The performance of lowland rice (Oryza sativa L.) cultivars on iron toxic soil augmented with compost. O.A. Dada and J.A. Aminu

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1 Journl of Stress Physiology & Biohemistry, Vol. 9 No , pp ISSN Originl Text Copyright 2013 by Dd, Aminu ORIGINAL ARTICLE The performne of lowlnd rie (Oryz stiv L.) ultivrs on iron toxi soil ugmented with ompost O.A. Dd nd J.A. Aminu Deprtment of Botny, University of Ibdn, Ibdn, Nigeri *E-Mil: odd247@yhoo.om Reeived July 10, 2013 Performne of lowlnd rie grown on nerobi wetlnd soil is gretly ffeted by iron toxiity disorder in Nigeri. Better nutrient mngement nd ultivtion of resistnt vrieties hve been reommended s strtegy to mnge this nutrient disorder. Informtion on intrspeifi lowlnd NERICA ultivrs grown on iron toxi soil ugmented with ompost is snty. Therefore, the effet of different rtes of ompost on growth, dry mtter nd grin yield of lowlnd NERICA ultivrs grown on iron toxi soil ws investigted. A greenhouse experiment omprising of three (two NERICAs nd ITA 212) lowlnd rie ultivrs nd four vrying rtes of ompost rrnged in ompletely rndomized design with six replites ws onduted in greenhouse of Botny Deprtment, University of Ibdn. Dt olleted on growth nd yield prmeters were nlysed using ANOVA nd LSD t P Correltion nd simple liner regression were used to estlish reltionship between growth nd iron toxiity sores. Results showed tht iron toxiity signifintly (p 0.05) redued growth nd yield of lowlnd rie. Growth nd grin yield of NERICA ultivrs were signifintly better (P 0.05) on soil ugmented with ompost thn ontrol. Grin yield ws signifintly relted to the number of leves ffeted by iron toxiity. Cultivting lowlnd NERICA-L- 1 on iron toxi soil ugmented with 8t h -1 of ompost will enhne better growth, dry mtter hrteristis nd inrese lowlnd NERICA grin yield. Key words: Iron toxiity, lowlnd NERICA, ompost, wetlnd, grin yield

2 The performne of lowlnd rie (Oryz stiv L.) ultivrs... ORIGINAL ARTICLE The performne of lowlnd rie (Oryz stiv L.) ultivrs on iron toxi soil ugmented with ompost O.A. Dd nd J.A. Aminu Deprtment of Botny, University of Ibdn, Ibdn, Nigeri *E-Mil: Reeived July 10, 2013 Performne of lowlnd rie grown on nerobi wetlnd soil is gretly ffeted by iron toxiity disorder in Nigeri. Better nutrient mngement nd ultivtion of resistnt vrieties hve been reommended s strtegy to mnge this nutrient disorder. Informtion on intrspeifi lowlnd NERICA ultivrs grown on iron toxi soil ugmented with ompost is snty. Therefore, the effet of different rtes of ompost on growth, dry mtter nd grin yield of lowlnd NERICA ultivrs grown on iron toxi soil ws investigted. A greenhouse experiment omprising of three (two NERICAs nd ITA 212) lowlnd rie ultivrs nd four vrying rtes of ompost rrnged in ompletely rndomized design with six replites ws onduted in greenhouse of Botny Deprtment, University of Ibdn. Dt olleted on growth nd yield prmeters were nlysed using ANOVA nd LSD t P Correltion nd simple liner regression were used to estlish reltionship between growth nd iron toxiity sores. Results showed tht iron toxiity signifintly (p 0.05) redued growth nd yield of lowlnd rie. Growth nd grin yield of NERICA ultivrs were signifintly better (P 0.05) on soil ugmented with ompost thn ontrol. Grin yield ws signifintly relted to the number of leves ffeted by iron toxiity. Cultivting lowlnd NERICA-L- 1 on iron toxi soil ugmented with 8t h -1 of ompost will enhne better growth, dry mtter hrteristis nd inrese lowlnd NERICA grin yield. Key words: Iron toxiity, lowlnd