đánh giá hàm lượng nitrat trong một số loại rau trồng tại vùng sản xuất rau chuyên canh túy loan, huyện hòa vang, tp.đà nẵng



KHOA SINH  








RAU  
LOAN,









- 



KHOA SINH  












 : 





- 



, 


               

Đà Nẵng, ngày 5 tháng 5 năm 2015







  
h. 
nh 

 

Đà Nẵng, ngày 5 tháng 5 năm 2015










 
 1
 1
 2
 2
 2
 2
 2
.  3
 3
 3

 4
 5
 5
1.2. VAI     SINH TR V PHT TRIN C  6
1.3. QU NH CHUYN   TRONG  7
 7
1.5. NHNG Y  G TN D NITRAT

TRONG  9
1.5.1. nh hng  9
1.5.2. nh hng  11
1.5.3. nh hng ca t trg, n t  mc  h lunitrat trong rau 11
 13
.  16
 16
 16
 17
 17

 17
 17
 18
 20
 22
.  23
 23
 25
 27
3.4. H 31
3.1.1.  34

3.1.2. H 37
3.1.3.  39
 42
4.1.  42
 42
 43





1. BNN
2. QCVN
3. 
4. TCCP
5. TCVN












 

  19
  25
  29
  32
 34
  37
 39

 



  16
 ) 16
3. ) 17
  18
  26
  29
 34
  37
  39
1

 
1. 

 
  
               



             

 
u
. 
  
ng. 

  nhanh . 


 
 

 
 
TP. 


2

2.  
2.1. 


TP.  
2.2. 
- 
- 



3. 

  


4.  


- .
- .
-  .
3



1.1. 
1.1.1. 
 
Vang
         
o
  
o
    
107
o

o

 
- .  
 

g 
 - Nam


              
N


- 

  
  79,84%

-ma, gra-phit 
             
.   
 m  
4

            



  
 n.
-




1.1.2. 



 

0
C;  -
-
  
            -   
-- -77%.
 

             



  
 t
5



1.1.3. 



 



 theo  


      
 

 
- 
1.1.4. 
013Vang
 73.691 ha [19]. 
 
      
              
             

ha. chim 7,6% [19]. 


6

  
 
t.
1.2. VAI     SINH TR V PHT TRIN
C 

 l yu t quan trng ng u i vi c th sg v n l nh
phn c n ca cc prn, ct c bn bu hn s sg. T l ni trong
cy bin ng t 1- 6% trng lng cht kh [29]. Nit nm trong nhiu hp
cht c bn n thit cho s pt trin ca cy nh dip lc v cc ct men.
Cc baz nit l thnh phn c n a axit nucleic, trong cc ADN v ARN
ca nn tbo, ni c tr cc thg tin di truyn ng vai tr quan trng
trong vc tg hp pr. Do vy n l yu t c bn trong vc ng ho
cacbon, h ch s pht n ca b r v ht cc yu t dinh dng .
Cy trng c n  n l c mu xanh l cy thm, sinh trng
ke mh, chi bp pht n nhanh, nng sut cao.
[10]i vi rau, n l yu
t tc ng t ln n sinh trng pht n nh cu cao cy, din ch .
Vi ci b xanh khi s dg lng ni t 120N - 180 N/ha th chu cao
cy, ch s dn h l ng n. Chiu cao y i tng n khi tng lng
,  mc 120 kg N/ha cu cao cy l 23,7 cm so vi 10,5 cm khi khng
bn ; ra l, trng lng trung bnh cy cg tng dn khi ng lng
 b, t cao nht  mc n 120 kg N/ha [23]. Cy thiu  l c mu
ng, sinh trng m, ci cc, c khi b thui cht, m ch rt ngn thi
gian h lu hon thnh chu k sng. Vi i bp liu lng n c quan h
vi ng t  mc 200 kg N/ha, ng sut ci bp t cao nht 430 ha, 
mc di 200 kg N/ha th nng sut t p 320 ha [17]. Bn tha n l
cy c u xanh ti, thn l mm,  l nc cao, dmc u bh, dlp
 v thi gian sinh trng ko . Bn nhiu n vkng cn i th dn
7

