BNH CY I CNG

BNH HI CY TRNG DO DINH DNG V CC C CHT ---oOo--1. t vn Ngy nay con ngi chng ta mun tng ti a nng sut cy trng, lm c iu th cn phi s dng mt lng ln phn bn v cc cht sinh trng. Nhng i vi cc loi phn hu c v phn vi sinh th li cho kt qu lu di, khng nh mng mun ca chng ta. V vy vic s dng phn v c v cc cht ho hc c p dng ngy cng nhiu. Nhng m vic s dng chng th u phi lun ng v mang li hiu qu cao u, v th a s nng dn dng khng ng, khng hp l nh l d tha phn a lng (N, P, K) hay thiu loi phn v lng (Fe, Zn, Cu, B) dn n nh hng n nng sut cy trng. Vn t ra y l nghin cu cc tc ng ca dinh dng ln cy trng v hai mt li v hi t c nhng gii php nhm lm tng nng sut cy trng m t gy hi n chng. Mi nguyn t dinh dng c mt vai tr nht nh, s thiu ht ca bt k nguyn t dinh dng no cng u nh hng n sinh trng v pht trin ca cy. S thiu ht dinh dng c th do t trng khng tho mn vic bn b sung dinh dng khng hoc nhng cy trng khng s dng c hoc bn phn mt cn i. Bn cnh bn tha dinh dng cng gy nhng tc hi. Ngy nay trong Nng nghip ang i mt vi nhng loi bnh do vic s dng cc loi nng dc khng ng cch, ng lc, ng nng cn thit, hay l k thut canh tc cn thiu khoa hc, khng ng bin php th hin qua ng c hu c la, ng c st, ng c phnV vy vn nghin cu bnh cy do nhng nhn t trn gy ra ang c cc nh khoa hc khp ni nghin cu. 2. nh ngh a Bnh sinh l cy trng l g? Cy trng ci cc, km pht trin, nng sut cy trng gim y chnh l bnh sinh l cy trng, chng khc vi cc bnh k sinh do nm, virus, vi khun gy ra. Bnh sinh l khng mang tnh truyn nhim, nguyn nhn ch yu do iu kin dinh dng, ch kh, nc trong t, thi tit, kh hu... gy ra. Phn bn l g? Phn bn l cc hp cht c cung cp cho thc vt y mnh tng trng. Phn bn thng c trn vo t cy hp th bng r, hoc phun cy hp th qua l. Phn bn c th l phn hu c (c thnh phn l cc cht hu c), hoc phn v c (gm cc cht ha hc hoc cht khong v c n gin). Phn bn c th c to mt cch t nhin nh l mc hoc khong cht c sn trong t, hoc c sn xut bng cc quy trnh t nhin (chng hn ) hoc ha hc (chng hn quy trnh Haber). Cht c l g? Trong ng cnh sinh hc, cc cht c l cc cht c th gy h hi, bnh, hoc t vong cho cc c th, thng bng cc phn ng ha hc hoc cc hot tnh khc trn phm vi phn t, khi mt s lng va c c th sinh vt hp th vo. (theo Wikipedia) S dinh dng khong l s nghin cu v cch thc m thc vt hp thu v ng

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V Thanh Hng - Nguyn Vn Tuyn

BNH CY I CNG ho cc ion v c. C 16 nguyn t khong gi vai tr thuyt yu trong i sng cy trng m chng khng th thiu hoc thay th bng nguyn t no khc c: N, P, K, Mg, Ca, S, Fe, Cl, Zn, Mn, B, Cu, Mo 3. Hnh thc v hin trng gy hi. 3.1 Bnh do tc nhn dinh dng 2.1.1 Cc nguyn t a lng m (N) Trong cy NO3- c ht vo s b kh thnh NH4+. Khi bn nhiu m m iu kin kh NO3- khng thun li (thiu vi lng cn cho hot ng ca men chuyn ho chng hn), m trong cy tn ti nhiu di dng NO3- khng thun li cho ngi tiu th sn phm. Qu trnh quang hp khng cung cp gluxit v qu trnh h hp khng cung cp xto axit cho cy, m trong cy gy hi tn li ti nhiu di dng NH4+ c cho cy. NH4+ c th c cy hp th nhanh vo trong t bo nn thng lm cho pH trong t bo tng nhanh, trong khi t bo s dng chm nn lng NH4+ tch t trong cy gy c. Tuy nhin, s hp th NH4+cng thay i tu theo loi thc vt, i vi la NH4+ to ra c hiu qu. Vic cung cp NH4+ cho cy cng ch n tnh cht ca phn. V d khi bn (NH4)2SO4 cy hp th NH4+ rt nhanh cn SO42- nn mi trng tr nn axt. Hn na,v NH4+ b trao i vi H+ trong r, s hp thu ammunium gn lin vi s axit ho ca vng quanh r. NH4+ c hp thu r phi c ng ho thnh glutamine. Nu c s tch t NH4+ t do trong cy (do cung cp qu d tha trong t) s xut hin triu chng ng c r rt; V NH4+ l mt cht c mnh cho t bo, vi chc nng l mt cht khng bt cp ca s quang phosphoryll ho trong lc lp. -Triu chng tha m: Bn tha m do cy phi ht nhiu nc gii c amon nn t l nc trong thn l cao, thn l vn di, mn mi, che bng ln nhau, li nh hng n quang hp. Ging la truyn thng (ging c) cao cy, bn nhiu m d b non. m hu c ho tan (amin, amit) trong nhiu cy d mc bnh. Bn nhiu m lm tng kch thc l, nht l v mt din tch l; cy thng c h thng r km pht trin v do c t l l / r cao.L tr nn mng manh hp thu nng lng nh sng km, t l dip lc trong l c mu xanh ti li hp dn su bnh nn thng b su ph hi mnh, ng thi d ng. Bn tha m qu trnh sinh trng (pht trin thn l) b ko di; qu trnh pht trin (sinh trng sinh thc: hnh hoa qu ht) b chm li. Cy thnh thc mun. cc cy nh la, c alfalfa nu bn nhiu m th tr s C/N gim, dn n thi gian tr bng chm nh hng xu n nng sut. Khoai ty sinh trng vi ngun m phong ph cho thy s tng trng qu mc v thn l v ch cho nhng c nh (c th do mt cn bng v cht iu ha sinh trng). D m tri c chua b nt Bn tha m phm cht nng sn km, gi tr sinh hc thp: t l NO 3- trong rau, qu d vt qu ngng cho php, rau c v nht, hydrocacbon thp, t l m cao da mui d b kh. m l nguyn t linh ng, khi cy thiu m th m t l gi chuyn v l non nn cc l gi rng sm, th hin l gi trc. -Triu chng thiu m: Cy thiu m thung sinh trng km, dip lc t kh thnh lp nn l thng b vng a, cy ci cc, ln, l hp, tri mau chn, nng sut km; s l, s chi, s nhnh t, kch thc nh. Triu chng trn xut hin l gi, cc l ny chuyn sang mu vng, trong

