Showing 4 results for H. Rahimian
A. Davoodee, E. Majidi, H. Rahimian, M. Valizadeh,
Volume 9, Issue 2 (summer 2005)
Abstract
The fire blight with the bacterial causal agent, Erwinia amylovora (Burrill) winslow etal. is one of the most important diseases of the pome fruits that causes the economical losses to quince, pear and apple productions, respectively, in some parts of country. To determine the infection severity of the 43 raturally infected pear cultivars in collection of karaj horticulture research division and also for studing the reaction of these cultivars against disease, the evaluation was performed by the USDA standard system for these cultivars in collection. In this study, although the most of cultivars had been infected on the natural conditions, but disease severity was significantly different between them. By the USDA system, pear cultivars were divided in the 2 classes. Percentage of pear cultivars in very susceptible and moderately susceptible classes were 81.4 and 18.6 respectively. Also for dividing the pear cultivars, beside of USDA method, SPSS software and the cluster analysis were also by the UPGMA method and cultivars were divided into 3 clusters, but it seems that the classification of cluster analysis did not conform with USDA system. Correlation of I.V.S in the artificial tests and the disease severity by natural infection was very significant (r= -0.83).
A. Nezami, A. Bagheri, H. Rahimian, M. Kafi, M. Nasiri Mahalati,
Volume 10, Issue 4 (winter 2007)
Abstract
The present experiment was aimed to evaluate the freezing tolerance of two cold tolerant (MCC426 and MCC252) and a cold susceptible (MCC505) chickpea genotypes. The study was carried out in a split-plot factorial design with three replications. Factorial arrangement of genotype and acclimation (acclimation and non acclimation) were imposed as main plot and temperatures (0, -4, -8, -12, 16, -20ºC) as subplot. The effect of freezing temperature (FT) on plant survival was significantly different among genotypes (p<0.05). According to the average effects of acclimation and FT, the plant survival in MCC426 and MCC252 was 40% and 31% respectively more than in MCC505. Lethal temperature for 50% response (LT50) and temperature resulting in 50% lower dry matter (DMT50) in MCC426 were –10.8ºC and
–8.4ºC, respectively and were lower than the other genotypes. Acclimation increased the freezing tolerance such that MCC426 tolerated up to –12ºC without any mortality, however, at this temperature, plant mortality rates in MCC252 and MCC505 were 25.7% and 67.7%, respectively. Plant regrowth was affected by the intensity of FT, such that plant dry weight (PDW) and stem height (SH) in –12ºC decreased about 63% and 50%, respectively, compared with non - frozen control plants. The most freezing damage was observed in MCC505, -12ºC treatment caused 90% decreases in PDW and SH, but at this temperature, PDW and SH in MCC425 decreased 55% and 49% and in MCC252, the reduction was about 60%and 54%, respectively. It seems that the use of controlled experiments would contribute to the evaluation of freezing tolerance and screening programs in chickpea germplasm for the estimation of LT50 and DMT50 .
N. Sahebani, A. Kheiri, H. Rahimian, A. Sharifi Tehrani,
Volume 10, Issue 4 (winter 2007)
Abstract
The effect of Rathayibacter tritici on the movement of Anguina tritici larva and nematode function as vector of ear rot bacterium was conducted in the laboratory (Agarose plates) and greenhouse conditions. The results showed that the contact of nematode larva with high concentration of bacterium or long duration of nematode-bacteria contact can decrease the movement and the efficiency of nematode function as the vector of the disease, and in some cases it resulted in the mortality of the nematode. No differences were detected in the mobility of larva in the concentrations less than 102 CFU and less than 0.5 hour of nematode-bacteria contact times and their controls (exposed to water alone). Movement of the nematodes appeared to be random under these conditions. It can be concluded that Rathayibacter tritici did not act as an attractant to Anguina tritici larva. These results suggest that the attachment of a large number of bacteria to nematode (as an essential vector of the bacterium) would induce nematode weakness and mortality. So it is possible that ear rot bacterium can parasite ear cockle nematode, or the nematode is a host for this bacterium .
L. Khodaei, H. Rahimian, R. Amiri, M. Mesbah, A. Mirzaei Asl, S. K. Kazemitabar,
Volume 11, Issue 1 (spring 2007)
Abstract
Genetic male sterility is controlled by one pair of ressesive allele (aa) in sugar beet. This trait is used in most breeding programes. The exsistance of the character in a line or population facilitates transfer of important trait to the breeding material (for example resistance to plant disease). Also, it is possible to increase genetic diversity of monogerm populations by using genetic male sterility. The time and cost of transferring of this gene will be decreased, if the character is tagged with a molecular marker. Bulked segregant analysis using 302 RAPD primers in two F2 populations (231 and 261 population) was performed for the the identification of RAPD markers linked to the genetic male sterility gene. DNA preparation from 8 male fertile and male sterile plants were separately mixed. At first, the primers were tested on bulks. The primers with polymorphic bands were tested on individual plants of the bulks. Only if the polymorphism of the primers was confirmed, they were tested on the other individual plants. Finally, 10 and 6 markers were identified in 231 and 261 populations, respectively, which their distances to male sterility gene were lower than 50 cM. AB-8-18-600r marker was the nearest marker to male sterility gene. This marker showed only 3 and 1 recombination in 231 and 261 populations, respectively. The distance of this marker and genetic male sterility locus was estimated as 5.3 cM in combined F2 populations.
