seleeted at random, i n c r e a s e d f r o m t h e R"P t o t h e H s i t e s ( ' P a b l e I ) . ' I ' h e moutitt-d m distilled water, and exatiimed under mt)st s i g n i f i e a n t c h a n g e s f r o m t h e r i d g e t o p t o t h e 1 00 X antl 400 X magnilieation. Inleetion was ealcu- b a s e w e r e t)bserv e d in av a i l a b l e P (liv e - l o l t i i n e r e a s e , latcd a.s the j^ercent of the 50 segments m whu h anv / ' s j O - 0 1 ) , t o t a l K j e k l a h l N ( l i v e - f o l d i n e r e a s e ) , a n d mveorrhizal struetures vvert' observed. 'Phe speeifie st)il m o i s t u r e ( t w o - f o l d i n c r e a s e ) . O r g a n i e m a t t e r fotni of the inlection was also recorded, i.e. presenee also i n c r e a s e d s i g n i f i c a n t l v I r o m r i t l g c t o p t o b o t t o m , of internal hyphae, arbusetiles or v e s u k ' s . |{ach a l t h o u g h tlic .MS a n d I? sitt's w e r e n o t s i g n i f i c a n t l y segnn'iit was ranketl to indicate proportion of total t h l k - r c n t ( T a b l e I ) . Soil n i t r a t e - X e o n e e n t i a t i o n d i d k n g t h observed to he ink'c ted by mveorrhizal lungal n o t differ a m o n g t h e s i t e s . \ f g e t a t i o n w a s l o w - l y i n g structtircs (O^-^O",,, 1 = 1 2 5 " , , , 2 = 26 50",,, ( < 10 e m h e i g h t ) at tlie wintisvvept R T s i t e , w h i l e was
tlownslope the vegetation beeame increasingly sttati-
caleulateti for each trcatmi'iit, hereafter referred to as 'extent of in(ee(ioii '. All segments were scored for presence ol abseiici' of arhiisculcs and vesicles.
3 — 51 - 7 5 " , , ,
4 = 76 1 0 0 " , , ) .
A
mean
rank
glasses. T o t a l vfgetative cover (sliruh canopv' pkis
fied i n t o s h r t i b c a n o p v ' w i t h u n d e r l y i n g Itirbs a n d Lintlerlymg vegetatitjii) m e i e a s e t l I r o m t h e R ' P t o 15 site ( R ' P = 4 0 2 " , , , M S = 7 0 - 9 " , , a n d H = 1 2 4 - 3 " , , ) . From
Stiitistics Soil physteal and chi'iiiical characteristics of the sites were iiuliv idually analvzeel using Kriiskal-Wallis tests (non-parametrie analysis of variance), follovvetl by D u n n ' s iiroeeclure for simultaneous testing of the rank means ('/ar, 1984). Total spore numln-rs and T a b l e 1. Soil fyhysioil re
from
densitv
t h e WV t o H
with t h e M S a n d M sites, t h e
had propt)rtionately
high
SH a n d low
G'. fascicnUitiim
d e n s i t i e s ( ' F a b l e 2 ) . I k>wev e r , b o t h
G. fascicuhitum
a n d SI5 w e r e c t ) t n m t ) n alt)ng t h e sltijie
gradient,
t)cctirring
in 1 0 0 " , , of t h e s a m p l e s
mtlitated
the greatest
t]uantitativ e
similarity,- o e c u r r e d for t h e M S a n d H s i t e s ( 6 4 8 " , , ) , w h i l e t h e WV a n d H s i t e s w e r e least s i m i l a r
varied
among
the various
In the P-fertile H soil, mycorrhizal infection was not as prt)nouneed as that observed in the t)thcr st)ils (Table 3). Arbuscule lret]tiencies were partictilarly knv, ranging frtim 6 tt) 1 I ",,, and no significant differences in any t)f the mfectitin p a r a m e t e r s were observed. However, frequency of arbusetiles jiresent in ht)st rt>ot samples was found tt) ct)rrclate with the I' concentrations t)f shoots of the same plants (; = 0-55, P s S 0-05), while vesicle frequencv and sht)t)t P were not correlated in the H st)il. In the P-inlertile R'F st)il, a strong positive et)rrelatit)n (;- = 0-85, / ' s^ O-OOl) was k u m d between arbsetik- frequeney and shoot P et)nccntratit)n t)f the host plants ('Fables 3, 4). X'esiele frequenev and shoot P eoncentration were alst) ct>rrclated, though t-it)t as strongly (;- = 0 5 5 , /• < 0-05) in plants grown in this st)il.