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V Thanh Hng - Nguyn Vn Tuyn

BNH CY I CNG khi cc l non bn trn vn cn xanh. mt s loi thc vt (bao gm c chua v mt s dong bp) phn cun l c mt s im mu tm, do s tch t ca sc t anthocyanin -Phng tr: cy ang tnh trng thiu m, nu mun phc hi nhanh, ngi ta c th pha dung dch c cha m phun ln l, sau vi ngy cy s c phc hi. Cc ho cht c cha m nh Ur, Ca(NO3)2, KNO3 u t ra c hiu qu cho cc loi cy. Nng v thi gian phun thay i theo tng loi cy trng. Ln (P) Gia m v ln c quan h mt thit. m v c c hp th v tch lu trong m cy nhanh khi hm lng ln gim. Khi hm lng ln nhiu trong vng r s hp thu m v c gim. S ho gi ca cy sm hn khi hm lng laan cao. -Triu chng thiu ln: La thiu ln cy ci cc, nhnh km; b l la ngn, phin l hp, l c t th dng ng v c mu xanh ti; s l, s bng v s ht trn bong u gim. Thiu ln va phi cc l non c v bnh thng song cc l gi hn chuyn sang mu nu ri cht. Mt s trng hp l c xut hin mu (huyt d ng) hay tm do sc t anthocyanin xut hin nhiu phn thn v cun l Cy b u, cy ly du cn c cung cp ln khng ln, khng vi th thi trng lc l kt qu tng kt ca nng dn v vai tr ca ln i vi cy b u v cy ly du. Trong rung la thiu ln th khng thy c to pht trin. giai on cn nh th s phn ct t bo nh sinh trng b ngng tr, nn v sau cy tng trng theo chiu di thng rt kh Trong trng hp c tm thn mc rt thp; cc loi hnh c r mc ngn, l khng pht trin. nhm cy cho c nh lhoai lan, khoai ty triu chng xut hin l khng ng k, nhng c khng pht trin. Nhm cy h cam qut th hin din l khng r lm, v qu dy, v chua, mi sng v thi gian sinh trng ko di. Cy n qu thiu ln qu xu x. Ln c th c vn chuyn t cc l gi v cc c quan non, c quan ang pht trin dng vo vic tng hp hp cht hu c mi. Do vy triu chng thiu ln xut hin cc l gi trc. -Phng tr: Mun cha tr nhanh chng, ngi ta thng dng phn KH 2PO4 (0.30.5%) phun ln l hay c th dng phn calcium phosphate pha thnh dung dch ri phun ln l. Tuy nhin cn ch thm v khong Mg. Phn kali (K) Khi thiu K+ , sinh trng b nh tr v s ti chuyn v K+ c htc y t cc l v thn trng thnh; khi thiu trm trng th cc b phn ny tr nn vang a v hoi t, tu thuc vo cng nh sng m cc l phi by. S ho lignin ca cc b mch cng b h hi, iu ny cng l yu t nh hng n kh nng chu ngp ng ca cy thiu K+. K tch t cc l non hn l cung l. Cc cht m khi cy hp thu thng dng NO3-, sau s b kh cho NH4+ v amino acid, cui cng tng hp nn protein. Nu thiu K th phn ng ny s b nh hng, cy tch t nhiu ion NO 3- tr nn v ch. Trng hp cy hp thu N dng NH4+ nu thiu K s a n vic tch t nhiu NH4+ gy c cho cy, v qu trnh amino acid khng xy ra. Khi s cung cp nc ca t b gii hn, cy b mt sc trng v ho l triu chng tiu biu cho s thiu K. i vi cy K kh nng chu hn clin quan n nhiu nhn t: vai tr ca K trong iu tit kh khng v s quan trng ca K + i via th nng thm Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 3

BNH CY I CNG thu trong khng bo, duy tr hm lng nc trong m cao ngay c di iu kin han. Cy trng thiu K thng mn cm hn vi sng gi; mc t bo c lin quan n s thiu nc. S thay i v hot tnh ca enzyme v thnh phn hp cht hu c din ra trong khi thiu K lm cho cy trng c tnh mn cm cao hn i vi s tn cng ca nm bnh. S thay i thnh phn ny cng nh hng n cht lng dinh dng v ch bin sn phm sau thu hoch.Trong trng hp khc, s thit hi v cht lng sn phm c lin quan trc tip n hm lng citric acid v v vy ch nh hng gin tip bi K. Thiu K cy d b ho, K cn nh hng n vic to lp mt s cht nh Thiamine (vitamin B1), khi cung cp nhiu s gy tr ngi cho s hp thu Ca v Mg, ng thi gy ra s hp thu Fe d dng Khi t l kali trong cy gim xung ch cn bng 1/2 n 1/3 so vi bnh thng th triu chng thiu kali trn l mi xut hin. Cho nn khi triu chng thiu kali xut hin trn l th nng xut gim do thiu kali m vic bn kali khng b p c. Do vy, khng nn i n lc xut hin triu chng thiu kali ri mi bn kali cho cy. Kali tn ti di dng ion ngm nc, nh hnh thc tn ti ny m kali rt linh ng. Khi t khng cung cp kali th cc kali cc b phn l gi c chuyn v cc b phn l non, v c quan hot ng mnh hn m bo cho cc hot ng sinh l ca cy tin hnh bnh thng. Do vy hin tng thiu kali xut hin l gi trc. Thiu kali vic vn chuyn ng c hnh thnh qua qu trnh quang hp l v cc c quan d tr gp kh khn. V d cy ma dinh dng kali bnh thng, tc vn chuyn ng t l xung thn l 2,5cm/pht, th cy thiu kali tc vn chuyn gim xung ch cn bng mt na. Do tc ng n qu trnh h hp v quang hp, kali nh hng tch cc n vic trao i m v tng hp prtit. Thiu K+ m nhiu m (NH4+) tch lu c cho cy. Kali thc y vic tng hp protit do vy hn ch c tch lu nitrat trong l. Thiu kali m hu c ho tan tch lu to thc n di do cho nm nn cy d mc bnh. Kali hn ch tc hi ca vic bn tha m. -Triu chng thiu K: La thiu kali l c mu lc ti trong khi mp l c mu nu hi vng. Thiu kali nghim trng trn nh l c vt hoi t mu nu ti trong khi cc l gi pha di thng c vt bnh tim la. s chi rt nhiu nhng khng nhng kh mc di c Ng thiu kali l b mm i, un cong nh gn sng v c mu vng sang. Khoai ty thiu kali l qun xung, quanh gn l c mu xanh lc, sau mp l chuyn sang mu nu. cc cy hai l mm, nhng l ny khi s tr nn hi vng, c bit gn vi nhng vt nhn sm mu (nhng m cht hoc i mu) m chng bao lu sau s pht trin. Phn ba l c nhng m, u tin mu vng nu, k n mu vng chy sau lan dn vo bn trong l, xut hin l gi, khng c l non. Phn chu vi ca l c nhiu m trng sau lan dn vo bn trong. Cui cng l b kh ri cht. Triu chng thiu K xy ra mnh nht lc kt tri v to ht. mt s loi cy rau ci th ba v ngn l c vi im trng nh, l mc tm li khng xo ra, cc cy cho c th r khng thnh c c. Cc nhm cy h u c thn lng ngn, ng knh thn rng, t s thn/r thp. nhiu cy mt l mm, nh ng cc nhng t bo ngn v mp l cht trc tin v s hoi t tri ra cc phn non hn, nhng phn thp hn ca cun l. Bp v cc loi ng

