جستجوی مقالات مرتبط با کلیدواژه « پوسیدگی ریشه و طوقه » در نشریات گروه « گیاهپزشکی »

The present study aimed to evaluate the resistance of 14 common tomato cultivars in the south of Kerman province and Hormozgan province, including Afra, Badro, Basimo, Bernetta, Brivio, Canyon, Comodoro,Elisa, Golsar, Karun, Matin, Sunseed 6189, 4129 and 8320 at the stage of four true-leaves against Fusarium oxysporum f. sp. radicis-lycopersici, under greenhouse conditions and to study the presence or absence of frlresistance gene in the tomato cultivars based on the SCARFrl marker. Based on the results of comparison of the disease index, morphological characteristics including root length, shoot height, root fresh and dry weight, shoot fresh weight and total fresh weight as well as frl gene amplification using SCARFrl-F/SCARFrlR primers, Canyon, Comodoro, Karun and 4129 were recognized as the most resistant and Bernetta, Elisa, Golsar and Matin were recognized as the most sensitive cultivars to FORL UJFCC1919. Other cultivars including Afra, Badro, Basimo, Brivio, Sunseed 6189 and 8320 showed different degrees of sensitivity to this pathogen. Using SCARFrl-F/SCARFrl-R primers, a 1000 bp fragment was amplified in the cultivars Canyon, Comodoro, Karun and 4129 which indicates the presence of frl gene with dominant homozygous (RR) alleles. Using this primer, a 950 bp fragment was amplified in Bernetta, Elisa, Golsar, Matin and 8320 cultivars, which indicates the absence of the frl gene and the presence of homozygous recessive (rr) alleles. In addition, in Afra, Badro, Basimo, Brivio and Sunseed 6189 cultivars, two 900-1000 bp fragments were amplified, which indicates the existence of heterozygous (Rr) alleles in these cultivars.

In this experiment was conducted during growing seasons of 2009-2010, rice fields in different parts of rice growing areas in Fars and Ilam provinces to identify Root and crown rots of rice. Cylindrocarpon hederae was identified as the disease agent, by using Booth identification key. In order to determine the pathogenicity of isolates, Anbarboo rice cultiuar was used. This is the First report of the association of root and crown rots of rice and C. hederae in the world.

The pythium spp. are known as the principle agents of seedling blight, damping-off and root rot of cucurbits. This study was performed for determination of Pythium species involved in this diseases as well study their pathogenecity on different cucurbits. The numerous samples were taken at cultivation seasons 2006- 2007 from the fields of cucumber, tomato, egg plant, muskmelon, cucurbit, melon, and watermelon, situated in Mashhad, Chenaran, Ghochan, Fariman, Torbtejam, Gonabad, Kashmar, Khvaf, Neishboor, Sabzevar, Torbateheydarieh, Kalat, Dargaz, Sarakhs, and Taibad (North East of Iran). sixty pythium isolates were obtined from the diseased samples in total. They were identified based on morphological and micrometric characteristics. The results showed that 46. 44% are belonging to the P. ultimum var. ultimum, 16. 66% to the P. aphanidermatum, 13. 33% to the P. amasculinum, 10% to the Pythium Group HS, 16. 6. 66% to P. oliganderum, 3. 33% to the P. paroecondrum, and 3. 33% to the P. echinulatum. The P. amasculinu، P. echinulatum and P. paroecondrum are the first report from Iran. The Pythium Group HS and P. oliganderum are also the first report from cucurbits in Iran. The pathogenesity test of isolates showed that P. ultimum var ultimum، Pythium Group HS، P. paroecondrum، P. aphanidermatum and P. echinulatum are pathogenic on cucumber, tomato, egg plant, muskmelon, cucurbit, melon, and watermelon, while P. amasculinum was not Pathogenic on melon and cucurbit.

Pythium aphanidermatum is one of the most important agent of root and foot rot of cucumber, particularly in the warm humid climate. Induction of host resistance by microorganisms or by the synthetic compounds is recently considered as one of the biological control method of disease. Trichoderma harzianum Bi is a good candidate for induction of resistance in plant against diseases. The maximum level of resistance of seedlings to P. aphanidermatum after inoculation with T. harzianum Bi was determined using completely randomized design in greenhouse condition. The results based on the fresh root weight and root rot index of seedlings showed that the maximum level of resistance against P. aphanidermatum is induced 7 days after treatment of cucumber seedlings by T. harzianum. The variation of peroxidase activity, its isozymes, and the total soluble proteins in root extract induced by T. harzianum Bi in cucumber seedlings was determined by colorimetric and native Electrophoresis methods before and after inoculation the seedlings by P.aphanidermatum. The results showed that the maximum level of resistance induction in seedlings treated by T. harzianum Bi coincide with maximum activity of peroxidase. The peroxidase activity was evaluated by Guaiacol oxidation rate in the presence of H2O2 and changing of solution color to orange reddish, measured by the variation of light absorption per min/ mg soluble protein of root extract. The same experiment realized on T. harzianum Bi, P. aphanidermatum and the combination of two fungi demonstrated that both fungi can influence individually the peroxidase activity, but it is more pronounced and more stable and persistent in the case of seedling inoculation by combination of two fungi in comparison to the control.