Effect of water stress on growth of three linseed (Linum usitatissimum L.) varieties

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1 DOI /s RESEARCH Open Access Effect of wter stress on growth of three linseed (Linum usittissimum L.) vrieties Lilin Wmui Kriuki 1*, Peter Msinde 2, Stephen Githiri 1 nd Arnold N. Onyngo 3 *Correspondence: lilinkriuki96@gmil.com 1 Deprtment of Horticulture, Jomo Kenytt University of Agriculture nd Technology, Juj, Keny Full list of uthor informtion is ville t the end of the rticle Astrct Linseed (Linum usittissimum L.) is n nnul oil crop tht ccounts for pproximtely 1 % of the world s oilseed supplies. It produces seeds tht re rich in the helth-promoting ω-3 ftty cid, α-linolenic. In Keny, linseed is grown in the Rift Vlley nd Western regions, plces which often experience drought. This study ws imed t evluting the effect of wter stress on growth of three linseed cultivrs nd to estlish the extent of drought tolernce in the three cultivrs. A greenhouse pot experiment in completely rndomized design ws conducted t Jomo Kenytt University of Agriculture nd Technology, Keny. The pots were well wtered until the fourth week when wtering ws completely withheld to hlf of the pots (stressed) while the other hlf (well wtered control) ws mintined t 9 % field cpcity. Destructive hrvesting ws done when the stressed pots were t 9, 7, 6, 5, 4 % field cpcities nd t permnent wilting point. The experiment ws replicted thrice nd ws repeted twice (Ferury My nd August Novemer 214). There were no significnt differences in production of leves, plnt height, numer of tillers nd iomss etween the three vrieties in oth sesons. Sujecting the linseed vrieties to permnent wilting resulted in reduced production of leves, growth in height, production of tillers nd dry weight y 2 4 %. Decline in ll growth prmeters egun when 3 8 % of ville soil wter hd een used up. There existed liner reltionships etween the vrious evluted growth prmeters. These reltionships were not influenced either y the wter sttus of soil or the vrieties. Reltive wter content for the three linseed vrieties declined fter % of ville soil wter hd een used up. Keywords: Aville soil wter, Drought tolernce, Numer of leves, Numer of tillers, Plnt dry weight, Plnt height, Reltive wter content Bckground Linseed (Linum usittissimum L.) hs een mjor source of industril oil for products like pints, linoleum, polish, inks nd cosmetic (Green nd Mrshll 1984; Zhng et l. 27). Currently, linseed is importnt s functionl food from the point of view of its nutrition nd phrmceuticl vlue, nd its nutritious components include oil, protein, lignin, resolvle fier, minerl nd vitmins (Wu et l. 28). Notly, linseed is the est source of the n-3 ftty cid, α-linolenic cid (ALA), which constitutes nerly 55 % of its totl ftty cids. This percentge is 5.5 times more thn the next est sources of α-linolenic cid (Bloedon nd Szpry 24). ALA is n essentil ftty cid which cn e metolized to eicospentenoic cid (EPA) nd docoshexenoic cid (DHA) 216 The Author(s). This rticle is distriuted under the terms of the Cretive Commons Attriution 4. Interntionl License ( which permits unrestricted use, distriution, nd reproduction in ny medium, provided you give pproprite credit to the originl uthor(s) nd the source, provide link to the Cretive Commons license, nd indicte if chnges were mde.