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V Thanh Hng - Nguyn Vn Tuyn

BNH CY I CNG cc khc thiu K s pht trin cng yu t, v r d nhim nhim vi sinh vt gy bnh thi r. Lm cho cy d b ng. -Cha tr: dng dung dch KH2PO4 phun ln l cy, nng khng c qu 0.7% thng lm l cy b chy. Sau c th dng phn ht KCl, K 2SO4 bn trc tip vo t, la cn bn 3-4 kg/1000m2. Cc loi rau ci t 6-7 kg/1000m2. Khi s dng K nn ch l phi s dng bn 3-4 ln khng bn tp trung 1 ln s a n tnh trng thiu Mg, Ca. Canxi (Ca) Thiu Ca th hin cc phn non ca cy c l v Ca c i hi lin kt vi cc ng a pectate cho s thnh lp lp chung mi trong phin t bo,hnh thnh gia hai t bo con, hay v Ca c cn thnh lp micritubules ca si trc phn bo. M b bin dng v hnh th vn vo l do hu qu ca s thiu Ca v cc vng s cht rt sm; l mc khng bnh thng, b gn song, c nhiu m v ra l b mt mu. M ca l v cc im tng trng ca cy trng thng b cht v lm cho cy b cht t. R cy km pht trin v th hin triu chng nhy nha. Ca kt hp vi pectin to thnh calcium pectate trong lp chung, cn thit cho s vng chc t bo v m thc vt, m hot ng ca enzyme ny b c ch bi nng Ca cao. Do trong cc m thiu Ca tiu biu l s phn r ca vch t bo v s mm nhng ca m. T l calcium pectate trong vch t bo cng quan trng cho s mn cm ca m thc vt i vi s xm nhim ca nm v vi khun cng nh s chnh ca tri. Ca cn c vai tr trong qu trnh bin dng thc vt, trng hp thiu Ca, cy khng th ng ho nitrate c. -Triu chng thiu Ca: l khng bng phng, hp, nh, ba ca l b un cong vo trong. c chua ba l c nhiu im mu , v sau l b vng a kh ho v cht. i vi cy cho c th phn l non trn khng xy ra trc khi l vng a, nhn nheo, v sau nh hng lm c mo m v phn nhnh. -Tha Ca s lm cho pH ca t tng ln gy tr ngi cho vic hp thu Mg, Mn, Zn, Fe, Bo. -Cha tr: dng phn CaCl2 hay phn Ca(HPO4) pha thnh dung dch (t 0.3-0.5%) phun ln l cy, vic phun ny c li l khng lm thay i pH ca t. Ngi ta ch n vic thiu Ca l do bn nhiu K v N. Mt s cc hoa mu rt d thiu Ca gm c chua, ci salad, hnh c, c ci trng Magi (Mg) S a vng ca l trng thnh l triu chng d thy nht ca s thiu Mg. S vng a ny thng l gia gn, bi v cc t bo tht l cnh b mch lu tr cholorophyll lu hn t bo nhu m gia chng. Theo ng vi chc nng ca Mg trong s tng hp protein, t l ca m protein b gim st v ca m khng protein gia tng trong cc l thiu Mg. cy thiu Mg tc quang hp b gim st v c s tch t ca carbonhydrate. Khi cy thiu Mg th s vn chuyn carbohydrate t v tr ngun n ni cha b tn hi, ngay c lng tinh bt m d tr ca cy c c v trng lng ht ca cc loi ng cc cng b gim st. Magi rt linh ng, sn sang di tr t cc l gi n cc l non hn cho nn triu chng thiu magi c khuynh hng xut hin cc l gi trc. Magi c trong thnh phn dip lc nn l nguyn t khng th thiu trong dinh dng cy trng. Kali va ui magi ra khi phc h hp ph trong t va i khng vi Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 5

BNH CY I CNG magi v mt dinh dng nn ch bn nhiu kali dn n thiu magi cho cy, thm ch c th lm cho cy mt bnh. Thiu Mg lm gim lng P trong cy v c ch qu trnh tng hp cc hp cht photpho hu c; c ch tng hp polixacarit-tinh bt v c ch qu trnh tng hp protein. S thiu Mg lm nh hng n lc lp, n sinh tng hp dip lc v lm cho riboxom b phn r thnh cc phn di n v. Hm lng Mg cao trong l (1.5% trng lng kh) c th tr thnh mc khng hong di iu kin kh hn. Khi tim nng nc ca l tt xung, nng Mg2+ trong ngun trao i gia tng 3-5 mM ln n 8-13 mM (hoa hng dng). Vi nng Mg2+ cao nh vy, trong stroma ca lc lp, s c ch s quang phosphoryl ho v s quang tng hp. -Triu chng thiu Mg: cy c th hin trn hnh thi l xut hin cc vt v cc di mu dc theo gn l. L vng a, mp l cng ho vng da cam hoc v sm. Quang hp xy ra rt km. s lng t bo gim thp. Th khm nhiu mu l c trng bnh thiu Mg. mt s vn nho, phn Mg gip cho lng ng trong tri tng. Mg cn gip cho ln di ng d dng. Mt s cy thiu Mg hm lng lactic acid gim 25%, citric acid gim 85%, malic acid gim 20% nguyn nhn l qu trnh h hp gim. Trong thi k sinh dc lc to tri v ht, th mt s l nm chung quanh tri s vng a do s di chuyn ca Mg vo tri. nhm cy h ho bn, nh bp, thiu Mg th hin din sc vng v vng xanh xen k ln nhau. Trng hp da leo, cy thuc h bu b th phn gn l vn cn mu xanh, nhu m bin i sang mu vng. c chua triu chng nh trn v sc l un cong xut hin ni gn tri. Nhu cu Mg ca cc cy h u cn nhiu hn cy la. -Tha Mg: c th gy c cho cy, gim bt tc hi bng cch bn vi tng pH v Mg hp thu vo cy trong iu kin pH thp. -Cha tr: khi l va c triu chng thiu Mg th phun dung dch MgSO4 (1-2%) ln l, gip cy khng b rng l. Mt s vn cy n tri thiu Mg c th rng n 60% l. Nu Mg trong t qu cao, ngi ta c th ngn chn bt cho cy khng hp thu bng cch bn nhiu vi vo trong t hay dng dung dch CaCl2 (0.3-0.5%) phun ln l s lm gim hp thu Mg Lu hunh (S) u tin xc b ng thc vt cht th hp cht S b phn gii dng SH2 u tin c kh nng gy c v nh vi khun thiobacillus phn gii bin thnh SO4 cy hp thu tt. S cng c th c hp th l thng qua kh khng dng kh SO2, l mt cht bn mi trng c phng thch ra t vic t chy than v g SO 2 c chuyn ho thnh bisunphit HSO3- khi n phn ng vi nc trong t bo v trong dng ny n va c ch s quang tng hp v ng thi gy ra s hu hi chlorophyll. -Triu chng thiu S: Cng nh thiu m bao gm s nht nht tng qut ton l, k c b mch (gn), kch thc l nh. S khng th ti phn b t nhng m trng thnh trong vi loi. V th s thiu thng c ghi nhn trc tin l non. Tuy nhin nhng loi khc hu ht l tr nn vng a cng mt lc hoc ngay c l gi trc tin. cy ca cao l vng a, v sau bin sang nu . c chua, tr cc l non b un cong l c mu xanh nht d b rng, ng knh thn v r b h thp. Cy u nnh thiu th hm lng ng gim, hemicellulose gia tng. Thiu S th khng to lp protein nn cy tch t nhiu nitrate v NH3 gy c cho cy. Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 6

