Effects of different concentrations of NPK fertilisers on growth and development of wild okra (Corchorus olitorius)

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1 AGRICULTURE AND BIOLOGY JOURNAL OF NORTH AMERICA ISSN Print: , ISSN Online: , doi:1.5251/jn , ScienceHuβ, Effects of different concentrtions of NPK fertilisers on growth nd development of wild okr (Corchorus olitorius) Themkzi K. Ginindz*, Michel T. Msrirmi, Pul K. Whome nd Tjudeen O. Oseni Horticulture Deprtment, Fculty of Agriculture, University of Swzilnd, P.O. Luyengo M25, Luyengo, Swzilnd, Southern Afric. Emil: ABSTRACT Wild okr (ligush) [Corchorus olitorius L.] is n importnt indigenous vegetle in Swzilnd. Although the crop is populr vegetle mong rurl communities, not much hs een done to produce it using nitrogen, phosphorus nd potssium fertilisers. The purpose of this study ws to investigte the effects of different concentrtions of NPK fertilisers on growth nd development of Corchorus olitorius (ligush). Different concentrtions of NPK fertilisers (, ( nd were pplied in n experiment lid in Rndomized Complete Block Design (RCBD) wherey in the, no fertilizer ws pplied. It ws noticed tht there were significnt (P<.5) increses in ll the growth prmeters tht were mesured in the pots where fertiliser ws pplied followed in decresing order y, nd lstly the. There were lso significnt (P<.5) differences of yield fresh mss nd dry mss of ligush. The plnts grown in the pplied pots hd the highest fresh (142.7 g) nd dry yield (31. g) mss followed in decresing order y, nd lstly the. The lest fresh (14.8 g) nd dry yield (3.3 g) mss ws recorded in plnts grown in the pots. Plnts tht grew in the pplied fertiliser gve the highest yield of wild okr, under the conditions of this experiment. INTRODUCTION Fertiliser is mteril tht is dded to the soil to supply one or more elements required for plnt growth nd development (Msrirmi et l., 212). The mjor three elements re nitrogen, potssium nd phosphorus, the secondry elements re clcium, sulphur, mgnesium nd other elements re oron, mngnese, iron, zinc, copper nd molydenum (De, 1988). Fertilisers enhnce the nturl fertility of the soil or replce the chemicl elements tken from the soil y hrvesting, grzing, leching or erosion. Orgnic fertilisers include properly mnged rnyrd mnure, compost nd green mnure. Mnure contins nitrogen nd phosphorus. It is sometimes modified with superphosphte to mke it etter lnced fertiliser. Compost, decyed to reltively stle, morphous stte, is mde from plnt mterils mixed with mnure nd some soil. Green mnure is herceous plnt mteril ploughed into the soil tht hs not undergone decy (Iymurenye nd Dick, 1996). Artificil fertilisers re inorgnic fertilisers formulted in pproprite concentrtions nd comintions which supply three min nutrients: nitrogen, phosphorus nd potssium (N, P nd K respectively) for vrious crops nd growing conditions. Nitrogen (N) promotes lef growth nd forms proteins nd chlorophyll. Phosphorus (P) contriutes to root, flower nd fruit development. Potssium (K) contriutes to stem nd root growth nd the synthesis of proteins. The common inorgnic fertilisers include mmoni (82% nitrogen), NPK comintions, ure (48% nitrogen), superphosphte, mono- nd disicmmonium phosphtes (contining nitrogen nd phosphte), clcium, mmonium nitrte chloride, potssium chloride (murte of potsh) (Jyweer nd Mikkelsen, 1991). Wild okr (Corchorus olitorius) is n nnul lefy vegetle, elonging to the Tilicee fmily. It is populr lefy vegetle in West Afric nd is thought to hve originted in Indi (Akorod, 1988; Normn, 1992). C. olitorius is known s ligush in Swzilnd. It is commonly known s Tssu jute, Jew s mllow, nd ush okr nd krin- krin in other countries

