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Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

PHN I: T VN Vit Nam l mt nc nng nghip, trong thi gian va qua, nng cao nng sut thu hoch ngi nng dn khng ngng s dng cc loi phn bn ha hc. S canh tc lin tc trc tip lm cho t trng thiu cht dinh dng nghim trng, t b chai cng, gim ph nhiu, tnh cht vt l, ha hc v sinh hc ca t trng b thay i. b p phn cht dinh dng b mt i, hng triu tn phn ha hc c bn xung t trng mi nm. Tuy nhin ngi ta c tnh lng phn bn m cy hp th ch khong 40-50% lng phn bn cho cy trng. Nh vy lng phn bn cn li s ha vo khng kh, thm vo t hoc theo dng nc ra sng, sui v lm nhim mi trng, iu ny gy lng ph c v tin ca, sc lao ng, lm tng cao gi thnh sn phm, gim tnh cnh tranh trn th trng. Bn cnh s hot ng ht cng sut ca cc nh my sn xut phn ha hc, lng phn bn m cy khng hp th gy nh hng nng n n mi trng sng v lm nh hng n sc khe ca con ngi. Dn s th gii gia tng i hi lng lng thc thc phm sn xut ra cng tng, tc l phi tng nng sut cy trng. Mun gii quyt vn ny, bn cnh vic to ra nhiu ging cy trng mi c nng sut cao cn cn phi bn cc loi phn hp l ci to t, lm cho t khng b kit qu (Chu Th Thm et al., 2006). S xut hin v s dng phn ha hc t gia th k XX c ph bin trn khp th gii v nhng li ch thc t v cng to ln m n mang li. Tuy nhin, ngi ta nhn ra nhiu khuyt im khi sn xut v s dng loi phn ny. Qu trnh sn xut phn ha hc i hi chi ph u t ln, nguyn liu sn xut c th lm kit qu ngun ti nguyn khng phc hi c (du m). Mt khc, khi s dng phn ha hc trong mt thi gian di c th lm ph nhiu ca t gim, nhim tng nc mt, nhim c t (Nguyn Ph Th, 2006), nh hng xu n cht lng sn phm, c th gy hi n sc khe con ngi (L Vn Tri, 2001). v nh hng n mi trng khng kh ca tri t ci to t v khc phc nhng hu qu do vic sn xut v s dng phn bn ha hc, ngi ta s dng phn hu c thay th mt phn v c th tin ti thay th hon ton lng phn ha hc. Nhng phn hu c truyn thng (phn xanh, phnChuyn ngnh cng ngh sinh hc 1 Vin NC&PT Cng ngh Sinh Hc

Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

chung, phn rc) kh c th p ng c nhu cu ca mt nn nng nghip hin i. S pht trin ca mt nn khoa hc tin tin in hnh l s pht trin ca ngnh cng ngh sinh hc cho ra i mt sn phm mi: phn hu c vi sinh (gi tt l phn vi sinh). Kt qu nghin cu ca nhiu quc gia trn th gii cho thy vic s dng phn bn vi sinh vt c th cung cp cho t t 30-60 kg nit (m)/ha/nm, thay th n 50% lng ln v c cn bn v lm tng ph nhiu ca t. Cc ch phm c cha vi sinh vt cn lm tng kh nng trao i cht trong cy, nng cao sc khng v chng bnh cy trng, lm tng cht lng nng sn, tng thu nhp cho nng dn (theo www.vneconomy.vn s ra ngy 29/10/2007) T li ch thc t v nhu cu cp thit ca vic nghin cu, s dng phn vi sinh, cc nc trn th gii ni chung v Vit Nam ni ring ang tin hnh nghin cu v trin khai ng dng rng ri, c nhiu sn phm c cp php v lu hnh t nhiu nm nay. Tuy nhin, chim lnh c lng tin ca nng dn v thay th tp qun sn xut ca h t vic s dng phn ha hc sang s dng phn vi sinh cn l mt bi ton kh. Li gii ca bi ton ny l phi lm sao kt hp mt cch hon ho gia cht lng, gi thnh v s tin dng. S dng nhng cht mang d tm, r tin mang tnh cht tn dng cc ph thi t cc quy trnh sn xut cc sn phm khc l mt hng i ang c ch nht. V ngoi vic lm gim chi ph sn xut, hn ch vic nhp khu phn ha hc, to thm nhiu cng n vic lm th cn gp phn nng cao li nhun cho nng dn, ng gp vo qu trnh sn xut lng thc thc phm an ton, lm gim nhim mi trng v xy dng m hnh pht trin bn vng trong Cng - Nng nghip. B bn ma l mt s la chn ph hp v b bn ma nu c x l ng cch s l mt mi trng hu hiu cc vi sinh vt pht trin, to tin cho mt sn phm phn vi sinh cht lng tt, gi thnh h. Khng nm ngoi nhng mc ch trn, ti Kho st kh nng sng st ca vi khun Gluconacetobacter diazotrophicus trong cht mang b bn ma c thc hin.