BNH CY I CNG l cy b chuyn thnh mu lc nht, cy chm ln, cc l non ng mu vng, nng hn l rng hoc cht t cc cnh. Khi cy c ph c biu hin thiu S l mi ra b trng. 2.1.2 Cc nguyn t vi lng St (Fe) L do m s thiu sc em li mt s c ch nhanh s thnh lp cholorophyll cha c thu hiu hon ton. Sc tch t trong l gi tng i khng di chuyn trong m lipe, cng nh trong t, c l do n c lng t ni sinh trong t bo l di dng mt oxide khng ho tan hay trong dng cc hp cht ferric phosphate hu c hoc v c. Bng chng trc tip v hnh thnh s lng t ny th thiu, v c l mt vi hp cht khng ho tan cha bit khc c hnh thnh tng t. Mt dng n nh v phong ph ca st trong l c tn tr trong cc lc lp nh mt phc hp protein-st gi l phytoferritin. S xm nhp ca st vo dng chuyn vn lipe c th c ti thiu ho bi s thnh lp ca nhng hp cht khng ho tan nh vy, mc d phytoferritin dng nh i din cho ngun d tr st. Mt kin khc gii thch s di ng km ca st l n c th xm nhp vo mch lipe mt lng va phi nhng sau thot (r r) vo mch g v di chuyn tr li cng mt l ban u. Trong vi trng hp khi n b ly vo mt b phn t mch g, s ti phn phi ca n vo nhng m tr hn vo ht s b gii hn. -Triu chng thiu: Gy cho cy bnh bch tng hoc lm xut hin nhng vt hoi t mu vng trn l. Thng xut hin phn non nht ca cy, t di dng mt mu dc theo gn l cho n ton b phn non ca cy ng mu vng vt, s vng a ny i khi tip theo bi s vng a ca cc gn l, v th nhng l non ngay c tr nn mu trng vi nhng triu chng hoi t. Tuy nhin khi ton b l tr nn vng l cy trong tnh trng thiu st trm trng dn n nh tr sinh trng, cy c th cht. S thiu Fe thng c tm thy trong nhng loi mn cm, c bit trong h hoa hng, bao gm cy bi v cy n tri v trong ht ng cc nh bp. ngoi ng s thiu Fe xy ra khng ng u. Ti mt s ni cc cy c biu hin vng l non trong khi nhng khu vc ln cn l c th xanh. Ngay c hai cy gn nhau cng c khi mt cy l non chuyn sang vng v cy khc l vn xanh. Thng gp triu chng thiu st trn cy n tri hn trn cc loi hoa mu khc. -Tha Fe: gy ng c st, biu hin thng nhng l bn di, bt u t nhng im nu nh u l v bt u lan dn xung y. Thng nhng im ny lin li gn gia,mu xanh ca l khng thay i. Trng hp trm trng l c mu nu tm. -Cha tr: Cc cy c triu chng thiu nu c phun dung dch FeSO4 1% trong vng 2 tun mt s l s tr li xanh, khng nht thit l ton b l xanh tr li. Dip lc t trn l c th xy ra tng im trn l, hiu qu hi phc thng xy ra l non. Mangan (Mn)

Quan st bng knh hin vi in t ca lc lp l rau dn cho thy rng s vng mc ca Mn gy nn ri lon ca mng thylakoid nhng c nh hng n cu trc ca nhn v ti th.

Lp DH7TT

V Thanh Hng - Nguyn Vn Tuyn

BNH CY I CNG Hm lng Mn trong cy 20-500 ppm/trng lng kh, trung bnh hm lng trn 500 ppm c th gy c. i vi la vi nng 2500 ppm vn cha biu hin bt thng. -Triu chng thiu Mn: trn l xut hin mt s vng a gia gn trn l non hoc gi, cc vt hoi t lm m, cc m ny s cht, mc d nhng ri lon khc nhau nh vt xm trn cy kin mch, m nhn trn cy u, vng lm m ca c ci ng; cy citrus th thng to thnh thng to thnh nhng vng mu xanh dc theo gn chnh, phn tht l c mu vng nht. Thiu Mn lm tng cc nguyn t khong c tnh kim gy mt cn i cht khong.. S tha Mn cng gy bnh cho cy. Mn v Fe c ch tc dng ln nhau trong cy. Tnh trng d tha st t do trong t phen BSCL thng a n hin tng thiu Mn ca cy trng. Triu chng thiu Mn c khc nhau, t cc chm mu xm hoc mu vng trn l, tu loi cy trng. -Tha Mn: gy ng c, r cy mu nu, l b mt mu v cht kh t ra l vo. Molipden (Mo) Mo trong c th thc vt t 0.1-300 ppm, nhng lng cy cn ch c 0.04-0.05 ppm; v hm lng ny tng ln 0.5 ppm vn cha c cho cy. m NO3- sau khi hp th vo trong cy s b kh tng hp proteon. Qu trnh ny cn c Mo lm cht xc tc, nn khi thiu Mo th ion NO3- d tha dn n d tha NH3 c cho cy. -Triu chng thiu Mo:vi khun Rhizobium khng th c nh m cho cy nn trng hp ny cy c triu chng thiu m, bin dng l cy h u, nt sn km pht trin, l un cong dng mung v nu lc ny bn thm N th cy khng th tng hp protein m cng tch t NO3- cng lm cho s sinh trng ca cy km. Mo cn cho tng hp leghemoglobin cht mang oxi ca nt sn. Khi thiu Mo nt sn tr nn mu vng hay mu xm (bnh thng c mu hng). t chua thng thiu Mo v t linh hot, cy sinh trng km. Qu trnh tng hp protein b c ch, cy c mu lc nht ging triu chng thiu m. i khi trn l xut hin cc m ng nh sau tr nn vng v cc m ny ri rc khng ln dn ln na. Hm lng Mo cao cng gy c i vi cy. Nu trong nng phm hm lng Mo n >20mg/1kg cht kh th ng vt n rau ti s b ng c Mo, cn ngi n th sinh bnh gut (podagra) a phng, hin tng xy ra ni c m Mo. ng (Cu) -Triu chng thiu Cu: Biu hin u tin l chp l, chp l tr nn trng. Cc l non hp, tr nn xanh m v mu sc v b vn vo hoc nu khng th b bin dng, thng biu hin nhng chm hoi t; s sinh trng ca lng gim kt qu l cy ln dng bi. Cc vn cam qut thnh thong b thiu, m trong trng hp nhng l non cht dn n tn gi bnh cht ngn. Trn cy n tri thn i khi b nt v chy nha. gy ra s pht trin chm, xut hin s hoi t, mt nc cy ho. i vi h ho tho, khi thiu Cu nghim trng, u l b trng, bng khng pht trin c. i vi cy n qu thiu Cu gy hin tng kh nh. Thiu Cu cy d b nm bnh, nht l i vi khoai ty, c chua. Km (Zn) - Triu chng thiu:

Lp DH7TT

V Thanh Hng - Nguyn Vn Tuyn

BNH CY I CNG Thiu Zn hu nh xy ra trn l, l nh vng dng hoa hng ca to, o v h o pecan. Nguyn nhn t s gim sinh trng ca l non v lng thn. Mp l thng b vn vo v nhn nheo v din mo. S vng a ca gn thng c xut hin trong l bp, u, v cy n tri chng t rng Zn tham gia qu trnh to dip lc t hay ngn cn s ph hu dip lc t. Cc l non c mu xanh nht, thiu t gn l c mu xanh, tht l c mu xanh nht. Trng hp trm trng cc l non c th bin i thnh mu trng nht, l non nh, cy mc thnh bi, lng km pht trin, cy ra hoa to tri t, nng sut khng ng k (c th lm gim 50% nng sut cy trng). Cn lm nh tr s sinh trng ca r. Trong cc phng php x l trn c u v nhc im khc nhau, tu thuc vo tng loi cy trng m liu lng v cch x l cng thay i. Cc loi cy thn g nht l h chanh bi rt nhy cm i vi km. S thiu ht km trong cy lm xut hin bnh l c trng cc lng t v l b km hm sinh trng, xut hin s hoi t cc t bo nh m l, lm tng tinh th oxalat canxi trong l. S thiu km lm gim qu trnh tng hp axit amin quan trng l triptophan. Gy ra qu trnh ri lon qu trnh trao i photpho v nhiu qu trnh sinh l nh quang hp, h hp Thiu Zn xem nh l nh tr tng hp ARN m tip theo l ngn cn tng hp protein. V vy, cy thiu Zn th ngheo protein. S kim gi thn trong iu kin thiu Zn c th do nguyn nhn mt phn t yu cu biu kin ca n sinh sn mt hormone sinh trng thc vt, indoleacetic acid (IAA). - Chun on: xc nh tnh trng nghi ng thiu Zn, cc cy c th c phun vi dung dch sulphate km (0.5% ZnSO4 v 0.25% vi) v quan st s phc hi ca cy; nu cy tht s thiu Zn thi gian phc hi sinh trng t 10-14 ngy. Cc l mi s xanh v khng c du hiu thiu km no. S thnh cng ca th nghim phun km gia tng nu cy trng c phun khi xut hin triu chng thiu km sm. - Cha tr: + Bn phn xung t bng cch ri hay bn theo hng + Phun ln l + Ngm ht ging + Nhng r + ng mt ming km vo thn cy. Boron (B) N c chuyn vn chm chp ra khi cc b phn ca m lipe mt khi n c vn chuyn ti t m g. Do thiu B thng xut hin phn non. Cy thiu B cho thy mt bin i rng v triu chng, tu thuc vo giai on v tui cy, nhng mt trong nhng triu chng sm nht l chp r khng dn di ra mt cch bnh thng, km theo bi s tng hp c ch ca AND v ARN. S phn bo trong nh chi cng b c ch, cng nh trong nhng l non. B gi mt vai tr khng xc nh nhng thit yu trong s gin di ca ng phn. Thiu B s nh hng xu n cc c quan sinh sn. B lm cho carbohydrate d vn chuyn qua mng t bo. Sn phm ng ho tch lu trong l v cc ni sinh trng non s thiu ng. Hm lng B trung bnh 15-100 ppm l , nu trn 200 ppm th c th gy ng c. - Triu chng thiu B: Cc im sinh trng ca thn r cht dn. Nguyn nhn c th do qu trnh trao i acid nucleotic b o ln. Lm gim s phn bo ca cc m phn sinh, s sp xp bnh thng ca cc h thng mch dn b ph hu lm cn tr s vn chuyn sn phm ng Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 9

BNH CY I CNG ho n cc c quan khc. Lm hm lng ATP thp trong cc im sinh trng ca thn b gim. Nh thi tim ca c ci, nt thn ca cn ty, rut nc ca c ci ty (turnip) v m kit nc ca to; Gy hin tng tch lu cc cht phenon, cht auxin v lm h hi cc t bo nh thn, chp r (ch yu 2 l mm) gy hoi t cho m cy. Cn lin quan n s tch lu axit cofeic v axit chlorogenic nhng cht c ch sinh trng. - Tha B: gy ng c B thng th hin triu chng vng, nu v cht cy. Bt u t mp l ri lan dn vo trong. Clo (Cl)

Triu chng thiu Clo: l s sinh trng gim, ho kh u l v s pht trin ca nhng im vng a v hoi t, cc l thng t n mu vng chy, gy nn hin tng ho nh l sau khi trn l xut hin cc m cui cng l c th c mu ng thau.R tr nn ngn v chiu di nhng tr nn to hay c dng chu gn chp r. Clo th him thy thiu trong t nhin, do tnh ho tan v hu dng cao ca n trong t v v n cng c chuyn vn trong bi hay trong nhng git hi nc t hon bi gi v ma n l, ni m s hp thu xut hin. Niken (Ni) Thc vt thiu Ni tch lu nhiu Ur trong l v do xut hin bnh hoi t nh l (Lincoln Taiz et al, 2006) Ngoi ra Fe2+ v Al3+ nu d tha cng gy ng c cho cy gii quyt cp bch l bn bng bn phn sulphate mangan. Bin php ra cht c i vn l bin php c bn v c hiu qu lu di hn. 3.2 c cht Tri qua mt thi gian di dng nhiu phn bn ha hc, thuc tr su tuy mang li nng sut cao cho la nhng cng li nhng hu qu nng n, t trng trt b thoi ho, chua ngy cng tng gi l hin tng axit ho t trng trt hay gi mt cch khc l t b phn nhn to khi ph < 5,5. Mt nguyn nhn khc do thm canh km, s dng cht hu c ti nh vic dng rm, r sau thu hoch bn trc tip cho la thi gian phn hu ngn khng iu kin khong ho hu c to ra mt s c t nh Fe2+, Al3+, SO42-, H2S, CO2 v cc axit hu c, 2.2.1 Ng c hu c: Nguyn nhn: L do nng dn thng gieo s ngay sau khi thu hoch v trc dn n ng c cht hu c do rm, r, tn d thc vt ca v trc khng c x l v cha kp phn hu do b vi lp trong iu kin ym kh (ngp nc) to ra cc cht c gc hu c nh: phenol, hydro sulphite (H2S), ethylen, axit hu c rt c cho cy la. Hnh thc: Cc cht c ny tch lu ngy cng nhiu s lm nh hng n tin trnh khong ho dng liu t dng hu c sang dng v c cung cp cho r ca cy la. ng thi cc axit hu c v H2S s gy nn tnh trng cnh tranh Oxy vng r, lm cn tr qu trnh hp th dinh dng v gy hi cho r ca cy la. Triu chng: Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 10

