(wl.J.Agron.! Riv. Agru"., 2()(Jf), 3.-.103-412
Forage Potential of Winter Cereal/Legume lntercrops
in Organic Farming
Marco Mariotli
lo•Alessandro Masoni
l,Laura ErcolP, Iduna Arduini
l 'DipanimelllO ,/i Agrollomia e Gestione Unh'enira tli PislIVia Sali Michele degli Scol..; Z.56/24 PJ..m. llal)'
lScllola SI/periore(Ii Studi Unh'ersitari e di Per/ez.;QnilmenW Satl/'Aml(l Pialza Murti,i della Libertà 33. 56127 Pi$O. Ilul)'
Recehed: 3 Aprii 2006. Acceplcd: 7 lui)' 2006
Abslract
This research pcrformcd lOasses'S the potential or cen:alJI.egume intercropplng lO enhancc fornge )'icld and qualil) "'hen compared "'l,h cereal sole crops under l.he conslrains imposed by UE organlc farming regulalions..
Solecrops(Se)and intercrops (IC) or\"'0winler cereals. barIe)' (/hm/tu",n/Igl/reL.)And durum ""heat(Triric:flm durum Des!.). and '\000 Icgurnes. \\-hile lupin (LupitlllSa'busL) and common \clch (V/{"I(J sUlil'oL).""ere e\'atuat· ed al t\\O ha....·esl limes for dI) matler yield(DMY).crude prolein cOIlCCOiralion (CPC). and nllrogen yield (NY). Yield \'atuC$ and dry mattcr concenlration(DMe)"'ere generally hlgher when cereab were al Ihe hard dough com-pared lO the late milk siage. On average. inlercropping increased rorage yicld by 72%. NY b) 190%. lInd CPC by 40 g kg'. compared IO cercai sole crops. bUI lhe choice of legumc species arfccled lhe ) ield advanlagc and the com-posilion of forage. Land equi\lIlent ratio (LER) of imercrops was al\\ays higher than l. ranging from 1.39 lO 1.61. Iruercropping also enhanccd weed suppression. compared lO sole crop.
Ke.l'-K·ords. barie)'. oommon \·clch. durum wheal, intercropping. organic fllrming. \\hlle 1upin
•
l. Inlroduclion
In receot years. organic farming has widely de-veloped and now rcpresenls an importanl sec-tion of agriculture. Originally, organic farming
was first or'III an ideologicaIconcepl belonging
to the alternative culture, in contrast with the current modcls or economie devclopmcnt and soci al organization. Today. organic farming has became a wcll cstablishcd production system. lhat attracls both human and financial rc-sources. is prol1table and meets thc demands of a fast-growing market. In Ualy, the agricultural
land in organic farmiog has risco from s I% in
1992 to 7% in 2()()..1 (MiPAF. 2006).
Liveslock produclion <lnd cultivation of Iegume species are basie elements or organic farming systems, bccause Ihe agronomie utiliza-tion of manure and biological nitrogen I1xautiliza-tion
are essential to supply nutrients lo erops (Doyle and ToPI', 20(4). In lIaly. 50% or thc land uscd for organie eultivalions is eovcred with forage Icgumcs.20% with cercals. 20% with trce crops
and 10% with other hcrbaccous crops. Among
cercals, about 70% are rcpresented by winter
ccreals. whcrc3s rnaizc eonstitulcs only7%
(Mi-PAF.2(06).
111C organic livcslOCk productioll guidclincs
(VE Regulalions 2092/91 llnd liID4/99)
reeom-mend thal for caule the daily intake forages
(pasture, ha)' alld silage) must be at least 60%
with concenlratcs eomposcd no morc than 40%
of thc diel. Winler cercai grain is the most com-mon concentrate in Italy and silages are gcncr-ally produced with maize and winler cereals.
The productioll of hay wilh organic farming praclices does noi pose particular problems whcn forage legumcs are used. whereas the
MariolU M .. A.. t::rro/iC.Arditili! /.
duclioll of conccnlrates and silagcs with grain cereals is much more dirricuh, because the ab-sence or chemical fertilizers and herbicides dras-tiUtlly reduces thcir yicld. In particular, forage yield or winter cereals is less arfected than thal of maize. because winter cereals require lcss nu-trienl input, are more competitive against weeds, <lnd, at least in northern-ccntral !taly, they do not require irrigation. Wintcr cereals are productive and ensilc well (Crovetto cl al., 1998; Edmisten et al.. 1998(1) but forage CPC is low (Cherney and Marten. 1982; EdmiSlen Ct al., 1998b; Juskiw el al.. 2000).
Theunissen (1997) found thal in organic farming. inlercropping or a winter cercai with a legume provided higher forage yield and bctler silage quality than <Iwinter cercai sole crop. In·
tercropping is defined as the simultnneous growing of twO or more crop species in the same ficld (Andrews and Kassam. 1976). llle major agronomie advantages of intercropping are higher yicld. increased qualit}'. higher ability to adapt to dimatic and biotic stresses.. owing lO the mutuai protection and support between consociated species (Trenbath, 1976). lhese ad-vantages derive from better utilization of env;-rOnmental resources (nutrients. water. and solar radiation) when the interspecies competition is weaker than intraspecific compctition (Willey.
1985: Caporali Cl al., 1987). by
intcr-cropping legume species with grasse$, nilrogen may be transferred from the former to the lal· ter (Orori and Stern, 1987, Heichcl and Hcnjum, 19(1). This Iransfer can be particularly impor-lant in absence of N-fertilization, Iypical or or+ ganic rarming (Jensen. 1996: Andersen el <Il..
2(04). Without mineraI N fertilization, barleyl
pea, oat/pea, wheat/bean and oatfberseem
dover intcrcropping increased forage yield by 20-50%, compared to the winter cereals sole crap (GhaHarzadeh, 1997; Ohanbari-Bonjar and
Lee. 2003; CarCl aI.,20(4).
The efficiency of an intercropping systcm, compared to sole cropping, can bc evaluated by LER. defined as Ihe relative land arca (or growth resource) required when growing a sole crap to produce the yield achieved in inter· cropping (Mead and Willey, 1980). Barley/pca (Hauggaard-Nielsen et al., 200l; Andersen et al.. 2004; Chen et al., 2(04). oat/vetch (Ercoli Cl al., 1997; Mariotti et al., 19(8), wheat/pea (Caporali el al., 1998) and whca1fbean intercrops
(Ghan-bari-Bonjar and Lcc, 2003) had LER valucs greater than I, indicating an intereropping ad-vantage over sole eropping.
