Biomass and Phosphorus Accumulation, Partitioning and Remobilization during Grain Development in Wheat under Phosphorus Deficiency

Transcription

1 INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY ISSN Print: ; ISSN Online: /21x/ DOI:.17957/IJAB/ Full Length Article Biomss nd Phosphorus Accumultion, Prtitioning nd Remoiliztion during Grin Development in Whet under Phosphorus Deficiency Muhmmd Irfn *, Muhmmd As, Jvid Ahmed Shh, Muhmmd Ahmed Akrm, Nizmuddin Depr nd Muhmmd Yousuf Memon Soil nd Environmentl Sciences Division, Nucler Institute of Agriculture (NIA) Tndojm-76, Pkistn * For correspondence: irfn1513_uf@yhoo.com Astrct We investigted the effect of phosphorus (P) deficiency on iomss nd P ccumultion, prtitioning nd remoiliztion in whet over the course of grin development period in pot study. Whet cultivr NIA-Sunder ws grown with P (6 mg kg -1 soil) nd without P (only ntive soil P i.e., 2.23 mg kg -1 soil) following completely rndomized design. Plnts were hrvested t nthesis nd susequently every 5 dys fter nthesis (DAA) up to mturity nd prtitioned into vrious orgns. The leves, chff, flg leves nd stems cted s P source wheres grins cted s P sink during grin development. The period of DAA ws the rpid phse of P ccumultion in grins under oth P tretments. Whet plnts remoilized 2.3 nd 1.52 g plnt -1 of pre-nthesis ccumulted iomss towrds grin, contriuting 6.22 nd 53.73% of grin yield under dequte nd deficient P, respectively. Likewise, nd 6.99 mg plnt -1 of pre-nthesis ccumulted P ws remoilized to grin which contriuted 84.7 nd 7.56% of grin P contents in P-fertilized nd P-deficient plnts, respectively. However, the post-nthesis P uptke mounted to only 9 nd 18% of totl P ccumultion t mturity under dequte nd deficient P, respectively. The results suggested tht P remoiliztion from vegettive tissues ws key mechnism contriuting significntly to grin P contents during grin development phse s post-nthesis P uptke from soil ws typiclly low. Moreover, P deficiency considerly diminished iomss nd P remoiliztion in whet therey influencing grin yield. 219 Friends Science Pulishers Keywords: Biomss remoiliztion; Pre-nthesis P ccumultion; Post-nthesis P uptke; Remoiliztion efficiency; Whet Introduction Phosphorus (P) is vitl element for plnt growth nd is mong the mjor drivers for glol crop productivity (Stewrt et l., 25). It is non-renewle element required for numerous physiologicl nd iochemicl processes within plnts (Fgeri et l., 213) nd is n essentil constituent of key iologicl molecules such s phosphte esters, ATPs, DNA, RNA, nd phospholipids (Wtne et l., 26). It is the second most limiting nutrient for sustinle crop productivity fter nitrogen (Brdy nd Weil, 28) nd its deficiency cn e found in nerly 67% rle soils round the gloe. In Pkistn, more thn 9% soils re deficient in ioville P primrily due to high clcium cronte contents, high se sturtion nd low orgnic mtter (Irfn et l., 218). Although totl P contents re undnt in most soils of the rid nd semi-rid regions worldwide, ut the plnt ville P frction in the soil solution is seriously low rnging from.1 µm only (Hlvin et l., 25; Hinsinger et l., 211). Plnts hve evolved n rry of morphologicl, physiologicl nd moleculr dptive mechnisms to cope with P-deficiency, such s ltered root rchitecture (Aziz et l., 25), higher root-shoot rtio nd root elongtion (Irfn et l., 217), enhnced croxylte exudtion (Aziz et l., 211), etter Pi uptke cpcity (Shen et l., 25), recycling of internl Pi (Ael et l., 22), reprioritizing metolic P utiliztion (Aziz et l., 215) nd remoilizing P from vegettive to reproductive orgns (As et l., 218). In cerels, ccumultion of P into grins is derived from two sources; post-nthesis P cquisition y plnt roots tht is trnsferred directly to grins, nd remoiliztion of P stored in vegettive prts prior to nthesis (Sntiveri et l., 24). Phosphorus uptke occurs throughout the plnt growth period nd continues until physiologicl mturity. During grin development, significnt P remoiliztion occurs from leves nd stems to developing grins (Btten, 1992). Similrly, the reserves ssimilted in vegettive prts efore nthesis my uffer grin yield ginst dverse conditions to current ssimiltion. Phosphorus is reltively moile element in plnts which cn move esily mong vrious orgns (Mrschner, 1995). Under stressed conditions, cycling of minerl nutrients i.e., re-trnsloction from shoot to roots vi phloem, nd recycling i.e., trnsloctions of cycled nutrients ck to the shoot vi xylem re significnt mechnisms for plnt growth. Phosphorus is either trnsported directly vi To cite this pper: Irfn, M., M. As, J.A. Shh, M.A. Akrm, N. Depr nd M.Y. Memon, 21x. Biomss nd phosphorus ccumultion, prtitioning nd remoiliztion during grin development in whet under phosphorus deficiency. Int. J. Agric. Biol. :