BNH CY I CNG R nht l b r b thi en v c mi hi c trng, trn l c vt bnh m nu hoc cc l b vng xn mu, l khng c khuynh hng xo ngang m dng ng ln, cy la vng v ln, la pht trin km, t nhnh, khng bt phn. Thng xut hin t 15-30 ngy sau khi s, c ni b sm hn khi la mi s vi ngy v gy thit hi rt nng. Ng c hu c c th xy ra trong sut qu trnh sinh trng ca cy la, c bit l giai on u nu b nng c th lm cho cy la b cn ci v c bn phn hoi th cy la cng khng pht trin, giai on tr ng m b ng c hu c kt hp vi cc bnh hi khc nh bnh o n, bnh m vn th cng lm cho cy la b bnh nng hn, nu c tr th cng b lem lp ht. Bin php phng v cch khc phc: - Nn gin thi v gieo cy c thi gian cho rm, r kp phn hu thnh cht hu c d tiu, tt nht l s 2 v la xen canh vi 1 v mu bng ng hoc cc cy h u (u xanh, u tng, lc,) m vn m bo mc thu nhp. - Nn ct gc r, thu gom rm tp trung t hoc phn, cng c th xung ging ngay sau khi lm t, nhng m bo cho la khng b ng c cht hu c nn t trng t nht 2 tun trc khi xung ging. Kinh nghim ca b con nng dn tnh Vnh Long l dng thuc tr c (200 lt/ha, pha 100cc/bnh 16 lt, 2 bnh/cng) phun ln gc r gip cho gc r mau phn hu. - Trong trng hp cy, vi gc r trn mt rung th nn t trng 3 tun mi nn gieo s li. Cy, vi rm r xong tho nc ngp khong 2 tun sau tho ht nc v thay nc mi vo lm t gieo s. - i vi cc rung la ang b ng c cht hu c, trc tin b con cn tho ht nc rung cho rung kh nt chn chim, cho t thng thong nh c bt kh CO2, ri phn Supe ln hoc phun phn bn qua l kahumat, hydrophos,c hm lng ln cao, tho nc mi vo v lm c sch bn. Trong iu kin la khng b ry nu tn cng th nn tho nc cho mt rung kh nt chn chim, t ba ri li a nc mi vo theo chu k 3-4 ln/v s hn ch c hin tng ng c cht hu c rt cao. Tuy nhin, trong trng hp rung ang b ry nu tn cng vi mt s ln th nn u tin gi mc nc phng chng ry nu tt hn trong thi gian phun thuc dp dch sau mi tho nc nh hng dn trn y. Trong thi gian ny cn phi ngng bn phn m. Ch 6-7 ngy sau, nh cy la ln thy ra r mi c mu trng l cu la thnh cng. Tip tc bn phn DAP (1-1,5 bao/ha) + phn Ur (1 bao/ha). - C th ch ng gii quyt ng c cht hu c ngay t u v bng cch phun thuc Gramoxone tiu dit ht tt c cc loi c di hoc la ri, la cht hay gc r khi cy, vi chng b phn hu nhanh hn. 2.2.2 Ng c phn: Nguyn nhn: do vng c tng phn gn mt t, xa knh gch hoc nm trong khu bao khp kn b thiu nc, c vng vng trn mt t hoc trn mt nc bm vo gc la. Triu chng: Cy la b ln dn, b r c mu vng nu, qun queo, khng c r mi v vut trn ngn tay cm thy nhm, l b vng v chy kh chp l, trn l c nhng chm nu st nh. La chm bn r hi xanh, la cy xung b chuyn sang mu nu ta, khng nhnh hoc b ko di thi gian sinh trng, kh tr, nu ng c nng c th b tht thu v b tr mi khng gi.

Lp DH7TT

V Thanh Hng - Nguyn Vn Tuyn

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BNH CY I CNG Cch phng chng: - Lc lm t trc khi s cn phi nh rnh phn tho x phn trc khi cn thit. - Nu nm trong vng t phn nhiu, phi o mng phn chung quanh rung m phn lc tho nc cho kh t gia v. - Sau khi tho nc kh gia v v cho nc vo xong, cn phi theo di r la xem c b phn hay khng. Nu c, th ri 100-200kg vi bt/ ha. Ngoi ra cn c th dng thn cy chui tiu bm thnh mnh rc ra rung, rc tp trung ni la b vng v c biu hin ng c (theo kinh nghim lu nm ca cc b con nng dn). Cch iu tr: - Ngng bn phn m (NPK,DAP, Ur). - Tho nc phn ra khi rung (x phn). - Ri vi bt cho rung (200 kg/ha). - Cho nc ngoi kinh rch vo (thay nc). - Phun phn bn l Hydrophos (giu P). 3 ngy sau quan st r la. Nu c m r trng ra l la phc hi. C th bn phn bnh thng. 2.2.3 Ng c phn bn: Nguyn nhn: mt s trng hp do iu kin khch quan hay do thi quen tng liu s dng ca nng dn khi bn phn qua gc hay phun phn qua l lm cho cy trng hp thu mt lng dinh dng ln trong mt khong thi gian ngn lm cho cy b ng c. Triu chng: l thng b ho, vng, trng hp cy ang mang qu th qu b vng v rng,hin tng ny c th xy ra mt s khu vc hoc b nng c th b c din tch. c bit l hin tng ng c hay xy ra khi phun phn bn qua l qu liu. Trong nhng trng hp nu khng gii c ngay s lm mt ma v trng hp nng cy s b cht. Bn phn d tha c th lm gim nng sut v lm hi n cht lng qu. V d, cc qu t cy c bn qu nhiu phn c th nh hn bnh thng. Chng c th c v dy hn, hm lng ng thp hn v pht trin chm hn. Lm dng phn bn cn lm nhim t v nc ti. Bin php lm hn ch v cch khc phc: - lm hn ch nhng trng hp ri ro xy ra, trc ht nng dn cn tm hiu k sn phm, nhng sn phm c cht lng cao v c n nh cao v cht lng mi nn dng. Nu c th cn phn tch t v l cy theo di chnh xc tnh trng dinh dng ca cy v iu chnh chng trnh phn bn. Khi nm c cc thng tin ngi ta s c kh nng ti u ho cc phn bn v qua lm tng nng sut v lm gim gi chi ph. 2.4. Mt s trng hp ng c khc: Ng c do thuc c: - Cc t non ca l la c mu xanh m, l la b a trn se li ging nh l l hnh. - Mt bi la c th b ng c bnh qun t 1-3 t non. Ng c do Toxicity: - Nguyn nhn: do b con nng thng s dng qu d tha cc nguyn t vi lng nh: Cu, Xn, B, Mn,Hin tng ny thng xy ra trn t c hm lng axit cao. - Triu chng: thng xut hin nhng m chm nh v pha ca ra l, nghim trng hn l ton b ra l ho qun li nh triu chng thiu kali. Lp DH7TT V Thanh Hng - Nguyn Vn Tuyn 12