Chuyn ngnh cng ngh sinh hc

2

Vin NC&PT Cng ngh Sinh Hc

Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

PHN II: LC KHO TI LIU2.1. Phn vi sinh. Gii thiu v phn vi sinh. 2.1.1.1. Khi nim Theo TCVN 6169:1996, phn bn vi sinh vt (gi tt l phn vi sinh) l sn phm cha mt hay nhiu dng vi sinh vt sng, c tuyn chn c mt t theo tiu chun hin hnh. Thng qua cc hot ng ca chng sau qu trnh bn vo t to nn cc cht dinh dng m cy trng s dng c (N, P ,K, . . .) hay cc hot cht sinh hc, gp phn nng cao nng xut v (hoc) cht lng nng sn. Phn vi sinh bo m khng gy nh hng xu n ngi, ng thc vt, mi trng sinh thi v cht lng nng sn. 2.1.1.2. Phn loi o Phn bn vi sinh vt c nh nit

1.

Phn bn vi sinh vt c nh nit (tn thng gi: phn m vi sinh) l sn phm cha mt hay nhiu dng vi sinh vt sng, c tuyn chn vi mt t theo tiu chun hin hnh, c kh nng c nh nit t khng kh cung cp cc hp cht cha nit cho t v cy trng, to iu kin nng cao nng sut v (hoc) cht lng nng sn, tng mu m ca t. Phn vi sinh vt c nh nit v cc dng vi sinh vt ny khng gy nh hng xu n ngi, ng thc vt, mi trng sinh thi v cht lng nng sn. Vi sinh vt c nh nit l vi sinh vt sng cng sinh hay hi sinh vi cy trng, hoc vi sinh vt sng t do trong t, nc, khng kh, c kh nng to khun lc c trng trn mi trng nui cy khng cha hp cht nit (mi trng NfM, YMA, Ashby). Cc vi khun c nh Nit: vi khun c nh nit khng thuc cy h u thuc cc ging Achromobacter, Acetobacter, Alcaliganes, Arthrobacter, Azomonas, Bacillus, Beijesinekia, Clostridium, Camplylobacter, corynebacterium, Decxia, Desulfporibrio, Enterobacter, Herbaspirium, Lignobacter,3

Mycobacterium,

Methyllosinys,

Pseudomonas, Rhodopspirillum, Rhodopseudomonas v Xanthobacter (Wani, 1990).Chuyn ngnh cng ngh sinh hc Vin NC&PT Cng ngh Sinh Hc

Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

Mt s loi c tm thy trong vng r cy ng cc ch yu l Azobacter v AzoSpirillum; mt s vi khun c nh m ni sinh trong cc cy ch (ma) c tm thy l vi khun Gluconacetobacter diazotrophicus o kh tan Phn bn vi sinh vt phn gii hp cht photpho kh tan (tn thng gi : phn ln vi sinh) l sn phm cha mt hay nhiu dng vi sinh vt sng c tuyn chn vi mt t bo t tiu chun hin hnh, c kh nng chuyn ho hp cht photpho kh tan thnh dng d tiu cung cp cho t v cy trng, to iu kin nng cao nng sut v (hoc) cht lng nng sn. Phn ln vi sinh v cc dng vi sinh vt ny khng nh hng xu n ngi, ng thc vt, mi trng sinh thi v cht lng nng sn. Thng qua cc hot ng ca vi sinh vt phn gii hp cht photpho kh tan, cc hp cht photpho kh tan c chuyn ho thnh dng d tiu i vi cy trng. Vi sinh vt phn gii hp cht kh tan to vng trn trong sut bao quanh khun lc (vng phn gii) trn mi trng cha ngun photpho duy nht l Ca3(PO4)2. Nhm vi sinh vt c bit c kh nng ha tan ln (Subba Rao, 1983; Gaus, 1990) bao gm vi khun Bacillus megaterium, B. Circulans, B. subtilis, Pseudomonas straita, P. rathonis; nm Aspergillus awamori, Penicillium digitatum, Trichoderma sp; nm men Schwanniomyces occidentails. o Phn bn vi sinh vt phn gii cellulose Phn bn vi sinh vt phn gi cellulose (tn thng gi: phn vi sinh phn gii cellulose) l sn phm cha mt hay nhiu dng vi sinh vt sng, c tuyn chn vi mt t theo tiu chun hin hnh c kh nng phn gii cellulose , cung cp cht dinh dng cho t v cy trng, to iu kin nng cao nng sut v (hoc) cht lng nng sn, tng mu m ca t. Phn vi sinh vt phn gii cellulose v cc dng vi sinh vt ny khng nh hng xu n ngi, ng thc vt, mi trng sinh thi v cht lng nng sn. (http://www.cuctrongtrot.gov.vn/ChuyenTrangPB/chuyentrangPB/indexCTPB.aspx? tacn=techologystandar&type=first&num=1). Phn bn vi sinh vt phn gii hp cht photpho