2 Irfn et l. / Int. J. Agric. Biol., Vol., No., 21x phloem or recycled through the roots to er vi xylem (Mrschner, 1995). However, the extent of circultion nd trnsloction of P mong vrious tissues modified t different developmentl phses in whet is still uncler. During vegettive nd erly reproductive phses in whet, cron (C) nd P re primrily ssimilted in the stems nd leves (Dords, 29). The effective stem reserve storge is usully determined y the growing conditions from seed germintion to nthesis. Much of these reserves re remoilized to developing grins representing significnt contriution to finl grin yield (Dords, 29). Remoiliztion of stored C nd P generlly depends on three fctors: () ility of genotype to store ssimiltes in vegettive prts until nthesis, () sink strength which is generlly dependent on spike length, numer of grins per spike nd grin size, nd (c) the efficiency with which the stored reserves re remoilized to grin which is influenced y the genotype nd environment (Fgeri nd Bligr, 1999; Prystup et l., 24; Pmpn et l., 27). Phosphorus ccumultion t nthesis differed mong crop genotypes, ut the genotypic vritions for totl P contents t nthesis re primrily ssocited with the differences in iomss ccumultion. Accumultion of P under optiml growing conditions is high while it declines under stress due to reduced cron ssimiltion (Blum, 1998). At mturity, whet grins re mjor sinks of P constituting upto 9% of the totl shoot P while 2 9% of this eing remoilized from other orgns (Btten nd Wrdlw, 1987). Most of the P uptke occurs y nthesis nd remoiliztion cn ccount upto 56 63% of totl grin P ccumultion t mturity (Msoni et l., 27). Contriution of pre-nthesis ssimiltes remoiliztion to grin yield vried from 7 57% (Ehdie nd Wines, 21), while contriution of P remoiliztion to grin P contents rnged from 11 % (Ppkost, 1994) depending upon genotypes, P vilility nd climte. Phosphorus prtitioning mong plnt orgns is lso ltered under P deficiency i.e., more preference is given to reproductive orgns t the expense of P contents of vegettive orgns (Dords, 29). Phosphorus uptke nd remoiliztion during grin development in whet hs received much less ttention in contrst to nitrogen. Therefore, the overll ojectives of the present study were to investigte the extent of iomss nd phosphorus ccumultion nd their prtitioning in whet plnts over the course of grin development under P-fertilized nd P-deficient conditions. Moreover, the effect of P-fertiliztion on remoiliztion of pre-nthesis ccumulted iomss nd phosphorus in vegettive tissues nd their contriution to grin yield nd grin P contents ws lso investigted. Mterils nd Methods Plnt Mteril nd Site Description Uniform nd helthy seeds of whet cultivr NIA-Sunder were otined from Plnt Breeding nd Genetics Division of Nucler Institute of Agriculture (NIA) Tndojm, Sindh Pkistn. The experiment ws conducted in net-house during Ri, under nturl conditions t NIA, Tndojm (Ltitude 25º North nd Longitude 68º Est). The climte of the study re ws rid with 136 mm verge nnul precipittion. The men dily mximum nd minimum tempertures during experiment were 27 nd 9.8 o C, respectively, men reltive humidity ws 54.9%, nd men sunshine ws 8. h dy -1, while men evportion ws 2.7 mm dy -1. The mximum totl rinfll (3. mm) ws recorded in Jnury, 217. The meteorologicl dt for the whole crop growth period (15 Novemer, Mrch, 217) is illustrted in Fig. 1. Bulk soil (15 cm surfce lyer) ws collected from experimentl frm re of NIA, Tndojm. A composite smple of respective soil ws ir dried nd grinded to pss through 2 mm sieve nd nlyzed for vrious soil physico-chemicl chrcteristics (Tle 1). Briefly, the selected soil ws silt lom in texture chrcterized s lkline in rection, high in ville potssium while low in orgnic mtter, nitrogen, nd ville phosphorus. Pot Experiment Plstic pots (19 cm dimeter, 3 cm depth) inner lined with polythene sheet were filled with seven kilogrm of thoroughly mixed soil. Experiment ws designed following completely rndomized design with fctoril rrngements. Soil in ech pot ws moistened with cnl wter prior to sowing of seeds for ttining pproprite moisture for seed germintion. Five seeds in ech pot were mnully sown nd fter seedling emergence; three plnts were mintined nd llowed to grow till mturity. Plnts were grown t two phosphorus levels; deficient P (without externl P ddition or only ntive soil P i.e., 2.23 mg kg -1 ) nd dequte P (ddition of P t the rte of 6 mg kg -1 soil). The required quntities of P ccording to tretment pln nd potssium t the rte of 3 mg kg -1 soil were pplied t the time of whet sowing while, nitrogen ws pplied t the rte of 7 mg kg -1 soil in three equl splits viz., t sowing, two, nd five weeks fter sowing. The fertilizer Ure (46% N), triple super phosphte (TSP, 46% P 2O 5) nd sulphte of potsh (SOP, 5% K 2O) were used s the source of nitrogen, phosphorus nd potssium, respectively. Pots were irrigted ccording to plnt requirements during the entire crop period. Plnts were hrvested t nthesis nd therefter every 5 dys fter nthesis (DAA) upto mturity from oth P levels. At ech hrvest, plnts were divided into stems, leves, flg leves, chff nd grins. Phosphorus Assy nd Estimtion of Remoiliztion Chrcteristics Plnt mteril ws dried in forced ir-driven oven t 7 o C for 72 h nd grinded to pss through.42 mm screen using Wiley s mill (3383L, Thoms Scientific, USA) fitted with stinless steel ldes. The totl P concentrtion in plnt mteril ws determined following yellow color method s descried y Chpmn nd Prtt (1961).

