ALLEVIATION OF SALINITY- INDUCED STRESS IN CASH CROPS BY MULTI-K (POTASSIUM NITRATE), FIVE CASES TYPIFYING THE UNDERLYING PATTERN.

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1 ALLEVIATION OF SALINITY- INDUCED STRESS IN CASH CROPS BY MULTI-K (POTASSIUM NITRATE), FIVE CASES TYPIFYING THE UNDERLYING PATTERN. O. Achile Hif Chemicls LTD, P.O. Box 10809, Hif By, Isrel, Keywords: cbbge, chloride, grpefruit, lettuce, mize, nitrte, penut, potssium, sodium, tomto, yield, Abstrct The use of enhnced potssic plnt nutrition is n efficient method of preventing sodium-induced stress in mny crops. In ddition, the use of enhnced nitrte fertiliztion is potent tool in precluding chloride-induced stress in mny crops. The ppliction of Multi-K (potssium nitrte) is shown here s very efficient method of combting the forementioned stresses nd enhncing crops performnces under sline conditions. This concept is vlidted shown here for five modertely slinitysensitive crops representing the three min sectors of griculture: A) sweet corn for nnul field crops, B) citrus for perennils, nd C) tomto, lettuce nd Chinese cbbge for greenhouse-grown vegetbles. By dding Multi-K to their nutrition progrm, these crops were better ble to cope with slinity conditions despite higher EC levels resulting from this tretment. The incorportion of Multi-K t 2, 8 or 14 mm in the nutrition scheme of slinized sweet corn significntly incresed dry mtter production nd er yield. Slinity tretments ( mm of Cl - ) mrkedly incresed Cl nd N contents of grpefruit leves, thereby reducing the totl yield of the trees nd their cnopy volumes, but hd minor effect on K content of the leves. By mintining constnt concentrtion of 2 mm Multi-K in the irrigtion wter, the dverse effects of slinity tretments on the trees were voided. The resulting yields incresed from 3 to 38%. Slintion (50 mm NCl) of the nutrient solution of greenhouse tomtoes mrkedly decresed K content of the leves, fruit-set rte, number of flowers, dry weights of the plnts, fruit sizes nd stem heights. Adding Multi-K t 2, 4 or 8 mm to the slinized nutrient solution reversed these effects, despite mrked increse in EC. Moreover, severl vegettive prmeters were improved over the non-slinized controls. Three levels of Multi-K (1, 5 nd 10 mm) were tested on slinized (52 mm of Cl - ) hydroponiclly grown lettuce nd Chinese cbbge. The highest yields of fresh weight of both crops were obtined from the 5 mm Multi-K tretment, under both sline nd non-sline conditions. Slintion incresed the concentrtion of N nd Cl in plnt tissue nd reduced the levels of N nd K; the opposite occurred in plnts fed by the medium nd high levels of Multi-K. All the forementioned results clerly demonstrte tht plnts cn successfully cope with stresses imposed by mm N nd Cl, by continuous ppliction of Multi-K t 2 8 mm. A generl model cn explin ll phenomen involved. 1

2 1. Introduction The common dogm is tht ll deleterious effects of slinity re cused by two primry mechnisms. A) Non-specific, osmotic-relted dehydrtion. B) Impct of ccumultion of specific toxic ions (e.g. chloride, sodium, mgnesium, sulfte nd boron,) on plnt cells nd their dverse effects on crucil physiologicl processes. An extensive list of studies (e.g. Br et l., Feigin, Kfkfi et l & 1982) show tht pproprite nitrte nutrition of ssorted crops cn prevent deleterious effects of soilsolution chloride. Other ppers (e.g. Hepksoy et l. nd Tbn et l.) hve shown tht K llevites N deleterious effects under sodic conditions. K lso hs n extremely importnt nd unique role in the ctivtion of numerous enzyme systems (Evns et l.). It is the purpose of this pper to confirm tht sodium nd chloride ions re the key plyers in this system nd tht combting their uptke nd reducing their involvement in plnt physiology is more importnt thn reducing high electricl conductivity (EC) of the soil solution. Furthermore, ll experiments described clerly demonstrte tht despite incresing the EC of irrigtion wter, proper nutritionl regime cn reverse the negtive effects of slinity nd restore crops performnces found t much lower slinity levels. All experiments were done with crops deemed to possess (Ms) moderte sensitivities to slinity. All crops were irrigted with intentionlly slinized wter, nd the performnces were compred to prllel tretment in which Multi-K (potssium nitrte) ws dded to wter. Multi-K is binry, high qulity specilty fertilizer. It is composed of 100% mcronutrients: 13% nitrogen, ll in nitrte (NO 3 - ) form, nd 46% K 2 O. It is virtully free of sodium, chloride, perchlorte nd other detrimentl elements or hrmful residues. It is redily nd fully wter-soluble, mking it n idel fertilizer for top-dressing, fertigtion nd folir feeding. This pper is compiltion of severl representtive studies (Ims et l., Br et l., Levy et l. Stti et l., nd Feigin et l.), feturing substntil dt estblishing the concept tht constnt ppliction of miniml rtes of potssium nitrte considerbly ids in lleviting slinity problems. These results fit perfectly into the frmework produced by Nitsos et l. (superiority of K for the ctivtion of strch synthetse); Benzioni et l. (the specific role of K s vehicle for trnsporttion of nitrte nd mlte into nd within the plnt), nd Ben-Asher et l. (vlidity of these models for sline environment). 2. Mterils nd methods 2.1. Sweet corn experiment Sweet corn cv. Jubilee seedlings were grown in n ero-hydroponic system in Isrel. A stndrd fertigtion solution ws slinized by 5 rtes of 4/1 (M/M) mixture of NCl nd CCl 2, nd ugmented with 2, 8 or 14 mm of Multi-K. Plnt performnces were checked upon completion of development t 52 dys fter plnting Citrus experiment The experiment ws performed in 1999 in n orchrd, locted in the Besor re, of Isrel, with its rid climte nd sndy soil. Mrsh seedless nucellr grpefruit trees, 3 yers old grfted on vriety of rootstocks were trickle-irrigted with intentionlly slinized (NCl & CCl 2 t w/w rtio of 2/1, respectively) wter with slinity grdients 2

