Tgp chi Khoa hpc Tmdng Bgi hpc Can Tha Phdn B: Ndng nghiip. TTiiiy sdn vd Cong n^ Sinh hpc: 35 (2014): 91-96^'''
Tap chl Khoa hgc Tru'dng Oai hpc Can The*
website: sj.ctu.edu.vn
D^^C DIEM VI TRI BE TRUTVG VA ANH HlTdNG CUA THCH GIAN PHUN NlTdC
DfeN QUA TldNH N d T R T J N G 6 C B U ' O U D 6 N G {PILA POLITA)Ngo Thi Thu Thao', Le Van Binh' va Nguyen Thi Bich Tuyen'
' Khoa Thuy sdn, Truong Bgi hgc Cdn ThoThdng (in chung:
Ngdy nhan: 30/05/2014 Ngdy chdp nhgn: 30/12/2014
TUle:
Characters of egg releasing position and effects of water spraying time intervals on the hatching process of black apple snail (Pila polita) Td: khda:
Oc buau ddng, Pila polita.
phun nude, ly li nd, Ihdi gian
Keywords:
Black apple snail, Pila polita.
water spraying cycle, hatching rate, hatching time
ABSTRACT
This study was conducted to find out the distribution of the black apple snail egg batch in the pond and the effects ofthe water spraying cycle on the hatching process. Four water spraying cycles were tested during snail egg incubation as follow: 1).3 hours; 2).6 hours; 3). 9 hows tmd 4). 12 hours. Egg batches were located on coir substrates and incubated into 12 rectangular PVC tanks (3 egg batches/lank). The results showed that the snail eggs were laid near the pond walls at high frequency (43.5%) and few egg batches were found on the plant trunks around the pond (6.5%).
Hatching rate of snail eggs cfier every 6 hours (90.8%) was significantly higher (p <0.05) than that with 3 hours (68.9%). Conducting 3 or 6 how- water spraying cycle, hatching time was II.O lo II.3 days which were significantly shorter (p<0.05) than fi-om 9 hows (15.9 days) or 12 hours (18.2 days). Our findings indicated that snail eggs were incubated with 6- hour water sprcrying cycle obtained the best hatching rate, and shortest incubation time.
TOM T A T
Nghiin ciru dugc thitc hiin nhdm tim hieu su phdn bd ciia bge trung dc buau ddng (Pila polita) trong ao vd dnh huang cua cdc thai gian phim nude lin ty le nd vd thdi gian nd. Co 4 chu kyphun nuac khdc nhau dugc dp dung trong qud trinh dp trimg dc buau dong la I). 3 gia; 2). 6 gio; 3).
9 gio; 4). 12 gio. Boc trimg dc dugc dgt tren gid the xo dira trong ro nhira, sau do dp trong 12 bi composite. Kit qud nghien cuu cho ihAy ti le trung dc bucm dong dugc di sdtbaao ludn a mite cao (86.9%) so vol nhimg bge tning de a trin thdn cdy mgc quanh ao (13.1%). Ty li no cua trimg dugc phun nude sau moi 6h la (90,8%) cao han vd khdc biit cd y nghia (p<0,05) so vai 3 gid (68,9%). Vdi chu ky phun nude 3 gia/ldn hogc 6 gid/ldn cd thdi gian nd la 11,0 -11,3 ngdy ngdn han (p<0,05) so vdi 9 gid/ldn (15,8 ngdy) hay 12 gia/ldn (18,2 ngdy). Ty 1$ na cita trung dp voi chu ky phun nuac Id 6 h/ldn cao, thdi gian dp trung ngdn hon vd cd the dp dyng de ddng trong thirc ti.