NERICA, ompost, wetlnd, grin yield Nigeri hs wide rnge of rle rie growing environments inluding the inlnd vlleys (Singh et l., 1997). The inlnd vlley of West Afri whih overs 30% of the totl rie produing re is highly prone to iron toxiity (Audebert, 2006; Olleye et l 2009). Low lnd rie growing environment overs out 75% of Nigerin rie growing eosystems. Despite being the lrgest rie produer in West Afri, Nigeri is still rie-defiit ntion (Rhji nd Adewunmi 2008). One of the mjor onstrints to rie prodution in the inlnd vlleys of Nigeri is iron toxiity. Iron toxiity is nutritionl disorder using poor growth nd severe yield loss in West Afrin lowlnd rie field. This nutritionl disorder is often used by the mirobil redution under flooded onditions of insoluble iron-iii (Fe 3+ ) into soluble iron-ii (Fe 2+ ), whih n be tken up by rie plnts in exess mounts. Under the redutive effet of this environment, ertin soil teri rete nerobi respirtion (ATP synthesis)

3 Dd, Aminu 209 resulting in lrge quntity of ferrous ion (Fe 2+ ) solution (Ditt nd Shrwt, 2006, Ayeni, 2011). The soures of the iron ould be from the soil solution in the lowlnd itself or by nturl seepge or runoffs from djoining slopes. The Fe 2+ solution formed usully uses element disequilibrium in the soil solution, whih is trnsloted into plnt. Iron toxiity is hrterized by bronzing or yellowing of oldest rie leves whih often led to retrdtion of growth ftors espeilly plnt height, tillering potentils s well s higher level of pnile sterility. Redution in rie produtivity hs been reported to be diretly proportionl to onentrtion of Fe 2+ in the solution nd the tolerne of the ultivr type (Msjo et l., 1986; Abfrin, 1989 nd Audebert et l., 2006). Report of Audebert (2006) reveled tht this problem n be solved with the development of tolernt vrieties, the use of pproprite ropping systems, fertilizer pplition nd wter mngement. However, there re still number of hllenges tht deserve urgent ttention in iron toxiity inidene in lowlnd rie in Nigeri. Ditt nd Shrwt (2006) reported tht pplition of nutrients suh s N, P, K nd Zn ould help in ontrolling hrmful effet of iron toxiity on rie field. Nonetheless, fertilizer utiliztion mong poor resoure rie growers is still below the reommended rte. Quntity of fertilizer pplied espeilly to rle rops by Nigerin frmers hs been generlly sub-optiml (Philips et l., 2009). A report hs lso shown tht fertilizer per pit onsumption in Nigeri t 9 kg/h is one of the lowest in sub-shrn Afri (CARD, 2009). This is premised upon vilility nd ffordility of this input, onsequently lowlnd rie ultivtion in Nigeri is still fed with deleterious effet of iron toxiity resulting from defiient nutrient mngement. Another mens of ontrolling iron toxiity is by ultivting resistnt vriety. However, the new lowlnd NERICA lines re yet to be widely tested under iron toxiity stressed environments. If fertilizer uptke s well s plnting resistnt vrieties tends to minimize the toxi effet of exess iron on growth nd grin yield; it is not ler if ugmenttion of iron toxi soil with ompost derived from ttle dung + mize stover will help in mitigting the effets of iron toxiity on lowlnd NERICA ultivrs. Therefore this study ws onduted to exmine the effet of ompost on growth, biomss nd grin yield of two lowlnd NERICA nd ITA 212 rie ultivrs grown on iron toxi soil in Nigeri. MATERIALS AND METHODS Study site The study ws pot experiment rried out in greenhouse of the Deprtment of Botny, Fulty of Siene, University of Ibdn, Ibdn between August - Deember, The experimentl re is loted t N nd E t n