2 Pge 2 of 16 y elongses nd desturses in humns (Chen et l. 22). It is well known tht ALA increses the sorption of long chin-polyunsturted ftty cids (LCPUFA), especilly EPA nd DHA, nd decreses the risks of physiologicl disorders such s colon tumor (Dwivedi et l. 25), rest cncer (Chen et l. 26; Thompson et l. 1996) nd therosclerosis (Prsd 1997; Ymshit et l. 25). In Keny, linseed is grown in the Rift vlley nd Western Keny regions (Riungu 1988), regions which often experience drought conditions. Severl vrieties of linseed exist t the Ntionl Plnt Breeding Sttion in Njoro (Riungu 1988). These re however lrgely not chrcterized in terms of their response to vrying growth conditions (Personl communiction). There is therefore need to evlute the fctors tht ffect linseed production. Diepenrock et l. (1995) reported high genotype-environment interctions in Europe, with yields vrying considerly etween sesons nd loctions. Nemtllhi nd Seidi (211) found significnt differences in the response of severl linseed genotypes to drought, with some eing drought tolernt nd others eing drought sensitive. Plnts re often exposed to vrious environmentl stresses under oth nturl nd griculturl conditions. Drought stress is one of the most importnt environmentl stresses limiting growth nd productivity of plnts. Drought cn significntly influence plnt performnce nd survivl nd cn led to mjor constrints in plnt functioning, including series of morphologicl, physiologicl nd metolic chnges (Fisher nd Murer 1978; Ludlow nd Muchow 199). Drought ffects photosynthesis directly nd indirectly nd consequently dry mtter production, nd its lloction to vrious plnt orgns (Myki et l. 1976). Drought stress lso reduces lef expnsion nd production, nd promotes senescence nd scission (Krmnos 198). Ahmd et l. (27) reported 39 % dry mtter reduction in whet when wter levels were reduced from 9 to 3 %FC. Rmos et l. (1999) reported inhiited ccumultion in fresh plnt mss y 88 % compred to dry iomss (85 %) when moisture levels dropped from 1 to 3 %FC for cv. EMGOPA-21. This reltively lower influence of drought on dry iomss thn on fresh mss signified presence of disturnces in wter reltions. Lzcno-Ferrt nd Lovtt (1999) reported decrese of % in dry iomss in young en plnts sujected to drought nd significnt increse in rtio dry mss/ fresh mss (DM/FM). It is considered tht incresed rtio DM/FM is stress prmeter t plnt level (Bker 1993; Augé et l. 21). The cpcity to mintin high reltive wter content (RWC) vlues under drought ws reported in drought tolernt en cultivrs (Zltev 25) nd in Astrglus gomiformis Pom. nd Medicgo stiv L. (Gori et l. 21). For en plnts this could e explined y their ility to ccumulte gret quntities of proline nd other osmotic ctive compounds which re involved in the reduction of osmotic potentil nd in osmotic djustment (Zltev 25). Linseed is drought tolernt (Nemtllhi nd Seidi 211). However genotype environment interctions hve een shown to e high for linseed (Diepenrock et l. 1995), nd yields vry considerly etween sesons, depending on loction nd wether. The ojective of this study ws to evlute the effect of wter stress on different growth prmeters nd the reltive wter content of three linseed vrieties, nmely, nd.

3 Pge 3 of 16 Results The soil tht ws used for this experiment hd ph of 6.2, electricl conductivity of.12 ds/m which re within the norml rnge for most crops (Okleo et l. 22). Production of leves y well wtered nd stressed plnts ecme significntly different (P <.5) from 4 dys fter plnting (Fig. 1). The well-wtered produced 92 nd 1 leves during the Ferury My nd August Novemer 214 sesons respectively (Fig. 1, ). The stressed plnts produced 74 leves during ech of the two sesons. However, there were no significnt differences in the three vrieties production of leves in response to moisture levels in oth sesons (c, d). The well wtered nd stressed plnts did not vry significntly in height until fter 4 dys fter plnting. Well wtered plnts grew to heights of 39 cm while stressed plnts reched 31 cm (Fig. 2, ). For the three tested linseed vrieties, plnt height ws not significntly influenced y moisture level (Fig. 2c, d). nd were tller thn during the Ferury My seson while ll the vrieties ttined similr heights of 34 cm in the August Novemer seson. In oth Ferury My nd August Novemer 214 sesons, the numer of tillers ws higher in well wtered plnts from 4 dys fter plnting (Fig. 3, ). The difference ws significnt only during the August Novemer seson (P <.5). The well wtered plnts produced 4 5 tillers compred to 3 4 tillers in stressed plnts. The three linseed vrieties did not differ significntly in production of tillers in oth sesons (Fig. 3c, d). In oth sesons, produced the highest numer of tillers with 4 5 tillers, while the lest numer of tillers ws produced y in oth sesons with 2 3 tillers. Numer of leves/plnt Numer of leves/plnt Ferury-My 214 Well wtered Dys fter plnting August-Novemer 214 Well wtered Dys fter plnting Fig. 1 Production of leves y linseed vrieties (c, d) grown under wter stress (, ) during the periods Ferury My nd August Novemer, 214. Verticl rs show LSD.5 c d