3 Rinfll (mm d -1 ) Influence of P-deficiency on Biomss nd P-remoiliztion / Int. J. Agric. Biol., Vol., No., 21x Tle 1: Selected physico-chemicl chrcteristics of soil used in experiment (-15 cm surfce soil) Soil chrcteristics Unit Vlue Method/ Reference Physicl chrcteristics Snd % Bouyoucos (1962) Silt % ~ Cly % ~ Texturl clss - Silt lom ~ Chemicl chrcteristics ph (1:2.5) - 8. Anderson nd Ingrm (1993) EC (1:2.5) ds m ~ Orgnic mtter %.83 Nelson nd Sommers (1982) Oxidizle Orgnic Cron %.36 ~ Totl Orgnic cron %.48 ~ Kjeldhl nitrogen %.4 Jckson (1962) AB-DTPA extrctle phosphorus mg kg Soltnpour nd Workmn (1979) AB-DTPA extrctle potssium mg kg ~ AB-DTPA extrctle zinc mg kg ~ AB-DTPA extrctle iron mg kg ~ AB-DTPA = mmonium icronte-diethylene trimine pent cetic cid Mx. nd min. temperture (ᵒC), reltive humidity (% d - 1 ), sunshine (h d -1 ) nd evportion (mm d -1 ) Rinfll Mximum temperture Minimum temperture Reltive humidity Sunshine Evportion Dys Fig. 1: Dily mximum nd minimum tempertures ( o C dy -1 ), reltive humidity (% dy -1 ), sunshine (hours dy -1 ), evportion (mm dy -1 ) nd rinfll (mm dy -1 ) during whole whet growing period from crop sowing to hrvesting Briefly, the plnt mteril (.3 g ech) ws wet digested in ml of di-cid mixture of nitric cid nd perchloric cid (5:1, v/v) in conicl flsk, kept overnight nd then plced on hot plte until cler solution ws otined. After digestion, volume ws mde upto ml with distilled wter nd then filtered. The ml of cler filtrte nd ml of mmoniumvndomolydte regent were used to develop yellow color. Totl P concentrtion ws determined y reding light sorption t 47 nm wvelength using spectrophotometer (U-29UV/VIS, Hitchi, Jpn). The vrious chrcteristics relted to iomss nd phosphorus remoiliztion within the whet plnts were derived ccording to Cox et l. (1986), Ppkost (1994), Ercoli et l. (28). Phosphorus Contents (PCt) PCt (mg plnt 1 ) = P concentrtion in pln tissue (mg g 1 ) Dry mtter (g plnt 1 ) Biomss Remoiliztion (BR) BR (g plnt 1 ) = Dry mtter t nthesis (Dry mtter of leves + culms + chff t mturity) Biomss Remoiliztion Efficiency (BRE) Biomss remoiliztion BRE (%) = Dry mtter t nthesis Contriution of Biomss Remoiliztion to Grin Yield (CBRG) Biomss remoiliztion CBRG (%) = Grin yield t mturity Phosphorus Remoiliztion (PR) PR (mg plnt 1 ) = P contents t nthesis (P contents of leves + culms + chff t mturity) Phosphorus Remoiliztion Efficiency (PRE) Phosphorus remoiliztion PRE (%) = P contents t nthesis

4 Irfn et l. / Int. J. Agric. Biol., Vol., No., 21x Contriution of Phosphorus Remoiliztion to Grin P Contents (CPRG) Phosphorus remoiliztion CPRG (%) = Grin P contents t mturity Sttisticl Anlysis The dt relting to iomss production, P ccumultion nd remoiliztion chrcteristics of whet under dequte nd deficient P tretments ws nlyzed sttisticlly using computer softwre STATISTIX 8.1 (Anlyticl Softwre, Inc., Tllhssee, FL, USA) ccording to the methods of Steel et l. (1997). Grphicl presenttion of dt ws crried out using Microsoft Excel (Redmond, WA, USA). A completely rndomized design with two fctors ws employed for nlysis of vrince nd lest significnt difference test t P.5 ws used to seprte differences mong tretment mens. Results Dry Mtter Prtitioning in Whet Plnts during Grin Development The dt pertining to dry mtter production y vrious prtitioned plnt prts i.e., stems, flg leves, leves, chff, nd grins throughout the grin development period is given in Tle 2. Whet plnts were hrvested t nthesis nd every 5 dys fter nthesis (DAA) up to 45 DAA from dequte nd deficient P tretments. Stem dry iomss continued to ccumulte from nthesis to mturity nd ws recorded mximum (5.7 nd 4.72 g plnt -1 ) on 3 DAA under dequte nd deficient P supply, respectively. The highest dry iomss of flg leves under dequte P (1.23 g plnt -1 ) nd deficient P (1.11 g plnt -1 ) ws oserved on 25 DAA. Likewise, leves dry mtter during grin development period reched to mximum (2.2 nd 1.77 g plnt -1 ) on 25 DAA t dequte nd deficient P, respectively. The chff dry mtter rnged from 1.5 g plnt -1 t nthesis to 2.75 g plnt -1 on 2 DAA under dequte P nd.64 g plnt -1 t nthesis to 2.41 g plnt -1 on 25 DAA under P deficiency. Grin weight continued to increse with time nd ws influenced gretly y the P levels. Mximum grin weight under dequte P (4.31 g plnt -1 ) ws recorded on 45 DAA which ws sttisticlly identicl to 4.23 g plnt -1 on 4 DAA. Similrly higher grin weight of 3.46 g plnt -1 ws recorded on 45 DAA under P deficiency tht ws t pr to grin weight on 35 nd 4 DAA. Averged over ll hrvestings from nthesis to mturity, dry mtter prtitioning to vrious prts of whet plnts under oth P tretments ws in the order of stem > grin > chff > leves > flg leves. Tissue P Concentrtion nd Redistriution during Grin Development Phosphorus concentrtion [P] locted into different vegettive tissues (i.e., stems, flg leves, leves nd chff) continued to decline throughout the period of grin development under oth P supplies, however [P] in grins continued to incresed till mturity (Tle 3). The [P] in ove ground vegettive prts ws higher in P-fertilized plnts compred to P-deficient plnts nd followed similr pttern of reduction under oth P tretments. The men [P] in vegettive tissues ws in the order of flg leves (2.4 nd 1.66 mg g -1 ) > stems (2.1 nd 1.5 mg -1 ) > chff (1.87 nd 1.47 mg g -1 ) > leves (1.68 nd 1.14 mg g -1 ) under dequte nd deficient P, respectively. Under dequte P supply, [P] in stems, flg leves, leves nd chff decresed grdully from nthesis to 25 DAA nd then declined shrply till mturity. In P-deficient plnts, [P] in vegettive tissues decresed grdully from nthesis to 3 DAA nd then reduced shrply upto 45 DAA. The [P] in grins ws higher on DAA nd ws reltively lower in susequent dys until mturity in oth P tretments. The vrious oveground plnt prts growing with P ddition hd round 2-fold higher P contents thn plnts with P-deficiency (Tle 4). Stem P contents continued to increse grdully from nthesis to 2 DAA nd then declined until mturity under oth P levels. The flg leves, other leves nd chff ccumulted mximum P contents on 15 2 dys of grin development nd then illustrted decresing trend until mturity under oth P tretments. The significnt increse in grin P contents ws oserved t oth P levels which continued to increse upto mturity. The men grin P contents of P-fertilized plnts were lmost 1.5-fold higher compred with those of P- deficient Plnts (11.62 vs mg plnt -1 ). The verge P contents in oveground prts followed the order of grin (11.62 nd 8.26 mg plnt -1 ) > stems (7.76 nd 4.47 mg plnt -1 ) > chff (3.86 nd 2.54 mg plnt -1 ) > leves (2.93 nd 1.76 mg plnt -1 ) > flg leves (2.13 nd 1.49 mg plnt -1 ) under dequte nd deficient P, respectively. Biomss nd Phosphorus Accumultion in Whet t Anthesis nd Mturity Phosphorus deficiency cused significnt (P.5) reduction of iomss production nd P ccumultion in whet plnts t nthesis nd mturity (Fig. 2 nd 3). The iomss of oveground prts (stem + leves) of P-fertilized plnts t nthesis ws 7.76 g plnt -1 s compred to 5.36 g plnt -1 in P-deficient plnts. At mturity, strw iomss in P- fertilized plnts ws 5.47 g plnt -1 while it ws 3.84 g plnt -1 in P-deficient plnts. Grin yield ws reduced in reltion to P deficiency (2.84 g plnt -1 ) nd incresed in response to P ddition (3.85 g plnt -1 ). Totl oveground iomss (strw + grin) t mturity ws 9.31 g plnt -1 in P-fertilized nd 6.68 g plnt -1 in P-deficient plnts. The P contents in vegettive prts t nthesis were 2-fold higher in P-fertilized plnt s compred to P-deficient plnts. Similr pttern ws lso oserved for strw nd grin P contents t mturity.

5 Influence of P-deficiency on Biomss nd P-remoiliztion / Int. J. Agric. Biol., Vol., No., 21x Tle 2: Dry mtter prtitioning (g plnt -1 ) in vrious plnt prts of whet cultivr NIA-Sunder during grin development period under dequte nd deficient P levels. Vlues re mens of three replictes Stem dry mtter Flg leves dry mtter Leves dry mtter Chff dry mtter Grin dry mtter DAA P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient 2.36 j 1.54 k.76 j.6 k 1.28 hi 1.15 i 1.5 k-m.64 m i 2.4 jk 1.1 d-g.82 ij e 1.51 e-h 1.93 d-h.92 lm hi 2.96 i d.99 e-h c 1.65 c-f 1.99 c-g 1.74 f-j d-f 3.58 gh c 1.6 -f e c f.59 fg.33 g cd 3.9 e-g c-f e e.94 f.63 fg d e e d 1.66 e 1.41 e c d 1.3 c-f d 1.61 c-g e 2.85 cd 2.64 d c-e 3.83 e-g.93 f-i.87 g-j 1.69 c-e 1.57 d-g 1.86 e-i 1.57 g-k c e-g 3.63 f-h.85 h-j.8 ij 1.62 c-g 1.4 f-i 1.49 g-k 1.32 j-l c e-g 3.6 gh.84 h-j.79 ij 1.4 f-i 1.37 g-i 1.45 h-l 1.4 i-l Men LSD.5 (T) LSD.5 (P) LSD.5 (T P) DAA = dys fter nthesis; T = time (i.e., DAA); P = phosphorus levels; T P = interction etween time nd P levels. Mens shring identicl letter(s) in the sme column indicte non-significnt differences (LSD test, P.5) Tle 3: Phosphorus concentrtion [P] (mg g -1 ) in vrious nlyzed plnt prts of whet cultivr NIA-Sunder during grin development period under dequte nd deficient P levels. Vlues re mens of three replictes [P] in stem [P] in flg leves [P] in leves [P] in chff [P] in grins DAA P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient c-e c c c d-f cd cd d-f d 2.3 d-f cd 2.79 c 2.24 e c-e 2.48 c-e 2.2 ef cd 2.41 de 1.94 f c d-f 2.1 f 1.43 g 1.7 cd 1.14 e-g 2.34 e 1.85 f 4.7 -c d c 1.38 e-g 2.16 f 1.49 g 1.36 d-f 1.3 fg 1.79 f 1.5 g c e cd 1.3 f-h 2.8 f 1.39 gh 1.41 c-e.85 gh 1.51 g 1.35 g d-f g-i 1.2 h-j 1.45 g.98 ij.97 g.58 h.79 h.65 hi e 3.9 d-f g-j.91 i-k 1.11 hi.7 jk.95 g.55 h.69 h.56 h-j 4.17 c-e 3.83 ef jk.64 k.77 jk.58 k.86 gh.61 h.41 ij.32 j 4. d-f 3.57 f Men LSD.5 (T) LSD.5 (P) LSD.5 (T P) DAA = dys fter nthesis; T = time (i.e., DAA); P = phosphorus levels; T P = interction etween time nd P levels. Mens shring identicl letter(s) in the sme column indicte non-significnt differences (LSD test, P.5) Tle 4: Phosphorus contents (mg plnt -1 ) in vrious plnt prts of whet cultivr NIA-Sunder during grin development period under dequte nd deficient P levels. Vlues re mens of three replictes P contents in stem P contents in flg lef P contents in leves P contents in chff P contents in grins DAA P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient P dequte P deficient 6.36 de 2.56 hi 2.19 d 1.63 e d 2. f-h 3.5 gh 1.7 ij d 3.23 hi d 4. -c 2.44 e-g hi c 4.64 fg d d-f 5.51 c 3.91 ef e cd de de 3.4 fg 1.52 g e 2.44 cd 1.49 e 3.4 cd 1.99 f-h de 4.38 ef 2.85 fg c 6.17 e 2.64 c 1.64 e 2.75 d-f 1.83 g-i 4.78 cd 3.63 e-g 7.79 d 6.11 de c 6.12 e 2.37 cd 1.43 e 2.58 e-g 1.36 h-l 3.95 ef 3.13 f-h c ef 3.88 f-h 1.34 e.85 fg 1.64 h-j.9 j-l 1.45 jk 1. j-l f-h 3.29 g-i.92 f.56 gh 1.55 h-k.77 l.98 j-l.74 kl c hi 2.31 i.65 f-h.45 h 1.21 i-l.83 kl.6 l.45 l c Men LSD.5 (T) LSD.5 (P) LSD.5 (T P) DAA = dys fter nthesis; T = time (i.e., DAA); P = phosphorus levels; T P = interction etween time nd P levels. Mens shring identicl letter(s) in the sme column indicte non-significnt differences (LSD test, P.5)

6 Biomss production (g plnt -1 ) Irfn et l. / Int. J. Agric. Biol., Vol., No., 21x Fig. 2: Biomss production of whet cultivr NIA-Sunder t the time of nthesis (i.e., strw) nd mturity (i.e., strw, grin nd totl) under dequte nd deficient P levels. Vlues re mens of three replictes. For ech prmeter, rs not shring identicl letter(s) indicte significnt differences mong ech other t two P levels (LSD test, P.5). LSD vlues for strw iomss t nthesis = 1.27; strw iomss t mturity =.97; grin yield t mturity =.89; totl iomss t mturity = 1.98 Phosphorus contents (mg plnt -1 ) Fig. 3: Phosphorus contents of whet cultivr NIA-Sunder t the time of nthesis (i.e., strw) nd mturity (i.e., strw, grin nd totl) under dequte nd deficient P levels. Vlues re mens of three replictes. For ech prmeter, rs not shring identicl letter(s) indicte significnt differences mong ech other t two P levels (LSD test, P.5). LSD vlues for strw P contents t nthesis = 2.48; strw P contents t mturity = 1.1; grin P contents t mturity = 1.77; totl P contents t mturity = 3.2 The strw P contents t nthesis vried from mg plnt -1 under dequte P to 12.6 mg plnt -1 under P deficiency. At mturity, grin nd strw P contents were nd mg plnt -1 in P-fertilized, while 9.79 nd 5.62 mg plnt -1 in P-deficient plnts, respectively. Biomss nd Phosphorus Remoiliztion Strw Strw Grin Totl Anthesis Adequte P Deficient P The dt regrding iomss nd P remoiliztion under dequte nd deficient P supply hs een illustrted in Fig. 4 nd 5. Biomss remoiliztion nd the contriution of prenthesis ssimilted iomss to grin yield were higher in P-fertilized plnts s compred to P-deficient plnts. Mturity Strw Strw Grin Totl Anthesis Adequte P Deficient P Mturity Biomss remoiliztion in plnts with dequte P ws 34% higher those of P-deficient plnts (2.3 vs g plnt -1 ). Biomss remoiliztion efficiency ws not ffected significntly with P tretments nd vried from 29.57% in P- fertilized plnts to 28.44% in P-deficient plnts. The contriution of pre-nthesis ssimilted iomss to grin weight ws 11% higher in plnts growing with dequte P (6.22%) compred to P-deficient plnts (53.73%). Phosphorus remoiliztion ws 47% higher in P-fertilized plnts thn P-deficient plnts ( vs mg plnt -1 ). The P remoiliztion efficiency in P-deficient plnts ws slightly higher thn P-fertilized plnts (54.72 vs %). The remoiliztion of pre-nthesis ccumulted P contriuted 84.7 nd 7.56% to grin P contents t mturity under dequte nd deficient P, respectively. Discussion The prime ojectives of the present study were to investigte how phosphorus deficiency influences the iomss nd P ccumultion, prtitioning into vrious plnt tissues nd remoiliztion in whet during grin development. In current study, phosphorus deficiency cused significnt decline in dry mtter ssimiltion nd further prtitioning into vrious plnt tissues s reported in erlier investigtions (Demots- Minrd nd Jeuffory, 21; Prystup et l., 24). Elliot et l. (1997) hve reported tht iomss production nd lloction of ssimiltes to reproductive orgns is directly influenced y the P supply (Elliot et l., 1997). Previling growth conditions nd genotypes lso contriute gretly to influence dry iomss etween nthesis to mturity in winter whet (Dords et l., 28). Whet is known to remoilize its pre-nthesis storge of ssimiltes to grin upto 73% (Ppkost nd Ggins, 1991) nd 57% (Ehdie nd Wines, 21). We found in present study tht remoiliztion of pre-nthesis ssimiltes contriuted 6.24 nd 53.67% of grin yield t dequte nd deficient P, respectively. The contriution of pre-nthesis ssimiltes to grin is importnt to sustin grin yield under unfvorle circumstnces limiting photosynthesis, nutrients nd wter uptke (Yoshid, 1972; Arduini et l., 26). Remoiliztion of ssimiltes fcilittes the plnts to withstnd restricted production of photosynthtes under stressed situtions (Siddique et l., 1989). A key fctor regrding the roles of ssimilte reserves in grin filling is the loss of cron either from vegettive tissues or developing grins tht is ssocited with respirtion. Phosphorus deficiency my impir mitochondril respirtion nd lter cron metolism in mny plnts (Vnce et l., 23). Aout one third of the reduction of crohydrtes from stem during grin filling could e ttriuted to respirtory losses in whet (Wrdlw nd Willenrink, 1994). The cron reserves in leves nd stems re the prominent contriutor to grin filling in whet s tller plnts owing to their higher storge cpcity hve greter potentil to support grin filling for longer period (Blum, 1998).

7 Influence of P-deficiency on Biomss nd P-remoiliztion / Int. J. Agric. Biol., Vol., No., 21x Biomss remoiliztion Fig. 4: Biomss remoiliztion (BR), iomss remoiliztion efficiency (BRE) nd contriution of iomss remoiliztion to grin yield (CBRG) of whet cultivr NIA-Sunder under dequte nd deficient P levels. Vlues re mens of three replictes. For ech prmeter, rs not shring identicl letter(s) indicte significnt differences mong ech other t two P levels (LSD test, P.5). LSD vlues for BR =.49; BRE = 1.58; CBRG = 6.7 Phosphorus remoiliztion Adequte P Deficient P BR (g per plnt) BRE (%) CBRG (%) Adequte P Fig. 5: Phosphorus remoiliztion (PR), phosphorus remoiliztion efficiency (PRE) nd contriution of phosphorus remoiliztion to grin P contents (CPRG) of whet cultivr NIA-Sunder under dequte nd deficient P levels. Vlues re mens of three replictes. For ech prmeter, rs not shring identicl letter(s) indicte significnt differences mong ech other t two P levels (LSD test, P.5). LSD vlues for PR = 2.38; PRE = 3.41; CPRG = 3.98 At nthesis, phosphorus concentrtion [P] in oveground vegettive tissues of P-deficient plnts ws significntly lower thn P-fertilized plnts. While the [P] locted in vrious plnt prts continued to decline throughout the grin development under oth P supplies. The reduction in [P] followed the order s flg leves < stems < chff < leves, wheres [P] in grins incresed. The decline in [P] of vegettive tissues during the period from nthesis to mturity is the indiction of P remoiliztion towrds grin (Juli et l., 216). Ppkost (1994) stted tht the reduction in [P] is usully slow during erly plnt growth nd ecomes extensive t lter stges. Thus, dely in P remoiliztion until Deficient P PR (mg per plnt) PRE (%) CPRG (%) the lter stges of senescence could e key mechnism responsile for ensuring continuous ccumultion of iomss nd photosynthtes throughout the grin filling. The synchroniztion of P decline from vegettive tissues seems prudent to fcilitte min photosynthetic orgns such s flg leves to crry on function optimlly for s long s possile (Bertheloot et l., 28). Whet plnts employed such types of strtegies in reltion to nitrogen lloction for photosynthetic tissues during grin development (Bertheloot et l., 28; Wng et l., 216). The period of DAA ws the rpid phse of P ccumultion in grins under oth P tretments. However, the P contents of oveground prts were incresed y 48% (t nthesis) nd 43% (t mturity) with P ddition. In contrst, pek loding of P into rice grins occurs from 6 15 dys fter flowering (Wng et l., 216). The mesure of the ility of crop to trnsport P from vegettive tissues to grin cn e expressed s remoiliztion efficiency (Muurinen et l., 27). The P remoiliztion in current study ws noticed higher in P-fertilized thn P-deficient plnts. Although the P remoiliztion efficiency ws sttisticlly identicl in oth tretments ut the contriution of pre-nthesis P remoiliztion to grin ws gretly influenced y the P tretments nd recorded higher in P-fertilized plnts (7.53 vs %). Dords (29) estimted the contriution of ssimilted P trnslocted to seed in the rnge of % in whet. The efficiency of genotype to remoilize P reserves (source) to grins (sink) during grin development is genetic controlled trit nd my vry mong different genotypes (As et l., 218). Therefore, this phenomenon might e the reson ehind non-significnt effect of P supplies on remoiliztion efficiency. In some cses, remoiliztion efficiency ecomes stle cross genotypes nd environments. When post-nthesis P uptke is cesed, erly senescence nd limited photosynthetic ctivity results in enhnced remoiliztion from vegettive tissues (Brottin et l., 25; Kong et l., 213). This suggests tht whet tend to rely hevily on remoiliztion of P from vegettive orgns during grin development indicting tht post-nthesis P uptke from soil is typiclly low. Similr findings hve lso een reported in other crops such s durum whet nd rice (Msoni et l., 27; Dords, 29; Juli et l., 216). In contrst, flooded rice ppers to e different in which post-flowering P uptke from soil during grin filling is criticl contriutor (4 7%) to the grin P contents (Juli et l., 216). Conclusion Phosphorus ccumultion in whet grins origintes from two sources i.e., post-nthesis P uptke from soil y plnt roots, nd P remoiliztion from eril prts. In current study, the period of DAA ws the rpid phse of P ccumultion in whet eing grins s strong P sink while vegettive prts (flg leves < stems < chff < leves) cts s source of P during grin development.

8 Irfn et l. / Int. J. Agric. Biol., Vol., No., 21x Post-nthesis P uptke contriuted only 9 18% of totl P contents t mturity. Therefore, P remoiliztion from vegettive tissues ws key mechnism which contriuted gretly to grin P contents during grin development s postnthesis P uptke from soil ws diminutive. Phosphorus deficiency lso decresed whet grin yield y reducing the remoiliztion of pre-nthesis ccumulted iomss nd P reserves in different tissues. References As, M., J.A. Shh, M. Irfn nd M.Y. Memon, 218. Remoiliztion nd utiliztion of phosphorus in whet cultivrs under induced phosphorus deficiency. J. Plnt Nutr., 41: Ael, S., C.A. Ticconi nd C.A. Deltorre, 22. Phosphte sensing in higher plnts. Physiol. Plnt., 115: 1 8 Anderson, J.M. nd J.S.I. Ingrm, Tropicl Soil Biology nd Fertility. CAB Interntionl, Wllingford, UK Arduini, I., A. Msoni, L. Ercoli nd M. Mriotti, 26. Grin yield, nd dry mtter nd nitrogen ccumultion nd remoiliztion indurumwhet s ffected y vriety nd seeding rte. Eur. J. Agron., 25: Aziz, T., D. Steffens, Rhmtullh nd S. Schuert, 211. Vrition in phosphorus efficiency mong rssic cultivrs II: Chnges in root morphology nd croxylte exudtion. J. Plnt Nutr., 34: Aziz, T., H. Lmers, D. Nicol nd M.H. Ryn, 215. Mechnisms for tolernce of very high tissue phosphorus concentrtions in Ptilotus polystchyus. Plnt Cell Environ., 38: Aziz, T., Rhmtullh, M.A. Mqsood nd T. Mnsoor, 25. Differences in phosphorus sorption, trnsport nd utiliztion y twenty rice (Oryz stiv L.) cultivrs. Pk. J. Agric. Sci., 42: 8 13 Brottin, A.C., C. Lecomte, C. Bouchrd nd M.H. Jeuffroy, 25. Nitrogen remoiliztion during grin filling in whet: genotypic nd environment effects. Crop Sci., 45: Btten, G.D. nd I.F. Wrdlw, Senescence nd grin development in whet plnts grown with contrsting phosphorus regimes. Aust. J. Plnt Physiol., 1: Btten, G.D., A review of phosphorus efficiency in whet. Plnt Soil, 146: Bertheloot, J., P. Mrtre nd B. Andrieu, 28. Dynmics of light nd nitrogen distriution during grin filling within whet cnopy. Plnt Physiol., 148: Blum, A., Improving whet grin filling under stress y stem reserve moiliztion. Euphytic, : Bouyoucos, G.J., Hydrometer method improved for mking prticle size nlysis of soils. Agron. J., 54: Brdy, N.C. nd R.R. Weil, 28. The Nture nd Properties of Soils, 14 th edition. Prentice Hll, Upper Sddle River, New Jersey, USA Chpmn, H.D. nd P.F. Prtt, Methods of Anlysis for Soils, Plnts nd Wters. University of Cliforni, Division of Agriculturl Science, Riverside, USA Cox, M.C., C.O. Qulset nd D.W. Rins, Genetic vrition for nitrogen ssimiltion nd trnsloction in whet. III. Nitrogen ssimiltion in reltion to grin yield nd protein. Crop Sci., 26: Demots-Minrd, S. nd M.H. Jeuffroy, 21. Prtitioning of dry mtter nd nitrogen to spike throughout the spike growth period in whet crops sujected to nitrogen deficiency. Field Crops Res., 7: Dords, C., 29. Dry mtter, nitrogen nd phosphorus ccumultion, prtitioning nd remoiliztion s ffected y N nd P fertiliztion nd source - sink reltions. Eur. J. Agron., 3: Dords, C.A., A.S. Lithourgidis, T. Mtsi nd N. Bryinnis, 28. Appliction of liquid cttle mnure nd inorgnic fertilizers ffect dry mtter, nitrogen ccumultion, nd prtitioning in mize. Nutr. Cycl. Agroecosyst., 8: Ehdie, B. nd J.G. Wines, 21. Sowing dte nd nitrogen rte effects on dry mtter nd nitrogen prtitioning in red nd durum whet. Field Crops Res., 73: Elliot, D.E., D.J. Reuter, G.D. Reddy nd R.J. Aot, Phosphorus nutrition of spring whet (Triticum estivum L.). 1. Effects of phosphorus supply on plnt symptoms, yield, components of yield, nd plnt phosphorus uptke. Aust. J. Agric. Res., 48: Ercoli, L., L. Lulli, M. Mriotti, A. Msoni nd I. Arduini, 28. Postnthesis dry mtter nd nitrogen dynmics in durum whet s ffected y nitrogen supply nd soil wter vilility. Eur. J. Agron., 25: Fgeri, N.K. nd V.C. Bligr, Phosphorus-use efficiency in whet genotypes. J. Plnt Nutr., 22: Fgeri, N.K., A. Moreir nd A. dos Sntos, 213. Phosphorus uptke nd use efficiency in field crops. J. Plnt Nutr., 36: Hlvin, J., J.D. Beton, S.L. Tisdle nd W.L. Nelson, 25. Soil Fertility nd Fertilizers. Person Eduction, Inc., Upper Sddle River, New Jersey, USA Hinsinger, P., E. Betencourt, L. Bernrd, A. Brumn, C. Plssrd, J. Shen, X. Tng nd F. Zhng, 211. P for two, shring scrce resource: Soil phosphorus cquisition in the rhizosphere of intercropped species. Plnt Physiol., 156: Irfn, M., J.A. Shh nd M. As, 217. Evluting the performnce of mungen genotypes for grin yield, phosphorus ccumultion nd utiliztion efficiency. J. Plnt Nutr., 4: Irfn, M., M. As, J.A. Shh nd M.Y. Memon, 218. Grin yield, nutrient ccumultion nd fertilizer efficiency in red whet under vrile nitrogen nd phosphorus regimes. J. Bsic Appl. Sci., 14: 8 86 Jckson, M.L., Soil Chemicl Anlysis, pp: Englewood Cliffs, NJ: Prentice Hll Inc Juli, C., M. Wissuw, T. Kretzschmr, K. Jeong nd T. Rose, 216. Phosphorus uptke, prtitioning nd redistriution during grin filling in rice. Ann. Bot., 118: Kong, X., Z. Luo, H. Dong, A.E. Eneji, W. Li nd H. Lu, 213. Gene expression profiles deciphering lef senescence vrition etween erly nd lte senescence cotton lines. PLoS One, 8: e69847 Mrschner, H., Minerl Nutrition of Higher Plnts. Sn Deigo, CA: Acdemic Press Msoni, A., L. Ercoli, M. Mriotti nd I. Arduini, 27. Post - nthesis ccumultion nd remoiliztion of dry mtter, nitrogen nd phosphorus in durum whet s ffected y soil type. Eur. J. Agron., 26: Muurinen, S., J. Kleemol nd P. Peltonen-Sito, 27. Accumultion nd trnsloction of nitrogen in spring cerel cultivrs differing in nitrogen use efficiency. Agron. J., 99: Nelson, D.W. nd L.E. Sommers, Totl cron, orgnic cron nd orgnic mtter. In: Methods of Soil Anlysis, Agronomy, No. Prt 2: Chemicl nd Microiologicl Properties, 2 nd edition, pp: Pge, A.L., R.H. Miller nd D.R. Keeney (eds.). Americn Society of Agronomy, Mdison, Wisconsin, USA Pmpn, M., M. Mriotti, L. Ercoli nd A. Msoni, 27. Accumultion nd remoiliztion of dry mtter, nitrogen nd phosphorus in durum whet s ffected y genotype nd environment. Itl. J. Agron., 14: 3 13 Ppkost, D.K. nd A.A. Ggins, Nitrogen nd dry mtter ccumultion, remoiliztion, nd losses for Mediterrnen whet during grin filling. Agron. J., 83: Ppkost, D.K., Phosphorus ccumultion nd trnsloction in whet s ffected y cultivr nd nitrogen fertiliztion. J. Agron. Crop Sci., 173: Prystup, P., R. Svin nd G.A. Slfer, 24. Grin numer nd its reltionship with dry mtter, N nd P in the spike t heding in response to N P fertiliztion in rley. Field Crops Res., 9: Sntiveri, F., C. Royo nd I. Romgos, 24. Growth nd yield responses of spring nd winter triticle cultivted under Mediterrnen conditions. Eur. J. Agron., 2: Shen, J., H. Li, G. Neumnn nd F. Zhng, 25. Nutrient uptke, cluster root formtion nd exudtion of protons nd citrte in Lupinus lus s ffected y loclized supply of phosphorus in split-root system. Plnt Sci., 168: Siddique, K.H.M., R.K. Belford, M.W. Perry nd D. Tennnt, Growth, development nd light interception of old nd modern whet cultivrs in Mediterrnen type environment. Aust. J. Agric. Res., 4:

9 Influence of P-deficiency on Biomss nd P-remoiliztion / Int. J. Agric. Biol., Vol., No., 21x Soltnpour, P.N. nd S. Workmn, Modifiction of the NHCO 3 DTPA soil test to omit cron lck. Commun. Soil Sci. Plnt Anl., : Steel, R.G.D., J.H. Torrie nd D.A. Dicky, Principles nd Procedures of Sttistics-A Biometricl Approch, pp: McGrw-Hill Book Inter. Co., Singpore Stewrt, W.M., D.W. Di, A.E. Johnston nd T.J. Smyth, 25. The contriution of commercil fertilizer nutrients to food production. Agron. J., 97: 1 6 Vnce, C.P., U.S. Cludi nd L.A. Deorh, 23. Phosphorus cquisition nd use: criticl dpttion y plnts for securing nonrenewle resource. New Phytol., 157: Wng, F., T. Rose, K. Jeong, T. Kretzschmr nd M. Wissuw, 216. The knowns nd unknowns of phosphorus loding into grins, nd implictions for phosphorus efficiency in cropping systems. J. Exp. Bot., 67: Wrdlw, I.F. nd J. Willenrink, Crohydrte storge nd moiliztion y the culm of whet etween heding nd grin mturity: the reltion to sucrose synthse nd sucrose-phosphte synthse. Func. Plnt Biol., 21: Wtne, T., M. Oski, H. Yno nd I.M. Ro, 26. Internl mechnisms of plnt dpttion to luminum toxicity nd phosphorus strvtion in three tropicl forges. J. Plnt Nutr., 29: Yoshid, S., Physiologicl spects of grin yield. Ann. Rev. Plnt Physiol., 23: (Received 21 Mrch 218; Accepted 18 Septemer 218)