elevtion of 215m ove the se level. One hundred nd ninety two poly pots of 14 m dimeter with 18.5 m depth were eh filled with 3kg soil olleted from vlley bottom known to show iron toxiity fetures. Composting Compost ws prepred from ombintion of ttle dung nd mize stover. Cttle dung ws olleted t the Fulty of Veterinry Mediine while mize stover ws olleted from tehing nd reserh frm, both sites loted in the University of Ibdn, Ibdn. The ompost ws prepred bsed on C:N rtio of 3:1using hep method desribed by Oworu nd Dd (2009). Soil olletion Soil used for the study ws olleted from vlley

4 210 The performne of lowlnd rie (Oryz stiv L.) ultivrs... bottom long Awolowo Hll Strem, University of Ibdn. The soil showing Fe toxiity symptoms (substnes tht looks like oil spills in the flood wter nd reddish stins in the soil) ws olleted with spde within 0 15 m depth. The soil ws ir-dried under shde before nlysis. Compost nd soil nlysis At 75 dys fter preprtion, mtured ompost smple ws tken to lortory for physiohemil nlysis fter being ir-dried t Deprtment of Agronomy, University of Ibdn, Ibdn. Soil nd ompost smples were nlysed for ph s desribed by MLen (1982); totl Nitrogen using miro Kjeldhl proedure followed by distilltion desribed by Bremner nd Mulvney (1982); Orgni Crbon using the method desribed by Wlkley (1947); Aville potssium nd sodium by flme photometry; phosphorus nd extrtle tions suh s C 2+, Mg 2+ nd Fe 2+ by Atomi Absorption Spetrophotometer (AAS). Also soil physil properties like snd, silt, ly nd bulk density were lso determined. Proedures desribed by IITA (2002) were dopted in determining the physil nd hemil properties of the two smples. Compost pplition nd iron toxiity simultion Eh pot ws filled with 3kg of soil nd rrnged in ompletely rndomized design. Eh designted pot ws inorported with 0g, 6g, 12g nd 18g of ompost equivlent to 0, 4, 8 nd 12t h - 1 per tretment week prior to sowing. To ensure toxiity, 3000mg of FeSO 4.7H 2 O ws dissolved in 1 litre of distilled wter s desribed by Olleye et l. (2009). The pots were wtered to field pity with 250 ml of the 3000mg L -1 of Fe solution 24 hours before sowing. The pots were regulrly flooded with the solution every other dy. Plnting mterils NERICA-L-1, NERICA-L-2 nd ITA 212 were obtined from Afri Rie Centre, Ibdn substtion loted within Interntionl Institute of Tropil Agriulture (IITA), Ibdn. The two NERICA ultivrs re lowlnd rie ultivrs with snty informtion on their response to iron toxiity wheres ITA 212 is lowlnd rie ultivr suseptible to iron toxiity. Tretments nd experimentl design There were 12 tretments derived from ombintion of three lowlnd rie ultivrs (NERICA-L-1, NERICA-L-2 nd ITA 212) nd four ompost rtes (0, 4, 8, nd 12 th -1 ). The 12 tretments were rrnged in ompletely rndomized design (CRD) nd replited six times. There were two plnts per tretment in eh replite. Sowing nd pot mngement Six seeds were sown per pot through diret drilling. Two Weeks After Sowing (WAS), the seedlings were thinned to two plnts per pot. Eh pot ws kept weed free s weeds were removed regulrly. Dt olletion Growth dt Dt were olleted on number of leves nd tillers formed by visul ounting; plnt height ws determined by mesuring from the bse to the tip of the tllest lef t the middle of the plnt. Lef Are (LA) ws mesured by mesuring the length nd mximum width of eh lef in the middle tiller nd ompute the re of eh lef bsed on the length-width method : LA = K x L x W. Where LA = Lef Are, K = 0.75 t vegettive stge nd 0.67 t the mturity stge. L = length of lef nd W = mximum width of lef (Gomez, 1972).