4 Pge 4 of 16 Plnt height (cm) Plnt height (cm) Ferury-My 214 Well wtered Stresses Dys fter plnting c August-Novemer 214 Well wtered Dys fter plnting Fig. 2 Effect of wter stress (, ) on plnt height of linseed vrieties (c, d) during the periods Ferury My nd August Novemer, 214. Verticl rs show LSD.5 d Numer of tillers/plnt Numer of tillers/plnt Ferury-My 214 Well wtered Dys fter plnting c August-Novemer 214 Well wtered Dys fter plnting Fig. 3 Men numer of tillers produced y linseed vrieties (c, d) grown under wter stress (, ) during the periods Ferury My nd August Novemer, 214. Verticl rs show LSD.5 d

5 Pge 5 of 16 There ws significnt difference in dry weight etween well wtered nd stressed plnts eyond 4 dys fter plnting in oth sesons (Fig. 4). Well wtered plnts produced significntly higher dry weight rnging g/plnt compred to g/plnt for stressed plnts (Fig. 4, ). In the Ferury My 214 seson, gve significntly higher dry weight (.77 g) (Fig. 4c) compred to (.64 g) nd (.6 g) (P <.5) from 45 dys fter plnting. However, in the August Novemer seson, the three cultivrs did not differ significntly in dry weight even t dy 55, lthough still gve higher dry weight thn the other two vrieties (Fig. 4d). Decline in production of leves in oth sesons strted t frction of ville soil wter (FASW) of.5 (Fig. 5, ; Tle 1). The decline ws similr for the three vrieties. Production of leves however cesed t point when the rtio of leves of the stressed plnts to the well wtered ws.6.8. During the Ferury My seson, decline in plnt height for the stressed plnts egun t FASW of.56. This decline however strted t.2 FASW during the August Novemer seson (Tle 1). Severe stress cused plnts to cese incresing in height. In oth sesons, this hppened when the rtio of the stressed plnts ws.7.8 tht of the well wtered plnts (Fig. 5c, d). For the three vrieties, increse in numer of leves resulted in liner increse in dry weights (Fig. 6; Tle 2). The rte of this increse ws independent of the vriety nd ws similr in oth sesons. In the two sesons, unit increse in lef numer resulted in.1 times increse in dry weight for ll the vrieties. Dry weight/plnt (g) Dry weight/plnt (g) Ferury-My 214 Well wtered Dys fter plnting c August-Novemer 214 Well wtered Dys fter plnting Fig. 4 Dry weight ccumultion y linseed vrieties (c, d) grown under wter stress (, ) during the periods Ferury My nd August Novemer, 214. Verticl rs show LSD.5 d

6 Pge 6 of Ferury-My August-Novemer 214 Numer of leves rtio c 1.1 d Plnt height rtio FASW FASW Fig. 5 Rtio of numer of leves (, ) nd plnt height (c, d) of stressed plnts to well wtered plnts in response to chnging frction of ville soil wter (FASW) for linseed vrieties grown during the periods Ferury My nd August Novemer, Tle 1 Reltionship etween slope nd frction of ville soil wter criticl points (FASW c ) nd their 95 % confidence intervls (CI) for the non-liner functions in Figs. 5, 8 nd 1 Ferury My 214 August Novemer 214 Slope 95 % CI FASW c 95 % CI Slope 95 % CI FASW c 95 % CI Leves Height Dry weight %RWC There ws liner reltionship etween increse in plnt height nd increse in plnt dry weight for ll the vrieties in oth sesons (Fig. 7). A unit increse in plnt height for nd resulted in.28.3 times increse in dry weight during oth sesons (Tle 3). A unit increse in height for produced.38 times increse in dry weight in oth sesons. This increse ws significntly higher thn tht for nd.