Generally, intercropping cercai and legume species produce a forage with a higher CPC than cercaI sole crops. owing to the presencc of legume spccies in the mixed forage. Increase in CPC was about 15 g kg·1in lhe trilicale!bcan
in-tercrop (.ledel and Helm, 1993). ranging from 20 to
40
g kg'l in thc barlcy/pca and oal/pea in-tercrops (Carr et al .. 2004; Chen et al.. 2004) (lnd was about 60 g kg-1 in thc wheat1pca (Salawu etal., 2001; Ohanbari-Bonjar and Lee, 2003). Intcrcropping also enhanccs wecd supprcs-sion. owing to lhe higher plant densily thal ercases shading ami eompetition for water und
nutrienls. reducing both germination and
growth or wecds (Liebman ct al.. 1988). Marked reductions in weeds were recorded in wheat tercropped with bean. chickpca, lenii! anel pea (Bulson et al., 1990; Alam et al.. 1997), and in barley/pea intereropping (I-Iauggaard-Nielsen et ,1.,2001.),
A major problcm with inlcrcropping for for-age is determining the optimal harvest ti me be-cause t!le growth cycle of consoci<lleu species is oflen noi synchronized. Dry matter concentra-tion of rorage is crucial to obtain good silage. lllC optimal DMeor forage ranges from 300to
400 gkg-I (Gardncr and Wiggans. 1961:
Edmis-ten et aL, I998a) ;1nd il is generally achicved by harvesting ccrcal crops during the mitk to lale milk stages (Ghanbari-Bonjar and Lee, 2003).
Thc objective of aur rcsearch was lo assess the potcntial or winter cereaillegume inlercrop-ping to enhance forage yield and qualily when compared with cercai sole crops under thc con-slraints impOsed by European Union organic rarming regulations. The spccies chosen. widely cultivated in the mediterranean area. were
bar-ley and durum wheal as winter cereals and
white lupin amI commoll velch as legumcs.
2. J\fatcrials and mcthods
111e rescarch WaS carried out in 2002-2003 at the Dcpartmcnl aI Agronomy and Agroecosystcm Management of the Univcrsity or Pisa, haly. Tbe study arca was locnted on an alluvial plain in Tuscany (43" 40' N. lO" 19' E). The climatc is cold. humid Mediterranean with mcan annua!
//111.J Agroll. / Riv.Agro/l.. 2()()(i,3:403-412
•
maximum and minimum daily air tempcratures of 9.5 and 20.2 0(' respectively. and
prccipita-tion of97\ mm. with 663 mm received from
O-vcmbcr through lune (Moonen et al .. 2001). Main soiJ physicai 3nd chemical properties wcre33.9% sand, 20.8% silt, 45.3% day, 7.2 pH. 21.5 g kg' organic maller (Walkley and Black
mClhod). 1I.2 g kg' tOlal (Scheibler
mcthod). 1.2 g kg" lalal nitroge-n (Kjeldhal mClhod), 43 ppm av,lilllbie P (OISCll method),
[ti? pplll available K (Dirks-Sheffcr mcthod).
Trealmenls wcrc thc sole erops
or
"Emilia"barlcy (B). '-Creso" durum wheat (W), "Multi-lalia" white lupin (L). and "Nilra" comman velch (V). and thc inlercrops of barley/lupin
(BIL). barley/vclch (BN), durum wheatllupin
(\VlL). and durum wheat/vetch (WN). Sole crops and intercrops were harvestcd at milk and dough ripening stagc of cereals. The cxperiment was arranged in the ficld in a splil·plot design. with foragc Irealmenl as the main plol and har· vest lime as Ihe subplol. with lhrce rcplicmions. Subplot dirncnsions were 5 by lO m. Thc previ-ous crop was alfalfa cuhìvated from 1999 lO 2002 withoul fertilizcr or herbicide applications. Soi! prcparation consisled in medium deplh plowing (30 cm). carried out in Oclober 2002. l-inal secd bed prcparalion was carried oul just prior to sowing by harrowing twice. \\ith a disc
harrow and a rotating harrow. Tne
sym-biosis belween white lupin and ils specific rhi-zobium (Rhizobi/lm lupi"ii) was promoted by mixing Ihe seeds of while lupin with slightly wet soil where a while lupin crop had bcen culti-vated in the prcvious year. Sowing look piace on II Novcmber 2002, in 15-cm spaced rows for the sole crops llnd 7.5-cm spaced rows for the inlcrcrops. Intercrops wcre sown in a 1:1 addi-tive design in alternate rows. Seed densities for
SC and IC were 400 viable seeds per for
barley and durum wheat. 80 for while lupin. and 150 for common velch. Throughout the slUdy. the ficld was managed aceording to organic agri-culture guidelines with no use of fertilizers or herhicides.
To determinc piani population, tolal number of emerged planls was counled twO weeks after emergence in an arca 0.65 m2 in thc center of
each 1'101.
Forage was h'lrvesled at late l11ilk stage (SI age 77) and hmd dough stage of ccreals (SI age 87) as descibed by lildoks et al. (1974).
For white lupin and common vetch thc seales of Lopcz-Bcllido and Fuenles (1990) and Ca-ballero el al. (l996a) werc used. rcspccli\dy. Barley rcached the latc milk stage on 21 May and the hard dough stagc on 30 May. Durum wheat was harvestcd abouI len days later lhan barlcy, reaching late milk stage on 2 June and hard dough stage on IO June. AI Ihese dales white lupin was betwcen R4 (beginning of l'od filting) and RM(malur:lIion) slage and common ve{ch was at pod filling on both datcs. Differ· enccs in the phenology within each spccii:s.. both SC and ICs. were noi obscrved. The forage
grown in l area was cuI at 5 cm abovc soil
leve I and was separalcd in cereals., legumes. and \\ccds. Winter cercai and Icgume planls werc di· vidcd inlo slems. lea\'cs. and infiorescences (spikcs :llld/or pods). Piani parts were o\en dried for dry maller dClermination al 75 C lO constant weight and anal)'zed for nilrogen con· cenlration by the microKjcldahl method (Brcm-nar. 1965). Crude l'rotei n eoncentration was cal-culaled rtlultiplying N eoncenlratioll by 6.25 (AOAC, 1990) and N yidd was obtained by multiplying tllc N concentration by DMY.
