KHOA HQC CONO NOHl
d A c d ie m r a h o a v A p h a t t r i £ n t r A i
C U A C A Y D U A IMUIJC
(IMypa frutica ns
W u r m b )
T A I b a v l ji x ie n u o c IVlAlXI, l o v A im g q t
O D O N G b A im g s o n g C l i u LOIMG
L6 Thj Thanh Thuy1, Trin Van Hiu1
t6m t At
Nghidn cuu dugc thuc hi£n tr£n cay dua nuoc d ba di£m thupc huy£n Trin D£, Dai Ngai tinh Soc Trtng vi
huy^n Cang Long, tinh Tra Vinh tu 11/2010 d&i 2/2012 nhim xac djnh dac di£m ra hoa vi phit tridn budng
cua ciy dua nuoc 6 ba vung sinh thai nuoc min, nuoc ngpt vi nuoc lgr. M6i viing khao sit 40 buong hoa, 50
bui dira nuoc va 10 tau la moi. Su ting trudng cua hoa vi trai dugc tinh toin theo phuong trinh ting truong
dx/dt = kx (a-x) cua Robertson (1908, trich dan bdi Reed, 1920). K£t qui cho thiy d ba vung nude min,
nuoc lgr vi nude nggt ciy dira nude ra hoa tip trung trong miia khd tir thing 11 ddn thing 4 nim sau. Ti 1$
ciy dira nude ra buong hoa d vung nude min li cao nhit (72%), thip nhit li vung nude ngpt (60%). Thdi gian
can thi^t de buong hoa d ca ba vung phit tri&i dat kich thudc tdi da li 6 thing tir khi hoa nd. Vung nude
min cd khoi lugng buong hoa, chu vi buong hoa theo chidu cao, chidu rpng, kich thudc trai chic, chidu dii
cudng buong hoa vi chidu cao cua li luon nho hon so viing nude lgr vi nude ngpt Tong sd trii/buong vi ti 1$
trai chic khic bi£t khdng cd y nghia thdng k6 d ba viing.
Tir khoi: Dua nude, buong hoa, nuoc ngpt, nude Ip, nude m$n.
1 . BAT VAN B£
Dira nuoc (N ypa fru tica ns) dupe xem 14 cay chi
thi duoc tim thay trong hau hdt cic hd thong rung
ngap man nhidt doi (Hutton, 1996). Cay dua nuoc
thuong phat tridn d vung bai bdi, thuy tridu chay
cham va c6 nhidu phu sa (Toe et al., 2010). Trong dir
4n trong moi 5 tridu ha rung (chuong trinh 661) .cua
Chinh phu thi dira nuoc dung hang thu hai trong 10
loai diy dugc chpn dd trong rung phong ho chan
s6ng, bao vd moi trudng rimg ngap nuoc (Nguyen
Ngpc Binh, 2004). Theo Phan Van Den (2012) thi
95% hp trong dua nuoc d huydn Long My tinh Hau
Giang trong dira nuoc vdi muc dich 14 chong sat lo
dat. San pham tir c4y dira nuoc chu ydu 14 14 dua
dung dd lpp nh4, trai dung an tuoi nhu 14 mdt loai trai
c4y vdi thu nh4p trung binh 2.000.000 ddng trdn
1.000 m2. Trong khi dd, kich thich cho buong hoa tidt
nhua cd thd dung dd chd bidn th4nh dudng, giam,
rupu,... (Samarajeew, 1985). Theo Van Die (1974)
nang suit dudng tir nhua budng hoa cay dua nude cd
thd dat 15-20 tin/ha so vdi c4y mia chi dat 5-15
tin/ha/nam. M$c du hiu hdt c4c c4y thudc hQ Cau
Dira ddu cd thd t4c ddng cho nhua budng hoa tidt
nhua (Tuley, 1965), tuy nhidn, mdi logi c4y lgi cd
1 Bp mon Khoa hpc c iy trong • Khoa N dng nghiep v i Sinh
hpc Ung dyng, Dgi hpc Can Th o
50
phuong ph4p khai th4c kh4c nhau, phu thudc chu
ydu v4o dac tinh cua timg c4y. Do dd, dd khai th4c
dugc nhua buong hoa phuc vu cho nhu ciu san xuit
thuc phim thi cin bidt dugc d$c tinh ra hoa phit
tridn tr4i cua c4y dira nude. 6 Vidt Nam noi chung v4
ddng bang sdng Cuu Long (DBSCL) ndi ridng hiu
nhu chua cd cdng trinh nghien cuu nao vd c4y dua
nude. Do dd, dd tai dugc thuc hidn nham myc tidu
x4c djnh d4c didm ra hoa v4 phit tridn tr4i cua ciy
dua nude d ba viing nude m4n, nude ngpt v4 nude lgr
14m co sd cho vide nghidn cuu c4c bidn ph4p dd s4n
xuit nhua budng hoa.
