T O N G H E N COU DEN TRIEN KHAI - 5AN XUAT
Da o qua n g\if t difdng
BANG VAT LIEU BAO TBAI tf 8»C
NGUYEN TH!
T U Y I TMAI, HO
T H IHUY,
N G U Y I NBAO VE
Sd Nong nghiep va Phat trien Nong thon Vinh Long
Muc tieu cua nghien cihi la xac djnh hieu qua cua l(y thuat mang bao sau thu hoach doi vol chat liftfng va thdi han bao quan cua qua quyt DiToftig d nhiet dp S^C (60% RH). Thi nghiem dUtfc bo'tri theo the thufc hoan toan ngiu nhien vdi 6 nghiem thufc (doi chu'ng, bao PP, PE, PVC, Chitosan 0,25%, Citra shine) va 4 lan lap lai, mdi lan lap lai la 24 trai. Ke't qua cho tha'y, trong dieu kien bao quan of nhiet dp SoC (60% RH), trai quyt DUomg diTpc bao bing bao PP CO the keo dai thoi gian bao quan tren 7 tuan vdi ty le hao hut trpng lutfng tha'p (0,660%), khdng nam benh, mau sdc vo trai dep, ham liTtfng vitamin C it bj suy giam (9,76 mg/100 ml) va cac chi tieu chat lUdng khac (tong chat ran hda tan, ham lilpng dUdng tong sd'va acid tdng sol diTpc duy tri dn djnh.
Mir dau
Ton that ndng san sau thu hoaeh la van de ldn ddi vdi nha lam vUdn va cac nha xua't nhap khau. Trai eay cd mui thudc nhdm khdng cd dot pha hd hap, cd ddi sdng sau thu hoach tUdng dd'i dai, nhUng tdn that sau thu hoach van kha cao (cd the tif 15 de'n 30%) do dieu kien bao quan va nam benh sau thu hoaeh. O Viet Nam, trai quyt Dudng (Citrus reticulata Blanco var.
Duong) cd gia tri kinh te cao va dien tieh san xua't ngay cang dUdc md rdng. Do vay, viec tim ra bien phap thieh hdp de ban che tdn that sau thu hoach la rat quan trpng de tang thu nhap cho ngUdi san xuat va tieu thu.
Vat lieu va phuvng phap nghien
Cihi
Co nhieu phUdng phap bao quan trai cay sau thu hoach, trong dd bien phap khdng che thanh phan khi bang each bao trai dem lai hieu qua kha cao. Mdt bien phap bao quan trai cay khac dd la bao quan trong dieu kien nhiet dp tha'p. Ca hai bien phap nay deu liim giam hd hap, ban che bdc thoat hdi nUdc nen giup keo dai ihdi gian sdng va duy tri chat lUdng trai sau thu hoach. Dd'i vdi quyt DUdng, bao quan cl nhiet dp 8"C cd the bao quan dUde 5-6 tuan vdi ty le hU hdng tha'p va khdng CO bieu hien tdn thUdng lanh.
Chung tdi da tien hanh thi nghiem tren Irai quyt Dudng dUdc thu mua tai vUdn
(huyen Lai Vung, tinh Ddng Thap). Chon trai khdng bi khuyet tat, sau benh, 25-30%
dien tich vd trai chuyen sang mau vang va tUdng ddi ddng deu ve kich ed. Khdi Iffdng trung binh 130g/trai.
Cac vat lieu bao trai dffdc sii dung trong thi nghiem gdm cd: (1) Ttii nhUa polyethylene (PE); (2) Ttii nhUa polypropylen (PP); (3) Mang ddng gdi thifc pham bang nhifa polyvinyl chloride (PVC) - day la san pham dffdc nhap tff Phap, cd dac tinh co dan manh, cd kha nang dm sat vao be mat vd trai. do Cdng ty trach nhiem hffu han Tan Bach Dat phan phdi, siin pham dffdc xff ly an toan va dffdc Bp Y te cho phep sti dung trong bao bi thifc pham;
(4) Chitosan dang bpt hda tan trong acid acetic, san pham thUdng mai do Dai hoc Thiiy san Nha Trang cung cap; (5) Chat bao quan trai eay sau thu hoach Citra.
Thi nghiem dUdc thifc hien tai Phong thi nghiem Bd mdn Khoa hpc cay trdng, Khoa Ndng nghiep va sinh hpe Ung dung, TrUdng Dai hpc Can Thd.
