» TRAO DOI
DAC DIEM HINH THAI CUA Phyjophthora Cap^sici GAY BENH CHET NHANH FJO TIEU VA TINH
KHANG THUOC METALAXYL CUA CAC MAU NAM PHAN LAP
GI6I THIEU
Hd tieu la mdt trong nhQng m a t h a n g ndng san cd gia tri xua't khau dQng h a n g thQ 5 d Viet Nam. NhQng den n a m 2007 dien tich san iQpng tieu giam dot ngpt so vdi nam 2006, do gia ca bap benh va sau benh hai bung phat t h a n h dich. Dae biet la b e n h chet n h a n h da phat sinh p h a t trien m a n h d mdt so vung trdng tieu trpng diem cua ca nQdc, gay m a t mau t r a m trpng, t h a m chi gay m a t t r a n g (Tran DQc Tung, 2007).
B e n h c h e t n h a n h do n a m Phytophthora spp la benh nguy hiem tren cay hd tieu d Viet Nam cung nhQ tren nhieu vung trdng tieu tren the gidi. Chan doan benh dQa vao cac trieu chQng dien hinh nhQ : la bi ua vang, cay heo ru nhanh; cac dot t h a n bien mau t h a m den va rung. Benh tien trien nhanh tQkhi phat hien trieu chifng dau tien den khi tieu chet hoan toan ehi trong vdng 7 - 1 0 ngay.
Benh chet n h a n h day tieu r a t khd phdng tri, ddi hdi phai ed mdt quy trinh phdng trQ tdng hpp, rieng thud'c hda hpc chi dQpc xem la bien phap m a n g tinh tinh the khdng diet trQ dQpc m a m b e n h t r o n g da't (Doan Van Ai, 2007)
Nghien cQu nay de cap den viec md ta cdc dac diem h i n h t h a i cua n a m Phytophthora Capsici gay benh chet nhanh hd tieu trdng tai huyen Cam My
— TRINH TH! PHLTONG VI, TRAN THj H U O N G
LE QUYNH NHJ, PHAM THj MINH KIEU, LE D I N H DON Bo mon Bdo ve thiJc vgt, khoa nong hoc, DHNL TP. Ho Chf Minh
Ho tieu b! b?nh chet nhanh. Anh: VTnh Sinh
16 ^ TAP CHi KHOA HOC VA CONG NGHE
TRAO D O I «
tinh Ddng Nai va xem xet a n h hQdng cua Metalaxyl den kha ndng sinh trQdng cua mdu n a m trong dieu kien in vitro.
VAT LigU VA PHl/ONG PHAP 1. P h a n lap n a m :
Mdu r i va gdc tieu benh dQpc thu nhap tQ cac cay tieu vQa mdi xuat hien trieu chQng heo ru, tai vung chuyen canh hd tieu thudc huyen Cam My - tinh Ddng Nai. M i u cay dQpc u tren mdi trQdng CMS chpn Ipe tai nhiet dp phdng trong 72 gid va giQ tren mdi trQdng PGA.
2. Md t a h i n h t h a i n a m Phytophthora t h e o phQOng phdp ciia Ho, ann va Chang (1995)
Theo ddi sQ phat trien cua m i u nd'm tren mdi trQdng CRA.
Cay mdt khoanh n a m cd dQdng kinh 4 - 5mm cd cung dp tudi vao giQa mdi trQdng trong dia petri. U dia tai nhiet dp 25 - 28 °C. Quan sdt, md ta mau sac va hinh thdi tan n a m .
Nghien cQu cdc chi tieu hinh thdi n a m tren mdi trQdng long CR 20%. Ca'y timg khoanh nd'm cd dQdng kinh 4 - 5mm vao trung t a m dia petri, u tdi trong 48 gid d nhiet dp 25 - 28°C, sau dd phoi sdng 24 gid. Theo ddi cdc chi tieu canh sinh bao tQ;
hinh danh, kich thQdc ciia tui bao tuf.