n s h lu nitrat trong y v m  nhim nitrat trong nc m [17].
1.3. QU NH CHUYN   TRONG T
Vic cung cp nit v cc chu trnh t cht trong t nhin ph
thc nhiu vo qu trh phn hu sinh hc cc hp cht cha nit trong mi
trng. Ton b nit trong chu trnh nit sinh hc din ra chyu qua hot

ng c h n a cc vi khun sg trong cy, cc o c v cc vi
khun ng sinh trong r ca mt s loi thc . Mc  p thu nhu
hoc  nitrat

ca cy trng ph thuc vo ti, li cy trg, mi trng
v cc u t khc. Mt s li rau nh bp c, c ci s dg c c
amonium v nitrat

nhng ci xon, cn ty, b cc loi u sinh trng tt
hn khi cung cp n  dg NO, cc li y nh c chua, khoai ty i
thh hp mi trng dinh dng c t lN-NO
3
/N-NH
4

cao. Nhit  cg
nh hng t ln n vic p thu nitrat

hn amoniac, c bit  nht
 2-
16
o
C.

1.4.  
nitrat 
nitrat 
n nitrat . 
 


.
Methemoglobin        
hemoglobin . 
   
methanh hemoglobin. B


 
8


t
1
.




 
tro
     (     )  

 

 S h lu nitrat

cao trong m cy khng gy c i vi cy
nhng khi s dng cy c m lng nitrat

cao c th lm hi gia sc v con

ngi c bit  tr em do nitrat

c ch y trong bmy u ho c kh
ng khthh nitrit. Trong d dy con ngi, do c dg a h vi sinh
vt, cc loi enzym v do c qu h ho sinh m nitrit

d dng c dng
vi cc acid amin tdo to thnh Nitrosamine gy nn ung th, c bit 
ung thd dy.






1


9

1.5. NHNG Y  G TN D NITRAT

TRONG 
1.5.1. ng 
nitrat trong rau
Theo cc nh khoa c th c  yu t gy tn d nitrat trong ng
n nh nht , h sng, t i, nc ti, bin php canh c nhng
nguyn nhn ch yu c c nh nng hc kng h  lpn bn c
bit l phn n. Hm lng nitrat trong ra mc   m l do n
qu liu , bn khg ng ch. Gim lng  n s lm m s

h y nitrat

trong rau [34]. Trong cc loi phn n dng cho cy trng
thphn n c s dg nhiu nt v g  u t then cht quyt
nh g sut cy trg. Thc t cy trng c cung cp n s pht
n mnh, tg hp c nhiu cht to nn sinh khi v tng n phm.
Nhng bn nu n trong iu kin quang hp, h hp m, khng 
xetoaxid  chn a N-NO
3

thh N-NH
4

ri thnh axitamin, ni 
h lu trong cy  ng nitrat hoc xianogen [8]. o chy theo
nng t v li nn, ngi sn xut  m ng   phn 
. Trong khi s ng phn  theo chiu ng gia tng thvic s
dng phn n v phn kali t , phi hp theo t l khng hp liu 
 lm cho m lng nitrat trong thng phm t cao [14].
Kt qu iu tra  3 huyn Thanh Tr, Gia m v ng Anh ca
thnh ph H Ni (2000) [15] cho ,  ng dn s dng lng n
ln  mt cn i vi phn n v kali; c bit i vi cy rau , lng
phn n s dg ph bin  mc 500 kg N/ha vi xu h, bp ci l 550
kg N/ha, c chua l 640 kg N/ha. Khi kho t nh nh s dg pn bn
cho rau mt s vng chuyn canh rau ca H Ni cng cho kt qu tng
t, lng phn n nng n s dng thng p t 2-3 ln so vi quy trnh
n xut rau an ton, trong khi  phn n v kali s dg rt t m ch
kng s ng. Cc kt qungn cu u khg h s ng lng ln
10