11le resource complementarit), of the intcr-crops was measured using the laod equivalenl ratio (LER). Aceording lO Mead and Willey (1980) land equivalent ratio for a cereal/legumc intercrop is the sum of thc partial LER (LER\) values for cercai (LERc) and legume (LERI):
LERx = YiclYsc
LER = LE Re + LERL
where Yic and Ysc are respecti,ely intercrop· ping and sole cropping forage DMY or NY of crops.
l'Ile competitive "bilit)' 01' the companian crops was calculated with thc aggressivity indcx (A). according to Snaydon (1991). This index is a measure of Ille ability of one componenl lo oblain limiting resourccs.. \\hen grown in mi x-turcs witll anolher componen!. compared with its abilily lo utilize Ihosc resources when grawn in pure stands. Aggressivit)' index, caJculated for lhe cereal component. can be expres.<;ed as:
A = LE Re - LERL
Data were anal)'zed by anal)'sis of variancc lO teSI Ihe cffcct of lile foragc trealment (FT), the harvest lime (HT), and tlle FTxHT intenle-tion. Signìficantly (P < 0.05) different Illeans
Mariolli M.. Mason;A.. Ertoli t ..Ardl/Ìlli I.
were separaled by Ihe leaSI signiflcant
differ-ence test (Snedccor and Cochran. 1980).
3. Results and discussion
3.1 Forage dry matter COllcel11mtiOfl Ufltl yield (md legmne proporriofl
The FT x HT inleraction was signiflcanl only
for forage OMe.The ranking of forage
Ireat-ments did not change al the two harvest stages: thus. the magnitude of differences belween vest times wilhin forages Ireatmcnts lend to the interaction.
Dr)' malter conccntration of forage in-crcased from the firsl lo the sccond harvest, as was expecled owing lO Ihc progress of cercai bi-ological c)'cle (Table I). According to Gardner
and Wiggans(1%1)and Edmislen et al. (1998a),
OMC of barIe)' and wheal sole crops forages
was oplimal for ensiling (inside lhe 300-400 g
kg-I range) al milk stage ond was slighlly
high-er Ihan optimum at dough slage. Dry matthigh-er coneenlration of lupin sole eroI' forage \Vas al-wo)'s 10wer Ihan the recommended values for cnsiling. and thal of \'elch was lower than the minimum threshold at Ihc flrsl harvest and with-in the oplimal range al the second harvest
(Table I). AI milk slage
or
cereals. oolh lupinintcrcrops had suitable forage OMC for ensil-ing, while DMC of oolh vetch intercrops was too low. Foragc DMC of ali intercrops harvest·
làblc 1. Dry malter cOlicentratiOIl (g kgI)or the forages or ìntcrcrops amI sole crol" al Ihe firsl Rnd Ihe sccond har-vesl. corresponding lo milk mld h:m.! dough slage
or
cere· als. Lupin R and VClcha werese
har\"cslcd al the barlcyripcning stages. Lupin w and VCleh"" were
se
harveslcd nt Ihc wheat T1pening sl3ges.Dry m:mer concenlralion (g kg I)
Forage Irealmen! First harvcSI Second han'est
Bllrley/Lupin BarleyNclch Whcal/Lupin \VhcatIVetch Barley Whcal LupinB Lupin", Veleha VClch",
t ValllC5inaorro," orcollimofol!O\\edby Ihc S;lIDelellerare
IlOl $ignificanlly diffeu'nl all's
ed al cercai dough stage was suil<lble for ensil.ing. Owing to Ihe lack of signiflcance of lhe inler-action F1'xHT Cor ali olher measured variables.. thc highcr forage yield. and Ihe more suitable OMC of forage at the hard dough stagc of each
cereal spedes.. only differences among FT from
this 1fT will be reported and discu'lSCd.
Differ-enCt.'S in the main effecl ofHTwill bediscussed.
Dry maller yield was generally higher when cereals are at the hard dough stage than in Ihe
la le milk slage(700.3 vs781.3 g ml for the late
milk and hard dough slages. respectively). Dry mattcr conccntration of foragc may be too high, howevcr, for ensiling cereal sole erops al the
hard dough slage while OMC of 1cgume sole
erops may slill be too low, except for veh.::h
har-vested whcn wheat is in tlle hard dough stage
(Table I). Our results demonstrate that
inter-cropping ecreals with legumcs allows ensiling at hard dough stage of cereals, compensating w;lh
highcr dry malter yield for (he decrease of
en-erg)' conlenl Ihal nOffilall)' occurs as cereals
ma-ture (Croveuo et al.. I99R).
AI dough siageoC wced biomass was
high in lupin SC, low in cereals
se
and nearlyabsenl in common veleh SC (Table2). Between
ccreals. values were higher in wheat than in
bar-Ie)' (Table 2). Compared wilh cercai Se.
inter-cropping reduced weed biomass by aboul 70%
in Ihe lupin inlercrops and b), 100%in the \'elch
le. This was expecled because wc applied an ad-ditive design of intercropping. wherc Ihc com-pom:nts were seeded al the sole eroI' rate and the final piani densil)' was the sum of the den-silies of the sole crops. Among Ihe four sole erops lestcd, the white lupin suffcrcd thc high· est weed competilion. Lupin production is high· Iy dcpcndcnt on herbicidc use in eonventional fanning, grcatly suffcring from weed eompeli-lion, owing to Ihe initial slow growth rale. wilh roselle shape Ihal prevents Ihe soi! caver before
winter (Lopez·Bellido and Fucnlcs. 1990;
Hu)'-ghe, 1991: Perry el al.. 1998). Common \'ctch. in contraSI, does noi suffer by \\ccd compctition. owing lO ils rapid gro\\1h and soil eover. Be-tween ccrcals. barlcy sccms lO compele better than \\ heal with weeds, probobly due to Ihe greatcr cari)' growth rate of barley eompared lo wheol (Couscns. 1996).
Compared lO convenlional Carming yield in Italy, organic managemenl reduced DMY of
lwl. J. Agron! Rlv. Agrol'.. 1006. 3:40.1-4/2
Tab1e 2. legumc. IOlal forage 3nd weed dry matter or intercrops and sole al llarJ dou)th stagc or ccn:ah.
LupinHand Vctchll ...ere
se
harv.:sted allhe barley ripening Lupin", and Vclch.... \loCTese
hllr\CSICd al the "Ileal ripcnlng stagcs..•
Foragc trc-almenl Cercai Legumc Total foragc
(g rn:) Barh:y/Lupin 618.3 ct 346.4 a 96·U c BarlcyNclch 358..7 b 526.1 c X84.8 d \VhcatlLupin 565.7 d 394.7 b 960.-1 c WhcatNctch 311.3 a 573.2 d d Barle)' 55·1.\ cd 554.1 a \\'beal 519.1 c 519.7 a LupinB 702.8e 702.8 b Lupin... 758.0
r
758.0be VetçhB 710.9 e 710.9 b VClch", 7902 f 790.2 ct In exll cutumn. \"3IUC$follovo"CdbYtlleQIDe)euer arenoisignifICantI)' differenl al P ..0.05.
Wccds 10.5 a 0.0a 2..1.0 ab 0.0a 36.0 b 653c IOHd 124.2 d 0.0a 0.0a
Villegas cl al.. 2001). and lupio by about 25%
(Fagnano and Posliglione. 1994). while it did noi modify that of velch (Ercoli Cl al.. 1997). In win-ter cereals. yield .... as probably reduccd by ni-trogen deficiency. indicming Ihal residual nitro-gen from Ihe preceding alfalfa \Vas not sufficient to achieve the maximum ccreal yield. The yicld of lupin was reduced by weed competition while the yicld of velch was noi affecled. owing lo its strong competilion wilh weeds and to ils N-fix-ing capacily (Papastylianou aod Danso, 1991).
Totale forage yield was greater for ali inter-crops eomparcd to sole inter-crops (làble 2). The for-age yield of lupin inlercrops \Vas aboul 10% highcr than velch ICs. lne propOrlion of Icgumes in the IC forage was highly differenl bclween lupin and velch ICs: lupin constituled 36% of the foruge yicld in thc B/L intercrop and 41% in the W/L IC, while vetch constitut-cd 600/0 of the forage yield in Ihe BIV intererop and 65% in the W/V le. In the ccrcallvctch ICs these values are higher than minimulll thresh-old valuc of 50% velch conieni. lhal Caballero et al. (1996b) slated would ensure a high qual-ily cereal/veleh forugc.
Compared to SC yicld. in Ihe cerealilupin ICs Ihe foruge yicld of cercals increased and thaI of lupin decreased. Darley gained more lhan wheal wilh lupin as companion crop and losl less Ihan wheat wilh vctch as companion crop (Table 2). These rcsults are in agreement with Ihose of Counsens (1996). Caporali el al.
(1998). and Ross Cl al. (2QO.l): Ihey concluded
Ihal barley was more compelitive than \\heal and auribule this advantage lO the early growlb
rale of barley, that is grealcr Ihan wheat: as Ihe results barley had a grcaler abililY lO supprcss Ihe companion crop.
Jannash and Martin (1999) found Ihal lupin compeled poorly wilh smal! grain ccreals. \\ hich have a higher initial growlh rate. In our rescarch lupin SC yicld was rcduced ;n Ihc inlercropping with cercals (Table 2).
In Ihe cereal/vetch ICs Ihe rorage yicld of ali Ihree spccies decreased. Cereal and \'elch yield was rcduccd by about 40% and Ihat of velch by aboul 20%. eompared lO SC yields. In olher re· seareh the vetch suffcrcd due lo competition by intcrcropped winter ccreals (Roberls el al., 1989: Caballero el al .. 1995). This uncxpcclcd re·
sult could be explained by thc abscnce of
ni-trogcn fcrtilization ehllraelerislic of Ihe organic farming methods in whieh veteh can compele
beller wilh eereals (Morcira, 19R9).
Inlereropping did \lol appreciably modify thc pIani population (Table 3). Tne percenlage of planlcd sceds Ihal ernerged as plants rangcd from 77 lO 91 % in SC plols and 75 to 90% in le rlots. lllesc data indicate Ihat inlercropping may noi influenee pian t populalion eSlablish-meni of the cereal and legumc crops,
prcsum-ably because inlcrspccific competilioll for
growlh rcsources among seedlings is minimal. lne proporlion or foragc dry maller as in·
f10rescenccs was modiricd by inlcrcropping in
lite lcgumc!i bUI not in thc cereals (Table 3). Compared to Se. Ihe numbcr of rcproduclivc plant parts ...as redueed in Ihc lupin companelll of Ihe cereaillupin ICs. and was increased in tlte ...elch componenl of the ccrealf\:etch ICs. as
op-!'dar/Olli M., Ar{l)'oni A .• ercoliL,Artlwn; J.
Tablt: 3. PianI populalion, proporlìon of foragc DM and numbcr of per p./alll of Ihe _ole
erops and eompmlion crops al hard dough slagc of ccrcals. Lupin'l VClchll wcrc
se
harvcslcdal Ihe barley ripenin" stagcs. Lupinwand Veteh.wwcrc.se
harvcsled al Ihe WhCll1 ripcning _tag.l"s.Plnnt populatiol1 Inflorescenees Foragc IrCilllllenl Barley/Lupin l3arleyfVetch \Vhcat/Lupin WhealfVelch Bllrlcy \Vheal Lupinu Lupin w Velch o VClch w Cercai Legume - - ( N 111')--351 at 61 11 144a 113b 340 a 60a 3..10a 112 b 3633 359 a M, 63a 121 b 116 b l'roporlion Cercai Legume _ _ (g kg ' foragc) -458 ab 19711 464 ab 236 b 430 il 253 b 433 a 346 d 4Mb 44\) [lb 323cd 404c 1'19 , 297 c Nurnbcr Cercai Legume - - (N pIalli ') -lA b 15 a LI ab 6.2 f 1.2ab 1.9b 0.911 6.6g 1.2 ab 1 I.IV 5.0c 5.3 cd 5.6 dc 5.R cf
t In cach. column. valucs foltowet.lbythe S<lmeleller are IIOt.ignificanlty difft::rcnl <liJ':IlIl.05.
posed to mean weight of inflorescences per plant, which was unaffcctcd by intercropping. In the cerealllupin the intcrspccific eompctition wilh thc cereals rcduccd Ihc numbcr of
inno-rcscences of Ihe lupin by
70%
in IheB/L
andby 64% in theW/L le.
Othcrs have rcporled that lupin sole crop rc-spondcd to environmcnlal stress primarily by dccreasing thc numbcr of reproduclivc organs (Herbert. 1977; Withers, 1979), and similar re-sults were reported for lupin illtercropping (Carruthers CI aL, 2000).
In thc ccrcal/vetch IC, however. the facilita-lion cffeet was obscrvcd, in that numbcr of the inflorcsccnccs per pIan! incrcascd by 11% in the BIV alld by 14"/Q in the WIV le. This higher
pro-portion of inflorescences in ccreallvetch ICs. compared lO thc SCs. was probabIy rciated to the higher a11l0ltnt of intcrecpted radialion by the dimbing vetch wilh thc ecrcals as tulor (Er-coli Cl al., 1993).
3.2 Forage cmde prolein col1cxnlratioll (Imi
lIi-lrogenyield
Crude prote!n concenlration of foragc of alI in-tcrcrops and sole erops did not vary according to harvest stage. while forage NY increased from milk to hard dough slage (126.7 vs 141.0
kg ha-t N for the late milk and hard dough
slages. respeclively). As cxpccled. l!le CPC of the foragc was lower in Ihe wintcr cerea! SCs than in the legumc ones (Table 4).
4. Crude prOle;n concenlf<ll;on llnd nitrogen y;cld of ccreal, legulIIcs 101111foragc h<lfVCSICd hard dough "age or cercals. Lupin ll and Vdcltll were se harveslcd al lh... barley Slagcs. Lupin" :lnd Vetchw\\cre
se
h!lrvestedal lite wheal ripening S\:lges.Crude protcin Nitrogcn yield
FOfllgetreMmenl ('...creai Legume Total furagc Cercai Legume 10tal for;tge
(g kg') (kg haI) Barlcy/Lupin 62.6
at
127.0:1 85.7 t> 61.9 d 70.4 <l 132.3 b l3arlcy/VclCh 61.3 a 151.6b<: 115.0 c 35.2il 127.6 b 162.9c \Vhcal/Lupin 61.7 ;1 115.2li 83.7 t> 55.9 cd 72.7 a 128.6 b WhcatNetdl 60.3 a 150.3 Ix: c 30.1 a c 167.9 cd Barley 59.9il 59.9a 5.1.1 be 53.1 :l Whc<l! 58.811 5R8a 48.9 b 11 Lupin H 146.3be 146.3 d 164.5 d 164.5 cd Lupin w 140.2 b 140.2 d 171\.1 dc 170.1 cd Velchtt 154.9 c 154.9 d 176.2c 176.2 d VCICh\\ 149.9 b<: 149.<:1 d 1!'ì9.5 f 189.5 e/tnl.J. Agro". / Ril'. AgrQn.. 2001'J. .JA()3·412
Crude prolein concenlration of forage was enhanccd by inlcrcropping. compared lO cereal SCS (Table 4). 111e incrcasc was highcr for thc cercaVvelch IC Ihan for Ihe ccreal/lupin IC likely !>ecause of differcnces in legume propor-lion of lolal yield of Ihc ICs. For Ihis rcason Ihc increasc of CPC was highcr in Ibc cereal/velch IC(abouI 58 g kg'l) than in Ihc cerealsllupin
le
(abollt 25 g kg I). Similar results were obtaincdby Ghanbari-Bonjar and Lec (2003) with
wheatlbcan le and by Carr Cl al. (2004) wilh barley/pca IC
Crude protcin conccntralion of cereals and ,ctch was not modificd by le while CPC of lupin was rcduecd (Tablc 4). The decreasc was rdalcd lO thc high rcduetion In thc wcighl of
innoresccnccs in thc intereropped planls.. since
CPC
of leaves. slems and innorescences of the lupin did not vary as a consequence of inter-cropping (dala non shown).Forage IV (Table 4) was 10\\-e$1 in
se
cc-rcals and highest in SC n'lch. Inlercropping produccd highcr l Y Ihan SC cercals. ncarlyin-crcasing Ihem lO Ihe le\'el of
se
\'etch. As av-eragc. Ihe NY of lupin intercrops was 2.6 times and Ihal of velch IC \loas3.2
limes highcr IhanNY of cercals
se.
111e NY of velch ICs washight:r lhan lupin ICs.
In the cercalllupin ICs. NY of the legume
was reduced and thal of Ihc cereal \Vas
in-crcased. compared lO
se
values. Bothcercal/lupin ICs had ubouI 8 kg ha·l highcr NY than cereal SCs (Table 4). The udvantage of both ccrcal/lupin ICs WIlS probably due lO this
highcr nitrogcn availability to thc ccreal by thc lupin. Similar rcsults were oblained by Palma-son ctal.(\992). owing (Odirect N lransfer from
lupin lO Ihe intcrcroppcd italian rycgrass. In ad-dition, several have reported Ihat lupin cultiva-lion can improve the yield of the subsequcnt
winter erop, lltlribuling the improvemem
lo the residual N (Jcnscn cl al., 2()().l; Puyne ct aL 2(04). Othcrs rdatcd thc positive effect of Ihe inlercropping with lupin lO improved P trilion of the cercai, due lO solubilizalion
or
P by the legume rools (Suong Cl al..2005). In our research. howcvcr. Ihis was not likely lO occurdue to thc high P contcnt of Ihe soil (Zentncr el al.. 1992).In addition. no visual symptoms of P dcficiencies in thc barlcy and wheal SC \\-cre observcd (Ozturk Cl aL, 2005).
In Ihe ccrcal/vctch ICs, Y of ali spccics was reduced. respccl lo SC ,·aluL'S.. and thc rcduc-lions Ihat were consislenl wilh Ihc DMY rc-ductions. In Ihis rcsearch. the transfer from vetch to companion ccrcals was noi evidenced. Othcr AUlhors have pointed OUI that the direct N transfer from ..:clch to Ihc intereroppcd cere-al eroI' is unccrtain (Papa.'>t)'liuDou and Danso.
1991: Kurdali et al.. 1996).
3.3 LatUfe(/II;\'O/CIIf '01;0
When LER < l there is a disadvanlagc to
in-Icrcropping und thc are used more
ef-ficiently by SC Ihan by le.\Vhen LER= I Ihere is no inlercropping advanlage nor disad\"anlage. respecl lO Ihe sole cropping syslcm: when LER > I Iherc is <In inlcrcropping advunt<lgc in lerms of improvcd use of environmental resources for plant growth (Mead and Willey, \(80).
Ali four inlcrcrops had lotal LER grcatcr than \ (Tablc 5). bolh on dry wcight and on ni· trogen yield basis. indicating a high yicld ad-vanlage and a high rco;ource eomplementarity from intereropping. Tolal LER wus higher in lupin ICs Ihan in vctch ICs. l'o oblain Ille SRmc yield of thc cercal/lupin ICs. SCs would require 60% higher lund arca. while to oblain tbc same yield or thc cercallvetch ICs. SCs would rcquirc
40-50% highCI' land arca (làblc5). Prlrtial LER
làblc 5. 3nd pòlrtial nnll lolal Land Equivalen! Ralio(LER)anll Aggrc!osivilY indcll (A) or thc intcn:rop<; on adry matler anll nitrogcn yicldbasis.
Intercropptng Dr) Matlcr basis Nitrote-en Yicld ha:.is
LER(,t LERL LER A LER1 LER, LER A
Barley/Lupin 1.12 a' 0.49 a 1.61 a 0.72a 1.17 a 0.4;\ a 1.59a a
BarlcylVctcb 0.68 b 0.78 b 1.46 b -0.09 b 0.70 b 0.76 b 1.46t> -oJJ6 b
WheatlLupin 1,09Il 0.52 a 1.61 a 0.57 c I 1-1 a 0.43 a 157 a 0.71 a
\\'hcatIVelc-h 0.6..1 c 0.76 t> L39b -0.13 d 0.65 c-
o.n
b 1.... 1 b -0.12t LER. and LER... LER or ccreal:s and kgurneo.. resre<'li\dy:
Marimt; M.• MasoniA.,Ercoli1-..Ardllim I.
shows the contribution of each species in thc ICs to lotal LER, thus demonslrating which species has mainly benefited from the associa-tion. In an additive design. partial LER values grcaler Ihan 1.0 indicale a stimulus. partial LER valucs equal lO l,O indicate no interaClion and partial LER valucs 10wer than 1.0 indicate a com-pelilion between species (Auslin et al.. 1988).
In thesc ICs Ihc ccreals received a slimulus by Ihe prcsence of Ihe lupin. with an expecled yield advantage up to 17% m'er SCs. Barlcy and
wheat were nOi complementary to lupin.
how-C\icr. because thc cercai dry mattcr and NY ad-vantage werc lower than the lupin disadad-vantage. Partial LER values of the lupi n was low. but these valucs were consistent with those
report-cd by Jannasch and Martin (1999) for
wheatllupin
le.
Aggressivily index indicates that in thc ce-rcal/lupin ICs cercals wcre dominant. and bar-ley cxhibitcd a higher competilive ability than wheat (Table 5). In both cereal/ve'ch ICs both spccies suffercd (rom inter-specific competi(ion. Thc disadvanll.lge was higher for Ihe cereals Ihan for (he Icgulllc. however. based on LER. suggesting that the Icgume \Vas dominanl in ce-real/vetch ICs.
4. ConclusiOlls
11lis cxperimcnt. carried out under the con-straints imposcd by UE organic farming guide-lines (Le. without addilion of chemical inpul),
has analyzcd possibility of improving silage
yield and qualilY of ccreals by inlcrcropping with tegulllc spccics.
Forage yicld was increased by intcrcropping <lnd, owing to Ihc high CPC of legume species, NY also il1crcascd.
011
average, intercropping incrcascd DM Y by 72%. NY by 190%, and CPC by 40 g kg-'. compared to cercaI sole crops. but Ihe choice of legumc species affecls (he yield and quality advantagcs. Cercals were the dom-inant specics in the ccreal/lupin ICs, and velch was the dominant species in Ihe cereaUvelch ICs. If the objcclive is lO maximize dry matter yield. inlcrcropping barley or durum wheat with while lupin is Ihe best choice. while if Ihe ob-jeclive is lo maximize N yield the besi choice is the intcrcrop wilh common vetch. Moreover. silage har\'est at cercai hard dough s(age isrec-ommendcd lO increase dry matter and crudc pro-Icin yield and to oblain a dry matter concentra-lioo of the forage suitable lO direcl cosiling.
Furthcr rescarch. however. is ncccssary lO verify thc possibilily of producing good quality silage from Ihese forages. Therc likcly are no problems for Ihe cereal/lupin forage. whereas the CPC of the ccrcallvctch forage could be too high to properly cnsilc: if that is the case Ihe vetch seeding proportion could probably be rc-duced.
Rcfcrences
Alam M.Z.. \-I.A .• Mamin \i.S.I .. Mamun A.A. 1997. [mcrcroppin& cffecl on \licro mfestation m \liheat. Bangladesh1. Sci. Ind. 32:31 t-316. Anderscn 1\I.K .. Hauggaard-Nielsen H.. Ambus P..
Jensen E.5o Biomass productlOn. s)'mbiOlic ni-trogen ril(ation and inotganic N usc in dual and
tri-componcnl annual inlcrerops. P1ant Soil. 266:273-287. Andre\lis DJ.. Kass.1m A.ll. 1976. The imporlance or mulliple cropping in increasing "'orld rood supplies. In: Papcndlck P.A .. S.1nche1. P.A.. Triplell G.B. (cds): Multiple Cropping.I-IO.ASA Spedal Publicalion 27. ASA. SSSA. esSA. Madison. Wl.
AOAC 1990. Official mclhods o( analysis.. 151h edilion. AOAC Arlinglon. VA.
AUSlill M.P.. FreS(;o L.F.f\L Nicholls A.O._ Gro\cs RH..
Ka}e I9&!. Competition anl.! Relative Yield: Es-timation :Jnd lnlcrprctation al Diffcrent Densilics and Under Various NUlrient Concentralions Using Silybum Marianurn :md Cirsillm VlIlgare. J. Eco!.. 76:157-171.
Bremnllr T.M. 1%5. Total nilrogcn. In: CA. B1ack Cl al. (eds..): MClhods of anlllysis.. ParI 2. 1149-1179. Agron. Monogr. 9.. ASA :md SSSA. MadiSUIl. Wl. Bulson Il.A.J.. Snaydon R.W.. c.E. 1990.
Intcr-cropping ilutumn·sown fièld bcans and whcal: cffecls on wècds undcr orgHilic fMming conditions. In: R. Unwin. (cd.): Org.mie and Low Inpul Agricullure. 55· 62. Hrilish Crop ProtCClion Council Monugraph 45. Brackndl. UK.
Caballcro R.. Goieocchca E.L. Ilcrnaiz p.J. 1995. For-age yiclds and qualit)' of common \eleh and oal SUll'n al vcrying sccding ralios and .'>Ceding ralcs or velch. Ficld Crop Res.. 41:13:;-140.
Cab;.llIero R.. Ilarro C. Rcbolè A.. AraUlO M.. Hernaiz pJ. 19963. Yield componenb and forage qualil)' or com-moli \eleh duringpodfilling. Agron. L &'t797-axJ. Caballero R.• Rebolè A. Barro C. Alzuela
c..
l're\ino1., Garda C. 1996b. r-armmg praclices and chemical bases (or a proposed qualil)' standard o( velch-cere-al ha)'s.. Field Crop Res.. 47:181-189.
lf(ll. J. Asmn. / Niv. Agron.,}()()(j•.1:4M-412
Caporali F..Paolioi R.. Campiglia E. 1987. lotercropping. Pari l. Biological ba'lCs and yield ad...antages.. Ri.... Agron .. 21:3-17.
CaporaliF..Campiglia E .. PaoliniR.Mancinelli R 1998. '!be effcC1 or crop species.. nilrogen fcrtili:l'.alion and
weeds on ilomter cercaI/peli intercropping. haI. J.
Agron.. 2:1.9.
C'arr P.M.• Honle)' R.D.• Poland Barie)'.oal.
and IXreal-pea miXlures as dryland forages in the
northcm greal plams.. Agron. J.. 96:6n-684.
Carrulhers K.. l'rilhiviraj B.. Fe O.. C10ulier D.. Martin
R.e.. Smilh D.L2000. Inlereropping com wilh
SO}'-beano tupin and forages: )'ield componenl responses. Eur. J. Agron.. 12:103-115.
Chen C. WCSICQlI M.• Neit K.• \VK:hman D.. Kno.'( M.
2(M).4.Ro.... configuratKm and nilrogen applicalion for
barlc}·pea inlercropping In Montana. Agron. J..
96:1730-1738.
Clierncy EP.. Marten G.C 1982. Small grain crop forage polenlial. Il, Inlerrelalionships among biologlcal. ehemical. morphological. and anatomical determi-nants of qualily. Crop Sci.• 22:240-245.
Couscns R.D. 1996. Comparati\le growth of IOohcaI_
bar-ley. and annual T)egTllss(Lolium rigidllm) in
mono-cuhure and mixlure. Ausl.J.Agr. Res..
Cro\lello G.M.. GalassiaG.. Rapellia L.S:mdruccia A ..
Tamburinia A. 1998. Effect of Ihe slage of maturil)'
on the nutriti\e value of ilohole c:rop wheal silage.
U\lCSI. Prod. Sci.. 55:21-32.
De Franchi A.S.. Ghcrbin P..Monteleone M ..Pardo A.
1995. Shoot and rool growlh and water uptakc of bar-Iey gcnotypes (IIQrrlt'llf" spp.) lOoith differenl live habitus in a hilly arca of southcrn Italy. Ri\l. Agron.• 29:48-59.
Do)'le
c.J..
Topp C.EE.2004. The economieopporlUni-ties for inereasing the use or rorage Iegumes in north
Europcan livcstock under both conventional
and orgnnic: rnanagcmenl. Renew. Agr. Food S)'SL.
19:15-22.
Edmislen K.L.. Green 1"1".. Mucller 11'., 13urns lC 199$a.
Willtcr lInl1Wtl small grain forage potemial. 1. Dry
matler )'idd in rcllltion lO morpholog.ieal eharael(:r-iSlics of four small grain speciesal six growth slages. Commun. Soil Sci. Pian .. 29:867·879.
Edmislcn K.L.. GrecnlT..MueUerlP..Burnsle.llJ'J8b.
\Vinter annual small grain roragc polenlial. II. Quan-tmeation of nutritive characlerislics of f(>ur small grain ,pecics at six growlh slages. Commun. Soil Sci. PIan.. 29:881-899.
Ercoli L. Mariotti M.. Masoni A. 1997. Radiation inler-ception or oal/velch intercrop. Riv. t\gron.. 31 :658--665.
Fagnano M.. Postiglione L. 199-t Produell\'e behaviour
or sweet cullivars ofLllpimu QlhlUin Southem Italy.
In: Proceedings of Ihc VII 1nternalional Lupin Con-fcrcm.'e. Evora. Por1Ug.11. 362-364.
Gardncr F.P.. Wiggans O.c. 1%1. Yield. moislure. and
crude prolcin cnmpositlon or spnng oalCUIfor
al dirfcrelU slagcs of m'Hurily. Agron. l,
Gharfanadeh M. 1'/97. Economic atlfJ biological
hene-fils of inteR:ropping bersccm with oat in
corn-soybcan-oal mlations. 1 Prod. Agrie.. 10:314-319. Ghanbari-Bonjar A .. Let: H.C. 200.1. Inlereropped .. heal
(Tri/kllll/ L) alld Ixan (Vìl/cifl Il/1m L) llS
a wholc-erop forage: effcrt of han-O;SI lime on foragt' yicld and qualily. Grass Forag<!Sci..58:28-36. Hauggaard-Niclscn H.• Ambusa P..Jensen E.5. 2<Xl1.
In-terspccifie competition. N use and inlerference wllh weeds in pea-barle) intercropping. Field Crop Res.. 70:101-109.
Heiehel o.H.. HcnJum K.1.1991. Dìmlrogcn fixation.
ni-trogen lmnsfer and produC1ivil)' of forage
grass-kgume communilics. CropSci..31:202-208.
HerbcnSJ.1m.Growlh and grain }icld ofLllplnus
a/-bw' al differenl plant populauons.. Nello' zeal.J.Agr. Res..
Hu)"ghc C 1991. Winter grolOoth of aulumn-sown white
lupin (Lllp"lllS Q/blu L): main apex gro"'lh model. Ann. Bot-London.
Jannascb RW" Martin Re. 1999. '!be polential for cap-luring Ihe forage yield of ""hile lupin b) inlercrop-ping wilh ccreals.. Biol. Agrie. Horllc.. 17:113-130. Jedel P.E.. Helm Hl. 199.1. FQrage polential of
real mi'(lures IO centrai Alberta. Can 1 Piani Sci.• 73:·U7-444.
Jenscn CR.• Joernsgaard IL Andcrscn MN..
Chris-tiansen IL..Mogenscn
v.a..
Friis Pelerscn C.T.2(M).4.The crfeC1 or as cornpared with peas and
oals on lhe )'icld of the winter barie)
crop. Eur. J. Agron .. 20:405-418.
Jcnsen E.S. 19%. narley uptake or N deposited in thc
rhizmphere of ficld pea. Sai! Biol.
Biochell1 .• 28:159-168.
Juskiw P.E.. Hclm Hl.. Salmnn D.E 2000. Foragc yield
and qualil)' for rnonocrops and mixlurcs of Slllllll
grain cercals. Crop Sci.. 40:1.18-147.
Kurd<lli E. Shar;tbi N.E.. A. 1996. Rllinrcd
vetch-barley mixcd cropping in lhc Syrian scmi-arid condi-tions. I. Nitrogcn nutritiùn using 15N isotopic dilu-tion. Plani Soi!. 1&.1:1.17·14H.
Liebman M.1988.Ecological suppression or wceds in
in-tercropping syslcms: a TC"icw. 111: Allicri M.A .. Liclr man M. (cds.): Wecd Management in Agroceosys-lems: Ecological Appro..1che't C'RC Press. Boca Ra-lon. Florida. USA. 197-212.
Lopcz-IJcllido L.Fucnt<:s M. 1990. GrolOolh. yicld. and Ylcld componenl of IUpin cuhi\"ars.Ay<Xl.1.82:I0.'i0---I0:56. Marioni M.. Ercoli L. Masoni A. [9I)R. Nitrogen and
phosphorus uptake in oal/WlCh intcreropping. Agrie. Rie..177:3746.
Mead R._ WilleyRW.1980. '!be c:oncept of a 'Iand equi\l-alenl Tatio' and advantagl.'s on yicJds from intercrop-ping. Exp. Agr.. 16:217·m
Martotri M., A., Erco!i L.Arduilli !.
MWAF 2006. [wcb pagcj January 2006. available from
intcrnet (li thc addrcss: hllpJfwww.politichea gri.
eolc.it/PRODUZIONEfAGRIUIO/I-IOME.ASP.
MooncnC.Masoni A .. ErcoliL..MariOl1iM ..Bonari E.
2001. Long-term ehanges in rainfall and temperature in Pisa. Ilaly. Agr. Mcd.. 131:66-76.
Morcira . 1989, '11Ic cffcçt of seed ralc and nitrogcn
fcrliliZcr on lhe yicld alld nutrili\'c \'aluc of oat-vetch mixtures. J. Agr. Sci..112:57-66.
Ofori F..Stern \V.R. 1987. Cereal-Iegume intercropping
s}'!items. Adv. Agron..41:41-90.
Ozlurk L.Eker
s..
Torum B..Cakmak 1.2005. Varialionin phosphorus effiClcncy among 73 bread and durum
whcal genotypes grown iII11phosphorus-dcficiem cal.
careQus soi!. P1:tnt Soil. 269:69-80.
Palmason F.. Danso S.K.A .. lIardarron G. 1992.
Nitro-gen accumulalton in sole and mixcd slands of s\\occt blue lupin (Lllpinlls ullgusti[ofillS L). ryegrass and oalS. l'lant Soil. 14'1135-142.
Pllync \V.A., Chen C.• 8all D.A. 2004. Agronomie po-lcntial or naTTow·1cafcd and while lupins in the in-I:md Pacific NoTlhwcst. Agron. J.. 96:1501-1508. Papastylianou I.. Danso S.K,A. 1991. Nitrogen fixalion
and traosfer in vetch :md veteh oals mixtures. Soil Bi-01. Biochem.. 23:447-452.
Perry M.W.. Dracup M.. Nclson P:. Jarvis R.. Rowland
I..Frencb RJ. 1998. Agronomy and farming systems.
In: GladstoncsJ.s..Atkins
c..
HamblinJ.(eds.): Lupins as Crop Plants. Biology. ProdUCIion and Utilizalion. 291-338. CAB Inlernalionai. WaUingford. UK. Robcrts CA.. Moorc K.J.. Johnson K.O. 1989. Foragcquality and yicld of wheal-\'etch al differcnt slagcs
or maturily and vclch sceding mles. AgrOll. 1.
81:57-60.
Ross S,M.. King J.R.. O'Oonovan J.L Spaner D.20Cl4.
412
Forage polcnlìal of inlcrcropping berseern clover with barley. oal. or trilicalc. Agmn. l, %:1U13-1020,
Salawu M.B.. Adesogao A.T.. \Veslon CN.. WiIliams
s.r.
2001. Dry rnll\ter yield and nUlrilhc \alue ol
pea/whcal bi-crops dirrcring io maturity al harvesl.
pea to whcal ratio 30d pca VllriclY. Anim. Fecd Sci.
Teçh'O94:77-87.
Snaydon R.W. 1991. Rcplacernem of additi\e for
competili\e J. Appl.&:01..28:93(}.946.
Sne<kcorG.w..Cochran \V.G. 1980.Stallstical rnelhods. scvcnlh cd. lowa State Universit) Press. Ames. Suong 1:T. Cu. HUlson J.. Schullcr K.A. 2005. Mixed
cul-ture of wheal(Tntlcutlt Q('slil'UllIL) \\o ith wbilc lupin
(Lup/lttlS a/bus L) impro\'cs the growlh and phos-phorus nUlrilion of thc "heat. PIani Soil. m:143-151. nLUcniueo l 1997 Applicfllion of mtereropping in
or-ganic agricullure. Bio!. Agtic. "onic.. 15:251-260.
Trenbath B.R. 1976. 1'1301 mtcractions in rni.. crop
communilics. In: Papendick P.A.•SanchezP.A..Tripleu
G.R. (cds.): Multiple Cropping. 129-169. ASA Sperial
PublicaliOll 27. ASA. SSSA. essA. Madison. Wl.
Villcgas D.. Aparicio N.. Bianco R.. Roro C 2001.
Bio-mass accumulalion and main stem elongation of du-rum \\oheat grown umler meditcrranean condilions. Ann. Bot-London. 88:617-627.
\Villey R.W. 1985. Evaluallon and presenlatìon of inter-cropping ad\anlages. Exp. Agr'O 21.119-133.
Withers NJ. 1979. EffeelS of watcr onL14pinus
al-bitI. Ncw unI.J.Agrie. Res..22:445--474.
Zadoks
le.
Chong TI .. Konznk c.F. 1974. A decimaicode for Ille growth slagcs or ccrcals. Wecd Res.. 1":415,"21.
Zenlner R.P:. Campbcll Cr\.. Scllcs F. 1992. Build-up in
soil availahlc l' nnd yield rcsponsc or spring wheat IO
sccd.placcd Il in a 2-l.-ycar in lhc Btown soil