Xde dinh dang lai eua cdc m i u nd'm b a n g 2 t e s t e r c h u a n Phytophthora cinnamomi loai A I v a Phytophthora cinnamomi loai A2. Tren cung
mpt dia mdi trQdng CRA, dat m i u nam cd kich thQdc 20 x 2 x 2mm song song m i u tester cd kfch thQdc tQOng tQ; ii dia cay trong tdi tai nhiet dd 25 - 280C.
Sau 10 - 14 ngay cau true hQu tinh se hinh t h a n h t r e n dQdng tiep gidp cua m i u n a m can xac dinh ket qua lai theo kieu A^,
\ vd A3.
3. Khdo sdt tinh khdng thud'c metalaxyl cua cdc m i u n a m
Cay khoanh n a m cd dQdng kinh 4 - 5 mm vao giQa mdi t r Q d n g CRA cd bd' s u n g Metalaxyl theo cae ndng dp Ippm, lOppmva lOOppm trong dia petri ed dQdng kinh 90mm.
U dia cay trong tdi tai nhiet dp 25 - 28°C. Thdng qua viec khao sat tdc dp sinh trQdng eua spi nam, dQpc do sau 2 va 5 ngay sau cay; dQa vao edng thQc tinh.
Dp hQu hieu cua thude hda bpc de danh gia ket qua. Dd hQu hieu (%) = ((Bl - B2)/B1)*100.
Trong dd :
B l : DQdng kinh trung binh cua t a n n a m tren mdi trQdng khdng cd thudc Metalaxyl.
B2 : DQdng kinh trung binh cua tan n a m tren mdi trQdng cd thud'c Metalaxyl.
(Ngd Thi Xuyen va Hoang Van Thp, 2006)
KET QUA VA THAO LUAN 1. Md t a c a c m a u n a m Phytophthora
Bang phQOng phdp phan lap trQc tiep tQ md cay benh tren mdi trQdng CMS chpn Ipe, da phan lap va iQu giQ dQpc 7 m i u nam Phytophthora sp. Tren cac day tieu vQa ed trieu chQng heo ru tai huyen Cam My tinh Ddng Nai!
Tan nam ciia 7 mau phan lap cd dang hoa hdng hoac xda ra dang hao cue, mep trdn deu.
He spi n a m cd mau t r a n g hoi bung, hiem cd spi nam khi sinh trong khdng khi, he spi cd dang san hd. Khdng xua't hien spi n a m t r Q o n g p h d n g h o a c Clamydospore t r e n ea mdi trQdng long va r a n (cd agar).
Canh sinh bao tQ dang don hoac dang bat qui tae hinh t h a n h t r e n mdi trQdng ed agar, rieng tren mdi trQdng long canh sinh bao tQ cd dang tdn du, day la dae d i e m n h a n d a n g quan trpng cua n a m Phytophthora Capsici.
Tui bao tQ thQdng rung sdm vdi eudng dai, thQdng ed 1 chdp
dang hinh cau hoac ndng dang ban cau. Hinh dang tui thay ddi tuy vao ty Ie D/R cua tQng mau phan lap; thay ddi tQ cd dang trQng, trQng rdng, trQng ngQpc, chanh, le ngQpc den keo dai dang ellip. Mae du sd do eua cac chi tieu hinh t h a i giQa cae m i u phan lap cd sQ khac biet, nhOng tat ea deu nam trong gidi b a n ciia mdt loai. Chang b a n m i u PeDSN07 - 1 cd chieu dai eudng rung bien thien trong khoang (37,5 -) 97,5 (-125) pm, trong khi m i u PeDN 0 7 - 6 lai cd kich thQdc cudng trung binh (15 - ) 82,7 (- 132,5) pm. Chieu dai Id phdng thieh eua mau PeDN 07 - 7 la (5,0 -) 6,0 (- 8,8) }im, rieng mau PeDN 0 7 - 5 lai bien dpng trong khoang (5,0 - ) 6,0 (- 10,0) pm; nhQng ehung deu dQpc xep vao loai cd Id phdng thich hep (5 - 10pm).