2 Agric. Biol. J. N. Am., 215, 6(3): 74-8 (Normn, 1992). In Swzilnd nd mny other tropicl nd su-tropicl regions, C. olitorius grows nturlly without fertilizer ppliction during the riny seson nd hs een considered s weed in mize fields. The genus Corchorus consists of 4-1 species tht vry in mny ttriutes, ut ll species re pprently highly firous. Other species lso grown s lefy vegetles re C. cutngulus nd C. tridens (Normn, 1992). Wild okr is n indigenous lefy vegetle nd hs een n importnt vegetle in Egypt since the time of the Phrohs, nd it is from there tht it gined its recognition nd populrity (Anon., 212). This vegetle hs formed prt of food for most people especilly in the rurl res nd low income erning group in tropicl nd su-tropicl countries including Swzilnd. The plnt s requirements for the different nutrient elements supplied in fertilisers needed for growth nd development my differ. Nitrogen, phosphorus nd potssium (NPK) fertilisers hve different concentrtions of the elements i.e., (2:3:2(22), 2:3:2(37) nd 2:3:4(39), needed y the plnts for their growth nd development. With the concentrtions of the NPK fertilisers different, the yield nd growth rte of the plnt my lso e different, thus the need to investigte the effects of different concentrtions of NPK fertilisers on growth nd development of wild okr. The ojectives of this study were to evlute the effects of three different concentrtions of NPK fertilisers on the growth, development nd yield of wild okr nd to increse food nd nutritionl security in Swzilnd. MATERIALS AND METHODS Experimentl site: The experiment ws conducted t the Horticulture Deprtment Experimentl Lthhouse in the Fculty of Agriculture, University of Swzilnd in Luyengo cmpus. Luyengo is under the Mnzini region, on the Middleveld gro-ecologicl zone. Luyengo is locted t 26 o 34 S nd 31 o 1 E with n verge ltitude of 75 m ove se level. The men nnul precipittion is 98 mm with most of the rin flling etween Octoer nd April. Drought hzrd is out 4%. Luyengo hs n verge summer temperture of out 27 o C nd winter tempertures of out 15 o C. The soil used for the experiment ws sndy lom soil (Murdoch, 1968). Plnt mterils: Wild okr seeds require seed dormncy reking tretment efore they re plnted. Seeds cn e dormnt for severl months (Pld nd Chng, 23). To rek seed dormncy, in this experiment seeds were immersed in justoiled wter for ten seconds nd were then llowed to dry overnight (Edje nd Ossom, 29). The treted seeds were then sown in seed try nd seedling mix which ws used s growing medium. The try ws plced in lth-house which hd 4% light intensity nd within seven dys of plnting hundred percent germintion rte ws oserved. Two weeks fter emergence nitrosol ws pplied to the seedlings to encourge uniform growth. At out six weeks fter germintion the seedlings were trnsplnted into plstic pots of 25 cm dimeter nd 2 cm height. The pots were filled with sndy lom soil which ws otined from the horticulture frm nd were plced on lck polyethylene sheet. One seedling ws plnted in ech pot t the centre of the pot. The pots were rrnged into three locks nd ech lock hd four lines for ech tretment. Weeds were led through hnd removl from the pots nd round the experimentl re. A hnd fork ws used to turn the soil round the plnts nd it helped to rek the soil cp so tht wter could infiltrte esily into the root zone. It lso helped to open up pore spces so tht there ws mple gseous exchnge etween the soil nd the tmosphere. Irrigtion ws crried out when there ws need with the help of tensiometers for irrigtion scheduling. Experimentl design: The tretments pplied were three different concentrtions of NPK fertilisers (,, nd (39) which were pplied t 6 kg /h while for the no fertiliser ws pplied. The tretments were lid down in rndomized complete lock design (RCBD). The tretments were pplied t trnsplnting nd the ring method of fertiliser ppliction ws used. In totl there were four tretments including the which were distriuted cross three locks. Tle 1 is n illustrtion of the field ly-out of the experiment. Tle 1: Field ly-out of the tretments lid in rndomized complete lock design (RCBD) BLOCKS TREATMENTS (RANDOMIZED) 1 2 Control 3 75

3 Plnt height (cm) Agric. Biol. J. N. Am., 215, 6(3): 74-8 Dt collection nd nlysis: The growth nd development prmeters tht were mesured nd used to ssess the effects of different concentrtions of NPK fertilisers on growth nd development of C. olitorius were, plnt height, numer of leves per plnt, lef length, lef width, numer of rnches per plnt, numer of pods per plnt, shoot fresh weight, shoot dry weight, root fresh weight, root dry weight, lef re, lef re index nd the root to shoot rtio. For the mesurements of these prmeters, five plnts from ech plot were smpled t rndom to otin n verge. Smpling of plnts for nlysis egn three weeks fter trnsplnting nd continued there fter every two weeks. A meter ruler ws used for the mesurement of the C. olitorius plnt height from se to the tip of the min shoot strting from three weeks fter trnsplnting up to nine weeks. The numer of leves ws counted from three weeks fter trnsplnting up to nine weeks. For the lef length nd width 3 cm ruler ws used for mesuring. On the ninth week, the numer of rnches nd numer of pods per plnt were counted nd the fresh nd dry weight of the hrvested shoots ws determined in the lortory using weighing lnce (Mettler Toledo scle, Greifensee, Switzerlnd). MSTATC (Nissen, 1989) sttisticl softwre ws used in the nlysis of the dt. Dt collected were sujected to nlysis of vrince (ANOVA) in RCBD. mens were seprted where significnt differences were detected using DNMRT t the 5% level of proility (Gomez nd Gomez, 1984). Soil nlysis: Soil smples were tken from the experimentl site using the zigzg method (Brdy nd Weil, 27); (four point determintion). The smples were tken to the Deprtment of Agriculturl Reserch nd Specilist services in Mlkerns, soil testing unit lortory for nlysis of physicl nd chemicl properties. The results of the soil nlysis tken efore the ppliction of NPK fertilisers on the onset of the experiment re presented (Tle 2). Most of the nutrients were elow the optimum level (Edje nd Ossom, 29). Hence there ws need for the ppliction of soil mendments in form of NPK fertilisers. Tle 2: Chemicl composition of the soil used in this experiment Prmeters ph Exchngele cidity (meq/1g) N (mg/kg) P (mg/kg) K (mg/kg) Mg (mg/kg) C (mg/kg) RESULTS Vlues Plnt height: There were no significnt (P>.5) differences in plnt height cross ll the four tretments t three weeks fter trnsplnting. At week nine, plnt height ws significntly (P<.5) higher in t 113.4cm, t 18. cm nd t 15.9 cm thn in which ws t 67.3 cm. Figure 1 shows the verge plnt height otined from ech tretment t nine weeks fter tretment ppliction Weeks fter trnsplnting Fig. 1: Effects of different concentrtions of NPK fertilisers on plnt height t week nine of C. olitorius L. Verticl rs re stndrd error (SE) rs elow nd ove the men. Lef re: At week three there were no significnt (P>.5) differences in lef re in ll the tretments. There were significnt (P<.5) differences in lef re t week five, where y plnts treted with hd 61.3cm 2, hd 58.9 cm 2 nd 76

4 Lef numer Brnch Numer Lef re (cm2) Lef re index Agric. Biol. J. N. Am., 215, 6(3): 74-8 hd 51.6 cm 2 respectively which were greter thn which hd 16.7 cm 2 (Figure 2). At week seven there were significnt (P<.5) differences in lef re. Plnts treted with hd the lrgest lef re, followed in decresing order y, nd lstly the. There were no significnt (P<.5) differences in lef re t week nine, s it egn to e constnt in ll the tretments (Figure 2). Lef re index: At three weeks fter trnsplnting there were no significnt (P>.5) differences in lef re indices cross ll the four tretments. There were significnt (P<.5) differences in lef re indices t weeks five, seven nd nine cross ll the tretments. The lef re index continued to increse with time during the durtion of the tretment; with hving the highest (45.3) nd the hd the lowest (4.8) (Figure 4) Weeks fter trnsplnting Weeks fter trnsplnting Fig. 2: Effects of different concentrtions of NPK fertilisers on lef re of C. olitorius L. Verticl rs re stndrd error (SE) rs elow nd ove the men. Lef numer: There were significnt (P<.5) differences in lef numer strting t week seven, with the plnts treted with hving the highest numer, followed in decresing order y those treted with, nd then the hving the lowest ( 172.3, 113.7,92.3 nd 35.3 respectively). The verge numer of leves