BNH CY I CNG Ng c do st (ion Fe2+): y l mt phn ng t nhin ca cy la, do b r la to ra mt lp mng ngn cn tr s xm nhp ca Fe bn ngoi mng r hoc c khi chng cn lm ngn chn cc cht dinh dng khc nht l i vi Pht pho v Kali. Ng c do Bore T (B): - Nguyn nhn: do nng dn bn qu d tha hm lng phn B. - Triu chng: biu hin ca ng c thng xut hin trn cc l gi, cc ra l v ngn l b chy xm hoc b bin thnh mu vng, i khi phin l c th xut hin cc m mu nu nh. Ng c nghim trng th cc l c th b rng hoc b ho cho ti khi cht. 4. Cc bnh do thiu tha dinh dng gy ra 4.1 Bnh ngt r (la) Nguyn nhn Nguyn nhn chnh l do t thiu oxi, gy tnh trng ym kh. Hin tng ny thng xy ra khi bn nhiu phn hu c cha hoai mc, t rung c thnh phn c gii nng, t khng c phi i, t ngp nc thng xuyn, Khi trong t tch t nhiu kh c nh CH4; H2S; cc ion Fe2+, Ngoi ra, khi khng oxi, cc cht hu c phn gii khng hon ton, to ra cc axt hu c lm tng chua ca t, tc ng xu n s h hp ca r. Triu chng: Khi bnh mi pht sinh th ngn l la bin vng, ngn l kh. Bnh nng th nhiu l pha trn b vng n 1/3 l, cy la ngng sinh trng, nhnh t, b r thi en c mi tanh hi, r mi khng pht sinh. Cha tr: Nhng chn rung nh trn, th cn bn lt vi bt 20-25kg/so (360m2) trc khi lm t +2-3 gi PenacR P (gi mu vng, c tc dng kch hot vi sinh vt c ch sinh trng mnh v c ch vi sinh vt c hi). Khng bn phn hu c cha hoai mc cho cc chn rung ny. Bn lt nhiu ln, nhiu kali, gim m. Cy xc hoc cy nng tay. Khi la chm b bnh, cn tho cn nc trong 5-7 ngy cho kh nt chn chim ( m khong 60%). Bn vi bt (25-30kg/so) hoc ln supe (15-20kg) lm c sc bn, phun phn bn qua l: A-H 503; K-H; Atonic; YogenR; m Thin nng, 2-3 ln, mi ln cch nhau 3-5ngy. Lm t v v sinh ng rung. Ch : tuyt i khng c bn m. Khi no l la xanh tr li, ra thm l, r trng mi th mi c bn m. Cn phn bit vi vng l do bnh o n l, bnh kh vn gy ra. 4.2 Bnh thi nh qu c chua Nguyn nhn: Do thiu calci khi qu ang c hnh thnh v do bn nhiu m, cy sinh trng nhanh, ri lon m do ma to, hn hn v t ta l khi trng trt. p lc nc l nhn t gy bnh quan trng. Do Nm Geotricum candidum xm nhp gy hi. Triu chng

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V Thanh Hng - Nguyn Vn Tuyn

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BNH CY I CNG Bnh thng xut hin trn cc qu xanh ang pht trin. Trn nh qu xut hin m mu nu, m lan rng dn tr thnh nhng vng th, lm v chuyn thnh mu en. Cc vng b hi co li gy bin dng qu, qu xanh, qu chn u c th b hi. Bin php phng tr - Chn t trng phi m bo nc ti v thot nc tt. - n nh m t. - Bn vi cho t trc khi trng t nht mt thng. - Bn y phn hu c, trnh bn tha m. - Khi thy c triu chng thi nh qu c chua c th s dng Clorua calci, Nitrat calci. 4.3 Bnh chy l la Nguyn nhn Bnh chy l la do nm Pyricularia oryzae gy ra. Triu chng u tin l la xut hin nhng vt mu nu nh nh u mi kim, sau lan dn to thnh nhng vt bnh c hnh con mt, phn gia vt bnh c mu xm trng, ra c mu nu. Nhiu vt bnh to thnh lm cho l la b chy kh. Bnh nng c th lm cht c bi la. Khc phc - S dng ging khng bnh: nn tham kho cc ging la no t nhim bnh trng. Nu vi ging la trng d nhim bnh nn chun b phun thuc phng tr sm. -S tha, s theo hng. - Gim bt lng phn m, ch bn theo nhu cu ca cy la. - Khng rung kh, thiu nc. - Thng xuyn theo di rung la pht hin bnh sm, kp thi phun thuc dit tr. Bin php phng tr p dng bin php 4 ng: dng ng thuc, pha ng liu lng ch dn, phun thuc ng lc, v phun ng ch (ng cch). Pht hin bnh v phun tr thuc sm mi t hiu qu. S dng cc loi thuc nh: Beam, Kasai, Fuji- one, Rabcide... Liu lng phun t 600800 lt (thuc pha) cho 1ha canh tc (75-100 bnh/ha). Khi phun phi h thp vi phun xung pha di phn gia v di ca l la, thuc bm vo thm dn v tr bnh hiu qu hn. 4.4 Hin tng lp, la Nguyn nhn La lp l do bn nhiu m; bn khng cn i m, ln v kali C 3 nguyn nhn gy nn hin tng lp, non: - Do c tnh ca ging - Do iu kin ngoi cnh ( thiu nh sng, ma nhiu, gi bo v t qu tt) - Do k thut canh tc( mt , bn phn v ti tiu khng hp l). + Hin tng rung la lp: Din tch l qu cao, qu trnh quang hp v tch lu cht kh tin hnh khng c bnh thng, lng gluxt l b gim st, t gim kh nng tng hp protit ca cy.

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V Thanh Hng - Nguyn Vn Tuyn

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BNH CY I CNG + Hin tng la : la sinh trng qu mnh, l nhiu, thn cao v yu. Do , sc chng ca cc t bn di khng chu ni sc nng ca cc b phn trn, dn n hin tng la non vo trc hoc sau lc tr. Bin php phng chng lp, : - Chn ging chu phn v chng ( thp cy, chu phn, l ngn hp v ng) - Bn phn m hp l v cn i vi ln v ka li. 5. Qun l Nguyn tc s dng 4 ng: Nguyn tc th nht ng lai.

Th no mi gi l ng lai phn hay ng lai thuc? s dng ng phn bn cho cy trng, iu u tin cn quan tm l trong thi im s dng, mc ch bn lm g? To v nui c, thc t v nui l, x l ra hoa hay nui trichnh mi giai an c mt lai phn thch ng, cn chi tit hn trong tng giai an li c nhng thi k khc nhau, nh thi k hnh thnh, ln ln v n nh (gi, chn) th cng c tng lai phn tng ng, v nh phn m c tc dng thc y tng trng, phn ln kch thch r, thc y hnh thnh mm hoa; phn kali c vai tr n nh, ci thin cht lngcn i vi thuc BVTV, s dng ng thuc cn phi bit i tng gy hi cy trng l g ? su g ?, bnh g ? thuc nhm no b cnh cng, cnh mm, bo t hay t nm cch gy hi ca chng ra sao? t cnh, cn l, chch ht, chy l, thi tri, x mt mi chn cho ng thuc phng hay tr. C lm c nh vy mi mang li hiu qu s dng v cng cn lu chn phn thuc t c nh hng n mi trng v thin ch. Nguyn tc th hai ng liu.