Trai quyt Dffdng sau khi thu ve dffdc rffa bang nffde sach, sau do nhiing vao dung dich Chlorine ndng dp 0,04% trong 5 phiit de xuT ly nam benh tren be mat vd trai trffdc khi bdtri thi nghiem. Thi nghiem dffdc bd tri theo the thffe hoan toan ngau nhien, cd 6 nghiem thffe va 4 lan lap lai.
mdi lan lap lai 24 trai.
Cac nghiem thffe trong thi nghiem bao gdm: (1) DC: Nghiem thffe ddi chffng.
khdng bao trai; (2) PE: Bao trai bang bao polyethylene (10x20 cm), due 5 Id, dUdng kinh mdi id la 1 mm; (3) PP (10x20 cm):
Bao trai bang bao polypropylene khdng due Id; (4) PVC: Bao trai bang mang co polyvinyl chloride, dang cudn, chieu rpng 40 cm, be diiy 12,5 pm, bao I ldp; (5) Chitosan: Bao trai bang Chitosan 0,25%;
(6) Citra: Bao trai bang cha't biio quan trai cay sau thu hoach vdi ten thffdng mai la
"Citra shine" (pha vdi nffde cat ty le 1:1).
Ta't ca cac nghiem thffe dffdc bao quan trong dieu kien nhiet dp 8"C (60% RH).
Ketquavathao luan
Ddnh gid cdm quan trdi quyt DUdng Ke't qua nghien effu cho tha'y diem danh gia ciim quan ciia trai quyt Dffdng d cac nghiem thffe giiim dan theo thdi gian bao quan. Sau khi bao quiin 2 tuan, diem danh gia cam quan cao nhat \k nghiem thffe bao PP vdi 91,9 diem, tha'p nha't la nghiem thffe doi chffng 88,9 diem, tuy nhien khdng cd sff khac biet qua phan tich thong ke.
Ke tff tuan thff 3 trd di, diem danh giii cam quan giffa cac nghiem thffe cd sff khac biet qua phan tich thd'ng ke d mffe y nghla
1%. Tuan thff 3, nghiem thffe dffdc danh gia cao nha't la nghiem thffe bao PP (89,9 diem), thii'p nha't van la nghiem thffe ddi chffng (84,3 diem). Tff tuiin thff 4, nghiem thffe ddi chffng, vd trai bdi dau nhiin. miit nffde va ehuyen sang miiu viing nen dicm danh gia cam quan riit thap (77,8 diC-m);
nghiem thffe bao PE, vd trdi chuyen sang
Hoat dOna
so thang 2.2011 ^ j ^ O ^ ^ I , 7 ^ ^ " 41
TCJ N G H E N CUU DEN TRIEN KHAI - 5AN XUAT
mau vang, tuy nhien vd trai van eUng, bdng nen diem danh gia van eao (86,9 diem); cao nha't van la nghiem thffe bao PP (88,0 diem). Sang tuan thff 5, nghiem thffe ddi chffng dffdc danh gia mat gia tri thUdng pham do diem danh gia cam quan xudng tha'p dUdi 75 diem (70 diem). Den tuan thff 7, chi cdn nghiem thffe bao PE (75,9 diem) va PP (79,5 diem) dffdc danh gia cdn gia tri thffdng pham. Nghiem thffe bao PP van giff dffdc mau sac, dp bdng vd trai kha td't nen diem danh gia cam quan cao hdn so vdi eae nghiem thffe edn lai den thdi diem ket thue thi nghiem liie 8 tuan. 0 thdi diem 8 tuan, diem danh gia cam quan nghiem thffe bao PP d mffe 74,1 diem.
Nhff vay, gia tri thUdng pham ciia trai quyt Dudng trong thi nghiem giam dan theo thdi gian bao quan va suy giam xay ra manh nha't d nghiem thffe ddi chffng.
Chffng td viec bao trai da ed tae dung bao quan tdt hdn khdng bao trai. Trong vat lieu bao trai thi bao trai PP cd tac dung tdt hdn eac vat lieu bao trai khae. Nghiem thffe bao PP ludn dat diem danh gia cam quan cao hdn eac nghiem thffe khac sudt thdi gian bao quan, mau sac vd trai dffdc duy tri kha tdt, den lue ket thiic thi nghiem vd trai van cdn giff dffdc mau xanh.