Z. PHUONG T fr V A PHUONG PHAP
Thi nghidm dugc thuc hidn trdn c4y dira nude b '
ba didm thupc huydn Trin Dd v4 Dgi Ngai tinh Sdc
Trang v4 huydn C4ng Long tinh T ri Vinh tu 11/2010
ddn 2/2012. Vung Trin Dd dac trung cho vung nude
mgn, viing C4ng Long d$c trung cho vung nude kr v i
vung Dgi Ngai d$c trung cho vung nude ngpt. Mdi
vung khio sit 40 budng hoa (10 budng h o a theo ddi
sy phit tridn, 30 budng dung dd thu «n&« kh*n s& sv
phit tridn budng hoa, trii), 50 budi dua nude (x ic
dinh mua vy ra hoa) v i 10 tiu l i mdi dupe hinh
thinh khoing 30 cm. C ic chi tidu th eo ddi bao gdm:
a) Mua vy ra hoa dugc ghi nhin b in g cic h ddm tdng
sd budng hoa xuit hidn/tdng sd l i c d (3 0 n g iy /lin ),
sy phit tridn vd chidu cao cu a l i d u gc d o tu goc ddn
NdNG NGHlfP VA PHATIRiIn n 0 N G IH 0 N - KY 1 -T H A N G 4/2014
KHOA HOC CONG N GHl
dinh tau Id (15 ngay/lan); b) khao sat su phat triln
buong hoa va trai (moi vung Idy ba buong hoa, lay 10
tr4i/buong): kich thuoc cua buong hoa, chieu dai
cudng buong hoa, chu vi cua buong hoa theo chilu
rpng v4 chilu cao (15 ngay/lan). Khoi luong cua
buong hoa, tdng sd trai/buong, ti Id trai chdc (30
ngay/ldn). Do min cua nuoc dugc do vao ngay 14
din 16 hang thang khi nuoc dang ldn, do 6 do sau
c4ch mat nuoc 20 cm. Su tang trudng cua budng hoa
dugc tinh toan theo phuong trinh tang trudng dx/dt
= kx (a-x) cua Robertson (1908, trich dan bdi Reed,
1920). Trong dd x la gia tri quan sat (qs), t la thdi
dilm quan sat, a la sd cuoi cung cua gia tri xqs+SE, tj
la thdi gian d gi4 tri x = a/2, k la hang sd.
s.n£tquAv a h Uoluan
3.1. Biln ddng vl dd m$n cua nude dr ba dilm
khio s4t
Qua khao sat do m4n cua nuoc d ba diem cd su
kh4c nhau va biln dong qua cac thang (Hinh 1).
Dilm thi nghidm thuoc huydn Tran Dl cd do man
cao nhait v4 dp man luon duy tri d muc rat cao vao cac
thing trong nam so vdi hai dilm cdn lai. Tai Tran Dd
dd man trong nude vao thang ba 14 cao nhat
(20,82±0,27%o). O dilm thi nghidm thuoc huydn Dai
Ngai thi dd min trong nude hau nhu luon on djnh va
gi4 trj dd man rat nho khdng vupt qua 0,l%o qua cac
thing. T?ii C4ng Long thi do man trong nude cd su
thay doi qua cac thang, vao cac thang mua khd do
m4n trong nude or dilm thi nghidm nay cd su gia
tang, dac bidt vao thang hai la thdng cd do man cao
nhit l,33±0,08%o. Theo to chuc Y te thi gidi (WHO)
dp man cho phep trong nude uong nam d nguong
0,25%o. Nhu vay, dua vao do man cd thi phan ra day
14 ba vung nude. Tran D l 14 vung nude man, Dai Ngai
14 vung nude ngpt v4 C4ng Long 14 vung nude lo.