7 Pge 7 of 16 Dry Weight/plnt (g) Ferury-My 214 Well-wtered August-Novemer 214 Well-wtered Well-wtered 1..8 Well-wtered Dry Weight/plnt (g) c. d Well-wtered 1..8 Well-wtered Dry Weight/plnt (g) e. f Numer of leves/plnt Numer of leves/plnt Fig. 6 Reltionship etween numer of leves produced nd dry weight ccumulted y linseed vrieties (, ), (c, d) nd (e, f) grown during the periods Ferury My nd August Novemer, 214 Decline in the rte t which plnts ccumulted iomss cused y wter stress during the Ferury My 214 seson strted t.43 FASW (Tle 1). It ws however reched t.62 FASW during the August Novemer 214 seson. In oth sesons, severe wter

8 Pge 8 of 16 Tle 2 The slope nd intercepts nd their stndrd errors for the liner functions in Fig. 6 Vriety Ferury My 214 August Novemer 214 Slope SE Intercept SE R 2 Slope SE Intercept SE R Dry Weight/plnt (g) Dry Weight/plnt (g) Dry Weight/plnt (g) Ferury-My Well-wtered Well-wtered Well-wtered c e. August-Novemer 214 Well-wtered Well-wtered d Well-wtered f Plnt Height (cm) Plnt Height (cm) Fig. 7 The trend of plnt height versus dry weight reltionships for linseed vrieties (, ), (c, d) nd (e, f) grown during the periods Ferury My nd August Novemer, 214

9 Pge 9 of 16 Tle 3 The slope nd intercepts nd their stndrd errors for the liner functions in Fig. 7 Vriety Ferury My 214 August Novemer 214 Slope SE Intercept SE R 2 Slope SE Intercept SE R stress cused plnts to cese ccumulting iomss. This occurred when the rtio of iomss of the stressed to well wtered plnts ws.3.5 (Fig. 8). There ws liner increse in plnt dry weight with increse in tillers for ll the vrieties in oth sesons (Fig. 9). A unit increse in numer of tillers resulted in times increse in dry weight; for the three vrieties in oth sesons (Tle 4). Reduction in reltive wter content cused y wter stress during the Ferury My 214 seson strted t.33 FASW (Tle 1). This decline egun t.75 FASW during the August Novemer 214 seson. As ville wter decresed, so did the plnt s reltive wter content (Fig. 1). Discussion The three tested vrieties did not vry in their production of leves. Linseed hs een reported to produce 6 8 leves y Vn der Voseen nd Mkmilo (27). Previous field reserch y Lilin et l. (214) reported tht,,, Jwhr nd produced leves with the vrieties not differing significntly in the production of leves. The current results re for pot experiment nd tht is proly why the reported numer of 92 1 leves is significntly lower thn the erlier numer. Exposure to conditions of wter stress resulted in significnt reduction in the rte of production of leves. This could e s result of reduced rte of lef initition with setting in of wter stress. The decline in the rte of production of leves ws first indicted when 5 % of ville wter hd een used up in oth sesons. During oth sesons, there ws reltionship etween production of leves nd ccumultion of dry mtter in the three vrieties; n increse in numer of leves ws ccompnied y corresponding increse in dry weight. Wter stress cn exert strong influence on lef re development y Rtio of dry weight Ferury-My 214 August-Novemer FASW FASW Fig. 8 Rtio of plnt dry weight of stressed plnts to well wtered plnts in response to chnging frction of ville soil wter (FASW) for linseed vrieties grown during the periods Ferury My () nd August Novemer (), 214