1 GIOlTHIgU
Oc buou dong de trttng ttong dat, toich noi cd dp am cao, sdng hogt dpng ve 6eni, vao miia khd toi chiing ngd he frong ddt va quay Igi hogt ddng
vao raua mua (Mary & OHver, 1996). Theo nghiin ciiu cua Nguyin Thi Binh (2011), vdo miia sinh sdn dc buau ddi^ toudng bdt cap vao ban dim va sau do mdt thdi gian con cai se de trttng. Tap tinh
TQP chi Khoa hpc TrudngDgi hgc Cdn JTia Phdn B: Ndng nghiip. Thuy sdn vd Cong nghi Sinh hpc: 35 (2014): 91-96 bat cap xudt hiin tu khi con due vd con cai da
thanh toye siito due vd todi gian bit cap keo dai hang gio ^Sng hd. Trudc khi de tning dc cd tiqj tinh Iam td, trttng dugc de diu Uong h i d^ ven bd each m§t nude 10 - 20 cm hodc frin cac gia toi, tdp tinh dau trttng nhdm han chi dnh sang true tiip Ien bpc trttng va gitt dp am cho bpc triing (Trdn Thi Kim Anh va ctv., 2010). Viec xdc ditto vj tri dc de trttng ngoai tu nhiin vd ky touat duy tri dp am cho bpc trttng bing cac chi dp phun nude khac nhau la
can thiil gdp phdn xay dung qui ttinh ky touat ttong qua triito san xuat gidi^ dc buau ddng.
2 PHU'ONG PHAP NGHIEN CUtJ 2.1 Dgc diem vi tri dc bugu ding de trttng N ^ e n cttu dugc touc hiin ttong 3 toang (thang 5, 6 va 7 ndm 2013) va touc hien tou mdu tgi 4 diem dugc ky hiiu ttt MI den M4 (Bang 1). Mdu tou true tiip bdng tay va quan sat bdng mat toudng.
Bang 1: Kich thirttc va dac diim cua cac dja diem thu mau
STT Dia tfiim P | c diem thiiy vuc K^^hieu
1 Ap Birto Hda, xa Binh Thgito
Ao cd tu nhiin, nude tinh. Kich toudc ao (45 x4,5x0,9m). Thuc vat thtty sinh: beo cam, beo caj, Iuc binh. Thuc velt che phtt ven bd.
Ap3,xaMS Long
Ao ca tu nhiin, nude tiito. Kichthudcao(50x5,5xl,6m). Thuc vgt totty sinh: beo cai, Iuc binh, bdng sung. Thuc vdt ven ba nhung tdn cdy khdng che phu mat ao.
Ap 3, xd MJ Ao cd tu nhien, nude tfrto. Kich toudc ao (45x5,5x 1 ,Im).
3 Long Thuc vat totty sinh: beo cam, luc binh, beo cai. Thuc vat ven bd va tan cdy cbe mat ao.
Ap 3, xd M?
Long
Ao nudi ca tra, nude ffito. Kich toudc ao (50^ 5,5><l,2m).
Thuc vdt totty sinh: Iuc binh, bdng siing. Tliuc vat ven bd va tan cay che mdt ao.
2.2 Anh huWDg cua cac che dp phun nirdc khic nhau din qud trinh nd cua oc biroii ddng
2.2.1 Bo tri thi nghiim
Bpc trttng dc buou ddng dugc thu ttt touy vuc tu nhiin d Ddng Thap vd v|n chuyin vi Khoa
"Hitty sdn - Trudng Dgi hgc Cdn Tho di ip nd. Bpc trttng su dung Uong thi nghiem la bpc trttng 1 ngdy mdi khi do tning cd mau bing tirto va mdng nhdt ben ngoai. Thi nghiem dugc bd tri ttong be composite (60x80cm), nude ttong bi dp dugc duy tri d mttc khoang 12 lit (chiiu. ca(]Lcd^uo^:Ajm),^
ddm bdo khdng ngip bpc t r f r n ^ f r o ^ fle'^wr oo^tn=
hi todng sue khi. Trttng dugc dp vdi mat dp 3 bpc/bi, bpc tiling dugc dgt tren gid toi xo dira (cit toanh hinh chtt nhdt 9^6 cm, tgo ranh fren gia toe
mdi ranh each nhau I - 2 cm) vd ddt Uong rd nhua hinh chtt nhat kich toudc 30>:20 cm (Hinh 1). Viic phun nude gitt am cho boc trttng dugc bat ddu tu 6 gid sdng vd kit toiic vao 18 gid hang ngay. Khoang tooi gian sau mdi Ian phun nude tuong ttng vdi cac nghiem tottc Id 3, 6, 9 va 12 gid. Mdi che dp phun nude dugc bd fri lap lgi 3 lan va stt dung binh tia cd toi tich 0,5 lit phun nude true tiip len bpc trttng, mdi lin phun nude ttt 5-10 phiit dam bao cho tat cd hat trttng deu udt. Nuoc diing de phun dugc lay ttt ao nudi ca, di lang tfr 5-7 ngay, sau do Ipc qua ludi 50 tim. Qua frinh quan sdt toay ddi mau sdc, hinh toai ctta bpc trttng vd tou sd dc con mdi nd dugc touc hiin hdng ngay. Viic toay nude dugc thuc hien 5 ngay/lin va thay toan bd Iupng nude ttong bi ap.