3 of five increments, with or without Multi-K. Irrigtion wter prmeters (including slintion gents nd fertilizers) were: chloride mg L -1, N mm, EC of the stndrd tretment ds m -1, nd of the Multi-K enriched tretments ds m -1. Multi-K ws pplied to the trees t constnt concentrtion of 200 ppm with every irrigtion cycle Greenhouse tomtoes experiment Tomto plnts of severl cultivrs were grown in greenhouse in the Sultnte of Omn on n inert medium nd fed by hlf-strength Hoglnd solution. The EC of this control tretment ws 1.2 ds m -1. In the slinized tretment, 50 mm NCl ws dded, thus incresing its EC to 5.5 ds m -1. In other tretments, Multi-K t 2, or 4 mm ws dded to the slinized nutrient solution. Consequently, the EC vlues of these solutions incresed considerbly. Severl vegettive- nd yield prmeters were recorded. 2.4.Chinese cbbge nd lettuce experiment Chinese cbbge (Pekinensis group, cv. Kzumi) nd lettuce (cv. Slins) were grown ero-hydroponiclly in greenhouse in Isrel. A stndrd nutrition solution ws used s control (1.8 ds m -1 ) or slinized by NCl nd CCl 2 t 34 nd 9 mm, respectively (6 ds m -1 ). Both of these solutions were ugmented with 1, 5 or 10 mm of Multi-K. Plnt performnces were checked t dys fter trnsplnting. 3. Results 3.1 Sweet corn experiment. Totl dry mtter nd er yield shred common slt-sensitivity pttern of liner decrese s the EC ws elevted beyond the threshold vlue. Incresing Multi-K concentrtion from 2 to 14 mm incresed dry mtter production nd er yield, see figure Citrus experiment. Slinity tretments mrkedly incresed chloride nd sodium contents of the leves, reduced totl yield of the trees nd their cnopy volumes, but hd minor effect on K contents of the leves. Multi-K tretments, however, considerbly countercted these phenomen nd incresed yields between 3 nd 38% for the vrious rootstocks (selected results re shown in figures 2-4). 3.3 Greenhouse- tomto experiment As shown in figures 5 & 6 slintion of the nutrient solution mrkedly decresed dry weight of the plnt, fruit size, plnt height, K content of the leves, fruit-set rte nd totl number of flowers on the min stem of the plnt. The ddition of Multi-K to the slinized nutrient solution reversed the dverse effects cused by the NCl, despite the mrked increse in EC, involved in this mesure. Severl prmeters were improved over the control s direct result of the tretment with Multi-K, i.e., fruit size nd plnt height (figure 5) K content of the leves nd fruit-set rte (figure 6) Chinese cbbge experiment Slintion of the nutrition solution resulted in the development of severe toxicity symptoms. Also, s shown in figure 7 yield dropped by 15% in the slintion tretment. Adding 1 mm of Multi-K hs further reduced the yield, but incresing Multi-K 3

