نشریه نهال و بذر
سال بیست و ششم شماره 1 (بهار 1389)

Quince (Cydonia oblonga Mill.) is categorized as a susceptible species of fruit trees to the chlorosis of iron deficiency. The use of resistant sources to iron deficiency could be the most economic and advantageous method for resolving the problem. Therefore in this study the susceptibility of thirteen quince genotypes from Esfahan was evaluated, using the leaf chlorophyll content as the index of iron deficiency intensity. The quinces were propagated on crataegus, pear and quince seedling rootstocks and evaluated both in the greenhouse and nursery conditions for two consecutive years. Among various scion/rootstock combinations, the quinces on the pear rootstocks demonstrated high incompatibility in the first year of transplanting. Other combinations did not show the incompatibility. A positive effect of nursery condition on the mean chlorophyll contents of the apical and basal leaves in all quince genotypes was also observed. Genotypes NB3, NB4 and SHA1 were less susceptible than others to the iron chlorosis on most rootstocks. Genotypes PH2 and KVD2 were moderately or highly susceptible. The quince rootstock increased, susceptibility of KVD1 to chlorosis, while crataegus and pear rootstocks decreased it. For KM1 crataegus rootstock, and for ET1 crataegus and pear rootstocks increased susceptibility of the genotypes. Other genotypes demonstrated variable behavior depending on the rootstock kind and environmental conditions

St. Lucie 64 (Prunus mahaleb L., SL-64) is a semi-dwarfing and adaptable rootstock with cherry and sour cherry cultivars. In the present study effects of various media and growth regulators on establishment, proliferation and rooting of this rootstock were investigated. Establishment was performed with the use of shoot tips and axillary buds, derived from greenhouse-grown one-year-old trees as explants. Multiplication of explants was performed using six different media. Results of mean comparison with Duncan’s test indicated that DKW medium with 0.5 mgl-1 benzyladenine with the multiplication rate of about 6.06 new shoot per explants were the best medium for proliferation of this rootstock. MS + 1mgl-1 BA and MS + 0.5mgl-1 BA with 4.06 and 3.81 new shoots per explants were at subsequent steps respectively. Further, the results of investigation of different rooting media after four weeks indicated that DKW medium without any growth regulator with up to 100 percent efficiency was the best medium. MS + 1 mgl-1 IBA and modified QL with 81% rooting per explants were at subsequent steps. For acclimatization of rooted explants, a medium contained peat moss, coco peat and perlite (2:2:1v/v/v) was used that resulted in production of healthy and vigorous plantlets with desirable growth.

Twenty-two bread wheat cultivars along with susceptible (Sholeh) and resistant (Azadi) control cultivars were evaluated for resistance to Russian wheat aphid of two growth stages including seedling and stem elongation in greenhouse. Five adult aphids per plant were used for infestation. Leaf chlorosis at seedling and stem elongation stages and leaf rolling at seedling stage were measured. Other morphological and agromic traits were also measured at the end of the experiment. Rasol, Mahdavi and Arvand were identified as resistant, and Karoun as susceptible cultivars at seedling stage. There was no significant correlation between leaf rolling and chlorosis at seedling stage. In stem elongation stage, Azadi, Tabasi, Bayat and Kavir were highly resistant and Sholeh, Karoun, Rasoul and Karoun were highly susceptible cultivars. At stem elongation stage, leaf chlorosis did not have significant correlation with other traits. At seedling stage, grain numbers per spike and pedincle length decreased significantly(21% and 23%, respectively) by infestation of aphid. At stem elongation stage, however, pedincle length and dry weight decreased significantly(20% and 17%, respectively). All cultivars were more susceptible at seedling than stem elongation stage.

To evaluate reactions of barley genotypes to drought stress during seed germination, seedling and adult plant stages, twenty genotypes and two cultivar were studied in controlled conditions and field experiment under normal irrigation and water stress conditions. Physiologic characteristics, drought tolerance indices and all characteristics of germination were measured. The results showed that with decrease of water potential (0 to 0.1Mpa) all characteristics of germination were significantly decreased. The highest germination stress index (GSI) were obtained by genotypes Lingnee 131/3/4679/105//Yea168.4 and CWB 117-77-5-9-5 and the lowest by genotypes 168.4 Lignee 131/ArabiAbiad and CWB117–77–9–7//Antares/ky63–1294. Positive and significant correlation was observed between germination percent and GSI. In field experiment, drought stress reduced early growth rate, relative water content and relative water loss. Based on stress tolerance index (STI), genotypes Grivita/CWB117-5-9-5 and Wieselburger/A hor1303-61//Sis were more tolerant to drought condition compared to the other genotypes. Positive and significant correlation was found between stress tolerance index (STI) and grain yield in both normal irrigation and stress conditions, early growth rate, germination percent in stress conditions and also with germination stress index at 5% probability level. Based on higher correlation between STI and grain yield in both normal and drought conditions, this index was found to be the best index for selecting drought resistant genotypes.

Winter cold is one of the most important environmental constraints that limits wheat growth, production and yield in many areas in Iran. Thus, selection for cold hardy cultivars could be a vital strategy to avoid winter cold damages and increase yield in cold affected areas. To screen genotypes for cold tolerance two series of crown freezing tests at different periods of winter season were performed in a randomized complete block design with three replications and 20 cultivars at Maragheh Dryland Agricultural Research Station during 2005. Genotypes at two stages of tillering were exposed to different freezing temperatures (ranged from -5 to -23) and their LT50’s were evaluated. In order to evaluate the effect of crown freezing time on cold tolerance a split plot analysis in time was used. Results revealed that genotypes No. 1, 3 and 15 with LT50 of -13˚c were the most cold tolerant and No. 4 with LT50 of -9.33˚c was the least cold tolerant. It was also found that genotypes during the first time of sampling were more tolerant than the second sampling time.

Seven rice varieties (Hassani, Deilmani, Sepidruod, Shahpasand, Saleh, Neda and IRFAON215) and their complete diallel progenies were grown in a randomized complete block design with three replications in the growing seasons of 2006 and 2007 at the Rice Research Institute of Iran (RRII) in Rasht. Genetic components, the mode of inheritance and heterosis of various physiological traits were studied by using seven-parent diallel mating design including reciprocals. Results revealed that both additive and non-additive gene effects were important for inheritance of days to flowering, plant height and panicle exsertion with preponderance of additive gene effects. Inheritance of harvest index was controlled only by additive effects. While, inheritance of grain yield, panicle length and flag leaf area were governed by non-additive gene effects. ‘F’ value, showing an excess of dominant alleles in the parents, was significant only for grain yield. The average degree of dominance (H1/D) 0.5 was within the range of partial dominance for days to flowering, plant height, panicle exsertion and harvest index. At least two major groups of genes controlled the inheritance of plant height, and panicle length and flag leaf area, four major groups the inheritance of harvest index and one group the inheritance the other traits. The highest value of relative heterosis was observed for panicle exsertion and grain yield. Wr-Vr graphic analysis indicated that increase of flag leaf area, plant height, panicle exsertion and panicle length was under the control of dominance alleles, but harvest index was increased by recessive alleles. Due to the importance of non-additive components for grain yield, panicle length and flag leaf area, biparental mating and/or reciprocal recurrent selection could be used for genetic improvement of these characters. Predominance of additive effects for remainder of the traits demonstrated that breeding methods based on selection may be advantageous in improving of these traits in rice using the studied materials.

Use of resistance cultivars is one of the major approaches to reduce crop damages caused by biotic stresses. Development of such cultivars requires identification, isolation and mapping of resistance genes. In this research, motif directed profiling (MdP) method was used to isolate resistance gene analogues (RGAs) in potato. For this purpose, seven degenerate primers designed based on conserved TIR domain of plant disease resistance genes were used to amplify RGAs in 46 F1 progeny derived from a cross between the diploid heterozygous parents SH83-92-488(SH) and RH89-039-16(RH) with highest recombination. In total, 454 polymorphic markers were produced that were mapped relative to SH×RH linkage map consisted of 10,000 AFLP markers. To identify RGAs, some of the bands were isolated and sequenced and out of which 66.11% (160 bands) represented significant similarity with known resistance genes and RGAs and most of them were mapped in chromosomal regions of potato or tomato having RGA clusters. Linkage map of these RGAs in relation to ultra dense (UHD) genetic map of the population, consisted of 10,000 AFLP markers, showed that most of the RGAs were organized in new or existed clusters or sub-clusters on the map. One hundred and seventeen markers were mapped in the positions corresponding to the resistance gene clusters on chromosomes 5, 6, 9 and 11 and 15 markers were mapped in approximate positions of quantitative resistance loci on chromosomes 1, 2, 4 and 7. The majority of these RGAs represent novel RGA sequences. The results of this research could be used in mapping of single resistance genes and quantitative resistance loci.