were oserved to e higher (172.3) with the plnts treted with nd lower (35.3) with the plnts which were not treted with ny fertiliser i.e. the from week five to week nine (Figure 3). Fig. 4: Lef re index of C. olitorius L. recorded etween 3 nd 9 weeks fter trnsplnting. Verticl rs re stndrd error (SE) rs elow nd ove the men. Brnch numer: There were significnt (P<.5) differences in the men numer of rnches cross ll four tretments which were counted t hrvesting. Amongst the tretments, hd the highest men numer of rnches (13.3) s shown in Figure 5, followed y with out 9.3 which ws followed y with 8.3 nd the hd the lest numer which ws 1.7 (Figure 5) c -1 Weeks fter trnsplnting NPK concentrtions Fig. 3: Effects of different concentrtions of NPK fertilisers on lef numer of C. olitorius L. Verticl rs re stndrd error (SE) rs elow nd ove the men. Fig.5: Men numer of rnches of C. olitorius L. t hrvesting. Brs followed y sme letter re not significntly different from ech other t P.5.Men seprtion y DNMRT. 77

5 Dry root to shoot rtio Pod numer Shoot mss (g) Agric. Biol. J. N. Am., 215, 6(3): 74-8 Pod numer: There were significnt (P<.5) differences in the numer of pods produced y ech plnt mong the four tretments t hrvesting. The plnts treted with hd the highest men numer of pods ( 23.3), closely followed y with 21.7, then with nd eing the lest(5.) s shown in Figure 6. The pplied NPK fertilisers did not significntly ffect susequent wild okr pod numer. 25 which hd the lest dry mss of 3.9 g s shown in Figure c Fresh mss Dry mss 2 15 NPK concentrtions 1 5 NPK concentrtions Fig. 6: Men numer of pods produced y C. olitorius L. t hrvesting. Brs followed y sme letter re not significntly different from ech other t P.5. Men seprtion y DNMRT. Shoot fresh nd dry mss: There were significnt (P<.5) differences with the shoot fresh mss t hrvest, of the plnts s ffected y the ppliction of different concentrtions of NPK fertilisers. The verge yield of fresh mss of ws the highest with mss of g, followed y the yield of tretment with g which ws closely followed y with g nd the hd the lowest yield of fresh mss of 19.4 g (Figure 7). There ws huge difference of out g etween the highest fresh mss yield nd the lowest fresh mss yield. Also noticed ws the significnt (P<.5) difference in dry mss cross ll the four tretments. The dry mss of the plnts treted with NPK fertiliser were higher thn tht of the. The highest dry mss (31. g) ws otined for plnts hrvested from the pots previously treted with nd followed in decresing order y those treted with (26.5 g), (23.) nd lstly the where no fertiliser ws pplied Fig. 7: Reltive fresh nd dry mss of C. olitorius L. t hrvesting. Brs followed y sme letter re not significntly different from ech other t P.5. Men seprtion y DNMRT. Root to shoot rtio: There were no significnt (P<.5) differences of the dry root to shoot rtio s shown in Figure 8 cross the tretments Fig.8: Dry root to shoot rtio of C. olitorius L. Brs followed y sme letter re not significntly different from ech other t P.5. Men seprtion y DNMRT. DISCUSSION The nutrient supply to the plnt ccording to Seuert, 1986; Msrirmi et l., 21 is of gret importnce, s the production of dequte food nd fier depends upon it. The uptke of these nutrients is influenced y the ction exchnge properties of the soil (Isell, 1978; Ogunlel et l., 25), nture nd density of NPK concentrtions 78

6 Agric. Biol. J. N. Am., 215, 6(3): 74-8 the roots, s well s the nture nd forms of these nutrients in the soil (Kmprth, 1978; Brer, 1978). Soil ph lso hs mjor role to ply in the dsorption nd retention of the plnt nutrients ginst losses from the root zone (Shongwe, 1989; Shongwe, 1992; Iymurenye nd Dick, 1996). According to soil nlysis results the soil ws sndy lom with ph of out 6. nd n exchngele cidity of.15 which showed tht the soil hd good cpcity of dsorption nd retention of plnt nutrients. Nitrogen s well s phosphorus plys n importnt role in the growth nd development of okr (Nihort, 1985; Errehi et l., 1998). NPK fertiliser hs een reported to give yield increse in okr (Btol, 