5 Iron toxiity sore (ITS) Dd, Aminu orgni mtter (46gkg -1 ) nd plnt nutrients The iron toxiity sore ws bsed on ITS evlution sore of Interntionl Rie Reserh Institute (IRRI, 1984) on 9 point sle. Where 1 = Very helthy nd 9 = extremely suseptible. Dry mtter At physiologil mturity when 90% of the pniles hve turned yellow, eh plnt ws uprooted per pot. The root portion ws wshed under flowing tp to remove ll soil prtiles. The plnts were seprted into shoot nd root portions nd spred on work benh to ir dry for six hours. The ir dried plnt smples were oven dried t 70 0 C to onstnt weight. Yield dt Dt were olleted on the number of pniles, number of tillers, number of effetive tillers nd grin yield (g/plnt). Sttistil nlysis Anlysis of vrine (ANOVA) ws used to nlyse the dt nd differenes in mens were seprted with lest signifint differene (LSD) t P 0.05 using Sttistil Anlysis System softwre Version 9. (SAS, 2002). Correltion nd simple regression nlyses were mde by relting grin yield to growth nd ITS prmeters. The model expressing the reltionship between grin yield (Y) nd independent vriles ws s given below: Y = f(x 1, x 2, x 3, x 4, x 5, e 1 ), Where: Y= grin yield, x 1 = Number of leves with iron toxiity symptoms, x 2 = Plnt height, x 3 = Number of effetive tillers, x 4, = Number of tillers, x 5, = Iron toxiity sore, e 1 = Error term. RESULTS Tle 1 show the results of physil nd hemil hrteristis of ompost nd soil (0-15m) used for the study. The ompost is rih in espeilly N (4.6gkg -1 ), P (15.3 mgkg -1 ) nd K (0.62 molkg -1 ) whih were higher thn those found in the soil used for the study. Growth response of lowlnd rie on toxi soil mended with ompost is presented in Tle 2. The results revel tht there were signifint differenes in the growth responses of the three rie ultivrs to vrying rtes of ompost pplied to mend the iron toxi soil. NERICA-L-2 hd signifintly highest number of leves in soil ugmented with 8t h -1 of ompost t the vegettive stge while NERICA-L-1 hd highest leves in soil mended with 12t h -1 of ompost t the reprodutive stge. However t mturity stge ITA 212 ultivr grown on soil ugmented with 8t h -1 ompost hd signifintly highest number of leves but not signifintly different from NERICA- L-1 ultivr grown on pot mended with 12t h -1 of ompost. Growth response of the three rie ultivrs inresed with inrese in ompost rte where better performne ws observed on higher ompost rtes between 8 12t h -1. Lef formed ws signifintly enhned by ugmenttion of iron toxi soil with ompost s miniml lef formtion ws observed in the ontrol plnts. Lef formtion ppered diretly proportionl to the rte of ompost pplied. At the erlier growth stge, the performne of newly introdued NERICA ultivrs ws better on ompost ugmented pots thn the suseptible ITA 212 ultivr whose performne peked t the senesene growth stge (Tle 2). This ould be linked to erly mturity trit of the NERICA ultivrs whih ould hve mde it possible for these improved ultivrs to espe the effet of iron toxiity in suh soil environment before it beomes intense. The performne of the three ultivrs with

6 212 The performne of lowlnd rie (Oryz stiv L.) ultivrs... respet to lef re showed tht NERICA-L-1 hd highest lef re ross the three growth stges in soils ugmented with ompost rtes rnging from 8 12t h -1. The performne of three ultivrs ws poor in ontrol plnts s it reltes to lef re overge (Tle 2). The results suggest tht plnts with higher lef re vlues re better in performne s result of the ility to pture solr energy nd ultimtely serve s n effiient soure for ssimilte prtitioning thn those of ontrol with low lef re. Hene the negtive effet of iron toxiity on lef re my hve diret influene in reduing ssimilte prtitioning into sink of the plnt. Applition of ompost to lowlnd rie ultivrs grown on toxi