lrt)ni
e a c h s i t e . I ' e r c e n t similaritv- i n t l i c c s ( b a s e t i o n a v e r a g e s p o r e tlensities)
mleetion
i n e a e h st)il ( ' F a b l e 3 ) . I n t h e R ' l ' a n d M S
soils, all measured p a r a m e t e r s of mycorrhizal tlcvclopmcnt were most p r o n o u t i t e d in plants inoctilateti with t h e fungal asseml^lage from the \i'V sue. 'Fhe R T int)culum was cspcciallv- vigorous in its native R'V st)il, where it prt)duccti arbuscule and vesicle lret]tiencics m o r e than twice as great as those [irodueed bv tht- H l n o e u l u m . In the M S soil, the extent t)f infeetit>n bv- the R'F int)culum was signifieantly higher than extents with the t)ther inocula. In addititm, t h e vesicle frequency prt)duced bv- this inoeulum was nearly dt)uble that iirtKitieed by the H int>cukim and five titncs that t)f t h e M S int)culated plants.
(tlesigtiateti
a m t ) n g t h o s e p r e v i o u s l y r e p o r t e t l lot- s e m i - a r i t i Absolute
liijecti-i-ity
(36",,).
3000
2000 -
1000 -
KffectiTity
Fig. 2. (ieneral tliaracterizalion of \ .A mveorrhizal spore p o p u l a t i t ) n s Iron-i e a t h sitt-. t ' o k i m n s i n t t i c a t t - s p e c i e s p r e s e n t a n d t h e i r t l e n s i t i e s : I'",i [luitrophospoi a iiiji't'iiiii'iis), C i m a e ((Jhiiniis imuroKii/iiuii). ( i l a s {(Jloiinis ftisciruliituin).
Sh (smafl hrown, timdentiHetl spore type). Total spore d e n s i t i e s ± SI-;
are: R T
72X + 7'),
MS
140')+lOd,
I!
Althotigh stomatal ct>ndtictance (g) and xylem pressure pt)tential ( X P P ) of .-). sniithii were ct)rrelated amt)ng plants in grouped t r e a t m e n t s withm both the R'V{r = 0-69, ;; = 259 divided approximately eqtially an-iong the k)ur treatments) and H (r = 0-71, „ = 250) soils, ct)niparison of regression line slt)pes revealed nt) significant differences a m o n g treatments within e i t h e r s o i l ( R T : F= df=3,242).
T a b l e 2 . Spore
* ' ** "" (n =
relative
densitv
1-28, d f = 3 , 2 5 0 ;
B: /''=2-l,
S i m i l a r l y , e l e v - a t i t ) n s t)f t h e r e g r e s s i o n
(",,)*
Species
RT'
MS
B
(jliiniiis Jasciculatiun (jliiniiis niiiiroeii)fiiiDi Sfi (unitlentiHetl) /uitropliosponi nijieqiiens
.15-1 •' ± 7 - 3 ( 1 0 0 ) ' .S-1 ± 1 - 7 ( 5 0 ) 57-2 ±,S-0 ( 1 0 0 ) 1-5 (30)
,S()-6± 1-9 ( 1 0 0 ) 7-1 ± 1-7 ( 1 0 0 ) 1 0 - 4 ± 1-S (10(1) 0-2 ( 2 0 )
Sl-7±2-O (100) 7-0±()-') ( 1 0 0 ) 1 0 - 4 ± I-') (1 f-5 ( 4 0 )
S p o r e r e l a t i v e t i e n s i t y is h e r e tlelinetl a s t h e l u i m b e r ol s p o r e s o l a p a r t i c u l a r t v p e a s a p e r c e n t a g e o f t o t a l s p o r e s . S o i l s c o l l e e t e d f r o m e a c h s i t e ; R ' P = r i d g e t o p , . M S = m i d s l o p e , B = fiase. V a l u e s a r e m e a n ± SI'". l ' " r e t | t i e n e y t)f o t c u r r e n c e = n u m h e r o l s a m | ) f e s i n v \ h i e l i a s p o r e t v p e o c c u r r e c i a s a p e r c e n t a g e o l t h e t o t a l s a m p l e s 1 0 p e r site).