Hinh 1: Cach b i tri boc truug trong bi i p (A) va phun nude giu am (B)
Tgp chi Khoa hgc Tmdng Dgi hpc Cdn Tha PhAn B: Ndng nghiip, Thiiy sdn vd Cong nghi Sinh hpc: 35 (2014): 91-96- 2.2.2 Cdc chi tieu theo doi
Nhiit do mdi irudng nude va khdng khi dugc do bdng nhi|t ki vao luc 7 gia sang vd 14 gio chieu hang ngay. Ham Iugng dam ammonia (TAN), NO2"
, dp kiem va pH dugc xac dinh hang tudn bang bd test SERA (Germany).
Ty If nd ctta timg bpc tning (%) = lOO^ (Sd con i c nd/Sd trttng).
Thdi gian nd (ngay) = Thai gian xudt hiin dc con dau tien.
Thdi gian na 50% (ngay) - Thdi gian xuat hien dc con ddu tien den khi bpc trttng nd 50%.
Thdi gian nd 90% (ngay) = Thdi gian xuit hien dc con ddu tiin din khi bpc trttng nd 90%.
VifC xdc dfnh chiiu cao (do ttt mep mieng vd din dinh vd) vd cdn khdi Iugng ctta 6c radi nd
Bang 2: Gid trj trung binh mdt sd yen t i mdi trudng qua cac dgt thu mlu
dugc tiin hdnh hang ngdy khi kiim fra ty If no tttng bpc tning frong cac nghiim tottc bo tri.
Stt dung phdn mim Excel d,h tinh cac gid frj trung binh, dp lich chudn va phdn ti'ch ANOVA mpt nhdn Id frong SPSS 16.0 di so sdnh sg khac biet giua cdc gia tri frung binh cua cdc nghiim tottc d mttc / K 0 , 0 5 bing phep tofr Duncan.
3 KET QUA VA THAO LU^N 3.1 Tim hieu sir phSn b i bpc trttng i c buuu ddng trong ao
3.1.1 Cdc yiu Id moi trudng
Trung binh nhiit cdc yiu td radi trudng qua cdc dgt tou dugc frinh bdy d Bang 3. Nhiit dd trung binh d cac dgt ton mau diu cao hon 29,06°C. Cdc yeu td dp kiim, pH, TAN vd N02- khdng biin ddng Idn trong thdi gian nghiin cuu (Bang 2).
Chi tieu
5/2013
Cac thang thu mau
6/2013 7/2013
Nhiet do ("C) pH TAN (mg/L) NO2- (rag/L) Kiim (mg CaCOs/L)
29,06±2,09^
7,34±0,19^
1,64±2,17^
0,45±0,40^
90,00± 18,80^
29,47±1,94*
7,42±0,16'' 1,64*1,20"
0,48±0,40"
82,08± 10,86°
29,47±1,62' 7,36±0,24*
1,64*1,19"
0,82*0,84'' 82,08^8,94' Cdc gid Irj irong cung mdt hdng cd chic cdi khdc nhau thi khdc biit cd y nghTa thdng ki (p<0, OS)
3.1.2 Phdnbd bge trimg dc buou ddng trong ao Trong thdi gian nghiin cfru, da quan sat toiy 558 bpc frirng i c buau ddng, bpc trttng tou toip d Bdng 3: Phdn b i bpc trung qua cac dgt thu mdu
toang 6 (174 bpc) va cao d toang 5 (196 bpc).
Trong dd cd 243 bpc trttng frin nin dit va 36 bpc frttng tten than cay (Bdng 3).