Ty le bfnh vd rung cudng trdi
Benh va rung eudng trai da khdng xay ra sudt thdi gian bao quan d nhiet dp 8°C. Den 8 tuan, nam benh ehffa tha'y xua't hien va cudng trai vin duy tri dffdc mau xanh, dinh rat chat vao trai. Dd'i vdi quyt Dudng, ed 3 loai nam gay hai tren vd trai sau thu hoaeh la nam Colletrotrichum sp, Penicillium sp vd Aspergillus sp. Tuy nhien, sau 8 tuan nam benh khdng phat trien ed the do trai da dUde xii ly nam benh bang Chlorine trUde khi bao quan.
Ndng dp de Chlorine cd the tieu diet dUde eae loai nam gay hai tren vd trai cay cd mui sau thu hoach phai tren 0,02%. Do do, viee xii ly nam benh bang Chlorine ndng dp 0,04% trong 5 phut da gdp phan ban ehe nam benh gay hai. Ket qua nay cung phu hdp vdi thi nghiem cua Ly Hoang Minh va ctv (2005), xil ly vd trai quyt Dudng sau khi thu hoach bang dung dich Chlorine ndng dp 400 ppm trong 5 phiit trUdc khi dUa vao bao quan da kiem soat nii'm benh. Cdn theo Salunkhe va Desai (1984), bao quan trai cay hp cam quyt d nhiet dp thap la bien phap hieu qua nhat
de han che' siI phat trien eua benh thdi trai, dae biet trong trUdng hdp mam benh nhiem sau vao ben trong trai ma viee xti ly benh khdng cdn hieu qua nffa. Viee nam benh khdng xua't hien da gdp phan ban ehe rung eudng trai, vi nam benh thUdng xam nhap vao ben trong trai qua cud'ng va gay ning eudng. Vi vay, cd the ndi rang trai quyt DUdng bao quan d nhiet dp 8°C va xuT ly bang Chlorine trUdc khi bao quan la nguyen nhan giup ban che rat td't nam benh va rung cudng trai.
Sir thay ddi mdu sdc vo trdi
Ke't qua thi nghiem cho tha'y, mau sac vd trai quyt DUdng bao quan d nhiet dp 8''C cd sU thay ddi theo thdi gian bao quan.
Chl sd dp khac mau (A E) ciia vd trai tang dan theo thdi gian bao quan. O tuan thU 2 sau bao quan, A E vd trai giffa cac nghiem thffe cd sff khac biet qua phan tieh thd'ng ke d mffe y nghia 1%, AE vd trai ciia nghiem thffe bao PP It bie'n ddi nha't (55,1) trong khi nghiem thffe dd'i chffng cd A E kha ldn (58,4).
O eae tuan tiep theo, nghiem thffe bao trai bang PP van duy tri dffdc mau sac kha td't thdng qua tri sd A E ludn tha'p hdn eae nghiem thffe khae va ed khae biet qua phan tich thdng ke d mffe y nghla 5% d tuan thff 3 va 1% d cac tuan tff thff 4 de'n thff 8. De'n tuan thff 8, mau vd trai d cac nghiem thffe da ehuyen sang mau vang ngoai trff nghiem thffe bao PP, the hien qua A E tha'p nha't (59,0), nghiem thffe bao trai bang Chitosan cd A E cao nha't (68,9).
Chi so'A E gia tang cang ldn so vdi ban dau chffng td mau sac vd trai thay ddi eang manh. Ket qua thi nghiem eho tha'y, A E vd trai d nghiem thffe bao PP ludn tha'p so vdi nghiem thffe dd'i chffng va eac nghiem thffe khae chffng td bao PP cd tae dung duy tri mau sac vd trai rat td't.
Ty le hao hut trpng lUdng
Ty le hao hut trpng Iffdng trai d eac nghiem thffe bao trai bang plasdc (PP, PE, PVC) tha'p hdn so vdi ddi chffng va bao bang mang mdng (Chitosan, Citra shine).
Ke't qua cho tha'y, sff giam trpng Iffdng trai xay ra trong sudt thdi gian tdn trff va giffa cac nghiem thffe cd sff khae biet qua phan tich thdng ke d mffe y nghia 1 % tff tuan thff 2 den tuan thff 8. Nghiem thffe dd'i chffng do khdng dffdc bao trai nen ty le hao hut trpng Iffdng ludn eao hdn cae nghiem thffe cd bao trai. Trong cac nghiem thffe bao
trai, nghiem thffe bao PP va PE cd ti le hao hilt trpng Iffdng tha'p nhat. De'n tuan thiI7 sau bao quan, ty le hao hiit trpng lUdng d nghiem thffe bao PP tha'p nha't (0,660%), cao nha't la dd'i chffng (12,50%). De'n tuan thff 8, nghiem thffe dd'i chffng khdng con gia tri cam quan nen ty le hao hut khong dffdc ghi nhan, ty le hao hut trpng Iffdng eao nha't la nghiem thffe bao Chitosan (13,30%), tha'p nha't vin la nghiem thilc bao PP (0,809%).