10 Pge 1 of 16 Dry Weight/plnt (g) Dry Weight/plnt (g) Dry Weight/plnt (g) Ferury-My Well-wtered Well-wtered Well-wtered c e. August-Novemer 214 Well-wtered Well-wtered d Well-wtered f Numer of tillers/plnt Numer of tillers/plnt Fig. 9 Contriution of tillering to ccumultion of dry weight y linseed vrieties (, ), (c, d) nd (e, f) grown during the periods Ferury My nd August Novemer, 214 decresing lef ppernce rte (Tury et l. 1992), durtion nd lef expnsion rte (Turner 1997) nd incresing the rte of lef senescence nd scission (Sinclir et l. 1984). Bzzz nd Hrper (1977) found the totl lef re of linseed to e lrgely determined y the numer of leves nd therefore concluded tht reduced lef numer due

11 Pge 11 of 16 Tle 4 The slope nd intercepts nd their stndrd errors for the liner functions in Fig. 9 Vriety Ferury My 214 August Novemer 214 Slope SE Intercept SE R 2 Slope SE Intercept SE R %RWC Ferury-My FASW August-Novemer 214 Fig. 1 Rtio of reltive wter content of stressed plnts to well wtered plnts in response to chnging frction of ville soil wter (FASW) for linseed vrieties grown during the periods Ferury My () nd August Novemer (), FASW.4.2. to wter stress proly ccounted for the low lef re index in rin fed plnts. For the three linseed vrieties, production of leves ws severely ffected y severe stress. A unit increse in numer of leves resulted in liner increse in dry weight, reltionship which ws similr for the three vrieties. Leves re photosynthetic sites nd therefore the more the leves the more the photosynthtes re produced nd ccumulted in the plnt. Totl dry mtter ccumultion hs een shown to e function of ssimilting orgns nd the photosynthetic cpcity of the lef cnopy (Bisco nd Gllngher 1977; Diepenrock nd Porksen 1992). In this study, wter stress cused reduction in numer of leves of 23 %. Wter stress cused s significnt decline in height of the three tested linseed vrieties. Well wtered plnts reched heights of 39 cm. Stress produced shorter plnts whose heights verged 31 cm; this ws true in oth sesons. nd vrieties reched the heights of 4 cm during the Ferury My seson. These were tller thn which grew to 36 cm high. As plnt ville wter reduced so did the rte of plnt growth in height. Hiruy nd Nigussie (1988) reported tht linseed growth to height of 5 8 cm. Lilin et l. (214) reported height of 6 8 cm for five linseed vrieties grown in the field. Mny erlier studies on other crops such rice (Dvtgr et l. 29), mize (Muhmmd et l. 21; Porro nd Cssel 1986; Herndez 198) nd sfflower (Mohmmd et l. 212) hve reported reduction in plnt height due to wter stress which they ttriuted to inhiition of cell elongtion or cell division. The sme cn e sid of the three linseed vrieties. In this study, reduction of 21 % in height resulted due to wter stress. There ws positive liner reltionship etween increse in plnt height nd increse in dry weight for the three linseed vrieties. Similr findings hve een reported y Lilin et l. (214) for five linseed vrieties plnted in the field.