Npdy Ting si bpc trttng Tren toan cay Trin nen dat Cach mgt nude 10-20 era Chim duin nude 5-10 cm
Sd boc tiling Tyle(%) Sd boc tning Tyle(%) S6 boc tning T*M(%) S6 boc tning Tyl«{%)
5/2013 196 15 7,7 83 42,3 91 46,4 7 3,6
6/2013 174 13 7,5 74 42,5 78 44,8 9 5,2
7/2013 188 8 4,3 86 45,7 92 48,9 2 1,1
-T6ng 36 243 261 18
Trung binh 6,5 43,5 46,7 3,3 Cdc dgt tou mdu cho thiy ty li sd bpc tning d i
tten nin dit (42,3 - 45,7%) va each mat nude 10 - 20 cm (44,8 - 48,9%) ludn xuit hien vdi tin suit cao hon so vdi bpc trttng de d giiia ao va trin todn cdy (4,3 - 7,7%) hay bpc trttng chun dudi nude 5 - 10 cm (1,1 - 5,2%). Ket qua tou mlu cho toiy rdng bpc trttng oc buou ddng d tten toan cay hay bpc tning chim hodn toan ttong nude khi dc buou ddng
de vao todi gian nude dang cap (vdo nhttng ngdy gitta va cudi todng dm lich), diiu nay toi hiin qua kit qua tou mdu vao todng 5 vd 6. Kit qud nghien cttu nay phtt hgp vdi nghiin cttu ciia Trin Thi Kim Anh vd ctv. (2010) va Nguyen Thi Binh (2011), cdc tac gid cho ring miia vu sinh sdn ctia i c buau ding tii toang 3 din todng 10 ttong dd tap tiimg tii thang 4 din thang 6.
Tpp chi Khoa hpc Tmdng Bgi hgc Cdn Tha Phdn B: Ndng nghiip, Thuy sdn vd Cong nghe Sinh hoc: 35 (2014): 91-96 Bang 4: Pban bo bge trung qua ckc diim tho mlu
Diem thu Tone s6 boc trims Trdn thto cay Tren n^n ddt Cach mat nucrc 10-20 cm Chim duoi nuoc 5-10 cm
S6 bpc tning T«lef%) S6 hgc trOmg Tvl«(%) S6 bpc tning T«Ie(%) So boc tning Tyl?(%)
M l 100 7 7,0 43 43,0 44 44,0 6 6,0
M2 64 3 4,7 29 45,3 31 48,4 1 1,6
M3 270 11 8,9 51 41,1 58 46,8 4 3,2
M4 124 15 5,6 120 44,4 128 47,4 7 2,6 Bang 4 cho toay sd boc trttng biin ddng tiieo
dja diim tou, frong dd sd bpc trttng dc buou ddn^ d diim M3 (270 bpc) cao hom rit nhiiu so vdi diim M2 (64 bpc trttng). LiJ do chtt yiu cd toi do su phan bd va che phtt ctta touc vgt ven bo va touc vat totty sirto da Idm gidm bdt cudng dp arto sang va biin ddng itoiit dp, day la rtoiing dieu kiin tou|n Ipi de dc buou ddng phan bd, bat c^p va sinh sdn ra nhiiu bpc triing hon d diem M3. Mpt Iy do khdc cd toi do d diim M3, ngudi ddn cd ^ touc giu lai dc bi me ttong cdc ao nudi cd do dd sd lugng dc toam gia sinh san cao hon va sd bpc trttng tou dugc cung nhiiu hon.
Ty Ii si bpc trttng de tten nen dat (41,1 - 45,3%) vd each mat nude 10 - 20 cm (44,0 - 48,4
%) cao ban so vdi dudi nude hogc giua ao. N ^ i n cttu ctta Tran Thi Kim Anh vd ctv (2010) vd Nguyin Thi Binh (2011) cho tiiiy tiudc khi de trirng dc cd tap tinli lam td, trttng dugc di.ddu Uong hd dat ven bd cdch mat nude 10 - 20 cm hoac fren cdc gia toi, tap tinh dau tning nhdm hgn chi anh sdng ttirc tiip lin boc tning vd gitt dp am cbo bpc tning. Nghiin ciiu ciia Nguyen Van Thudn va Le Trpng San (2004) ciing cho toiy dc buou ding de thdnh tiing dam vdo bic ddt, bttn hay ttin todn cay.
Hinh 2: Cac vi tri de trttng ciia oc buoTi ding. A: Tren thdn cSy; B: Tren nen ddt; C: Cach mat nude 10-20 cm; D: Dirdi mat nude 5-10 cm
ttong khi do nhiit dp moi trudng nude buoi sdrig 3.2 Anh hurdng ciia cac chi dp phun nufrc khac
nhau den qud trinh nfr cua trttng oc bucni dong 3.2.1 Biin dgng cdc yiu td moi trudng Nhift dd khdng khi budi sdng dao ddng ttt 26,7 - 29,9°C vd buii chiiu dao ddng ttt 28,3 - 36,0''C,
Uong cac bi ip dao ddng tii 26,1 - 30,0"C vd buoi chiiu dao dpng tii 27,3 - 34,0°C. Kit qua Bdng 5 cho toiy cdc yiu t i mdi trudng frong qua trinh ap dn dinh vd gdn nhu ddng nhdt giiia cac chu ky phun nude khdc nhau.