25
~ 20
t
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TttnOt — • -CingLong - D*i Ngli
* * * *
T X~
I 2 3 4 5 6 7 8 9 10 II 12
IMng
Hinh 1: Sy biln ddng dd m$n cua nude dr ba dilm
thi nghi£m huydn Trdn D l v4 huydn D<u Ngai,
tinh Sdc Trang v4 huydn C4ng Long, tinh Tr4 Vinh
3.2. Mua vu ra hoa
Cay dira nude d tat ca cac thang trong nam thi
dlu hau het cd su xuat hidn cua phat hoa mdi (Hinh
2). Tuy nhidn, d ba vung thi dua nude ra hoa tap
trung trong mua kho tu thang 11 den thang 4 ndm
sau. O vung nuoc man thi cay dua nude ra hoa tap
trung vao thang 11 ddn thang 3 ndm sau, trong khi
dd d vung nude ngot thi cay ra hoa tap trung nhidu
nhat tu thdng 1 ddn thang 4. 6 vung nude lp thi cdy
hau nhu ra hoa quanh nam. Nhu vay co thi thay
rdng, cay dua nude ra hoa tap trung vao cac thdng
mua kho vd thdng cuoi mua mua, vao cac thdng mua
mua thi cay rat it ra hoa. Theo Toe et al. (2010) thi
cay dua nude phat triln trong bai bdi, noi thuy triiu
chay cham, nude song cd nhilu phu sa ndn vao mua
kho muc nude khong qua cao Id dilu ki|n thudn lpi
dl c4y ra hoa. Tinh trong c4 ndm thi ti Id c4y dua
nude ra hoa cao nhat 14 d vung nude man (72%), kd
ddn 14 vung nude lp (68%) v4 thap nhat 14 vung nude
ngpt (60%). Ti Id ra hoa d ba vung n4y ddu cao hon so
vdi cay dua nude d Papua New Guinea 14 49%
(Paivoke, 1985). Su chdnh ldch vl ti 1| ra hoa cua ba
vung cd thi 14 do su kh4c bidt vl moi trudng sinh
sdng vi theo Joshi e t al. (2006) thi moi trudng thich
hpp cua dira nude 14 mot ti Id pha lodng cua nude
biln bdi ddng nude ngpt ch4y dpc theo hudng biln.
□ ViggoDc min ■ Ving <ux ngpt ■ Ving
nuoc lp
jil | -
.31 11 k i :i i In 11
I 2 5 4 5 6 7 I 9 10 !l 12
Ttagrakot
Hinh 2. Mua vy ra hoa cua cdy dira nude
d ba vung nude man, nude ngpt v4 nude lp
3.3. Chilu cao 14
Tai thdi dilm vira t4ch ra khoi 14 m? cho din 8
th4ng sau thi chilu cao 14 giua ba vung cd su kh4c
bidt d muc y nghia 5% qua phan tich thong kd (Hinh
3). Chilu cao 14 dira nude d vung nude lp v4 nude
ngpt kh4c bi|t khdng y nghia, nhung c4 hai lai kh4c
bidt cd y nghia so vdi vung nude man qua t4m th4ng
N6NG NGHlfP VA PHAT TRIEN N6NG TH6N - KY 1 - THANG 4/2014 51
KHOA HOC CbN G N G H l
khao sat. Thuc hi£n vi£c tinh toan theo phuong trinh
tang trudng cua Robertson (1908), chieu cao la dat
toi da la 713,9±75,2 cm (nude man), 841,5±88,1 cm
(nude lg) va 796,&t84,4 cm (nude ngot). Chi£u cao la
dat toe do tang trudng cue dai tai thdi diem 3,76
thang (nude man), 3,73 thang (nude lo) va 3,66 thang
(nude ngot). Tir thdi di<?m nay trd di thi toe do gia
tang v£ chieu cao cua la cham lai cho den khi 14 dat
chi£u cao tdi da. Thdi gian la tang trudng dat toe do
toi da d ca ba vung nam trong khoang 3,54 thang
sau khi tach ra khoi 14 me. L4 dira nude can thdi gian
khoang s4u th4ng d<? co th£ dat chi^u cao toi da. La
dira nude khi dat chi£u cao tdi da d ba viing nude n4y
gan bang vdi la d Singapore 14 9 m (Toe e t al., 2010),
nhung thap hon rat nhi£u so vdi d Papua New
Guinea 14 11,7-14,2 m (Paivoke, 1985).