Slow-scalding resistance (S-SR), is a new phenomenon in barley breeding programs, which due to the instability of major gene type of resistance has been gaining increasing attention. In order to determine presence of genotypes with S-SR, quantitative resistance of 50 barley genotypes with different reactions to the scald disease were studied using an alpha lattice design with three replications at two research stations in Canada (in Edmonton for three and in Lacombe for two years) and one location in Mexico (in Toluca for two years). For a better understanding of the genotypes’ reactions against the disease, nine differentials with known major genes for resistance to R. secalis were included in the experiments. Applying artificial inoculation of a mixture of six different single-spore isolates of the scald fungus, to measure disease progress, multiple disease assessments were undertaken for the disease severity and incidence under field conditions. Based on combined analyses of data, the genotypes were compared and the effects of genotypes, environments and genotype × environment interaction found to be significant. The results revealed that both disease severity and incidence showed a low rate of progress in slow-scalding lines. The reactions of all genotypes tested were further classified into resistant, slow-scalder, intermediate, and susceptible/fast-scalder categories using hierarchical cluster analysis. Interestingly, It was revealed that the Rh4 gene could play an important role in stability/durability of resistance in all studied environments. Slow-scalding genotypes such as UNA80, Osiris and Zavila revealed to be useful as desirable resources in barely breeding programs.

White bean (Phaseolus vulgaris L.) is an important legume food crop in Iran and many other countries. It is grown on 110248 hectares in Iran, mostly in Fars, Lorestan, Markazi, Zanjan and Chahar Mahal-va-Bakhtiari Provinces. Due to its high value in human nutrition and exportation, considering that most grown cultivars of Iran are the runner type beans, with low marketability values and susceptible to viral diseases, development of high yielding cultivars with high marketability value and resistant to diseases was the priorities in breeding of beans. White bean line WA8563-6 was first introduced in Iran through the yield trail nurseries received from CIAT in 1991. In observation nurseries carried out during 1992 and 93 cropping seasons, ten bean populations were evauated for yield and other characteristics, and 60 lines were selected. Preliminary and advanced yield traits carried out for six years (1995-2000) in four locations Khomein, Eghlid, Khorramabad and Zanjan resulted in selection of superior lines including WA8563-6. The average seed yield of this line was 2698 kgha-1 which was higher than that of the check cultivar, Daneshkadeh with average yield of 2541 kgha-1. The new line produced 2485 kgha-1 seed yield in farmers fields which was 35% higher than the yield of the local check cultivar. In greenhouse and field experiments with artificial inoculations, the new line was evaluated as resistant line to BCMV. Based on the high compatibility, high yield and good agronomic characteristics, it was officially registered by Agricultural Research, Education and Extension Organization in 2009 as a new cultivar Shokoufa, for cultivation in temperate and cold areas of Iran

White been line WA8592-1 was first introduced in Iran through the yield trail nurseries received fron CIAT in 1991. In observation nurseries carried out during 1992 and 1993 cropping seasons, ten bean populations were evaluated for yield and other characteristics, and 60 lines were selected. Preliminary and advanced yield trails carried out for six years (1995-2000) in four locations Khomein, Eghlid, Khorramabad and Zanjan resulted in selection of superior lines including WA8592-1. The average seed yield of this line was 2598 kgha-1 which was higher than that of the check cultivar, Daneshkadeh with 2541 kgha-1. The new line produced 2807 kgha-1 seed yield in farmers fields which was 17% higher than the yield of the local cultivar. In greenhouse and field experiments with artificial inoculations, line WA85592-1 was resistant to CMV, CYMV and BCMV. Based on the high compatability, high yield, erect plant type with intermediate growth habit (suitable for mechanized harvesting) and other good agronomic characteristics, it was officially registered by Agricultural Research, Education and Externsion Organization in 2009 as a new cultivar Pak, for cultivation in temperate and cold areas of Iran.

To introduce a new rice cultivar with high grain yield and desirable cooking characteristics for the warm regions of Kohgilouyeh-ve-Boyrahmad province, 203 lines of rice originated form IRRI breeding program were evaluated in preliminary and advanced yield trials from 1993 to 2000 in Choram Agricultural Research Station. In each year, data were recorded from different agronomical and morpho-physiological traits, and also for milling recovery, grain size, grain shape and appearance, cooking and eating characteristics. Based on the overall results, the line A7983 IR 62873-511-1-9 producing 7.748 tha-1 grain yield (mean of all years) showed no significant difference with the check cultivar Choran1 (7.862 tha-1), but in view of different stability parameters, showed very good stability for yield production in different years. The results of physico-chemical tests on cooking characteristics showed that this line with 20.72 percent amylase content, soft gel consistency and low gelatinization temperature (in compared to check cultivar with 27.92 percent amylose content, hard gel consistency and low gelatinization temperature) possessed a desirable cooking quality. It was moderately resistant to rice blast disease in many experimental and farmer’s fields. Due to better agronomic and especially cooking characteristics, this line was officially registered by Agricultural Research, Education and Extension Organization in December 2008 as a new rice cultivar named Karim.