pn n  kng hp l  nguyn nhn dn n hm lng nitrat cao
trong n pm.
Ngi c s ng mt lng ln phn n th thi gian kt thc bn
n trc thu hch cng lmt n tng t ph b tt c cc vng
trg rau trong c nc. Nng n thng thu hch rau ch sau khi n
n 3-7 ngy [3]. Ngi n xut hu nh khng quan tm n tn d
nitrat trong rau m thi gian thu hoch do th trng qut , c bit
vo ma khan him rau. Nhiu t qu nghin cu  chng minh ng,
tn d nitrat trong rau lin quan cht chti s cung cp n v qutrnh
quang hp trc lc thu hoch. Nu c  thi gian v iu n  cy
quang hp mnh to ra glucid v h hp to ra axetoacid thhm lng nitrat

trong cy khg n mc gy c. Do  thi gian bn n trc khi thu
hoh qt nh n tn d trong rau. Tuy y kh ng p th 
v ch lu nitrat

nhanh hay cm n ph thuc vo tng li rau. Hu
ht cc li rau c hm lng nitrat

t cao nt sau khi bn thc n n
cui t  10 ngy. Hm lng nitrat  ci bp t cao nht o ny
th 7 k t khi bn tc ln cu t c cc u lng n khc nhau v
ch thu hoh sau 14 ngy th hm lng nitrat trong ci bp mi gim hn
di ngng an tn [12]. Tn d nitrat trong rau n l v rau n qu cao
nht trong khog thi gian t 10  15 ny  lc bn ln cui n khi
thu hch, i vi rau n c l khng 20 n. Thi gian bn thc sau
ng cng xa ngy thu hoh th lng nitrat trong rau cng gim.
Khi nghin cu nh hng ca thi gian n thc n n cui i vi
mt s li rau trng h Lm g, c gBi Cch Tuyn (1998) [26]
cho bi i vi x lch tn d nitrat t cao nht khng 21 y khi ngng

bn (1569 mg/kg rau ti) sau  gim dn theo thi gian v n 25 ngy
th gim hn di ngng cho php (426 mg/kg rau ti). i vi u H
lan, u ce tn d nitrat t cao nht vo thi m 7 ny sau bn thc
11

ln cui vc gim dn  c ngy sau , nhng nu bn n  mc cao
(>300 kg N/ha) th sau 10 ny tn d nitrat mi gim ti mc cho ph
[13]. i vi  rt tn d nitrat c ch lu cao nht  thi im 20
ngy sau khi ngng n  v gim dn  cc ngy tip theo.
1.5.2. nh hng a 

D lng nitrat

trong rau chu nh hng rt ln ca yu t khhu
thi tit. Trong giai n cui chun bthu hoch, nu p thi tit nh, tri
m u th kh ng ch lu nitrat

t ln. Cc cy trng trong iu n bh
thng c d lng nitrat

p hn cy trng trong nh kh t 2 12
l, nht l cc cy n l, vi cng mt lng phn n ci bp trng
trong nh knh c m lng nitrat

cao hn so vi khi trg ngoi ng
[35]. Mt  cy trng ng lyu t lm tng hoc gim lng nitrat trong
cy. Khi trg y, lng nitrat s tng ln do iu kin chu ng yu.
Thi gian chu sng trong ngy di th m lng nitrat trong cy s gim,
u gim mc chiu sng 20% th hm lng nitrat trong qu da chut ng
n 2,5 ln. Nhit  g nh hng    hm lng nitrat

