Plant Growth Regulators in Spring Wheat. Anne Kirk, Craig Linde, and Pam de Rocquigny. Manitoba Agriculture

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1 Plnt Growth Regultors in Spring Whet Anne Kirk, Crig Linde, nd Pm de Roquigny Mnito Agriulture Lodging is mjor rop prodution issue, espeilly in high yielding environments. Yield losses n rnge from 5 to 40%, with the gretest losses ourring when lodging ours ten dys to two weeks following hed emergene. When the rop lodges erly in the seson, efore full stem elongtion, plnts my reover y elowing to n upright position. One the rop hs flowered, heds will not regin n upright position. Lodging n e mnged through vriety seletion nd gronomis. Crop vrieties vry in their resistne to lodging, with stem length, thikness of stem internodes, root struture, nd hed density nd shpe ffeting resistne to lodging. Produers re enourged to review lodging rtings in Seed Mnito when seleting vrieties. Seeding nd nitrogen rtes lso ply role in lodging. Internode shding inreses with inresing plnt popultions, whih n inrese internode elongtion nd rete tller, weker stems. High nitrogen rtes n hve similr effet with exessive tillering leding to inresed internode shding nd elongtion. Plnt growth regultors (PGRs) re nother mngement tool used to redue lodging. PGRs re syntheti ompounds tht lter hormonl tivity to modify plnt growth nd development. PGRs re used to improve rop stndility, s they re intended to produe shorter, thiker, nd stronger stems. There re two min groups of PGRs, ethylene relesing ompounds nd gierellin inhiitors. Gierellin inhiitors suh s Mnipultor (tive ingredient hlormequt hloride) re the more ommon type of PGR in Western Cnd. The effets of PGRs re not well known. There re reports of PGRs inresing yield, s well s reports of PGRs using stem elongtion nd reduing yield. The ojetive of this projet is to demonstrte the effets of PGR pplition on spring whet height nd yield. Methods Trils were onduted t the rop diversifition enters in Portge, Melit, nd Arorg in 2015, nd in Melit nd Arorg in Three spring whet vrieties were plnted t eh site, Wskd (CWRS, tll), AAC Brndon (CWRS, semi-dwrf), nd AAC Penhold (CPSR). In 2016 fourth vriety, Prosper (CNHR), ws lso plnted. Tretments inluded no PGR (hek), mnipultor t idel timing (GS 31), split pplition of mnipultor (GS nd GS31), nd n unregistered PGR PGR B (GS 31). Plnt height nd yield dt were olleted in oth yers of the tril.

2 Height (m) Results Plnt Height PGRs redued plnt height in ll vrieties in oth yers of the tril. On verge, the single nd split pplitions of Mnipultor redued plnt height y 7 m in 2015 nd 8 m in PBR B redued plnt height y n verge of 5 m in 2015 nd 7 m in 2016 (Figure 1 nd 2). In 2015 there ws no signifint height intertion etween vriety nd PGR tretment. In 2016 Wskd, the tller vriety, hd greter height redution with single pplition of Mnipultor thn AAC Brndon, AAC Penhold, nd Prosper. Chek Mnipultor Mnipultor split PGR B AAC Brndon AAC Penhold Wskd Averge Figure 1. Impt of PGR pplition on height of three spring whet vrieties nd verge height in Sttistilly signifint differenes re shown y letters ove the rs. Tretments within the sme yer with the sme letter re not signifintly different ().

3 HEIGHT (CM) Chek Mnipultor Mnipultor split PGR B AAC Brndon AAC Penhold Wskd Prosper Averge Figure 2. Impt of PGR pplition on height of four spring whet vrieties nd verge height in Sttistilly signifint differenes re shown y letters ove the rs. Tretments within the sme yer with the sme letter re not signifintly different (). Yield Averged ross ll vrieties, PGR pplition did not inrese yield in either yer of the study. In 2015, PGR pplition did not inrese yield for ny individul vrieties. In 2016, single pplition of Mnipultor resulted in 4 u/re yield inrese in Wskd ut did not inrese yield in the other vrieties. (Figure 4). Yield dereses with PGR pplition were oserved in oth yers of the study. Averged ross ll vrieties, in 2015 the split pplition of Mnipultor resulted in 3 u/re yield derese from the hek tretment (Figure 3). The split pplition of Mnipultor resulted in yield derese ompred to the hek tretment in AAC Brndon nd AAC Penhold in 2015, ut there ws no signifint yield derese with PGR pplition for Wskd. The single pplition of Mnipultor nd pplition of PGR B resulted in signifint yield derese ompred to the hek in AAC Brndon in 2015, ut not for AAC Penhold or Wskd (Figure 3). Averged ross ll vrieties, in 2016 PGR B resulted in 3 u/re yield derese from the hek tretment (Figure 4). Applition of PGR B resulted in yield derese ompred to the hek in AAC Brndon nd AAC Penhold in 2016, ut not for Wskd nd Prosper. Both the single nd split pplitions of Mnipultor resulted in yield derese in AAC Penhold in 2016, nd the single pplition of Mnipultor resulted in yield derese when pplied to Prosper (Figure 4).

4 Yield (u/) Yield (u/) Chek Mnipultor Mnipultor split PGR B AAC Brndon AAC Penhold Wskd Averge Figure 3. Impt of PGR pplition on yield of three spring whet vrieties nd verge yield in Sttistilly signifint differenes re shown y letters ove the rs. Tretments within the sme yer with the sme letter re not signifintly different (). Chek Mnipultor Mnipultor split PGR B AAC Brndon AAC Penhold Wskd Prosper Averge Figure 4. Impt of PGR pplition on yield of four spring whet vrieties nd verge yield in Sttistilly signifint differenes re shown y letters ove the rs. Tretments within the sme yer with the sme letter re not signifintly different ().

5 Conlusions In oth yers of the study miniml lodging ourred t the tril lotions nd in most instnes there ws no yield enefit to pplying PGRs. In 2016, single pplition of Mnipultor resulted in signifint yield inrese in Wskd ompred to the hek. Wskd is the tllest vriety inluded in this study, nd in 2016 more lodging ws oserved in Wskd thn the shorter vrieties. PGR pplition redued height of Wskd y 8 to 16 m on verge in 2016, whih my hve resulted in less lodging nd ould ount for higher yields. PGR pplition redued plnt height of ll vrieties, whih in the event of lodging, would e expeted to redue lodging nd inrese yield potentil. The results of this study re onsistent with other reserh tht hve showed inonsistent yield enefits with PGR pplition. PGRs n e used s risk mngement tool to redue lodging in high input systems, ut nnot e expeted to show onsistent positive yield response. Aknowledgements The stff t the Priries Est Sustinle Agriulture Inititive In. (PESAI) in Arorg, Westmn Agriulturl Diversifition Orgniztion (WADO) in Melit, nd Agriulture nd Agri-Food Cnd (AAFC) in Portge L Pririe were ruil to the suess of this projet.