DQa vao sd' lieu trong bang 2, so sanh vdi chi dan cua Ho, Ann va Chang (1995) cd the ket luan 7 mau n a m ed ten loai la Phytophthora Capsici.
Ca 7 mau phan lap deu cd kha n a n g tQOng h p p vdi t e a t e r chuan P. Cinnamomi loai A^.
Sau 10 ngay lai, bao tQ noan dQpc hinh t h a n h t r e n dQdng tiep gidp giQa mau phan lap t e s t e r A^. Dieu n a y ed t h e k h a n g dinh ca 7 mau n a m Phytophthora p h a n lap t r e n tieu bi benh chet n h a n h tai huyen Cam My thudc nhdm di hpp (Heterothallic) cd kieu lai A^ vdi tui dQc bao xung quanh tui noan (amphigynous). Ket qua nay phu hpp vdi ket qua xde dinh hinh thQc giao phdi (mating type) cua cae miu phan lap Phytophthora Capsici tai vQdn tieu hi benh chet nhanh d cdc tinh Binh PhQde, Ddng Nai, Ba Ria - Vung Tau eua Nguyin Vinh TrQdng (2006).
2. Khao sat tinh khang thude M e t a l a x y l e u a m d u n a m Phytophthora Capsici
TAP CHI KHOA HOC VA CONG NGHE • 17
» TRAO DOI
• M e t a l a x y l (N - ( 2 , 6 D i m e t h y l p h e n y l ) - (Methoxyacety) - DL - alanin methyl este) la boat chat cua 1 loai thude trQ nam, t a e ddng ndi h a p , ed kha n a n g iQu dan m a n h va phd dung rdng de phdng trQ cae b e n h do n a m Phytophthora gay ra t r e n mdt sd cay trdng nhQ ea chua, khoai tay, dQa, nho, vai, hd tieu. Hien nay, thude van dang dQpc sQ dung rdng r a i dQdi nhieu ten thQOng m a i k h a c nhau, tuy nhien da cd nhieu nghien cQu trong va ngoai nQdc k h a n g dinh da ed hien tQpng n a m Phytophthora k h a n g m e t a l a x y l . T h e o N g d T h i Xuyen (2004), P.Infestans t a i vung Da L a t da ed hinh t h a i t a n n a m t r e n m d i t r Q d n g metalaxyl. DQa vao hinh t h a i t a n n a m t r e n m d i t r Q d n g metalaxyl, de n h a n b i e t ba n h d m khde b i e t :
Nhdm C - t a n n a m cd dang bdng (cotton), spi n a m mpc ky sinh (phdng len).
N h d m F - t a n n a m d a n g n h i n (Flat), spn n a m mpc lan, sdt m a t thach.
Nhdm CF - t a n n a m vQa d dang F vQa d dang C.
O ndng dp Ippm, spi n a m mpc phdng len d trung t a m eua dia, va cang xa t a m spi n a m mpc Ian sdt thach, trong khi dd d ndng dp lOppm va lOOppm thi spi n a m mpc t h a n h khdi an sau xud'ng thach.
Cae mau P. Capsici phan lap d t h a n g 01 trong n a m 2007 cd dac diem la khdng trung binh vdi ndng dp thude, nhQng tinh k h a n g tang theo thdi gian m i u n a m tiep xuc vdi thud'c. O ndng dp Ippm, mau PeDN07 - 1 sau 2 ngay theo ddi, dp hQu hieu eua thude la 42,6%; nhQng d 5 ngay dp hQu hieu giam chi edn 23,9%. Rieng cac p h a n lap d t h d n g 3 va 4 n a m 2007 cd dae diem la k h a n g trung binh vdi ndng dp thud'c Metalaxy 1 ppm.