4 concentrtion to 5 mm significntly restored the yield to 109% nd 127% of the nonsline, nd the slinted tretments, respectively Lettuce experiment Dimeters of hed of greenhouse- grown lettuce plnts were mrkedly reduced in response to slintion of the nutrition solution (dt not shown). Consequently, s shown in figure 8 the yield of the plnts ws severely nd significntly ffected (-30%) by the slintion. Adding 1 or 5 mm of Multi-K hs significntly restored yield to 113% or 127% of the slinized tretment, respectively. Lef nlysis of the plnts reveled cler pttern of increse in K nd N (Kjeldhl) nd decrese in N nd Cl contents s direct response of the Multi-K tretments (tble 1). 4. Discussion The results cited in this pper clerly show the benefits stemming from pplying nitrte nd potssium in the form of Multi-K (potssium nitrte) s n nti-slinity gent. The sweet corn experiment shows tht the slope representing the dmge cused by slinity ws not ltered by the tretments, but the threshold for slinity dmge ws considerbly incresed s Multi-K ws employed t incresing rtes (figure 1). Sweet corn plnts were highly productive even t EC= 5 ds m -1, figure treble thn the vlue stted by Ms for non-sline conditions. This finding my stem from the fct tht K is the preferred monovlent ction in the photosynthetic system in mize, s found by Nitsos et l. Similr results were reported lso for penuts, which re nother nnul field crop, modertely sensitive to slinity (Silberbush et l.; Ben-Asher et l.). The citrus experiment clerly shows tht the constnt ppliction of Multi-K t low rte of 200 ppm (2mM) in the irrigtion wter considerbly llevites slinity-induced vegettive stresses, thus mrkedly incresing commercil yields. Multi-K incresed the resistnce of grpefruit trees to slinity-induced stress by fctor of nerly two versus the vlue cited by Ms (3.40 vs ds m -1, respectively). The greenhouse tomtoes experiment shows even further, tht the ddition of Multi-K t rte of 1/25 (M/M) of the concentrtion of the NCl used for irrigtion could reverse the slinity consequences nd improve plnts performnces over the control. Here, too, the plnts performed very well t elevted EC vlues of 7.5 ds m -1 versus nominl threshold of 2.5 ds m -1 determined by Ms. The greenhouse cbbge nd lettuce experiments similrly show tht these crops cn endure high EC vlues s long s their N & K nutrition is optiml. EC vlues of 6 ds m -1 nd bove do not necessrily result in yield drop lthough norml threshold ws conventionlly believed to be 1.8 nd 1.3 ds m -1 for these crops, respectively (Ms). It ws shown gin tht constnt Multi-K t 5 mm cn reverse the severe stresses resulting from NCl present t concentrtion n order of mgnitude higher. The generl model put forwrd by Ben-Asher et l. ppers to perfectly explin the slinity-induced phenomen described for ll crops noted in this pper. At norml, nonsline conditions, K ction is trnsporttion id fcilitting the uptke of nitrte nion from soil solution into the plnt roots. The nitrte is used for production of proteins. The K ction then becomes trnsporttion pltform fcilitting the movement of mlte nion from the folige to the roots, where it is used s n energy source for their functioning. When chloride previls in the soil solution, it competes with the nitrte nd 4

5 is uptken t high rtes, directly relted to its concentrtion. K ction then fcilittes its uptke but chloride cnnot be used, of course, s rw mteril in the production of proteins. Proteins production is seriously dmged nd the chloride is precipitted in lef tips, producing typicl tip-burns. Mlte movement to the roots is not impired. When sodium is excessive in the soil solution it competes with the potssium nd is tken up in high rtes, directly relted to its concentrtion. This uptke fcilittes the concurrent uptke of the nitrte, but is unble to ssist in the trnsporttion of the mlte to the roots, nd they re seriously undernourished. This, in turn, negtively ffects the wter-, minerl- nd physiologicl sttus of the entire plnt. The generl conclusion from ll these cses is tht the constnt ppliction of Multi-K t 2-10 mm in the irrigtion / fertigtion solution cn counterct the deleterious effects of the chloride nd the sodium in plnt metbolism. The most importnt dvntge of Multi-K versus mny other fertilizers is tht its contribution to slinity buildup is negligible. Both K nd nitrte, which re the building blocks of this fertilizer, re mcronutrients, nd therefore, they re tken up in lrge rtes while non-nutrient residues re not left in the soil. References Br, Y., et l Reltionship between chloride nd nitrte nd its effect on growth nd minerl composition of vocdo nd citrus plnts. J. of Plnt Nutr. 20: Ben-Asher, J. et l K uptke by root system grown in sline soil: A conceptul model nd experimentl results. Johnston, A.E., (Editor) Food security in the WANA region, the essentil need for blnced fertiliztion. Interntionl Potsh Institute. Bsel, Switzerlnd Benzioni, A., et l Nitrte uptke by roots s regulted by nitrte reduction products of the shoot. Physiol. Plnt. 24: Evns, H.J. et l Role of minerl elements with emphsis on the univlent ctions. Ann. Rev. Plnt Physiol. 17: Feigin, A Fertiliztion mngement of crops irrigted with sline wter. Pl. Soil 82: Feigin, A. et l Combined effects of KNO 3 nd slinity on yield nd chemicl composition of lettuce nd Chinese cbbge. Irrig. Sci. 12: Hepksoy, S. et l The effect of potssium fertiliztion nd rootstock on lef sodium content of stsum mndrins under sline condition. Hgin, J. nd Johnston, A.E., (Editor) Nutrient mngement under slinity nd wter stress. Technion- Isrel Institute of Technology, Hif, Isrel Ims, P. et l Yield nd wter use efficiency of sweet corn grown in solution culture s ffected by KNO 3 nd slinity levels. Act Hort. 401: Kfkfi, U. et l Effect of potssium nitrte nd mmonium nitrte on the growth, ction uptke nd wter requirement of tomto grown in snd soil culture. Isrel J. Agric. Res. 21:1330 Kfkfi, U. et l Chloride interction with nitrte nd phosphte nutrition in tomto. J. Plnt Nutr. 5: Levy, Y. et l Field screening of citrus rootstocks using trickle liner slinity grdient. Act Hort. 511: Ms, E.V Slt tolernce of plnts. Appl. Agric. Res. 1:

6 Nitsos, R.E. et l. (1969) Effects of univlent ctions on the ctivity of prticulte strch synthetse. Plnt Physiol. 44: Stti, S.M. et l Effect of incresing potssium levels for lleviting sodium chloride stress on the growth nd yield of tomtoes. Commun. Soil Sci. Plnt Anl. 25: Silberbush, M. et l Response of penuts grown in sline nutrient solution to potssium nitrte. J. Plnt Physiol. 132: Tbn, S. et l Effects of potssium on mcroelements distribution in mize plnts grown under slt stress. Hgin, J. nd Johnston, A.E., (Editor) Nutrient mngement under slinity nd wter stress. Technion- Isrel Institute of Technology, Hif, Isrel Figure 1: The effect of slinity nd Multi-K on the yield of sweet corn. Figure 2: The effect of slinity nd Multi-K* on chloride content of grpefruit leves. Er Yield (F. W. g/plnt) Multi-K Tretment 2 mm 8 mm 14 mm E. C. of Nutrient Solution (ds/m) Chloride in Lef D.M. (%) Troyer w/o Multi-K Troyer + Multi-K Sour ornge Cl - in irrigtion wter Figure 3: The effect of slinity nd Multi-K* on N content of grpefruit leves. Figure 4: The effect of slinity nd Multi-K* on the yield of grpefruit trees. N in Lef D.M. (%) Volkmerin w/o Multi-K Troyer w/o Multi-K Troyer + Multi-K Volkmerin + Multi-K Yield Increse (%) Volk Troyer Cl - in irrigtion wter Cl - in irrigtion wter *Multi-K ws pplied t constnt 200 ppm in the irrigtion wter. 6

7 Figure 5: The effect of slinity nd Multi-K on vegettive prmeters nd fruit size in greenhouse tomtoes. Figure 6: The effect of slinity nd Multi-K on folir K, flowering nd fruit-set rte in greenhouse tomtoes Control. EC=1.3 ds/m NCl (50mM). EC= Control. EC=1.2 ds/m NCl (50mM). EC=5.5 ds/m NCl + Multi-K (2mM). EC= NCl + Multi-K (4mM). EC=6.8 NCl + Multi-K (8 mm). EC= Plnt DW (g) Fruit size (g) Plnt height (cm) K lef content (%) Fruit-set (%) No. of flowers/plnt Figure 7: The effect of slinity nd Multi-K on the yield of greenhouse- cbbge (cv. Kzumi). Figure 8: The effect of slinity nd Multi-K on the yield of greenhouse- lettuce (cv. Slins). Fresh Yield (g/plnt) Dt collected t 55 D.A.T Non Sline Slinted EC= 6.0 EC= 1.8 EC= 5.5 EC= 5.0 b b Multi-K Rte (mm) Fresh Yield (g/plnt) Dt collected t 63 D.A.T Non Sline Slinted EC= 6.0 EC= 1.8 EC= 5.5 EC= 5.0 c b Multi-K Rte (mm) Tble 1: The effect Multi-K on lef composition of greenhouse- lettuce (cv. Slins) under slinity conditions. EC (ds m -1 ) Multi-K (mm) Lef composition K Kjeldhl-N N Cl