Tra Dc
-TiaOcii* Di^quni* - Cflg Longqunuf
EVfiirt • C*n Lonn Bi*
nude nho hon so vdi viing nude lg v4 nuoc ngot
11
i
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I
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r ! “ b 2 •
»
i o ! o o o
I •
,5 ’
» I
(a)
) 4 5 ft 7 I 9 10
(b)
Hinh 4. Sy ph4t tri£n (a) v4 tde dd ting trudng (b)
cua khdi lugng budng hoa dira nude d ba vung nude
m$n, nude lgr v4 nude ngpt
x tinh toan th eo ph ucm g trinh t in g tru dn g cua
R o bertson (1908, trich dan b d i R eed , 1920) vdi
Y=0,24x(8'56’’0 (n u d e m $n ), Y=0,27x(,I08’XJ (nu&c
lp ), Y=0,29xfI00&x) (n u o c n g p t)
Hinh 3. Sy ph4t tri&i (a) v4 tde dd ting trudng (b)
cua chi£u cao 14 dira nude d ba vung nude m$n, nude
lgr v4 nude ngpt
x tinh toan th e o p h u on g trinh td ng tru dn g cua
R o bertson (1908, trich ddn b d i R eed , 1920) vdi
Y=0,27xT13-92x) (n u o c m an), Y=0,27x(84l51'x } (n udc
lp ), Y^O^Gxf796, 79~x ) (nud e n g p t)
3.4. D$c tinh budng hoa
3.4.1. K h di lu pn g b ud ng hoa
Budng hoa dira nude dat khdi lugng tdi da d
th4ng thu s4u, sau dd dn djnh ddn th4ng thu mudi
(Hinh 4, 5). Dua v4o phuong trinh tang trudng cua
Robertson (1908) cho thay khdi lugng budng hoa
tang trudng cue dai d thdi di<?m 4,39 th4ng d viing
nude man, 4,08 d viing nude lgr v4 4,15 th4ng d vung
nude ngot Khdi lugng budng hoa d viing nude lgr v4
nude ngot cao hon so vdi viing nude man. O Papua
New Guinea, Paivoke (1985) nh4n thay khdi lugng
budng dira nude bi£n dong tir 6,1 d&i 30 kg/buong.
Nhu v4y, d viing nude man khdi lugng budng dira
I #
16 tuyl |7My) |Stta|) |10 tod
Hinh 5. Sy ph4t tri£n cua budng hoa dira nude d
vung nude ngpt
3.4 .2 . K ich th u d c b u o n g h oa
Chu vi budng hoa theo chi£u cao v4 chi£u rdng
tir khi budng hoa mdi no cho d£n giai doan b4y th4ng
sau khi hoa no d ba vung d£u cd su kh4c bi£t thdng
k£ d muc y nghia 5% d timg thdi di&n quan sat (Hinh
6 & 7 ). Buong hoa d viing nude lgr v4 nude ngot kh4c
bi£t khdng y nghia v4 c4 hai cung khac bi£t cd y
nghia vdi budng hoa viing nude m^n. Dya vao
phuong trinh ting trudng cua Robertson (1908) thi
chu vi budng hoa theo chi£u cao v4 chi^u rdng d^t
tdi da 14 89,9*8,2 cm v4 90,1±11,3 cm (nude m$n),
102,1± 10,6 cm v4 101,9tl3,3 cm (nude lg), 102,4±9,3
cm v4 101,8±12,8 cm (nude nggt). Chu vi budng hoa
theo chi£u cao va chi£u rdng gia tang tir khi hoa nd
v4 dat tde dd tang trudng eye tai tai thdi diem 3,1
th4ng v4 3,07 thing (nude m in), 3,06 thing vi 3,03
52 N6NG NGHlfP VA PHAT TR|£n NONG TH 6N -K Y 1 - THANG 4/2014
KHOA HOC C6NG NGHt
thang (nude lgr), 3,06 thing vi 3,05 thang (nuoc
ngpt). Nhu viy, chu vi buong hoa theo chilu cao va
chilu rpng a ba vixng la khic nhau Ion nhat la or vung
nuoc lp va thip nhit li vung nuoc min. Thoi gian can
thilt dl chu vi buong hoa theo chilu cao vi chilu
rong dat kich toi da li siu thing sau khi hoa ncr. Toe
dO ting truong cuc dai cua chu vi buong hoa theo
chilu cao vi chilu rpng nim trong khoang tir thing
thu ba din thing thu tu sau khi hoa no.