soil hd no signifint influene on plnt height of the rop t the vegettive growth phse. However, pplition of vrying ompost rtes hd signifint effet on height of the three lowlnd rie ultivrs t reprodutive nd mturity stges. NERICA-L-2 hd tllest plnts in soil ugmented with 8t h -1 of ompost t reprodutive. At the erly vegettive stge where no signifint differene ws notied implies tht the iron toxiity effet is not likely to hve hrmful effet on rie t the logrithmi phse. Shortest plnts were observed in ontrol soil whih suggests tht iron toxiity retrds rie growth s reported by Audebert (2006), Olleye et l. (2009). The response of the rop to ompost pplition on iron toxi soil with respet to height suggests tht ompost possesses some growth promoting substnes tht tend to enhne stem elongtion, whih is very importnt morphologil trit needed for suessful rie ultivtion in hydromophi environment. Tiller formtion ws dversely ffeted by iron toxiity s observed in the ontrol soil. Tiller prodution ws signifintly influened by ompost pplition. NERICA-L-2 nd ITA 212 hd the highest tillers in pots mended with 8t h -1. Highest tiller formtion ws observed in soil mended with 8t h - 1 in ll the three ultivrs lthough this observtion ws not signifintly different from tht in plnts ugmented with other ompost rtes (Tle 2). It therefore mens tht tiller formtion in iron toxi soil n be promoted by ompost pplition. This my be linked to the ility of orgni mtter omponent of the pplied ompost to promote better ertion nd retention of moisture while inresing buffering nd exhnge pity of soils thereby suppressing the deleterious effet of ferrous solution on the plnt growth (Weber, 1996, Arnon nd Edwrds 2005, Herviynti, 2006). Effet of ompost on biomss yield of the three rie ultivrs grown on iron toxi soil is shown in Tle 3. The results revel tht ompost pplition hd signifint effet on biomss yield of the three rie ultivrs. Shoot nd root biomss yield of ITA 212 ws signifintly highest in soil ugmented with 4t h -1 nd 12t h -1 of ompost respetively. Nonetheless, NERICA-L-1 grown in soil mended with 8t h -1 of ompost hd signifintly highest totl biomss yield. Lest biomss yield ws observed in unfertilized pots in ll the three ultivrs. Also, NERICA-L-1 soil ugmented with 8t h-1 hd the highest reltive growth rte of 0.11g dy -1 (Tle 3). The better biomss yield observed on ompost mended soil implies tht the ompost supplies suffiient nutrient for biomss umultion nd prtitioning for both biologil nd eonomi yield. It lso mens tht the ompost possibly serves s buffer in this idi soil whereby nutrient ontined in both soil nd ompost were possibly mde ville for neessry plnt metoli proess. The stedy growth rte observed in NERICA-L-1 plots fertilized with 8t h -1

7 Dd, Aminu 213 ompost implies tht ompost pplition to iron toxi soil n help redue the toxiity effet of dissolved Fe 2+ espeilly in wetlnd rie growing environment. Tle 4 presents the effets of ompost on yield nd yield omponents of lowlnd rie ultivted on iron toxi soil. Applition of 8t h -1 to NERICA-L-1 hd signifint effet on effetive tiller formtion, number of pniles nd grin yield. Wheres, highest hrvest index ws observed in NERICA-L-2 on soil mended with 8t h -1 of ompost, NERICA-L- 1 hd lest hrvest index in ontrol pots. Applition of ompost to iron toxi soil enhned yield nd yield omponents of lowlnd rie ultivrs. Highest grin yield observed in NERICA-L-1 grown in soil mended with 8t h -1 ompost indites tht the ultivr will perform optimlly under nerobi wetlnd soil when 8t h -1 of ompost is pplied. The ompost rte ppered optiml for this ultivr on iron toxi soil environment. Menwhile highest hrvest index obtined from lowlnd NERICA-L-2 soil nd higher hrvest index of NERICA-L-1 grown on soil ugmented with sme rte indites the