Nhff vay, bao trai quyt Dffdng sau thu hoaeh da ban ehe td't sif mat trpng Iffdng.
Trong dd, bao trai bang PP va PE cho ket qua td't nhat. Ket qua nay ciing tffdng dong vdi nghien effu cua Rodov va ctv (2000), viee bao gdi tffng trai ban che' tdt nha't sil mat mat trpng Iffdng va td't hdn bao sap.
Ddi vdi trai cay, hao hut trpng Iffdng trong thdi gian bao quan chu ye'u do mat nffde.
Viec mat nffde qua eao se anh hffdng den boat ddng sinh ly ben trong trai, ddng thdi lam giam dp cffng va thay ddi hinh dang trai. Theo Ly Hoang Minh va ctv (2005), ap dung bao gdi tffng trai bang plastic giff dffdc dp cffng trai tdt nha't va mat nffde tha'p nha't. Do dd, bao trai quyt Dffdng sau thu hoach bang PP va PE da giup han che dffdc hao hut trpng Iffdng va duy tri do cffng vd trai td't.
Hdm lUdng vitamin C
Sau 2 tuan dau tien, ke't qua phan tich ham Iffdng vitamin C ciia dich trai d cac nghiem thffe eho tha'y, ham Iffdng vitamin C ciia dich trai d eac nghiem thffe bao PP, PE (11,2 va 11,3 mg/100 ml) cao hdn cac nghiem thffe bao trai cdn lai va ddi chffng (10,0 mg/100 ml), tuy nhien khdng co sff khae biet qua phan tich thdng ke. Ham Iffdng vitamin C cua dich trai giam dan de'n tuan thff 4 nhffng giffa cac nghiem thu'c khdng cd sff khac biet qua phan tich thdng ke. Den tuan thff 5, ham Iffdng vitamin C giffa cac nghiem thffe cd siI khac biet qua phan tich thdng ke d mffe y nghla 5%, nghiem thffe bao PP cd ham Iffdng vitamin C cao nha't (10,3 mg/100 ml), tha'p nhat la nghiem thffe dd'i chffng (8,47 mg/100 ml). De'n tuan thff 6, ham Iffdng vitamin C d nghiem thffe bao PP van giff d mtfc eao (10,0 mg/100 ml) so vdi cac nghiem thffe khac nhffng khdng ed sff khac biet qua phan tich thd'ng ke. Tuan thff 7 thi ham Iffdng vitamin C giffa cac nghiem thffe c6 sff khac biet qua phan tieh thdng ke d miJc y nghla 5%, nghiem thffe bao PP vin duy
« KHOTHOC^°^^^"9^-2°^^
T C ; N G H E N COU DEN TRIEN KHAI - 5AN XUAT
tri dffdc ham Iffdng vitamin C cao (9,76 mg/100 ml), tha'p nha't van la nghiem thffe ddi chffng (8,22 mg/100 ml). Den tuan thff 8 thi nghiem thffe ddi chffng da hdng va ham Iffdng vitamin C giffa cac nghiem thffe cdn lai thi khdng ed sff khae biet qua phan tich thd'ng ke .
Vitamin C la chat de bi oxy hoa va chuyen thanh dang dehydroascobic, d dang nay nd de hi phan buy dffdi tac dung eiia nhiet dp (Quach DTnh va ctv, 1996; Lee va Kacler, 2000). Do dd, dieu kien bao quan d nhiet dp tha'p va bao trai da giup han che dffdc ham Iffdng oxy nen da ban che dffdc qua trinh oxy hda vitamin C ciia dich trai.
Trong dieu kien bao quan trai cam d nhiet do tha'p, ham Iffdng vitamin C hau nhff khong bi mat (Schirra va Chessa, 1988).