trong rau, nhit  quln gy tr ngi cho qu trh kh nitrat  r
nn m lng nitrat

trong rau s cao [31].
1.5.3. nh hng ca t trg, n t  mc  h lu
nitrat trong rau
Mi trng , nc lun lni p nn c ngn thi. i nhng
vng sn xut nng nghip mi trng t, nc chu h hng rt
ln ca qu trh  t mi trng theo ng tun hon
 s i o nng sn. Cc ngn cu nc ngoi vi vic s dng
ngn t nit h du chra ng n pn n c hthg v ln hn
200 kg N/ha c nh hng n vg n hon n trong sinh thi ng
rng: nitrat ho dn ti ra tri nitrat m  nhim ngun nc m, nc
12

ngm khi c nng  N-NO
3

> 10 mg/l [17]. Trong iu kin m kh
n phn n ng nitrat

cho t la
ngp nc c th xy ra qu trnh
phn nitrat ho (denitrification) gy mt n v lm gia ng thh phn kh
nh h (N
2
O) n  y ma axit [32].
Trong ng trng rau, t thog k,  m thh hp cho quh
xy ho, nitrat c hh thnh, rau d p thu. S hp thu n  dng nitrat

kng chuyn ho thnh prtin l nguyn nn m gim cht lng rau
q. Mt khc do s dg pn v c khng hp l s lm cho t b 
nhim: chua , nm nitrat, ch lu  trong  Trong
t cc ng n d u m y g hp thu c gm 2 dng c:
amonium

v nitrat. c dng n ny ch yu do qu h phn gii cht
hu c trong t hoc do bn pn n o t chun ho to th.
 hu c trong  u n thng khvxc tc ca cc enzim c
khng ho thnh amonium. n t trng n, amonium

nh nh k c
t khog ho ct hu trong t v b sung ct hu c o , cg
nh  vic phn v c bn vo c xy ho to thnh nitrit v nitrat.
Qu h ny xy ra theo hai bc
nh ht ng ca vi sinh vt
nitrosomonas, nitrosolobus v nitrosopira.

Nitrat h nh trong t, tu vo iu kin mt phn c cy ht,
mt pn b ra tri hoc b mt do qu trh phn n h. Bi vy bn
phn n vi lng ln v qu mn s nh thh nitrat

qu nhiu so
vi nhu cu a y trng s m ra tri  gy nhm mi trng hoc
ch lu nitrat

trong ng sn. Tuy vy ion NO
3

li c p ph t u v

rt t trong t nh phc h keo t, h ct ny lm cho nitrat

linh ng
di chuyn su hn v nh hng n ngun nc ngm [18]. Trong c loi
rau, lng nc cha t 90% tr ln do y cht lng nc ti nh
hng trc p n cht lng sn phm. Sng h ngun tim ng
c cht c hi trong  c nitrat

nhng  c ngi nng n s dg
13

hg ny  ti cho rau v hu qu t yu l chng sn c ch lu
trong  [2].
1.6. 
   [14] 
 

nitrat 
 p 
n
   
ng nitrat tro
19-55 --67 -50 
 n ng nitrat trong

 
c v 
 -2013,  -5/2013 [27]. K 
ng nitrat
trong rau x 748,1  


i
rau m  
 
qu
rau m mg/kg, ca
u h
559 
FAO.
14


 (2007) [5] 
 .


   
ng nitrat 
  mg/kg n 421 mg/kg   - ,   
             

- 1038-2442
 

  (2007) [8] 
ng nitrat  
 ng nitrat 
     . Ngh       
(2009) [13] 


 ng nitrat 
       ng nitrat  

 
 
 
N
     [37]       

15

, khoai
 


Anjana [30] trong
  

 

 trong th
          DU Shao-ting   
(2007) [39]
 
     mg/kg    Theo Surendra Prasad
(2008) [36] 

.



. 



       


16



2.1. 
2.1.1. 

  3   

- Lactuca sativa)

1.  )
- Brassica integrifolia)

2.  )