superiority of newly developed NERICA ultivrs over ITA 212 suseptible hek. The iron toxiity evlution sore (ITS) s proposed by IRRI (1984) reveled tht ITA 212 hd signifintly highest (6.82) ITS but not signifintly different from NERICA-L-2 (6.65) in ontrol pots, while lest sore (3.76) ws observed in NERICA-L-1 pots ugmented with 12t h -1 ompost (Tle 5). Menwhile the suseptible ultivr, ITA 212 hd lest ITS on soil mended with 12t h -1 ompost. This implies tht effets of iron toxiity on lowlnd rie n be redued by pplying pproprite quntity of ompost. The newly relesed lowlnd NERICA ultivrs tested in this study ppered firly suseptible to iron toxiity nd its growth my be retrded by the influene of dissolved Fe 2+ solution under nerobi sitution. Nonetheless, ugmenting iron toxi soil with ompost my be relile solution to redue hrmful effets of iron toxiity in flooded rie growing res s ITS redued with inrese in the rte of ompost pplition. This grees with the report of Audebert (2006) on lowlnd rie ultivrs. The reltionship between ITS nd growth s well s yield ftors is presented in Tle 6. ITS is signifintly relted to number of leves (r = ) nd grin weight (r = 0.24). Thus suggesting tht severe ITS will led to redution in number of leves formed. Also, number of leves formed is signifintly relted to lef re (r = 0.63), number of tillers (r = 0.46) nd grin weight (r = -0.33). Similrly, plnt height is signifintly relted to number of tillers, grin weight nd effetive tillering. This implies tht the more the tillering nd effetive tillers the more the grin yield. Sine grin yield is signifintly relted to the number of effetive tillers, it is unlikely tht improving soil ondition to enhne tiller formtion will help in improving grin yield in lowlnd rie prodution. Therefore reduing iron toxiity effet by pplying ompost to lowlnd rie field will help in boosting rie prodution in inlnd vlleys of Nigeri. The regression results in Tle 7 shows the level of vrition in grin yield (Y) explined by the independent vriles. The two vriles tht hve sttistilly signifint oeffiients re number of leves with iron toxiity symptoms nd number of effetive tillers. The two vriles re sttistilly signifint t 5% nd 1% level of signifine respetively. Number of leves ffeted is negtively signed inditing tht unit inrese in this vrile will derese grin yield. This suggests

8 214 The performne of lowlnd rie (Oryz stiv L.) ultivrs... tht the more the leves formed is ffeted by iron toxiity the less the grin yield. The number of effetive tillers is signifintly relted to grin yield inditing tht the more the number of pnile with fertile spikelets the more the quntity of grin produed by the rop. Thus the lower the effet of iron toxiity on lef the better fertile tiller prodution beomes nd ultimtely, the better the grin yield. Tle 1. Physil nd hemil hrteristis of ompost nd soil (0-15m) used for the study. Prmeters Compost* Soil ph(h 2 O) ph(kcl) Silt (%) Nd 6.1 Cly (%) Nd 10.8 Snd (%) Nd 83.1 Bulk Density Nd 1.7 Orgni rbon (g/kg) Totl Nitrogen (g/kg) Aville P (mg/kg) Exhngele tions (mol/kg) N C Mg K Extrtle mironutrients (mg/kg) Fe *Dry weight bsis Nd: Not determined Tle 2. Growth response of lowlnd rie grown on iron toxi soil ugmented with ompost Number of leves Plnt height (m) Number of tillers Lef re (m 2 ) plnt -1 plnt -1 plnt -1 plnt -1 Tretments Veg. Rep. Mt. Veg. Rep. Mt. Veg. Rep. Mt. Veg Rep. Mt. NERICA-L-1 x 0t/h b d e d NERICA-L-1 x 4t/h d e NERICA-L-1 x 8t/h de NERICA-L-1 x 12t/h de NERICA-L-2 x 0t/h e NERICA-L-2 x 4t/h e NERICA-L-2 x 8t/h d 4.50 NERICA-L-2 x 12t/h de d ITA 212 x 0t/h b f d ITA 212 x 4t/h ef ITA 212 x 8t/h de ITA 212 x 12t/h de b 3.33 d Men LSD (0.05) Dt re mens of four plnts from six replites. Mens with similr lphets re not signifintly different t P>0.05 of LSD Veg. = Vegettive, Rep = Reprodutive nd Mt = Mturity