12 Pge 12 of 16 Plnt cell division cuses plnt elongtion hence increse in plnt height. As these cells mture, they hve direct contriution to increse in iomss. Linseed hs een reported to produce 4 5 tillers (Ali et l. 211; Mohmmd et l. 212). In the current study, wter stress cused significnt reduction in production of tillers during the two sesons, of up to 25 %. Well wtered plnts produced 4 5 tillers which reduced to 3 4 tillers per plnt for those plnts where stress ws imposed. There were no vritions in numer of tillers produced y the three vrieties, though produced high numer of 4 5 tillers in comprison to which produced lowly 2 3 tillers. Erlier studies y Lilin et l. (214) reported up to 14 tillers per plnt. Studies on whet cultivrs Inql-91 nd Uq-2 y Akrm (211) found significnt reduction in tillers due to wter stress. Imposition of wter stress t the stem elongtion nd nthesis stge cused reduction from to 663. tillers per m 2. A minimum reduction in tiller numers per hill (from 19 to 18) on smti rice vrieties Bsmti-Super, Shheen- Bsmti nd Bsmti-385 ws reported y Akrm et l. (213). This ws ttriuted to the fct tht t the time of wter stress, mximum tillers hd een developed y the plnts. In greenhouse experiment, with two sugrcne genotypes (CP nd CP 1-239), Zho et l. (212) reported significnt reduction in numer of tillers due to wter stress. During the 29 experiment, the tillers rnged from 1 to 4 nd 2 to 6 tillers per plnt for the stressed nd well wtered pots respectively. The numers rose to 5 8 nd 6 1 tilers per plnt for the stressed nd well wtered pots respectively in 21. Gin (25) reported s mny s twice rnches/plnt in irrigted (2.5) compred to the unirrigted () linseed plnts. Increse in dry weight ws linerly relted to increse in tillers. This is ecuse ech individul dditionl tiller hd n ccompnying iomss. During oth sesons hd higher dry weight (.75.8) compred to nd which verged This is perhps from the higher numer of tillers it produced during oth sesons. The well-wtered plnts produced g/plnt of dry weights in oth sesons. This ws higher thn tht of the stressed plnts, which produced g/plnt dry weights. This could hve resulted from the individul direct contriution to dry weight y numer of leves nd plnt height, prmeters which lso vried significntly etween the well-wtered nd stressed plnts. As wter stress ffected individul prmeters, the whole ws trnslted into n effect on dry weight. The totl iomss produced y crop during its life cycle, in response to the existing environmentl conditions cn e defined s dry mtter (Hssn nd Leitch 21). Environmentl fctors cn indirectly influence crop dry mtter production through their effect on the rte of photosynthesis nd respirtion (Roertson 1984). Chrtzoulkis et l. (1993) reported 6 65 % reduction in dry weight in Kiwifruit cv. Hywrd growing under severe wter stress, in glsshouse. Hlil et l. (21) studied the effect of wter stress on eggplnt (Solnum melongen L. cv., Teorem F1). They oserved % reduction in dry weight under severe wter stress conditions (6 4 % pot cpcity) which ws ttriuted to metolic regultion of dption to wter stress. Totl dry mtter production in unirrigted plots ws significntly lower thn in irrigted plots throughout the life cycle of the linseed crop (Gin 25). Irrigtion incresed dry weight y 59 % from 59 to 763 g/m 2. In this study, s ville soil wter reduced, so did the of ccumultion dry weight. The tested linseed vrieties hd only ccumulted 55 % of potentil dry weight y the time they completely dried.