210
T. W. Ilenkel, W. K. Stnith and M. ('hristensen
Table 3. Myeorrluzal infection charaeteristies o/'Asropyron smithii f^ro7un with 7uirioiis inocula in RT, MS. and li soils
Soil
r MS
.Mvcor rhizal Infection .Xrbusculcs** Kxteiu' ("„)
Inoculum
("„)*
N\'1 RT MS Ii
0-0 86-X' ' 1 + 2 - 1 3 " " • • S3-8 ±3-58^' 7.S-0 ±4-26-'
0-0 2-5 + 0-15" 2-4 + 0-18"
NM RT MS H
0-0 H3-7 70-3 70-')
0-0
NM
0-0
RT
65-5
.MS
(,8-2 f)5-4
H
+ 4-8()» + 3-85" + 6-56"
2-2 ±0-1 7"
0-0
2-4 ±0-22" l-7±()-l()'' l-8±0-19" 0-0
±6-21" + 5-0(»" + 5-43"
0-0
47-6 ±6-9" 30-1 ±8-3"" 21-4 ±4-5" 30-8 ± 6-6" 23-4 ±4-3" 24-3 ±5-6" 0-0
1-7 ±0-18" 1-8 ±0-19" 1-8 + 0-26"
7-5 ±2-7" 1 1-0 ±2-7" 6-4+ 1-7"
\ csicli's*" ("n)
0-0
42-8 ±8-7" 19-4±2-7" 20-6 ±7-2" 0-0
57-1 ± 10-9 12-3 ±4-1" 3 2-6 ±5-0" 0-0 25-5 ±8-0^' 1 1-8 ± 5 - 1 " 14-4 + 5-1"
* I'ercciita).;c of root sef^menls containing any n-iycorrhr/,al tunt;al structLires. ' Mean ranking ot root se^n-ients on a 0-4 scale to indicate proportion ol let-ij.;th oecupied hy mycorrhizal Itin^al st ruct ures. ' IV't-c-enta^e ot root sc-^nients containing arhuscLiles or \-esieles. ''' .All \alues are mean ± SI'",, hased on exar-|-iination ol 501 cm root segments per pot, 8 pots per trcatrnent. -'"- I'or each soil, means m each eolumn followed hy same letter are not siKiuficantly cliHerent at / ' ^ 0-05. Table 4. Shoot dry iceii^lit and percent phosphorus of .Af^rcipyron snitthii i^rojcn 7cith various myeorrhizal nioeiila in the RT, MS, and B soils Soi
1 tioculLim
Shoiot Dry W t. Shoot 1'
N.M
1-5* ±0-17"' 1-2 ±0-15"
0-1 85 ±0-004'
1-2 + 0-18" 1-7 ±0-23" 2-9 ±0-16" 2-4 ±0-13'' 2-0 ±0-13'' 2-2 ±()-08"'' 3-9 ±0-21'' 3-3 + 0-19" 3-7 ±t)-23" 4-1 + 0-13"
0-315 ±0-33"'' 0-250 ± 0 - 0 2 3 '
RT MS Ii MS
NM RT MS Ii
NM RT MS Ii
0-335 +0-027'
0-271 ±()-0t)7 t)-318±t)-tlO9 0-307 ±0-031 0-292+t)-t)2l
* Values are mean ±S1';. ' I'Dr eaeh soil, means in each column toUowetl hy same letter are not sif^nilicantly dilterent at P s; 0-05. lines wi-re tiot siKtiiticantly ditlercnt ( R T : /'' = 0-18, dl = 3,2.S3; H: /l(ii;ist
nnror-
9 9 , 24.S 2.=i.S.