Liu dng l bao nhiu? Hu ht trn nhn bao b u c hng dn, nhng bin qu ln, nh s dng t 10-20 ml cho bnh 8 lt. Khi no th dng 10ml v khi no th dng 20ml?. Xt v gi tr kinh t nu dng 10ml th gi chng y, cn dng 20ml th gi li tng gp i, ni v kt qu s dng, nu dng 10ml th c dit c i tng gy hi khng? Qu tht l bi ton kh cho nng dn hin nay. Tuy nhin dng 10ml hay 20ml, trc ht cn xc nh l nga hay tr? Nu nga nn dng liu thp, bn cnh cng cn lu thit b phun, phun bng my th nn dng liu thpRing i vi phn bn th rt kh xc nh c liu dng no mi . Mun lm c iu phi phn tch nhu cu cy trng cn sn xut ra 1 tn l lm rau, hoa hay quchng ly i trong t bao nhiu dinh dng, c c nh vy mi s dng ng liu lng phn bn. Tuy nhin trong canh tc, nng dn cng c th ty theo sc sinh trng, sc u v nui tri ca cy trng m gia gim lng phn cho tng i, bn cnh cng cn lu iu kin th nhng v pH ca mi trng t. Nguyn tc th ba ng lc. Lc no th bn phn hay phun thuc mang li hiu qu cao nht? i vi vic bn phn, nn bn vo u giai on hay u mi thi k. Bn cnh cng cn quan tm n iu kin thi tit, kh hu lc ra sao? Bi chnh nhng yu t ny c tc ng rt ln n qu trnh hot ng ca l, r. Nu l, r hat ng km th kh nng s dng phn bn cng km. Do , bn phn trong iu kin ny cng khng phi l ng lcCn vic phun thuc lc no phng nga tr c su bnh tt hn? iu ny i

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BNH CY I CNG hi nng dn phi lm tt cng tc d bo, phi bit khi no i tng gy hi s n, chng n bng cch no? nh gi, ma, sng m, ngun nc sng hay do con nginu n ri th phi bit chng hot ng ra sao? ban ngy hay ban m? gy hi giai an no ca cy?...c c nh vy mi chn ng thi im thch hp x l. Nguyn tc th t ng cch. Mt khi xc nh c ng phn, thuc, pha ng liu lng v chn ng thi im x l m cch dng li khng ng th lm gim ti a hiu qu s dng. Trong s dng phn bn cc nh khoa hc lun lun khuyn co khi bn phn hy o rnh v bn vng theo hnh chiu ca tn cy, bi cy nhn c phn qua h thng lng ht ca r, m h thng lng ht li tp trung gn u chp r v tn ti khng qu 24 ting do quy lut pht trin ca c h thng r, bn cnh phn khi bn vo t phi c qu trnh ha tan, phn ly to cc ion v bm vo keo t. Do bn phn theo hnh chiu tn, phn c thi gian ha tan, r c thi gian tm n hp thu phn. i vi vic s dng phn phun qua l s khng mang li hiu qu m ngc li s lm tn thng cy (chy l) nu s dng khng ng cch. L cy trng, ngoi chc nng quang hp cn c vai tr thot hi nc qua h thng kh khng, l nhng l nh li ti nm phn ln mt di l v cng chnh ni y mi c iu kin hp thu phn qua l. Do khi s dng phn phun qua l cn phi phun tp trung mt di l. Ring vic s dng thuc BVTV cn ch n tng i tng gy hi trn tng b phn cy trng m c nhng cch s dng khc nhau, nh ri hay ti thuc quanh gc, bi (qut) thuc ni vt bnh, phun Vi vic s dng ng 04 nguyn tc trn, ngoi vic gim ti a chi ph u vo cho vic sn xut hng nng sn, cn to c mt sn phm an ton, sch bnh v khng gy nh hng n mi trng. Tuy nhin, lm c iu ny cn tng cng tt cng tc khuyn nng gip nng dn c kin thc v quy lut pht sinh, pht trin ca i tng gy hi; qu trnh sinh trng v pht trin ca cy trng, cng nh tc dng ca tng lai thuc BVTV, phn bn c bit l cng tc d bo ca ngnh l ht sc cn thit nng dn bit m ch ng phng nga. V sinh ng rung Nhng bin php k thut nhm to s thun li cho cy trng sinh trng v pht trin trong mi trng khng hoc t c ngun su bnh hi. V sinh ng rung gm cc bin php sau: - K thut lm t thch hp nh cy, phi i, xi, ba trc, ci to tnh cht l ho ca t, ng thi hn ch s tn ti v lan truyn ca su bnh. - Tr dit c di xung quanh rung v trong rung: ct c, pht b, p bn ln b v cc gii php khc nhm hn ch ngun thc n v ni c tr ca cc loi su bnh. - Thu gom v x l ng lc cc tn d ca cy trng sau khi thu hoch. kin c nhn - Ngoi ra chng ta cn phi c thi gian cho t ngh ngi gia cc ma v. i vi la th thi gian ny t 15-30 ngy. Nhm to iu kin cho cc vi sinh vt s phn hu cc hp cht hu c.

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BNH CY I CNG - M hnh canh tc cng l mt khu rt quan trng trong vic lm gim hay ngn chn cc mm bnh. Chng ta phi hn ch nhng hnh thc canh tc c canh, thm canh tng v nh trng la v 3; v thc t cc m hnh canh tc ny hiu qu khng cao, m cn gp phn vo vic lm tng dch bnh trn cy trng. - K thut canh tc: Mt gieo trng l yu t rt quan trng, nu gieo trng vi mt tha th ln ph t v khng gian ni trng, khng tn dng c ti a nhng yu t t nhin canh tc. Nu m gieo trng vi mt qu dy th dn n cy trng phi cnh tranh dinh dng, nh sng nc bnh cnh cc loi su bnh cng s d tn cng hn nh hng n nng sut cy trng nhiu hn. V d la, cc nh khoa hc khuyn co nn s hng vi lng ging 8-12 kg/hecta. Nhng a s b con nng dn li gieo trng vi lng trung bnh 15-20 kg/hecta. C bit Tnh Bin vng ng bo dn tc Kherme lng ging la em ra gieo trng ln n 25-30 kg/hecta. 6. Kt lun Bnh do dinh dng v cc c cht gy ra chng cng c tc hi v cng ln. Nng sut cy trng gim, cy trng th sinh trng v pht trin km, thm ch c th cht, cng l tc nhn gp phn cho nhng vi sinh vt khc tn cng cy trng (nh bnh chy l la do nm tn cng,) Bit c nhng tc hi ca tng loi nguyn t khong khi m s dng khng hp l. Vi nhng t im sinh l th hin r nt trn cy trng. Nhng nh hng ca cc c cht c cht i vi cy trng. t ra cp bch tuyn truyn chuyn giao k thut canh tc, s dng nng dc v phn bn n nng dn. Ngi nng dn th khng hiu r hoc nm bt c tt c nhng k thut nn vic s dng khng mang li hiu qu cao. Xc nh c nhng nguyn nhn, triu chng ca tng loi yu t dinh dng v c cht t a ra bin php qun l, phng trnh l bn phn cn i, hp l; s dng phn bn v thuc bo v thc vt theo nguyn tc 4 ng, ci thin li bin php canh tc nhm to ra mt nn nng nghip bn vng. Ti liu tham kho Phm Vn Kim, Cc nguyn l v bnh hi cy trng, HCT, 2000, trang 8-14 Nguyn Nh Khanh- Nguyn Lng Hng, 2007, Gio trnh sinh l hc thc vt, HSP. Ng Th o- V Hu Ym, 2005, t v phn bn, HSP L Vn Ho v Nguyn Bo Ton, 2005, Gio trnh sinh l thc vt, HCT, trang 80-96. www.sonongnghiep.angiang.gov.vn (s nng nghip An Giang) www.Irc.ctu.edu.vn (trung tm hc liu H Cn Th) http://www.mard.gov.vn (chi cc BVTV TPHCM) www.caylua.vn (Vin Khoa hc Nng nghip Vit Nam) www.ascardvn.com (Trung tm t vn v h tr PTNN, nng thn VN) http://www.dost-bentre.gov.vn (s KHCN Bn Tre)

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