26; Ogunlel et l., 25). The results show tht crop response in terms of growth nd development vries with the rtio of the NPK fertiliser pplied. Nitrogen (N) promotes lef growth nd forms proteins nd chlorophyll, whilst phosphorus (P) contriutes to root, flower nd fruit development nd potssium (K) on the other hnd contriutes to stem nd root growth nd the synthesis of proteins (De, 1988; Ogunlel et l., 25). Wild okr plnts treted with NPK fertilisers showed incresed vlues in the growth prmeters tht were mesured (plnt height, numer of leves, lef re index, lef re, pod numer nd rnch numer) compred to the. In this study of no fertiliser ppliction ws included ecuse in the wild the okr is not fertilized ut grows nturlly. Dry nd fresh yield were of higher vlues with effect of the NPK fertilisers on C. olitorius L. s plnts grown in soil treted with hd the highest fresh yield mss compred to the other fertilisers nd the hd the lest yield mss. Sme pplied with the dry yield mss which ws n indiction tht there ws higher level of nutrients in the plnts from the pots treted with NPK fertilisers. There were significnt (p<.5) differences in ll the growth prmeters tht were mesured s ffected y the different concentrtions of NPK fertilisers. Plnts tht grew in the pots treted with produced higher yield in terms of the numer of leves hrvested thn those of the other fertilisers nd the (no fertiliser) hd the lest numer of leves. It ws lso noticed tht the numer of rnches in these pots () were higher compred to the other pots, thus the highest numer of leves. This might hve y cused y the high percentge of potssium in the fertiliser which plys mjor role in photosynthetic rections, strch formtion, trnsloction of sugrs nd improved utiliztion of nitrogen (Shongwe, 1989; Msrirmi et l., 213). These results re in greement with those of Btol (26) who reported n improvement in growth nd development of C. olitorius L. grown using NPK fertilisers. Plnts grown in pots treted with fertiliser hd the highest yield in terms of pod numer compred to the other fertilisers, which might hve een the result of higher percentge of phosphorus in this fertiliser which s reported y Russell (1978) tht K hs fvourle influence on flowering, fruiting nd seed formtion. Plnts grown in pots where fertiliser ws pplied grew more vegettively thn those where the other fertiliser were pplied nd plnts grown where there ws no fertiliser ppliction grew the lest vegettively. This ws oserved on the lef re nd lef re index where oth prmeters showed higher vlues for the plnts from the pots treted with thn the in the other fertilisers. This could e ttriuted to the NPK rtio which is higher in which tke prt in photosynthetic rections nd strch formtion, trnsloction of sugrs nd improvement of the utiliztion of nitrogen (Shongwe, 1989; Msrirmi et l., 213). The use of NPK fertilisers in the production of wild okr hs proved to gretly increse yield compred to not using fertiliser t ll s prcticed in the communl res. A possile limittion to the use of NPK fertilisers mostly in the rurl res would e the costs of uying the fertilisers nd ringing wild vegetle into conventionl production hs fr reching effects of ttining food security nd reduction in mlnutrition. CONCLUSION AND RECOMMENDATIONS This study showed the potentil of incresing yield of C. olitorius L. using NPK fertiliser. It ws noticed tht there were significnt (P<.5) increses in ll the growth prmeters tht were mesured in the pots where ws pplied followed in decresing order y, nd lstly the. Plnts treted with performed well compred to plnts treted with the other fertilisers under the conditions of the experiment. Bsed on the results nd conclusion drwn from the reserch it is recommended tht C. olitorius L. cn e grown with NPK ecuse it resulted in higher yields compred to the other NPK fertilisers. It is lso recommended tht similr reserch e crried out, ut this time round irrigtion should e monitored in move to ger towrds commercil production of C. olitorius L. in Swzilnd. 79

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