Nghiem thffe dd'i chffng cd ham Iffdng vitamin C ludn tha'p nha't trong sudt thdi gian bao quan. Vi dffdc bao quan eiing dieu kien nhiet dp nen sff khae biet nay cd le do anh hffdng cua thanh phan khi xung quanh trai. Dieu kien khdng khi cd nhieu oxy ciing cd the la nguyen nhan lam cho vitamin C trong dich trai bi oxy hda manh.
Nghiem thffe bao PP giff dffdc ham Iffdng vitamin C eao den tuan thff 7 (9,76 mg/100 ml) chffng td thanh phan khdng khi thich hdp cd the ban che viec mat vitamin C.
Tong chat rdn hda tan (dp brix) dich trdi
Trong sudt thdi gian b^o quan trai quyt Dffdng, do brix cd sff thay ddi va ed xu hffdng tang dan. Sau 4 tuan bao quan, dp brix ciia nghiem thffe ddi chffng ludn cao hdn cac nghiem thffe cdn lai nhffng khdng CO khac biet qua phan tieh thd'ng ke. Tuan thff 5,6 va 7, dp brix giffa eac nghiem thffe CO sff khac biet qua phan tich thd'ng ke d mffe y nghla 1%, nghiem thffe ddi chffng CO dp brix tang eao nha't (9,65%), trong khi nghiem thffe bao PP tang khdng dang ke so vdi tuan dau tien (8,75%). Nhff vay, vi?c khdng bao trai sau thu hoaeh lam cho trdi d nghiem thffe ddi chffng mat nffde cao hdn, do dd dp brix cao hdn trai d cae nghiem thffe dffdc bao trai. Bat dau tff tuan thff 6, dp brix ciia nghiem thffe dd'i chffng CO xu hffdng giam dan (9,25% d tuan thff 6 va 9,10% d tuan thff 7), cac nghiem thffe c6n lai tie'p tuc gia tang dn dinh. Tffdng tff, c k nghiem thffe bao PVC, Citra shine va Chitosan ciing cd hien tffdng giam brix sau tuan thff 7 trong khi cac nghiem thffe bao
PP va PE tiep tue gia tang den tuan thff 8.
Nhff vay, da cd sff bien ddng ve dp brix dieh trai giffa cae nghiem thffe trong qua trinh bao quan. Quyt thudc nhdm khdng cd dot pha hd hap (Laville, 1994). Vi vay, sff gia tang brix trong giai doan dau ctia qua trinh bao quan chu yeu do mat nffde.
Nghiem thffe ed dp brix cao nha't la dd'i chffng va bao Chitosan, chffng td viec khdng bao trai va bao bang mang Chitosan lam trai hi mat nffde tffdng ddi ldn, lam gia tang dp brix. Trong khi do, cac loai vat lieu bao trai khac It mat nffde hdn nen dp brix gia tang khdng dang ke trong sudt thdi gian bao quan. Hien tffdng dp brix giam d giai doan eudi cd the dffdc giai thich do hien tffdng lao hda eiia trai, eac vat chat dff trff khdng dffdc tdng hdp them trong khi boat ddng hd hap lai suf dung cac chat dff trff de duy tri sff sdng cho trai.
Hdm liidng diidng tdng sd
Trong sudt thdi gian bao quan trai quyt Dffdng d dieu kien nhiet dp 8''C (60% RH), ham Iffdng dffdng tdng sd giffa cac nghiem thffe khdng cd sff khae biet qua phan tieh thdng ke. Ham Iffdng dffdng tdng .sd cd sff gia tang dan theo thdi gian bao quan. Tuy nhien, da khdng cd sff gia tang vffdt trdi d bat ky nghiem thffe nao ke ca nghiem thffe khdng dffdc bao trai. Chffng td, viec bao trai sau thu hoach bao quan d nhiet dp tha'p da khdng anh hffdng de'n ham Iffdng dffdng tdng sd.
Hdm iMng acid tdng sd
Ket qua nghien effu cho tha'y, ham Iffdng acid tdng sd cua dich trai d ta't ca cac nghiem thffe deu giam. Trong 6 tuan dau tien, ham Iffdng acid tdng sd giffa cac nghiem thffe khdng cd sff khae biet qua phan tieh thdng ke. Nhffng den tuan thff 7, ham Iffdng acid tdng sd giffa cae nghiem thffe ed sff khac biet d mffe <i nghia 5%.
Trong dd, nghiem thffe dd'i chffng cd ham Iffdng acid tdng sd tha'p nha't (0,326%).
