SEED AND PLANT IMPROVEMENT JOURNAL
Year:2009 | Volume:25-1 | Issue:2|Papers Count:11

Gelatinization temperature (GT) and amylose content (AC) are important traits in determination of rice quality. In the present work four rice cultivars namely Sang-e-Tarrom, Gerdeh, IR229 and IRRI2 were utilized in hybridization as parents, for genetic characterization and study inheritance of the related traits. Direct and reciprocal crosses were performed between parents Sang-e-Tarrom and Gerdeh, and IR229 and IRRI2 respectively. Inheritance of the related traits was studied in direct and reciprocal crosses for low and high GT and high and low, intermediate and high AC. For these evaluations only generations P1, P2, F1, F2, BC1, BC2 and their reciprocal crosses were utilized. Results showed that the gene intermediate dominates on low GT and also high amylose content were dominant on low and intermediate. From direct and reciprocal crosses Gerdeh ´ Sang-e-Tarrom and IR229 ´ IRRI2 it was shown that GT and AC expressions were under monogenic control of one major gene corresponding with several modifier genes. Gene dose effects play a tremendously important and effective role in segregation production among traits. Based on these results, selections can effectively be performed in later segregation generations for AC and in early generations for GT.

Development of Blumeria graminis f.sp. tritici (Bgt) on leaf surface of six advanced wheat lines and some resistance components were studied using a pathotype of Bgt having numerous virulence factors. Wheat lines were two resistant , M-81-13 and N-78-8, two moderately resistant, C-80-4 and N-80-6 and two susceptible, N-79-7 and N-80-19. Seeds of lines were sown in greenhouse and seedlings were inoculated with conidia. Plants were incubated and maintained in constant conditions (95-100% R.H. and 12 /12 hour light / dark period at 18-20oC) in the greenhouse. Latent period and colony size were measured regularly after inoculation, and different developmental stages of the fungus were studied under light microscope, The results showed that percentages of conidia germination, primary and secondary germ-tube, conidiophore and conidia formation, colony size and fungal development were lower in resistant line than those in moderately resistant and susceptible lines. Slow development of the pathogen on resistant lines due to these mechanisms of resistance, caused longer latent period in those lines.

To evaluate the resistance of nine hybrids of corn to European corn stem borer, an experiment was conducted in Moghan Agricultural Research Center in Parsabad during the cropping season in 2005, using a randomized complete block design with four replications. Ten randomly selected plants in each plot were evaluated for different traits related to the activities and loss caused by the pest in three growth stages of maize including stage 7-8 leaves (pest first generation), tassel appearance stage (pest second generation) and seed maturity stage (pest third generation). The results showed that maize hybrids differed significantly for different traits such as stalk tunnel length, plant height, stalk breakage percentage, number of holes made by the pest, diameter of ear husk and grain yield. Two hybrids K3047/2´MO17 and K74/1´Mo17 having the shortest stalk tunnel length, lower percentage of stalk breakage, lower number of holes and higher grain yield exhibited the best characteristics of resistance against the pest damage, compared to the other hybrids. Two other hybrids, 20NS´K19 and K74/1´K19 showed lower resistance characteristics based on the measure of those traits. The remaining hybrids responded differently to the measured traits.

Low-temperature (LT) is one of the limiting factors causing loss of yield in cereals in cold regions of Iran. Cold tolerance as measured by LT50 was determined for cold acclimated crowns of plants grown in the field at the Maragheh Research Station in 2004 and 2005 crop seasons. A randomized complete block design was set up for 90 bread and durum wheat genotypes in three and four replications under field conditions for cold and yield trials respectively. In general, advanced winter bread wheat genotypes showed intermediate levels of LT tolerance (average LT50=-15.63C). Day to maturity and grain filling duration had positive relation with cold tolerance (r = 0.46** and r = 0.54** respectively ). Grain yield showed negative significant correlation with cold tolerance (r = -0.23*). Results indicated that the late maturing genotypes, had more tolerance to cold, but in cold dryland areas selected lines not only should have high yield and good cold tolerance, but also they should have earliness and other good traits for resistance to terminal drought stress. Genotypes No. 15, 17, 23, 30, 41 and 53 had the highest grain yield and high tolerance to cold. Based on results the highest tolerance up take after hardening to cold, and after 1.5 to 2 months of hardening degree of cold tolerance will be decrease.

The present study was conducted in a randomized completely block design (19 genotypes ´ 4 replicates ´ 3 locations ´ 3 years) under rainfed conditions. Simple analysis of variance of grain yield was done for each experiment separately and homogeneity test of errors variance was calculated using F max Hartly test. The combined analysis of variance indicated that main effects of genotype and interactions of year´location and year´genotype´location were significant, but main effects of year, location and interaction effects of year´genotype and genotype´location were not significant. Three stability parameters were used to determine stable lines, including environmental coefficient of variation (C.Vi), Mean square of years within location for a genotype (MSy/l) and ranking method. All three stability tests proved that genotype no. 12 (Wi2291) was the best potentially genotype for rainfed condition. Furthermore, the stability of genotype no. 14 (Alanda/Harma-01/7/Gustoe/6/M64-76/Bon//…) was confirmed by CV and MSy/l methods. On the other hand, the selected genotypes had great agronomic characters and produced higher grain yield in three locations compared to the Izeh (Check cultivar). Line no. 15 (Roho/Alger/Ceres362-1-1/3/Kantara/4/..) and line no. 16 (Zanbaca/3/H.spont.21-3/Arar84//...) were selected for Gachsaran and Moghan respectively. The three used stability parameter were found to be useful tools for selecting stable genotypes under rainfed condition.