Tgp chi Khoa hpc Tmdng Dgi hgc Cdn Tha Phdn B: Ndng nghiip. Thuy sdn vd Cdng nghi Sinh hpc: 35 (2014): 91-90 Bang 5: Biin dpng cac yiu td mdi trirdng trong be ap fr cac nghifm thuc khac nhau
Chi tiiu Thdi gian giira cac lan phun nirdc (gifr)
12 Nhiit dp sang C€) 27,7*1,6" 27,5±i,6" 27,5*1,6^ 27,6*1,6"
Nhiit dp chiiu ("C) 29,5*2,5" 29,3*2,5" 29,4±2,5'' 29,4*2,5' pH 8,51*0,29" 8,60*0,31" 8,59*0,36" 8,59*0,35"
TAN (rag/L) 0,15*0,06" 0,14*0,04" 0,14*0,04" 0,13*0,04"
N02"(mg/L) 0,21*0,10" 0,20*0,08" 0,20*0,09" 0,21*0,07"
Dd kiim (rag/L) 114,4*17,9" 114,6*13.9" 119,3*13,4' 112,8*16,0"
Cdc gid Iri trong citng mpt hdng cd chit cdi 06ng nhau thi khdc biit khdng COy nghTa thdng ki (p>0,05) 3.2.2 Ty leva thai gjan na cua trimg 6c buau ddng am frong khoang thdi gian thich hgp (6 gid) _ , , , . , . , , ; . , * . , - Idm tang ty Ie nd ciing nhu nil ngan duoc todi Trung bmh ty le nd cua oc dai cao nhai kbi . . ' , . . . •- x . ' u • ^ •• /nAoo/x 1 i j ~ i-'n •• • 1-1 - g'^n no va ngugc Igt tiung giu am frong cac phun nuoc 6 gio (90,8%), ke den la 9 gia va 12 gio , . . ^... . . ; /-, ° M , - • j - - / n T-io £o/ TO no/-. \ *u'= u'!* .• -. -• /£o no/x % • khoang tooi gian qua ngan (3 gio) hogc qua dai (9 (78,6%; 78,7%) vd toap nhat a 3 gio (68,9%). Co . , 5 -i.v i . , O u . •_ - i . u - i u-
, , - 1 - X =, i . ,. . . i ,,:• i - hay 12 gio) sS lam bpc tnmg qua uat hay qua kho SU khdc bift rdt r6 vi tj Ii nd ciia dc khi phun nude
d todi gian 3 gia va 6 gid (p<0,05). Tuket qua frin cd toi nhan tody ring tning dugc phun nude giu
dnh hudng din qua ttinh phat triin phdi va ddn din
ty Ii nd toip.
Bang 6: M$t so chi tiiu trong qua trinh nd ciia trttng oc buou dong
So hat tning/bpc tning So 6c no/bgc triing TJl«nS(%) Khoi luong 6c mdi no (g) Chieu cao 6c m6i no (mm)
ThM 3 731±56' 555±150' 68,9±14,5' 0,02±0,0I' 4,05±0,03'
gian giO^ cic l^n 6 673±134' 609±130"
90,8±8,4' 0,02±0,01' 4,07±0,I2'
ph un nir^c (gior) 9 626±8"
490±103"
78,6±7,4"
0,02±0,02"
3,95±0,26'
12 634±87"
501±65' 78,7±6,2"
0,02±0,00*
3,88±0,10' Cdc gid Irj Irong cung mdt hdng co chit cdi khdc nhau thi khdc biit c6 y nghta ihong ki (p<0,05)
Bpc trttng dugc phun nude sau mdi 3 va 6 gia nhiin, thdi gian nd 90% cda dc buau ddng khi cd thai gian nd sdm lin lugt Id 11,0 va 11,3 ngay, phun nude sau 6 gid (13,8 ngay) tuang ducmg vdi ngdn hon rit rd (/7<0,05) so vdi trttng dugc phun phun sau 3 gid (14,0 ngay), nhanh han O<0,05) so nude sau moi 9 gid (15,9 ngay) va 12 gid (18,2 vol phun sau 9 gid (18,6 i^ay) va 12 gid (20,4 ngay). Trung binh todi gian nd 50% cua dc buou ngdy). Kit qud cho tody thdi gian gitta cac lin ddng khi phun nude sau 3 va 6 gid (12,7 i^ay) phun nude ttong khi dp trttng i c buou ding cdng cung ngdn hon rdt rd (p<0,0S)LSO£yfephun:nuacri- dai thi qua trinh nd cua trttng si chdm ban.
sau 9 gid (16,7 ngay) vd 12"gicr(i^rngay5!°'T^
Bang 7: Trung binh thdi gian nor ciia trung oc buoru dong fr cac thcri gian phun niifrc khac nhan ThM gian (ngiy)
Bat dSu no 50% so tning no 90% so tning no
3 11,0±2,1' 12,7±2,0' 14,0±1,9'
ThM gian giua cic lan phun ninyc (gicr)
6 9 11,3±2,4" 15,9±2,0' 12,7±1,7" 16,7±1,8' 13,8±1,9" 18,6±1,5'
12 18,2±1,7«
19,1±2,2' 20,4±2,0' Cdc gid tri irong citng mpi hang cd cha cdi khdc nhau thi khdc biil c6 y nghTa ihSng ki (p<0,05)
Ket qud nghiin cttu cho toij; ring, biin ddng gian phun nude gift dm sau 3 va 6 gid Iam cho trung binh ham Iugng cac yiu td mdi trudng nhu tifrng oc nd rit sdm (8 ngay). Nguyin Thi Bmh nhiit dd, TAN, NO2", dp kiim va pH diu frong (2011) ip trirng dc buau ddng cd todi gian nd 13 pham vi toich hgp cho ap trttng dc buou ddng. ngay dudi diiu kifn nhift dp khdng khi budi sang Trong 5 ngdy bit diu toi nghiem nhiit dp khdng 25,0 - 27,0°C va budi chiiu 28,0 - 29,5°C, khi nhiet khi (28,5''C din Sd^C) va nhi^t dp mdi tiudng nude dp khdng khi gidm xudng hrong ttng 22,5 - 24,5"C (30OC din 34^0 tuong dii cao kit hgp vdi todi vd 26,0 - 27,0°C toi todi gian nd Id 16 ngay. Trin
95
Tgp chi Khoa hpc Trudng Dgi hgc Cdn Tha Phdn B: Ndng nghiip, Thity sdn vd Cdng nghe Sinh hoc: 35 (2014): 91-96 Thi Kun Anh vd ctv. (2010) va Nguyin Thi Bmh
vd ctv (2011) diu cho ring dc cd todi gian nd 22 ngdy khi nhiit dd khdng khi buii sang 24,5 - 26,5''C va budi chiiu 27,5 - 28,5''C, khi nhiet do tang Iin tuong ttng 28,0 - 30,5''C va 32,0 - 35,5''C toi todi gian nd cfla i c chi cdn 13 ngdy. Cac tdc gia deu itoan djnh ring nhiit dp khdng khi cd anh hudng rit ldn din ty Ii nd vd thdi gian nd ciia dc buau ddng, nhift dp cang cao thdi gian phdt friin phdi cang nhanh, tuy nhien niu qua cao phdi se ngimg phat triin hay ty li di hinh se ldng lin. Viec phun nude cd thi ddng 2 vai ttd ttong qua trinh ap frttng, thtt nhdt Id cung cdp dp am phu hgp cho phdi phdt ttiin, thtt hai la hgn chi su biin ddng qud Idn cda nhiit dd (ddc biit la nhiit dd khdng khi).
Trong diiu kiin ttttng bi khd vd biin dp nhiit qud Idn, cdc phan ttng sinh hda ttong qua trinh phdn cat phfii cd toi bi tte chi hodc gidn dogn va do do cd khd ndng Iam chgm hogt ddng nd ctta trttng. Dieu ndy cd toe thdy ro trong kit qud thdi gian nd cua tning dc buau ddng d chu ky phun nude sau mdi 9
^ a hoac 12 gid ch§m hon so vdi 3 gid hodc 6 gid.