Tran Minh Tam (2000) cho rang, acid hffu ed eung la nguyen lieu de hd hap, vi vay trong qua trinh bao quan, ham Iffdng acid hffu cd hi giam xud'ng. Nhif vay, nghiem thffe dd'i chffng acid tdng sd giam thap nha't chffng td trai d nghiem thffe nay cd boat ddng hd hap manh hdn so vdi eac nghiem thffe cd bao trai. Den tuan thff 8, ham Iffdng acid tdng sd d cac nghiem thffe khdng khac biet qua phan tich thdng ke.
Ket luan
Trai quyt Dffdng dffdc bao trai sau thu hoach bang bao PP cd the bao quan tren 7 tuan trong dieu kien nhiet dp 8"C (60% RH) vdi benh va tinh trang rung eudng khdng xay ra, hao hut trpng Iffdng tha'p (0,660%).
Ddng thdi, hinh dang ben ngoai van dep, vd trai van bdng lang, mau sac vd trai It thay ddi so vdi luc thu hoach. Cae chi tieu ve chat Iffdng: Dp brix (8,60%), acid tdng sd (0,374 %), dffdng tdng sd (7,71%) dffdc duy tri dn dinh, ham Iffdng vitamin C dffdc duy tri d mffe cao (9,76 mg/100 ml).
De keo dai thdi gian bao quan va duy tri chat Iffdng trai quyt Dffdng sau thu hoach, nen bao trai sau thu hoach bang bao PP bao quan d nhiet dp 8"C •
Tai lieu tham khao
1. AOAC. 1984. Official methods of analysis.
Association of Official Analytical Chemists.
2. Laville. E. 1994. (ed). La protecuion des fruit tropicaux apres recolte. Cirad - oleacp. Tec. & Doc.
Lavoisier. 190p.
.1. Lee. S.K and A. Kacler. 2000. Pre-havest factor influent to vitamin C content of horticultural crop. Department of Pomology. University of Califonia. pp: 207-220.
4. Ly Hoiing Minh. Phan Thi Le Thi, Nguyen Quoc Hoi va Le Van Hoa. ZOO.'i. Anh htfdng ciia Chitosan. bao polyethylene ke't hop vdi biio quan lanh den chat lu'ong vii thdi gian bao quiin trai quyt DiTimg. Luan viin tot nghiep ky sU ngiinh trong trot.
Khoa Nong nghiep vii sinh hoc u'ng dung. Trifc)ng Dai hpc Ciin Tho.
5. Nguyen Thanh Tiing vii Thai Thi Hoa. 2004.
Anh hUiing nhiet do thii'p de'n chii't lUOng va th((i gian biio quan quyt Du'dng. Vien Nghien cu'u ciiy iin qua mien Nam.
6. Nguyen Thi Kieu, 2005. Anh hi/clng ciia kh!
Ozone trong iJc che sir phat trien ciia nii'm Aspergillus sp. Colletotrichum sp giiy benh tren trai cam Siinh, quyt Du'dng vii biTdi Nam Roi sau thu hoach. Luan van Thae sy trong trot, Khoa Nong nghiep vii sinh hpc iJng dung. TriTdng Dai hpc Can Tho.
7. Phan Thi Anh Dao, 2003. Khao sat stf ton thii't khoi lu'ong vii sif thay dt)i gia tri cam quan trong bao quan lanh. Luan van tot nghiep ky sir ngiinh cong nghe thiTc phii'm. Khoa Nong nghiep vii sinh hpc u'ng dung. TriTdng Dai hpc Can Tho.
8. Quach Dinh. Nguyen Van Tie'p vii Nguyen Anh Khpa. 1996. Cong nghe sau thu hoach vii che bie'n rau qua, NXB Khoa hpc va ky thuat H i Npi.
trang 284.
9. Tran Minh Tam, 2002. Bao q u i n vii che bien nong san sau thu hoach. NXB Npng nghiep H4 Npi
10. Trang Cong Minh. 2004. Xiic dinh nii'm hai tren vo triii quyt Ditifng (Citrus reliculalal sau thu hpach vii iinh hifc'lng ciia Gibberellic Acid (GA.M J e n sir phiit trien ciia mpt so nii'm benh chinh. Luiin viin tot nghiep ky sU' trong trpt. Khoa Nong nghiC'p v i sinh hpc ifng dung. Trifdng DMI hpc Cim Thd.
So thang 2 . 2 0 1 1 j ^ | ^ Q ^ , , ( ^ ( . - 43