9 Dd, Aminu 215 Tle 3. Biomss yield of lowlnd rie grown on iron toxi soil ugmented with ompost Tretments Biomss yield (g) plnt -1 Reltive growth Shoot Root Totl rte (g dy -1 ) NERICA-L-1 x 0t/h 8.91f 5.37b NERICA-L-1 x 4t/h 9.54efd 5.73b NERICA-L-1 x 8t/h 10.64de 5.86b NERICA-L-1 x 12t/h 10.74d 5.91b d NERICA-L-2 x 0t/h 8.69f 5.34b NERICA-L-2 x 4t/h 9.04ef 5.35b NERICA-L-2 x 8t/h 9.91def 5.49b NERICA-L-2 x 12t/h 9.90def 5.55b d ITA 212 x 0t/h b e ITA 212 x 4t/h b ITA 212 x 8t/h ITA 212 x 12t/h Men LSD (0.05) Dt re mens of four plnts from six replites. Mens with similr lphets re not signifintly different t P>0.05 of LSD Tle 4. Yield nd yield omponents of lowlnd rie grown on iron toxi soil ugmented with ompost Tretments Number of effetive tillers plnt -1 Number of pniles plnt -1 Grin yield (g) plnt -1 Hrvest Index plnt -1 NERICA-L-1 x 0t/h f NERICA-L-1 x 4t/h NERICA-L-1 x 8t/h NERICA-L-1 x 12t/h NERICA-L-2 x 0t/h NERICA-L-2 x 4t/h d NERICA-L-2 x 8t/h NERICA-L-2 x 12t/h def ITA 212 x 0t/h 0.67b 1.33d ef ITA 212 x 4t/h 1.33b 1.67d def ITA 212 x 8t/h 1.00b 1.67d def ITA 212 x 12t/h 1.17b g Men LSD (0.05) Dt re mens of four plnts from six replites. Mens with similr lphets re not signifintly different t P>0.05 of LSD Tle 5. Iron toxi sore of lowlnd rie grown on iron toxi soil ugmented with ompost Tretments Iron Toxi Sore Interprettion NERICA-L-1 x 0t/h 5.15b Tolernt NERICA-L-1 x 4t/h 4.50b Tolernt NERICA-L-1 x 8t/h 4.08b Highly tolernt NERICA-L-1 x 12t/h 3.76b Highly tolernt NERICA-L-2 x 0t/h 6.65 Firly suseptible NERICA-L-2 x 4t/h 4.99 Tolernt NERICA-L-2 x 8t/h 4.81b Tolernt NERICA-L-2 x 12t/h 4.67b Tolernt ITA 212 x 0t/h 6.82 Firly suseptible ITA 212 x 4t/h 4.08b Highly tolernt ITA 212 x 8t/h 4.32b Highly tolernt ITA 212 x 12t/h 4.24b Highly tolernt Men 4.72 LSD (0.05) 1.84 Dt re mens of four plnts from six replites. Mens with similr lphets re not signifintly different t P>0.05 of LSD

10 216 The performne of lowlnd rie (Oryz stiv L.) ultivrs... Tle 6. Correltion oeffiients (r) mong different trits of lowlnd rie grown on iron toxi soil ugmented with ompost Iron toxiity sore Number of leves Plnt height (m) Lef re (m 2 ) Number of tillers Grin yield (g) Number of effetive tillers Iron toxiity sore 1.00 Number of leves * 1.00 Plnt height (m) Lef re (m 2 ) ** Number of tillers ** ** 0.34** 1.00 Grin yield (g) 0.24* ** ** * 1.00 Number of effetive tillers ** ** 0.71** 1.00 * Correltion is signifint t the 0.05 level (2-tiled), ** Correltion is signifint t the 0.01 level (2-tiled). Tle 7. Regression results of ftors ffeting grin yield on iron toxi soil ugmented with ompost Funtionl form B 0 x 1 x 2 x 3 x 4 x 5 R 1 Adj. R 2 F Liner * Stndrd error *Prmeter estimtor nd F vlue signifint t 5%, + Prmeter estimtor signifint t 1% CONCLUSION Iron toxiity hd signifint effet on growth nd yield of lowlnd rie. Growth nd yield is signifintly relted to severity of iron toxiity. Applition of ompost to iron toxi soil is good gronomi prtie tht ould be employed in reduing the deleterious effet of dissolved Fe 2+ in lowlnd rie growing environments. Applying higher tonne (8-12t h -1 ) of ompost per unit re will be benefiil to lowlnd rie ultivtion in inlnd vlleys thn lower rtes. Newly developed interspeifi lowlnd NERICA ultivrs ppered better option thn the suseptible ITA 212. In onlusion, this study reommends pplition of 8t h -1 to lowlnd NERICAL-L-1in iron toxi environment suh s inlnd vlleys, rinfed lowlnd, irrigted lowlnd, deepwter nd mngrove swmp. ACKNOWLEDGEMENT The uthors knowledge AfriRie Center for providing the seeds used for this study. The sholrly support reeived from Dr. F. Nwilene nd Professor A. O. Togun or AfriRie Center nd Deprtment of Crop Protetion nd Environmentl