Khi ap trttng oc buou ddng vdi thdi gian phun nude 6 gio cho ty If nd dgt cao nhit (90,8%). Theo kit qua nghien cttu budc dau san xudt gidng dc buou ddng cua Nguyen Thi Binh va Nguyen Kim Dudng (2011) djnh ky cd tudi nude Ien bpc trttng
^ 1$ nd cua i c dgt 83,6% khi ap frin gia thi be chudi vd 46,5% khi ip fren khay xip. Indar (2003) nghiin cfru dp trttng oc buou vang Pomacea urceus bing cac che dd gitt im dugc duy fri 80% dm dp thi ty If nd trung binh ciia 6c dgt 96% (biin dpng ttt 89 - 100%), ttong khi dd niu dd ira biin dpng qud ldn (52 - 85%) thi ty li nd ttung binh gidm xuing chi cdn 35,2%. Cdc kit qua nghiin cttu cho toiy ring dO im ddng vai ttd guan ttpng frong qua frinh phat friin phdi ctta ca dc buou ding va dc buou vang. Duy fri chi dp gitt im phu hgp cdn ctt frin dgc diim chpn lua v{ fri di tning cda dc frong tu itoiin si gdp phin tdng ty Ii nd va nit ngan qud tiinh dp frttng.
Nhiit dp khdng khi va radi trudng nude cang cao toi phdi phat ttiin cdng nhanh, todi gian nd ngdn khodng 13-15 ngdy vd ngugc Igi toi phdi se phat ttiin chdm va todi gian nd keo ddi 20 - 22 ngay (Trin Thi Kim Anh vd civ., 2010; Nguyen Thj Binh, 2011). Mdt kit qua khdc nghien cttu vi dc buau ding ciing cho ring ttong qua trinh phdt triin phdi niu khdng cd dtt dp im toi hgt tning din din chuyin todnh mdu ttdng due, phdi bin ttong bj teo lgi vd khdng toi phat triin (Cowie, 2002).
4 KET LUAN VA DE XUAT 4.1 Kit lugn
Oc buou ddng de ttttng ttin nin dit vdi ly Ii cao (43,5%) so vdi d gifla ao va ttin toan cay (6,5%).
Ty Ii nd khi phun nude sau radi 6 gid dp ttttng (90,8%) cao ban vd khdc biil cd -y nghTa (/*<0,05) so vdi 3 gid.
Thdi gian nd ciia trttng dc dugc phun nude sau moi 6 gid (11,3 ngdy) ngan hon so vdi 9 gid (15,9 ngdy) va 12 gid (18,2 ngay).
4.2 De xuit
Trong qua ttirto ap tning i c buou ddng cdn gitt che dg phun nude sau m§i 6 gid di tou dugc ^ Ie nd cao hon vd todi gian nd sdm hon.
TAI LIEU THAM KHAO 1. Cowie, R.H., 2002. Apple snails
(Ampullariidae) as agricultural pests: their biology, impacts and manageraent. In: Molluscs as Crop Pests (ed. G.M. Barker): 145-192.
2. Indar W.R. 2003. Induction of spawning and artificial incubation of eggs in toe edible snail Pomacea urceus (Muller).
Aquaculture 215. 163-166p.
3. Mary, B.S. and P.O. Oliver, 1996. Land and freshwater raollusks and crustaceans. Departmei of Zoology, National museum of Wales, Catoay:
park, Cardiff CF 3 NP, UK (34): 22-68.
4. Nguyin Thi Binh va Nguyen Kim Dudng, 2011. Nghiin cttu sdn xudt con giing i c buou ding ttong diiu kien thuc nghiim.
Tap chi-khoa hpc, Trudng Dm hpc Viito.
Tdp 40 (so 4A): 14-25.
5. Nguyin Van Thudn va Le Trpng Son, 2004.
Giao ttinh dpng khong xuong 247 sing.
Nha xudt ban Dgi hpc Hui. 316 ttang.
6. Pizani, N.V, A.L. Estebenet and P.R. Martin, 2005. Effects of submersion and aerial exposure on clutches and hatchlings of Pomacea canaliculata (Gasttopoda:
Ampullariidae), Am. Malacol. Bull 20. 55 pp.
7. Trin Thi Kim Anh, Tg Thj Binh, Nguyin Thi Binli va Nguyin Thi Thanh Hoa, 2010.
Nghiin cttu mpt si dac diem sinh hpc sinh san cua oc buau ddng Pila polita. Tap chi khoa hoc, Trudng Dai hpc Vmh. Tap 39 (sd 3A). Trang 5-14.