. X i i H o r t , I . . K . , R O H S O N , .\. 1 ) . ..'s: i>|. H O I : K , < i . ( l ' ) S 4 ) . ' I ' l u ' ctlLTt ol
jihosphonis
on
tlu' l o i i n a t i o n
ot
luphai'
s ' f s i c u l a r - a r b i i s c u l a r n i y r o i rhi/.al l u n m i s ,
Nnc Ai.M.N,
in s o i l
(jlonuis
In' t h e
Jasniultiluni.
I'hylolofiisl 97, 4.17 446. M . !••., A i . L i ' N .
I-:.I t . S . S T A M L ,
I". I ) .( 1 9 H 4 ) .
t )ittiTi'ntial
nitlu' i^fspon.sr ol liontt'loitd i^fdcilis and l\L^'fo/)yiuni sffnth/i to \ ' . \ inycorrhizai'. lltillclili of llic 'I'linry liolanirdl Chili 111, A I . I . I : N , M . I"'. & B o o s . M . i s . M . ( i . ( t ' W . M . l-",ttcTts o f t w o s p u c u - s ot VA
niv'conlii/.al
;Vusi-ular m x e o r r h i z a l t i i n ^ i Phytolni^ist
S . IV ( 1 9 8 7 ) . sniilliii liurinj^
Colonization
oi'
K x d b . ) iiy x e s i e u l a r i h i ' rex e ^ e l a t i o n ol a
1 0 6 , 7.1.S 7 4 4 .
funKi
ami
Mdiidi;einenl,
U. W . (;oition
IV L . \ ' ,
oi
nix-eorrliizal
inleclions.
Xe7i'
Phytolnuist 80, 575 578. Alossi:,
li. ( I 9 7 2 « ) .
soil
from
in
i'rinis-
16i, Improx-ed
xcsieular^ariiuscuiar
.saline s o i l s .
.]lvcn/n!;id
76,
ol
P H e e t s of ditl'eretil
superpliosphate
eiulophytes.
Ai^riciilluriil
on
populations
Aitstrntidn
iind Aninidt
Jinirniit
Iliishdndry
of
i'ox\-|:i.I.,
C . i,l.. ( i 9 7 5 ) .
i'iant
^roxxth
of /-.'v^
1 8 , 57.1 5 7 8 .
responses
i-'actots
niveorrhizai luolo!;v 24, to
xcsicuiar^
a r b u s c - u l a r m y e o r r i i i z a . \ i i i . I p l a k e o f i> b y o n i o n a m i e l o x e r m i e e t e d xvitll e i i t i ' e r e n t /•.'«,/,«„/„. s p o r e t x p e s i n •'=!' I a b e i l e d soil.s •^''"'''' Plivtoloi;ist
7 5 , 56.i 5 6 6 .
i ' o x x l l . l . , (.'. i - l . ( 1 9 / / , ; ) . .\ i y c o r r h i z a s
in h i l i c o u n l r x
soiis
iil
o n e i o x e r i;roxxtli m u n s t ( - i i l e s o i l s . .Y("r
Zealdiid Jmirnal of Aariciiliurdl i ' o x x | . | I., C . i . l . . ( i 9 7 7 / ) ) .
Rcsciinh 20
Aiyconhizas
r i - s p o t i s e s in r y e y r a s s .
m
Ml
i48
Inii i - o u m r x - s o i i s
.A'e;;- /.cdlaiid
Joiirniil
of
\' -\:'ri
eullunil Residrcli 20, 495 502. i'oxx i:i I., C . i . 1 . Cv H A N O : ! . , | , ( 1 9 7 8 ) , A 1 x c o r r l u z a l (i\nii\ of s o l u b l e
i'oxxi;i I , C
and
nisolui-)ie
s o i l , Xcw
phos]ihat7
xesieuiar-arbusiuiar
root etieiis
e n d o p h x te
\'i',-;'
'^