« TrfcfXfBrt :
0)2343
(a) "* (b)
Hinh 6. Sy phit triln (a) v i tdc d0 ting tru6ng (b)
cua chu vi budng hoa theo chilu cao b ba vung nude
min, nu6c lp v i nude ngpt
x tinh toin theo phuong trinh tin g trudng cua
Robertson (1908, trich dan bdi Reed, 1920) vdi
Y~0,34xf892**) (nude m$n), Y=0,33x<1020*x >(nudc
lgr), Y*0,32x°02-3*X) (nude ngQt)
TlM^iMkhiMkMiihkD
ngpt 79,1-89,3 trai/buong. Giua ba vung tr£n khong
co su khic bi£t vl tong so trai/buong co thi dugc
giai thich la do tong so trai/buong hoa dua nude hau
nhu da dupe quylt dinh ngay trong giai doan buong
hoa dupe hinh thinh, do do hau nhu tdng so
trii/buong khong co su thay doi trong suot giai doan
buong hoa phat triln. Tuy nhi£n, tong so trii/buong
hoa cua ba vung nuoc nay cung nho hon so voi tong
sd trii/buong hoa d Papua New Guinea li 111
trii/buong (Paivoke, 1985).
J
9
-a
9
kk
•M
I 9 10
Hinh 7. Sy phit triln (a) v itd c do ting trudng (b)
cua chu vi bu6ng hoa theo chilu r0ng b ba vung
nude min, nude lp v i nude ngpt
x tinh toin th eo phuong trinh tin g trudng cua
Robertson (1908, trich din bdi Reed, 1920) vdi
Y-0,32xm i**) (nude m$n), Y -Q Jlxf™ ** } (nudc
lp), Y-0,31x°0lsr*} (nude ngpt)
3.4.3. Tdng sdtrii/budnghoa
Tdng sd trii/budng hoa b ba vung khdng cd sy
k h ic bi$t b muc i nghia 5% qua phin tich thong k l b
timg thing k h io s it (Hinh 8). Tdng sd trii/budng
hoa cua viing nude mgn trung binh v io khoing 77,3-
86,3 trii/budng, nu6c 77,3-94,7 trii/budng v i nude
Hinh 8: Tdng sd trii/budng hoa dua nude b ba viing
nude m$n, nude ngpt v i nude lp
3.4.4. Ti 16 tr ii chic/budng hoa
Ti 10 trii chic/buong hoa khdng cd su khic bi|t
or muc y nghia 5% qua phin tich thdng k£ giua ba
viing qua timg thing khio sit (Hinh 9 ). Khi budng
hoa dira mdi nor, chua x ic djnh dugc trii chic v i trii
lep do luc niy buong hoa mdi buoc vio giai doan thu
phan v i cd thi thay ring tat ca c ic trii dlu cd thi tro
thinh trii ch ic. 6 giai doan mdt thing sau khi hoa
no thi sd trii ch ic/buong cua budng hoa dira nude
tai ba vung dlu cao hon so vdi cic thing cdn lgi.