nhQng lai m a n cam vdi thude d eae ndng dp thudc cdn lai, ngoai trQ m i u PeDN 07 - 6. Cac m i u p h a n lap trong 01 n a m 2007 dQpc thu n h a p tai vQdn ed ty le cay chet cao, trong thdi diem benh dang trd t h a n h dich ldn, ndng dan dang sQ dun rat nhieu loai thud'c vdi thdi gian giQa eae lan phun thude ngan de d a p dich; rieng eae mau PeDN07 — 5^ PeDN07 - 6 va PeDN07 - 7 dQpc thu t h a p vao cdc t h a n g 3, 4 khi benh da d i i n bien cham, dp IQC benh giam khi thdi tiet khd hanh va vQdn thu thap mau cd dp IQC ben trong dpt dich cua cac t h a n g dau mua khd tha'p.
NhQ vay, tinh khang thud'c cua n a m P. Capsici ed the thay ddi tuy vao cQdng dp sQ dung thude hda hpc va theo thdi gian tiep xuc thudc h d a bpc eua nam.
Viec sQ dung lau dai cdc loai thud'c cd cung b o a t c h a t de
phdng trQ b e n h cd the d i n den nguy CO t d c n h a n gay benh k h d n g thudc r a t eao.
KET LUAN
P. Capsici la t a c n h a n gay benh chet n h a n h hd tieu trdng t a i huyen Cam My tinh Dong Nai; tuy giQa cae m i u v i n co SQ bien thien ve kich thQoe cua ede ehi tieu h i n h thai, nhong deu trong gidi ban cua loai. Ta't ea cae m i u p h a n lap deu cho ket qua lai thude kieu di hpp Ag. Tinh khdng thQdc metalaxyl eua n a m P. Capsici da xuat hien tuy p h a n Qng khdng chi d mQc trung binh. Ket qua kien nghi r a n g can ed chien iQpc cu the khi sQ dung thQdc hda hpc de phdng trQ benh chet nhanh day tieu, duy tri hieu qua lau dai.
T.T.P.V.-T.T.H,-L.Q.N.- P.T.M.K. - L.D.D.
TAI Lieu THAM KHAO
Doan Nhan Ai, 2007. Wpf s6 nguySn tic phdng trii b§nh chet nhanh trSn eiy tieu (pipper nigrum). Cac giai phap ky thuSt nang cao nang suat, ch^t lU(?ng v^ gl^
tri ho tieu, Ba R i a - V u n g Tau, 11/5/2007, trang 9 2 - 1 0 2 .
Ho H.H., Ann P.J and Chang H.S, 1995 The genus in Taiwan. Institute of Botany, Academia Sinnica Taipei, 85 Pages.
Nguyin VTnh Tuong, Edward C.Y.L., Lester W.B.,2006. H'inh thij/c sinh sin hUu tinh cua Phytophthora capsici Leonian, tac nhan gSy b^nh chit heo h6 ti6u. T?p chibao v6 thUcv^tS : 1 4 - 1 8 .
Ngo Thi Xuyen va Hoang Van Thp 2006. Khio sat tinh khang thudc l^etalaxyl, khi nSng nhiim tr§n cac gid'ng chi/a gen khang vi bio quin miu thu thip nim Phytophthora infesfans gay benh moc ci chua, khoai tiy. Tap ch( B i o v6 thi/c vat 6: 1 7 - 2 2
Trinh Thi Phudng Vy, 2004. Dinh danh nim Phytophthora spp bing kf thuit PCR (Phymerase Chain Reaction) kSt hap vdi md ti hi nh thii hoc. LuSn vSn tfit nghi§p ky su Nong hpc, Dai hpc Nong Lam TP. Ho Chf Minh, ViSt Nam.
Tran Duo Tung, 2007. Tinh hinh san xuat xuat khau ho tiSu quy I - 2007. Cic giii phap ky thuat nang coa ning xuit, chSt luang vi gii tri hd ti&u, B^ Rja - Vung Tau, 11/5/2007, trang 2 0 - 2 6 .