13 Pge 13 of 16 Reltive wter content (RWC) reduced with decrese in ville soil wter for the three tested linseed vrieties (Fig. 1). During the Ferury My seson, the %RWC strted to decline t.33 FASW while the decline egun t.75 FASW during the August Novemer seson (Tle 1). The RWC prmeter is considered s one of the esiest griculturl prmeters tht cn e used to screen for plnts drought tolernce (Boutr et l. 21). Drought tolernt plnt species mintined high RWC compred with drought-sensitive species in cultivrs of sugrcne (Mrcelo et l. 27). Stoynov (25) reported tht wter stress cuses decrese in RWC in ens species. Tmussi et l. (2) reported tht cultivrs of whet under wter stress showed decrese in the RWC. There re mny reports out the direct reltionship etween reltive wter content nd drought resistnce (Shimshi et l. 1982; Merh 21; Schonfeld et l. 1988) from which deductions on ility to djust intrcellulr wter reltions under drought stress conditions hve een mde. The vrition in the FASWs t which %RWC declined during the two sesons could hve risen from the differences in environmentl reltive humidity, which could hve een higher during the August Novemer seson thn during the Ferury My seson. This could hve lowered the rtes of evpotrnspirtion thus enling the soil to continue holding more wter for longer (dt not presented). The tested linseed cultivrs cn e considered s drought-sensitive since, during the Ferury My seson they mintined very low %RWC. Conclusion It ws concluded tht sujecting linseed vrieties, nd to permnent wilting results in reduced production of leves, growth in height, production of tillers nd dry weight y 2 4 %. Decline in ll growth prmeters egun when 3 8 % of ville soil wter hd een used up. The liner reltionships, which existed etween the vrious growth prmeters, were not influenced y the wter sttus of soil. Vrieties too did not influence these liner reltionships. Reltive wter content for the three linseed vrieties declined fter % of ville soil wter hd een used up. Methods This study investigted the effect of wter deficit on three linseed cultivrs (, nd ) grown in the greenhouse of the deprtment of Horticulture t the Jomo Kenytt University of Agriculture nd Technology (JKUAT), Keny. The experiment ws setup in completely rndomized design. Pots were weighed then filled with 2 kg soil otined from JKUAT frm. Ten seeds were sowed in ech pot efore thinning to one fter estlishment. Grvimetric soil wter content nd field cpcity for this soil were determined. Tretments were pplied 4 weeks fter sowing nd comprised withholding wter ppliction to hlf of the pots (stressed) until the plnts ttined permnent wilting point. The well wtered control ws mintined t 9 % soil field cpcity (FC) throughout the experimentl period y weighing the pots dily nd replcing the mount of wter lost. Destructive hrvesting ws done guided y the wter levels on plnts under stress; t 9, 7, 6, 5, 4 %FC nd t end point. The experiment ws replicted thrice nd ws repeted twice (Ferury My nd August Novemer 214). Dt on plnt height, numer of leves, numer of tillers, nd dry weight ws recorded. Reltive wter content (RWC) ws determined ccording to Turner (1986) where fresh

14 Pge 14 of 16 leves were tken from ech vriety t ech hrvest nd weighed immeditely to record fresh weight (FW). Then they were plced in distilled wter for 4 h nd weighed gin to record turgid weight (TW). These were then sujected to oven drying t 7 C for 24 h to record dry weight (DW). The RWC ws clculted using the eqution: RWC = {(FW DW)/(TW DW)} 1. All dt were sujected to nlysis of vrince (ANOVA) using PROC GLM in SAS portle version nd mens seprted using LSD procedure t the.5 level of significnce nd grphs plotted using Microsoft Excel nd SigmPlot 12.. Growth prmeters were expressed s rtio of stressed to the well wtered. Frction of ville soil wter (FASW) ws derived using formul; FASW = 1 {(Wc We)/(Ws We)} where Wc = current weight of pot, We = weight of pot t end point (permnent wilting point), Ws = weight of pot t sturtion. The reltionship etween the rtio of prticulr growth prmeter nd FASW ws expressed s non-liner function in SAS nd then plotted in SigmPlot 12.. The point t which the rtio egun to decline ws the frction of ville soil wter criticl point (FASW c ). Liner reltionships were lso derived etween numer of leves per plnt nd dry weight per plnt, plnt height nd dry weight per plnt, nd, numer of tillers per plnt nd dry weight per plnt, using liner regression procedure in SAS. All these were gin plotted in SigmPlot 12.. Arevitions ALA: lph-linolenic cid; ANOVA: nlysis of vrince; CI: confidence intervl; DHA: docoshexenoic cid; DM: dry mtter; DW: dry weight; EPA: eicospentenoic cid; FM: fresh mss; FC: field cpcity; FW: fresh weight; LCPUFA: long chin polyunsturted ftty cid; RWC: reltive wter content; TW: turgid weight. Authors contriutions LWK drfted the proposl nd designed the experiments. She cquired, nlyzed, interpreted nd lso presented dt. She lso drfted the mnuscript. PM ws involved in conception of reserch, the design of experiments, nlysis, interprettion s well s presenttion of dt. He ws involved in the criticl revision of the mnuscript. SG ws involved in conception of reserch, dt interprettion s well s presenttion of the dt. He ws lso ctively involved in criticl revision of the mnuscript. ANO ws involved in conception of reserch, dt interprettion nd presenttion, s well s criticl revision of the mnuscript. All uthors red nd pproved the finl mnuscript. Author detils 1 Deprtment of Horticulture, Jomo Kenytt University of Agriculture nd Technology, Juj, Keny. 2 School of Agriculture, Meru University of Science nd Technology, Meru, Keny. 3 Deprtment of Food Science nd Technology, Jomo Kenytt University of Agriculture nd Technology, Juj, Keny. Acknowledgements This study ws supported y Jomo Kenytt University of Agriculture nd Technology. Competing interests The uthors declre tht they hve no competing interests. Received: 14 July 215 Accepted: 13 My 216 References Ahmd F, Rhmtullh T, Aziz MA, Mqsood A, Thir MA, Knwl S (27) Effect of silicon ppliction on whet (Triticum estivum L.) growth under wter deficiency stress. Emir J Food Agric 19(2):1 7 Akrm M (211) Growth nd yield components of whet under wter stress of different growth stges. Bngldesh J Agric Res 36(3): Akrm HM, Ali A, Sttr A, Rehmn HSU, Bii A (213) Impct of wter deficit stress on vrious physiologicl nd gronomic trits of three smti rice (Oryz stiv L.) cultivrs. J Anim Plnt Sci 23(5): Ali S, Cheem MA, Whid MA, Sttr A, Sleem MF (211) Comprtive production potentil of linol nd linseed under different nitrogen levels. Crop Environ 2:33 36