Biology, University of Ibdn respetively is highly ppreited. REFERENCES Abifrin, A. O. (1989). Progress in breeding rie for tolerne to iron toxiity. In: WARDA Annul Report Bouké, Côte d Ivoire: West Afri Rie Development Assoition. pp Arnon, N.Q. nd Edwrds, C.A. (2005). Effets of vermiomposts on plnt growth. Pper presented during the Interntionl Symposium Workshop on Vermi Tehnologies for Developing Countries (ISWVT 2005), Los Bnos, Philippines November 16-18, Audebert, A. (2006). Dignosis of risk nd pprohes to iron toxiity mngement in lowlnd rie frming. In Iron Toxiity in Riebsed Systems in West Afri. A. Audebert, L.T. Nrteh, P. Kiepe, D. Millr nd B. Beks (Eds.) Afri Rie Center (WARDA). Cotonou, Benin

11 Dd, Aminu 217 Ayeni, L.S. (2011). Integrted plnt nutrition mngement: pne for sustinle rop prodution in Nigeri. Interntionl Journl of Soil Siene 6(1): Bremner, J. M., Mulvney C. S. (1982). Nitrogen totl. p In A.L. pge (ed.), Methods of soil nlysis. Agron. No.9, prt 2: Chemil nd mirobiologil properties, 2 nd ed., Am. So. Agron., Mdison, WI, USA. Colition for Afrin Rie Development (CARD) (2009). Ntionl rie development strtegy (NRDS). 73p. Ditt, S. nd Shrwt, L.K (2006). Iron toxiity of rie in West Afri: Sreening tolernt vrieties nd the role of N, P, K nd ZN. In Iron Toxiity in Rie-bsed Systems in West Afri. A. Audebert, L.T. Nrteh, P. Kiepe, D. Millr nd B. Beks (Eds.). Afri Rie Center (WARDA). Cotonou, Benin Drozd J. nd Weber J. (1996). The role of humi substnes in the eosystem nd in environmentl protetion. Abstrts of the 8 Meeting of the Interntionl Humi Substnes Soiety. ISBN , PTSH Wrolw, 330 pp. Gomez, A.K. (1972). Tehniques for field experiments with rie. The IRRI, Philippines. 45 p. Herviynti, Teguh B.P, Fehri A, Amrizls. (2006). Humi id nd wter mngement to derese Ferro (Fe 2+ ) solution nd inrese produtivity of estlished new rie field. J Trop Soils, 7(1): 2012 : 9-17 IITA, (2002). Resoures nd rop mngement: IITA 2002 Annul Report, Ibdn. IRRI, (1984). Terminology for rie growing environments. Interntionl Rie Reserh Institute, Mnil. Msjo, T. M., Alluri, K., Abifrin, A. O nd Jnkirm, D. (1986). Breeding for high nd stle yields in Afri. In: The Wetlnds nd Rie in Sub-shrn Afri. A S R Juo nd J A Lowe (Eds). Interntionl Institute of Tropil Agriulture, Ibdn, Nigeri. pp MLen, E.O., (1982). Soil ph nd lime requirement. Pp , In A.L. pge (ed), methods of soil nlysis, prt 2 : hemil nd mirobiologil properties. Am. So. Agron. Mdison, WI, USA. Olleye, O. A; Ogunkunle, O.A; Singh, B. N; Odeleye, F.O; Dd, O.A nd Senjobi, B.A. (2009). Elementl omposition of two rie ultivrs under potentilly toxi on Aquept nd Aquent. Not. Si. Biol. 1(1): Oworu, O. O nd Dd, O. A. (2009). Influene of Compost on Growth, Nutrient Uptke nd Dry Mtter Aumultion of Grin Amrnths (Amrnthus hypohondrius. L.) on Oxi Pleulstlf. Nigeri Journl of Siene 43: 7-18 Phillips, D; Nkony, E; Pender, J nd Oni, O.A. (2009). Constrints to Inresing Agriulturl Produtivity in Nigeri: A Review. Nigeri Strtegy Support Progrm (NSSP) Bkground Pper No. NSSP Rhji, M.A.Y nd Adewumi, O. A. (2008). Mrket supply response nd demnd for lol rie in Nigeri: implitions for self-suffiieny poliy Journl of Centrl Europen Agriulture 9(3): SAS. (2002). Sttistil Anlysis System (Version 9) by SAS Institute In., Cry, NC, USA. Singh, B. N., Fgde, S., Ukwungwu, M. N., Willirn, C., Jgtp, S.S., Oldimeji, O., Effisue, A. nd Okhidievbie, O. (1997). Rie growing environments nd biophysil onstrints in

12 218 The performne of lowlnd rie (Oryz stiv L.) ultivrs... different gro-eologil zones of Nigeri. Meteorologil Journl 2(1): Wlkley, A. (1947). A Critil Exmintion of Rpid Method for Determintion of Orgni Crbon in Soils - Effet of Vritions in Digestion Conditions nd of Inorgni Soil Constituents. Soil Si. 63: