The International Journal of Biotechnology

Transcription

1 The Interntionl Journl of Biotechnology journl homepge: NUTRIENT CONCENTRATION OF FORAGE SORGHUM (SORGHUM BICOLOR L) VARIETIES UNDER INFLUENCED OF SALINITY AND IRRIGATION FREQUENCY Sberi A. R Member of scientific bord of Agriculturl & Nturl Science Reserch Center of Golestn Province, Gorgn, Irn Siti Aishh H. Deprtment of Crop Science, University Putr Mlysi Serdng, Selngor, Mlysi ABSTRACT The responses of forge sorghum [Sorghum bicolor (L.)Moench] vrieties to slinity nd irrigtion frequency were studied from December 2008 to December 2009 t Universiti Putr Mlysi. Two slt tolernt vrieties of forge sorghum, nmely Speedfeed nd KFS4, were grown under slinity levels of 0, 5, 10, 15 ds m -1 nd irrigted when the lef wter potentil reched -1(control),-1.5 nd -2 MP. Slinity nd irrigtion frequency significntly (P 0.01) ffected nutrient concentrtion of forge sorghum vrieties tested. The fctoril tretment combintions were rrnged in rndomized complete block design with three replictions.sodium content decresed 7 nd 17% mong the irrigtion frequency tretments of -1.5 nd -2 MP, respectively. Abrupt increses in N contents were noticed t 5 nd 10 ds m -1 slinity when N ccumultion incresed 4 to 9 fold. Potssium diminished 29, 38 nd 54% under 5, 10 nd 15 ds m -1 slinity tretment respectively, nd decresed 4 nd 10% with increse in wter stress to -1.5 nd -2 MP respectively. Accumultion of K +, C 2+ nd Mg + in the shoots ws strongly inhibited by slinity.slinity substntilly reduced plnt growth s reflected by decrese in the dry forge yields, nd percent of mortlity t high slinity levels. The mximum dry forge yields were 45.1, 38.9, nd 38.5 g plnt 1 for frequent, intermedite, nd infrequent irrigtion regimes, respectively. Bsed on slinity, the forge dry weight in control plnts hd the highest yield (44.09 g plnt 1 ), while plnts under the high slinity tretment gve the lowest yield (32.76 g plnt 1 ). Keywords: Slinity, Irrigtion frequency, Nutrient concentrtion, Forge sorghum. 1. INTRODUCTION Abiotic stress is commonly known to reduce griculturl production (Slvov nd Georgiev, 2002). This includes soil slinity which ffects plnt growth nd development by wy of osmotic stress, injurious effects of toxic N + nd Cl ions, nd to some extent Cl nd SO 4 2 of Mg 2+, nd nutrient imblnce cused by excess of N + nd Cl ions. Slinity nd wter stress responses re multigenic, s number of processes re involved in the tolernce mechnisms (Sirm nd Tygi, 2004), such s vrious comptible solutes/osmolytes, polymines, rective oxygen species nd ntioxidnt defense mechnisms, ion trnsport nd comprtmentliztion of injurious ions. The sh content in plnts vries with species. It rnged from below 10% in the shoots of the excluders, to over 40% in the shoots of the vrieties which ccumulted high minerl levels. It incresed with increse in slinity of up to certin concentrtion depending on the species (Almodres et l., 2008). 163

2 Slt in soil nd wter cn reduce wter vilbility nd this cn led to stressful conditions for plnts. Wter stress restricts crop yields, prticulrly in the rid nd semi-rid zones. However, cultivtion of crop plnts under slinity nd wter stress conditions is unvoidble nd normlly prcticed in developing countries (Munns, 2002). Sorghum hugely importnt to developing countries it hs greter slt nd drought tolernces thn other summer forges. There re number of potentil forge sorghum vrieties which my be pproprite for vrious slinity levels of sewter, but the levels of slt tolernce mong most of the currently grown forge sorghum vrieties hve not been dequtely chrcterized (Qdir nd Oster, 2004). Informtion vilble on the effects of slinity nd wter deficit on shoot minerl concentrtion of forge sorghum cultivrs is lcking. We tested the growth nd nutritionl responses of sorghum to slinity nd drought stress, s sorghum is often grown under drought conditions in high slinity soils. Slt (NCl) nd drought ffect the wter sttus differentilly with respect to ech other. This study ws designed to investigte the effect of these biotic stresses on importnt physiologicl processes closely connected with the mechnisms of dptbility of sorghum to environmentl fctors. The current evlution ttempts to chrcterize two vrieties nd improve irrigtion mngement prctices for sline rble lnds tht my be considered uncultivble. The specific objectives of this study were: To determine shoot nutrient concentrtion nd biochemicl responses of forge sorghum vrieties to slinity nd irrigtion frequency. 2. MATERIALS AND METHODS The experiment ws conducted under rin shelter t University Putr Mlysi (02ºN ºE 2.867, 51m ltitude), from December 2008 to December The climtic conditions recorded under the rin shelter were 30 C men temperture, 90% humidity, 4.5 mm evportion nd 72.5% light t 12 m. Two selected (Foumn et l., 2003) slt tolernt vrieties, nmely Speedfeed nd KFS4, of forge sorghum [Sorghum bicolor (L.) Moench] were subjected to the slinity levels of 0, 5, 10 nd 15 ds m -1 of NCl concentrtions, nd irrigted when the lef wter potentil reched -1(control),-1.5 nd -2MP. The tretments were rrnged in rndomized complete block design with three replictions. Polybgs (40 cm 45 cm) were filled with mixture of top soil, pet moss nd snd t the rtio of 3:2:1 (v/v), respectively. The soil mixture hd ph of 5.4. During mixing, 60 g of CCO 3, 10 g complete fertilizer (15% N, P 2 O 5, K 2 O), 1 g of triple super phosphte (45% P 2 O 5 ) nd 2.4 g of ure (46% N) were dded to ech polybg. Soil field cpcity (FC) nd permnent wilting point (PWP) were mesured before nd fter the end of the experiment. The plnts were irrigted with nonsline wter for seedling estblishment nd with sline wter strting from the 2 weeks fter germintion ccording to the tretments. The mount of wter required for the irrigtion of ech tretment ws clculted using the following eqution:v= SMD A (Aslm et l., 2008) Where: V= volume of wter to be pplied (litre); A= polybg re rח= 2 SMD = ( FC - i ) D Bd /100: SMD = Soil Moisture Deficit FC = grvimetric soil moisture content t field cpcity (%) i = Soil moisture content before irrigtion (%); D = rooting depth (cm) Bd =bulk density (in this soil 1.5 g cm -3 ). Plnts were hrvested t the pre flowering stge nd wshed with deionized wter. Smples for nutritive qulity were stored frozen (t 0 C) nd sme prt of 72 smples of them were dried for lbortory nlysis during September to December Fully expnded lef (8th lef from soil surfce) nd stem smples from ech vriety were dried in the oven t 70 C for 72 hours prior to minerl nutrient nlysis. Oven-dried shoot (mix of stem 164

3 nd lef). smples were ground, digested nd nlyzed for N +, K +, C ++, nd Mg ++ using n Atomic Absorption Spectrophotometer (Perkin Elmer, 3110, USA). Dt were nlyzed using SAS Institute (2004) by proc.glm. Mens test ws performed using LSD (P 0.05). 3. RESULTS 3.1. Shoot Sodium Concentrtion (N) Sodium (N) content vried significntly (P 0.05) mong the slinity nd irrigtion frequency, interction of vrieties nd irrigtion frequency, interction of vrieties nd slinity s well s interction of irrigtion frequency nd slinity. Sodium content between the two sorghum vrieties ws not significntly different. The two vrieties responded significntly to slinity levels with 50, 70 nd 75% increse of sodium content t slinity levels of 5, 10 nd 15 ds m -1 respectively. Sodium content decresed 7 nd 17% mong the irrigtion frequency tretments of -1.5 nd -2 MP, respectively. Abrupt increses in N contents were noticed t 5 nd 10 ds m -1 slinity when N concentrtion incresed 4 to 9 fold (Tbles 1, 2 nd 3) Shoot Potssium Concentrtion (K) Potssium (K) content in shoots of the forge sorghum vrieties vried significntly due to slinity, irrigtion frequency nd interction of vriety nd wter stress tretments. Potssium ws the bundnt nutrient in shoots which under slinity rnging from to 4.63 mg g -1 DW, diminished 29, 38 nd 54% under 5, 10 nd 15 ds m -1 slinity tretment, respectively. K content in shoots decresed 4 nd 10% with increse in wter stress to -1.5 nd -2 MP, respectively (Tbles 1 nd 2) Shoot Potssium/Sodium (K/N) Rtio The effects of different slinity nd irrigtion frequency levels s well s interction of both tretments on shoot K/N rtio of forge sorghum were significnt. The K/N rtio decresed 89, 96 nd 98% with incresing slinity to 5, 10 nd 15 ds m -1, respectively nd 18% reduction observed t irrigtion frequency of -2 MP (Tble 1). Irrigtion frequency of -1 nd -1.5 MP did not show significnt effects on shoot K/N rtio of forge sorghum (Tble 3) Shoot Clcium Concentrtion (C) There ws significnt difference in C content of both forge sorghum vrieties between nonsline nd sline conditions, nd C content decresed 32, 46 nd 55% with incresing slinity to 5, 10 nd 15 ds m -1, respectively (Tble 1). KFS4 vriety hd slightly higher C content (4.42 mg g -1 DW) Shoot Mgnesium Concentrtion (Mg) The mgnesium (Mg) content in shoots of forge sorghum vrieties differed significntly due to irrigtion frequency nd slinity t P Mgnesium content in the lef nd stem tissue t highest slinity level (15 ds m -1 ) showed mximum reduction (76%) nd decreses t slinity 5 nd 10 ds m -1, were 36 nd 57% respectively. As wter stress enlrged from -1 MP to -1.5 nd -2 MP the mgnesium (Mg) content in shoots declined 14 nd 21%, respectively. The forge sorghum vrieties studied differed nd the highest Mg content ws found in KFS4 (2.75 mg g -1, DW). The trend in decresing Mg content with incresing slinity ws similr to C, nother divlent ion (Tble 1). 165

4 Tble-1. Sodium, potssium, clcium nd mgnesium content in shoots of forge sorghum vrieties following NCl nd irrigtion tretments. Tretments Sodium (mg g -1, DW) Potssium (mg g -1, DW) K/N Vriety KFS Speedfeed Clcium (mg g -1, DW) Mgnesiu m (mg g -1, DW) b Dry forge (g plnt - 1 ) b LSD Irrigtion frequency t LWP -1.0 (MP) 8.66 c t LWP b b b (MP) t LWP b b b (MP) b LSD Slinity (ds m -1 ) d c 7.06 b b b 4.40 b b 6.16 c c 39.79b bc 3.50 c c d 34.17c c 2.93 d LSD F vlue 2.03 ns 0.70 ns 4.37 * V I 4.99 * 3.25 * 0.61 ns V S 2.95 * 0.01 ns 0.69 ns I S 5.28 ** 0.37 ns 0.68 ns V I S 2.0 ns 0.74 ns 1.57 ns 0.41 ns 0.08 ns 0.03 ns 0.34 ns 1.06 ns 0.29 ns 0.50 ns 0.17 ns 0.70 ns MS error & CV Error CV (%) **, * nd ns re significnt t 0.01, 0.05 level nd non significnt, respectively Mens within columns followed by sme letters re not significntly different t 5% level (LSD Test) 166

5 Tble- 2.Vrietl differences in forge sodium nd potssium content s influenced by irrigtion frequency. Irrigtion frequency (MP) N (mg g -1, DW) K (mg g -1, DW) KFS4 Speedfeed KFS4 Speedfeed t LWP cd 8.39 d t LWP bc 9.01 cd t LWP b b LSD Mens within columns followed by sme letters re not significntly different t 5% level (LSD Test) Tble 3. Vrietl differences in forge sodium content nd potssium to sodium rtio s influenced by slinity. Slinity (ds m -1 ) N (mg g -1, DW) K/N rtio KFS4 Speedfeed KFS4 Speedfeed d 3.29 d c 7.69 c 1.16 b 1.06 b b b 0.35 b 0.36 b b 0.14 b LSD Mens within columns followed by sme letters re not significntly different t 5% level (LSD Test) 4. DISCUSSION In the present study Kcontent decresed nd N content incresed significntly with incresing slinity level (Tble 1). Although Mg content incresed significntly t the slinity levels of 5 to 15 ds m -1 nd irrigtion levels of -1.5 nd -2 MP in both forge sorghum vrieties, this might be due to the low entry of N without interfering with K selective chnnels or trnsporters. This would explin the high K/Nrtio (Tble 1). The K reduction ws pronounced in slinity stressed forge species over controls. These results could be explined in the following wys: (i) high externl N negtively ffects K cquisition due to similr physiochemicl properties of N nd K (Mthuis nd Amtmnn, 1999); (ii) KUP (potssium uptke permese)/hak (High Affinity K) trnsporters re extremely selective for Knd they re blocked by N when present in mm concentrtions (Snt-Mri et l., 1997); (iii) HKT1 (High Potssium Trnsporters) represents puttive pthwy for high ffinity K trnsport nd low ffinity N trnsport. At high N, HKT1 my be relevnt for N rther thn K uptke (Mthuis nd Amtmnn, 1999); (iv) mssive influx of N + into the cells vi non-selective ction chnnels (NSCCs) which occurs in the presence of excess N in typicl sline environments (Amtmnn nd Snders, 1999). Sodium (N) ion toxicity ppered unlikely in the two forge sorghum vrieties, which ws reflected in the shoot dry mtter yields nd lef firing. The results reveled tht tissue tolernce might be greter in some vrieties, but further studies re needed to clrify the bove issues (Hester et l., 2001). However, the ccumultion of osmolytes during stress is well documented. Severl studies hve demonstrted tht the dpttion to stress vries mong vrieties nd species. Kcr et l. (2002) indicted tht s slt concentrtion increses plnts tke up less wter nd the ion blnce (K ++ C ++ /N + ) in protoplsm is disrupted with the increse in N + ction nd Cl - nd SO4-2 nions, enzyme ctivity is depleted nd protein synthesis decreses. Slts in soil nd wter cn reduce wter vilbility to crops t ll stges of plnt development nd ffect physiologicl nd biochemicl processes vi ion toxicity, osmotic stress nd minerl deficiencies to such n extent tht yields cn be ffected (Hsegw et l., 2000; Munns, 2002). Irrigtion of the forge sorghums cn be delyed for bout two weeks till lef wter potentil reches -1.5 MP. Generlly, slinity tolernce is relted to mintining higher levels of K nd C, 167

6 becuse under sline condition these ions re involved in turgor control nd cell wll integrity, respectively (Crmer et l., 1985; Flowers nd Yeo, 1986; Wolf et l., 1991). This ws lso reflected in the present study with showing greter vlue of K nd C in KFS4 vriety however it ws not sttisticlly significnt. Osmotic djustment through synthesis of orgnic compounds hs been postulted to hve significnt role in slt tolernce (Mrcum nd Murdoch, 1994) Some studies showed; slinity tolernce is relted to mintining higher levels of K nd C, becuse under sline condition these ions re involved in turgor control nd cell wll integrity, respectively (Crmer et l., 1985; Flowers nd Yeo, 1986; Wolf et l., 1991). The results of the present study suggest involvement of dissimilr processes nd functions. The results showed tht both shoot-c nd shoot-k incresed with more frequent irrigtion. The responses in both shoot-c nd shoot-k to slinity were significntly liner nd liner response in dry mtter yield to lef-n ws lso observed. The present findings showed tht K + content not only stimulted the negtive effects of slinity on growth, but lso reduced dry mtter ccumultion prticulrly t low nd medium stress. This is in contrst to other studies which report meliortive effect of K + on slinity tolernce (Ottow nd Polle, 2005; Shirzi et l., 2005). Concentrtions of mjor ctionsviz. K, C nd Mg were found to decrese, but N content ws drsticlly incresed with incresing slinity levels. Dudeck nd Pecock (1985; 1993) lso reported tht incresing N ffected Mg nd K more thn C content in tissue of two forge sorghums vrieties studied. Clcium plys importnt roles in membrne integrity nd mintennce of ion selectivity for plnts (Mrschner, 1995). However, in the present study no significnt difference in shoot C content ws found between vrieties. The overll shoot K: N rtio ws highest in Speedfeed vriety. The reltive slt tolernce between species is relted to the mintennce of higher root growth nd high K: N rtio in the shoot (Storey nd Wyn Jones, 1979; Qin et l., 2001). It is cler tht minimum ccumultion of N is reflected by the mximum K: N rtio. Jcoby (1999) stted tht slt tolernce in plnts is generlly ssocited with low uptke nd ccumultion of N +, which is medited through the control of influx nd/or by ctive efflux from the cytoplsm to the vcuoles nd bck to the growth medium. Mny reserch groups reported tht slt tolernt plnts which re ion includers, often dpt to low wter potentils by ccumultion of inorgnic solutes to mintin turgor pressure nd totl wter potentil (Flowers et l., 1990; Alien et l, 2000). Due to limited knowledge on economic benefits in dopting corrective mesures, mny prefer to leve their lnds nd look for off-frm income employment. With incresing dependence of irrigted griculture on sline wter sources, effective strtegies cn be undertken to overcome/mitigte the dverse effects of different biotic stresses nd use lterntive sources of wter for irrigtion. This issue possibly gives fuzzy picture of the role of some spects of drought resistnce of sorghum, s crop equipped with severl mechnisms of drought tolernce (Abdul Mjid et l., 2007). 5. CONCLUSIONS The less nd lest frequent irrigtion s well s slinity significntly ffected shoot nutrient elements present, especilly with reduction in K nd incresing in N concentrtion. Mnging irrigted sline soils requires knowledge of slt tolernce in plnts. KFS4 vriety recorded higher vlues for yield (42.25 g plnt -1 ) compred to Speedfeed vriety which implies better resistnce or tolernce to drought nd slinity. The results obtined in this study would serve s useful guide for mnging forge sorghums in sline stressed field conditions. REFERENCES Abdul Mjid, S., R. Asghr nd G. Murtz, Potssium-clcium interreltionship linked to drought tolernce in whet (triticumestivum l.). Pk.J. Bot, 39(5): Alien, A., A. Altmn nd B. Heuer, Genotypic difference in slinity nd wter stress tolernce of fresh mrket tomto cultivrs. Plnt Sci, 152(1):

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