Dilu niy l i do b giai do?n mpt thing sau khi hoa no
thi budng hoa luc niy cung chua cd sy thay ddi ldn
v l kich thudc trii do dd lupng trii duge xic dyih li
trii ch ic tuong ddi cao. Tuy nhi£n, din thing thu hai
thi luc niy trii d i b it dau phit triln v l kich thudc v i
hiu nhu nhung trii dira nude tr£n cung mdt budng
se phit triln hinh dang dua hoin toin vio khdng
gian m i chung cd dupe, b giai do^n niy cd sy c?nh
tranh v l khdng gian d l t?o thinh hinh dang cua moi
trii. Do dd, b thing thu hai thi d i cd sy phin bi|t rO
rang giua trai ch ic v i trii lep, ddng thdi hinh d?ng
cua moi trii cung d i duge quylt djnh. Ti 1| trii
chic/buong tinh tir thing thu hai din thing thu 10
cua viing nude min trung binh vio khoing 47,8-
60,93%, nude ngpt 50,1-60,2% v i nude lp 48,963,4%.
N6NG NGHlfP VA PHAT TR|£n N6NG THON - KY 1 - THANG 4/2014 53
KHOA HPC CONG N GHl
Th an g u u k h i h o a nd
Hinh 9. Ti l£ trii ehac/budng hoa dira nude d ba
vung nu6c m$n, nude ngpt vi nude lgr
3.5. Khdi luong trii chic
Trai chic dat khoi lugng toi da d thang thu sau,
sau do on dinh toi thing thu muoi (Hinh 10). Phuong
trinh ting truong cua Robertson (1908) cho thay
khoi luong trai chic tang trudng cuc dai d thdi di£m
4,78 thang d vung nuoc man, 4,52 d vung nude lgr va
4,55 thang d vung nude ngot. Trong do, khoi lugng
trai chic d vung nuoc man khac biet cd y nghia so
vdi khoi lugng trai chac d hai vung nude ngot va lgr.
Nhu vay, khoi lugng trai chac cao nhat la d vung
nude lgr va thap nhat 14 d vung nude man.
d£u co su khic bi£t thong k£ d muc y nghia 5% d
timg thdi di£m quan sat. Dua vao phuong trinh tang
trudng cua Robertson (1908) thi chi£u dai trai gia
tang tir khi hoa no va dat toe do tang trudng cue t^i
tai thdi diem 3,14 thang (nude man), 3,0 thang (nude
lo), 3,06 thang (nude ngot). Tuong tu nhu khao sit d
Papua New Guinea, chi£u dai trai bi£n dong 12,4-
14,7 cm va chi£u rong trai 6,2-7,6 cm (Paivoke, 1985).
Nhu vay, chieu dai trai ldn nhat la d vung nude lo,
thap nhat la viing nude man. Thdi gian can thi£t d<?
trai dat kich toi da la sau thang sau khi hoa no. Toe
do tang trudng cuc dai v£ chi<ki dai cua trai nam
trong khoang tir thang thu 2 ddn thang thu tu sau khi
hoa nd.
14j 0 C o
-rn$wmm • « * * *
Hinh 10. Su phit tri£n (a) vi tdc dd tang truong (b)
cua khdi lugng trii chic cua trii dira nude dba viing
nude m$n, nude lgr vi nude nggt
x tinh to in th e o p h u on g trinh t in g tru o n g cua
R ob ertson (1908, trich d in b d i R eed , 1920) vdi
Y=0,33x<m5’x) (n ud e m $n), Y=0,36x(202-9'X } (n ud e
lo ), Y=0,35x(,9IO'x ) (n ud e ngQ t)
3.6. Kich thudc trii ch£c
Chi£u dai (Hinh 11) cua trii chic tir giai doan
mdt thing ddn 10 thing sau khi hoa nd d ba vung
Hinh 11. Su phit tri£n (a) vi tdc do ting trudng (b)
cua trii chic theo chi£u cao d ba viing nude min,
nude lgr vi nude nggt
x tinh toan th e o p h u o n g trinh ti n g tru dn g cua
R o bertson (1908, trich dan b di R eed , 1920) vdi
Y=0,32x<8- * x> (nude m $n ). Y -0 ,3 1 x * “ M >(nudc
lg ), Y=0,32xf904'x} (nude ngQt)
3.6. Chi£u dii cudng budng hoa
Chidu dai cudng budng hoa dira nude d ba viing
cd su khic bi£t d muc y nghia 5% qua phan tich
thong k6 d timg thdi didm khao sit (Hinh 12). Cuong
buong hoa dira nude dai nhat li d viing nude lg va
thap nhat la d viing nude min. Chi£u dai cudng
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