Chuyn ngnh cng ngh sinh hc

4

Vin NC&PT Cng ngh Sinh Hc

Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

o Phn vi sinh vt kch thch tng trng cy Phn vi sinh loi ny cha mt nhm nhiu loi vi sinh vt khc nhau, trong c vi khun, nm, x khun... Nhm ny c cc nh khoa hc phn lp ra t tp on vi sinh vt t. Vi khun tng hp kch thch t tng trng thc vt thng sng trong vng r ca thc vt c nh hng n s tng trng ca cy gi l vi khun vng r kch thch tng trng thc vt (PGPR= Plant Growth Promoting Rhizobacter) (Schoroth v Hancock, 1981). PGPR bao gm cc ging Actinoplanes,Agrobacterium, Alcaligenes, 1988). Nm r dng bi (VAM= Vesicular Arbuscular Mycorrhizae): cc nm c khun ty n su vo bn trong t bo nhu m r cy, chng ht nhiu dng cht t t cung cp trc tip cho thc vt. Ngoi ra nm cn c kh nng gip cy chu hn trong vng t sa mc, gip cy khng li cc loi nm gy hi khc (Mosse et al, 1981). Nm r bao gm cc ging Endogone, Glomus, Entrophosphora, Gigaspora, Acaulospora, Scutellispora. Ngi ta s dng nhng ch phm gm tp on vi sinh vt c chn lc phun ln cy hoc bn vo t lm cho cy sinh trng v pht trin tt, t su bnh, tng nng sut. Ch phm ny cn lm tng kh nng ny mm ca ht, tng trng lng ht, thc y b r cy pht trin mnh. Nh vy, ch phm ny c tc ng tng i tng hp ln cy trng. sn xut ch phm vi sinh vt kch thch tng trng ca cy, ngi ta s dng cng ngh ln men vi sinh vt. cc nc pht trin ngi ta s dng cc thit b ln men t ng, cng sut ln. nc ta, dng k thut ln men trn mi trng bn rn sn xut ch phm ny, bc u cho kt qu kh tt. (http://agriviet.com/news). 2.1.2. Tiu ch nh gi cht lng phn vi sinh 2.1.2.1. Phn bn vi sinh vt trn nn cht mang thanh trng Phn bn vi sinh vt trn nn cht mang thanh trng l sn phm, trong cht mang c tit trng trc khi cy vi sinh vt hu ch. Phn vi sinh loi ny c mt Chuyn ngnh cng ngh sinh hc 5 Vin NC&PT Cng ngh Sinh Hc

Amorphosporangium,

Arthobacter,

Azotobacter,

Bacillus,

Brandyrhizobium, cellulomonas, Enterobacter, Pseudomonas, Rhizobium (Weller,

Lun vn tt nghip i hc kha 32 _ 2010

Trng i hc Cn Th

t bo vi sinh hu ch (CFU * /g ( hay ml) phn bn) khng thp hn 1,0 . 108 t bo /g (ml) phn, t bo vi sinh vt tp khng ln hn 1,0 .106 t bo /g (ml) phn. Phn vi sinh loi ny c thi gian bo qun t 6 thng tr ln. 2.1.2.2. Phn bn vi sinh vt trn nn cht mang khng thanh trng Phn bn vi sinh vt trn nn cht mang khng thanh trng l sn phm, trong cht mang khng c tit trng trc khi cy vi sinh vt hu ch, c mt t bo vi sinh hu ch t 1,0 . 106 n 1,0 . 107 t bo /g (ml) phn. Thi gian bo qun ti thiu 6 thng (http://www.cuctrongtrot.gov.vn/ChuyenTrangPB). Cht lng phn vi sinh c nh nc quy nh theo nhng tiu chun ring bit nh: TCVN 6166:04 i vi phn vi sinh c nh m, TCVN 6167:96 i vi phn vi sinh ha tan ln... Ngoi ra, theo Nguyn Thanh Hin (2003)