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16 Pge 16 of 16 Stoynov ZZ (25) Effects of wter stress on lef wter reltions of young en plnts. J Cent Eur Agric 6:5 14 Tmussi EA, Brtoli CG, Beltrno J, Guimet JJ, Arus JL (2) Oxidtive dmge to thylkoid proteins in wter-stressed leves of whet (Triticum estivum L.). Physiol Plnt 18: Thompson LU, Rickrd SE, Orcheson LJ, Seidl MM (1996) Flxseed nd its lignn nd oil components reduce mmmry tumor growth t lte stge of crcinogenesis. Crcinogenesis 17: Tury KK, McKenzie BA, Andrews M (1992) Effect of wter stress nd nitrogen on cnopy development nd rdition interception of lentil. Proc Agron Soc NZ 22: Turner NC (1986) Crop wter deficits: decde of progress. Adv Agron 39:1 51 Turner NC (1997) Further progress in crop wter reltions. Adv Agron 58: Vn der Voseen HAM, Mkmilo GS (27) Vegetle oils. Prot. ISBN Wu M, Li D, Wng LJ, Zhou YG, Brooks MS, Chen XD, Mo ZH (28) Extrusion detoxifiction technique on flxseed y uniform design optimiztion. Sep Purif Technol 61:51 59 Ymshit T, Od E, Sno T, Ymshit T, Ijiru Y, Giddings J, Ymmoto C (25) Vrying the rtio of dietry n-6/n-3 polyunsturted ftty cid lters the tendency to thromosis nd progress of therosclerosis in poe / LDLR / doule knockout mouse. J Throm Res 116(5): Zhng ZS, Li D, Wng LJ, Ozkn N, Chen XD, Mo ZH, Yng HZ (27) Optimistion of ethnol wter extrction of lignns from flxseed. J Sep Purif Technol 57:17 24 Zho D, Brry G, Comstock JC (212) Sugrcne lef photosynthesis nd growth chrcters during development of wter-deficit stress. Crop Sci 53: Zltev Z (25) Effects of wter stress on lef wter reltions of young en plnts. J Cent Eur Agric 6(1):5 14