Crop Performance and Plant Microbe-Interactions are Affected by the Sequence and Frequency of Pulse Crops in the Canadian Prairie

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1 Crop Performnce nd Plnt Microbe-Interctions re Affected by the Sequence nd Frequency of Pulse Crops in the Cndin Pririe Nvrro-Borrell A 1,2 ; Di M 2 ; Hmel C 1,2 ; Fernndez MR 2 ; Gn Y 2 ; Germid J 1. 1 University of Ssktchewn, Ssktoon, SK, Cnd; 2 Semirid Pririe Agriculturl Reserch Centre, AAFC, Swift Current, SK, Cnd. Short summry: Different crop sequences best benefited different pulses nd whet in the field. Monocultures were inefficient in whet, where it reduced yield nd nitrogen level. In chickpe, monoculture resulted in devstting diseses. Whet yield ws gretest following pulses suggesting tht the microbil legcy of pulses is well suited to whet. Beneficil rbusculr mycorrhizl fungi nd drk septte endophytes were found to ssocite in different wys with different crops. Keywords: Crop rottion, fungi, pulses, whet Introduction: We re seeking the optimum frequency nd sequence of pulse crops in rottion systems with whet by nlysing the performnce of 14 different 4-yer crop rottion systems, t SPARC in Swift Current. Preliminry results obtined until phse-iii of the rottion will be presented. Different crop sequences best benefited different pulses. A chickpe-whet sequence benefited chickpe productivity more thn pe-mustrd; pe yielded more fter lentil-chickpe thn pe-whet, wheres lentil ws not ffected by crop sequence. Monocultures were inefficient in whet, where it reduced yield nd nitrogen level. In chickpe, monoculture resulted in devstting diseses, showing how the microbil legcies of crops cn feedbck on the performnce of the following crop. Whet yield ws gretest following pulses suggesting tht the microbil legcy of pulses is well suited to whet. Nowdys cropping systems must be nutrient nd wter efficient nd sequester crbon in soil. Pe ws the most N nd P use efficient pulse crop. Whet hd the lowest N efficiency, but hs high potentil for C sequestrtion, with higher strw C/N rtio thn pulses. Wter use efficiency in whet ws not influenced by previous crops. Our objective is to determine the optimum frequency nd sequence of pulse crops (pe, lentil, chickpe) in rottion systems by nlysing the performnce of 14 different 4-yer crop rottion systems in terms of yield production nd qulity, disese incidence, beneficil microbil ssocitions nd nutrient use efficiency.

2 Mterils nd Methods: Experimentl design The field experiment ws conducted t the Agriculture nd Agri-Food Cnd Semirid Pririe Agriculturl Reserch Centre (SPARC), Swift Current, Ssktchewn. Smples of crops, roots, rhizosphere soil nd microbes were tken from the plots of the field experiments, nd series of lbortory nlysis were conducted t SPARC Microbiology lbortory, where mesurements were mde using trditionl nd moleculr tools. We chose this experimentl site with the considertion tht chickpe cn only be grown well in the Southern res of the Pririe. The smpling ws t mid bloom stge. The plnt vrieties in the field were Lillin Hrd Red Spring Whet, CDC Frontier Kbuli Chickpe, CDC Medow Yellow Pe nd CDC Mxim CL Red Lentils. The tretments were tested in RCB design with 4 replictes (16 plots; plot size: 4 x 8 m, borders: 2 x 12 m) s shown in Tble 1. The experiment ws first conducted in nd ws replicted in Tble 1. Tretments in field experiment for biodiversity study corresponding to different sequences of pulses nd whet crops grown from 2009 to 2013.

3 Smpling Roots (0-15 cm) were collected week fter flowering of pulses nd lso on re-cropped cerel, nd soil ws smpled fter hrvest. Roots were wshed nd divided into representtive subsmples. One subsmple ws cut to 1 cm frgments, mixed nd stined for root coloniztion nlysis. The prmeters listed in Tble 2 were or will be determined s indicted. All smples were tken from the right hnd side of the plots while gronomy work ws done in left hnd side of the plot. Assessment of root coloniztion Root coloniztion ws determined using the gridline intercept method fter clering in 10% KOH nd stining in 5% Scheffer blck ink in vinegr (Giovnnetti nd Mosse, 1980). A photogrphic collection hs been developed from these smples trgeting the most common fetures tht llow us to recognize AMF nd DSE when colonizing the roots. Root density nd root length colonized by the fungi Two root subsmples were lso tken for the determintion of plnt root length per plnt in duplictes. Smples were weighed, freed from ll orgnic debris, plced in biopsy cssette nd stined in 0.8% Toluidine Blue solution for 5 min just before scnning, s described in Cost et l. (2001). Roots were spred prt on scnner try nd scn in n opticl scnner Epson Protection V700 Photo with Dul Lens System. Imge ws sved nd nlyzed using the progrm WinRhizo PRO V 2003 for Windows (Régent Instrument Inc., Québec). Root length ws expressed s the totl root length of n verge plnt in ech plot, by multiplying smple length by totl root weight, nd dividing by the mesured smple weight nd by the number of plnts smpled. Duplictes were verged to obtin one vlue per plot. Root length colonized (RLC) ws clculted s: coloniztion vlues X root length mesurements. Plnt productivity nd nutrient content nlysis Plnt mterils were smpled t hrvest mturity. Plnts on 0.5 m of four djcent rows were hnd hrvested, dried t 45 C, nd threshed. The dry mss of grin nd strw ws recorded nd plnt hrvest index (HI) ws clculted s the rtio of seed weight to the totl weight of the hrvested mteril. Strw nd grin smples were submitted to the SPARC Chemistry Lbortory for determintion of N nd P concentrtions in seed nd strw. The m 2 in the centre of ech plot ws hrvested with plot combine for yield determintion. Results: Different crops nd their sequence nd frequency in the field influenced the biomss, yield, strw nd seed nutrient content, soil wter nd nutrients nd the function of the microbil community ssocited to the subsequent crops. In 2011 whet mture biomss nd yield were greter when whet ws grown fter pulses compred with the whet monoculture (Fig.1). No differences were found mong these prmeters in the repetition of this tril in spce/time in 2012 mong tretments (dt not shown).

4 Mture biomss in whet grown in 2011 Yield of whet grown in 2011 Mture biomss (g) b p = Yield (Kg/h) b p < CHP LEN PEA WHT 0 CHP LEN PEA WHT Previous crops grown in 2010 Previous crops grown in 2010 Figure 1. Plnt mture biomss nd yield of whet grown in 2011 (tril ) fter different crops. Dt nlyzed with ANOVA nd LSMens Differences Student's t using JMP10 softwre (SAS Institute Inc., Cry, NC, USA). In 2011, P nd N use efficiency vried mong the crops sequences. P use efficiency ws higher in whet rottions. Among the pulse rottions pe monoculture hd greter P use efficiency thn lentil or chickpe monoculture. N use efficiency ws higher in pulses rottion nd lower in whet rottions (Fig.2). Figure 2. P nd N use efficiency in the crops grown in Dt nlyzed with ANOVA nd LSMens Differences Student's t using JMP10 softwre (SAS Institute Inc., Cry, NC, USA). Strw C:N rtio in the whet rottions ws higher thn in pulses rottions. Pulses residues re esier to decompose by the microbil community due to their lower C:N rtio compred to whet residues. However whet hs high potentil for C sequestrtion, with higher strw C/N rtio thn pulses which increses the nutritionl vlue of this crop (Fig.3).

5 Figure 3. Strw C:N rtio in Dt nlyzed with ANOVA nd LSMens Differences Student's t using JMP10 softwre (SAS Institute Inc., Cry, NC, USA). Crops differentilly ssocited with pthogenic nd beneficil fungi. Fusrium venceum ws more frequent in pe thn in other non-cerel crops, F. oxysporum ws more bundnt in lentil thn in pe, wheres Alternri spp. were most common in mustrd. Fusrium spp. were less frequent in subcrown internodes of whet thn in the roots of non-cerels (Tble 2). Tble 2. Root rot in noncerels (chickpe, pes, lentil, mustrd) nd percentge isoltions of most common fungi in 2011.

6 Beneficil rbusculr mycorrhizl fungi nd drk septte endophytes were lso found to ssocite in different wys with different crops. This supports tht plnt hve selective influence on soil microorgnisms nd tht plnt-microbe interctions re regulted by plnt fctors (Fig.4). Figure 4. Root length colonized by AM fungi nd drk septte endophytes in 2010 nd Levels not connected by sme letter re significntly different. Cpitl letters correspond to significnt differences in RLC colonized by DSE mong the crops. p< Smll cse letters correspond to significnt differences in RLC colonized by AMF mong the crops. p< ns: No significnt difference ws found. Preliminry conclusions: Whet plnts grow nd yield better when grown fter pulses compred with whet monoculture. Chickpe monoculture is highly susceptible to root rot disese. Pe is the most N nd wter use efficient pulse crop nd whet hs the lowest N efficiency. Whet hs high potentil for C sequestrtion, with higher strw C/N rtio thn pulses. Wter use efficiency in whet is not influenced by previous crops. Crop rottion cn stimulte specific soil microbil communities tht might directly influence the growth of successive crops. Cited References: Cost, C., Dwyer, L.M., Hmel, C., Mumb, D.fF., Wng, X.L., Ntis, L., Smith, D.L Root contrst enhncement for mesurement with opticl scnner-bsed imge nlysis. Cn. J. Bot. 79,

7 Giovnneti, M., Mosse, B An evlution of techniques for mesuring vesiculr-rbusculr mycorrhizl infection in roots. New Phytologist. 84,