Bread quality is one of the most important features of bread wheat cultivars under rainfed conditions. In this study grain quality characteristics and grain glutenin subunits in 25 advanced genotypes of bread wheat were compared with Sardari cultivar, the bread wheat check, under rainfed conditions. Considering glutenin sub-units genomic scores, genotypes no. 11 (OK82282//BOW/NKT/3/F4105W2.1) and 17 (Ghods*3/Kvvko//Ghods*3/kaz/kavko) gained the highest score 10. Genotype no. 18 with 9 genomic score ranked as the second best genotype. Genomic score for Sardari cultivar was 8. Some important grain quality characteristics for these genotypes were measured according to the standard methods of Cereal Research Department, Seed and Plant Improvement Institute, Karaj, Iran. For comparison of the genotypes for these characteristics, non-parametric rank method and finally averages of ranks were utilized. Protein percentage (Pr %) of ten genotypes were higher than Sardari. Genotype no. 8(MRAGHEH-79-80-2) was the best for Pr % and Zeleni number (Zln), the third best one for bread volume (BV) and grain hardness index (HI), the second best one for SDS index, and was ranked first for overall mean rank. This genotype is a releasing genotype in DARSI.

Two-spotted spider mite is one of the most important pests of common bean that causes significant losses on bean yield. Use of resistant cultivar is the most economical and effective way to control this mite. To study response of the adult plants of common bean to Tetranychus urticae, forty genotypes were planted in RCBD with three replications under free and mite infestation conditions in field. Moreover, to study the response of the seedlings, twenty three genotypes were also planted in RCBD with three replications and four observations under mite infestation condition in greenhouse. Analysis of variance for damage score and number of mite on upper and lower leaf surfaces in mite infestation conditions in greenhouse and field experiments and for yield and its components under both conditions in field experiment showed significant differences among genotypes. According to damage score and number of mite on leaves, genotypes Black-1170 and Black-1115 were recognized as the most resistant, and KS31167 as the most susceptible genotypes.

Identification and cultivation of grapevine cultivars with tolerance to drought stress is the most important aim in grape breeding program in Iran. Indirect selection of drought tolerant genotypes, on the basis of morphological characteristics, was started from 2002 in grapevine collection garden of Qazvin. Investigations were carried out all in randomized complete block design with four replications. Based on the results, three cultivars Chafteh, Siahangoor and Mollaee, exhibiting good morphological and phenotypic characteristics of drought tolerance were selected. Cuttings provided from these cultivars were planted in a nursery based on a randomized complete block design with four replications and maintained for two years. Four drought stress treatments of irrigation, up to the end of May, end of June, end of July and end of August were applied in the nursery in 2006. Data on susceptibility index (S) to drought stress and other characteristics were analysed statistically. Results showed that cultivar Chafteh had higher levels of tolerance to drought stress compared to the other cultivars.

Fajr (KSC 260) is an early maturity grain maize hybrid that has been developed from a cross between two inbred lines (K1264/5-1´K615/1). This cross was carried out in 1998, for the first time. Several Characteristics of Fajr hybrid were studied in different trials (preliminary, semi final, final and on-farm trails) over several locations during 1998 to 2005. The mean grain yield of the hybrid over all trials was 10.7tha-1 with a reasonable stability. It is earlier in maturity than commercial late and medium maturity grain maize hybrids such KSC704 and KSC647, in Iran. Its crop stand is uniform and attractive, leaves and stalks are green at maturity. Ears are thin but kernels are long, grain moisture at harvest is very low, therefore it is suitable for second crop in temperate zones of Iran. The Fajr hybrid was officially introduced in March 2008.

Dehghan (KSC 400) is an early-medium maturity grain maize hybrid that has been developed from a cross between two inbred lines (KE72012/12´K1263/1). This cross was carried out in 1997, for the first time. The characteristics of Dehghan hybrid were studied in different trials (preliminary, semi final, final and on farm trials) in several locations during 1997 to 2005. The mean grain yield of the hybrid over all trials was 10.8 tha-1 with a reasonable stability. It is earlier in maturity than commercial late and medium maturity grain maize hybrids such KSC704 and KSC647 in Iran. Leaves and stalks of Dehghan hybrid are green at maturity, its grain moisture at harvest is low, therefore it is suitable for late cultivation as second crop in temperate zones of Iran. The hybrid of Dehghan grain maize hybrid was officially introduced in March 2008.

Sepahan is a new bread wheat cultivar derived from progenies of a cross made between Azadi cultivar and some high yielding and resistant to rust advanced lines. All selections were made in Kelardasht and Iranshahr stations and early evaluations in Karaj. It was also studied in regional uniform yield trials in moderate stations including Kaboutar Abad. Results revealed that this line is more tolerant to drought, thus it's suitable for arid areas of Iran and it has higher yield than check cultivar (Mahdavi). It is of spring habit and early maturity, 95-100 cm plant height, grain color amber and thousand kernel weight of 40 gram. Sepahan has grains with average protein and gluten content 10.3% and 23% respectively. Based on these superiorities and good performance, the new line was released in 2006, under the name of Sepahan.