Seed and Plant
Year:2004 | Volume:20 | Issue:2|Papers Count:12

In order to study genetic diversity and determine the selection indices, sixty four rice promising lines and cultivars were evaluated using a simple latice design at Rice Research Institute of Iran, Rasht in 1999. Some morphological and agronomic characters were measured during plant growth and after maturity on ten plants selected randomly in each plot. Analysis of variance showed significant differences for most of the traits. Number of grains per panicle and flag leaf angle had the greatest genetic variations. Number of days to 50% flowering and days to maturity had the highest general heritability. Results of simple phenotypic and genotypic correlation indicated that length of panicle and number of tillers per plant had the largest effects on the grain yield. Cluster analysis based on all attributes, grouped the genotypes in four clusters. Therefore, it is suggested that hybridization between group 1 and 2 will provide more diversity and stronger heterosis.

High status of sesame (Sesamum indicum L.) among oil-seed crops, requires identification of relationship between yield components and yield potential. The information are important for its yield improvement. This study was carried out on 32 multi-branched sesame genotypes. Positive and significant correlations were detected between number of capsules per plant, number of seeds per capsule, length of main inflorescence and 1000-seeds weight. However, distance of the first branch and first capsule from soil surface showed significant and negative correlation with seed yield. Based on stepwise regression and consequently ordinary path analysis, number of capsules per plant, number of seeds per capsule, length of main inflorescence, and 1000- seeds weight had the highest direct effects on yield formation, respectively. Comparing with ordinary path analysis, sequential path analysis showed higher values for direct effects of main inflorescence length, number of capsules per plant, and 1000-seeds weight, and indirect effect of number of branches per plant and main inflorescence length through number of capsule per plant. Factor analysis showed three factors explained about 80% of total data variations. First factor compared number of capsules per plant, length of main inflorescence versus distance of first capsule and first branch from soil surface. The second factor had positive effects on capsule length, number of seeds per capsule, and 1000-seeds weight. Third factor had positive effects on number of capsules per plant and number of branches per plant. These results are similar to correlation analysis results. Based on path analysis and specificity of factors, selection for lower distance of first capsule and first branch from soil surface (which could be done in early fruit set stages) has the same results as the selection for higher number of capsules per plant and main inflorescence length toward yield improvement. The results of selection based on higher number of seeds per capsule and 1000-seeds weight (which have less direct effects on seed yield) could be achieved by selection based on longer capsule length. The latter traits could be measured non-destructively. The nature of third factor indicated selection based on number of branches per plant might result in an improvement in seed yield.

In order to study the genetic diversity of quantitative and qualitative traits of 36 lines and cultivars of rice, an experiment was conducted using a simple lattice design in 2000. In this study, 17traits including grain yield, number of panicle per plant, number of filled grains per panicle, 100 grain weight, leaf length, leaf width, leaf area, plant height, culm length, amylose content of the grain, gel consistency, panicle weight, grain length, grain width, grain shape, days to 50% flowering and maturity were measured on 10 randomly selected plants for each plot. Analysis of variance showed significant differences among genotypes for all traits and revealed the existance of genetic variation among genotypes. The phenotypic coefficients of variability were greater than the genotypic ones for all the traits although differences for most of them were small. The highest phenotypic and genotypic coefficients of variation were obtained respectively for gel consistency, leaf area, leaf width and number of panicle per plant. The highest general heritability was estimated for plant height and the lowest for panicle weight. Results of genotypic and phenotypic correlations indicated that number of panicle per plant, number of filled grains per panicle, panicle weight, days to 50% flowering and maturity had positive correlation with yield, wbile the rest of the traits had a negative correlation. Cluster analysis with Ward's method, classified all of the genotypes into five clusters. Genotypes of the third cluster including four pure lines Nos.4,21,22 and 24 had high yield, high number of panicle and filled grains per panicle, intermediate amylose and lower plant height, therefore, these suitable traits can be transfered through hybridization programs. Genotypes of the. first and fifth clusters can also be used to improve yield and grain cooking quality respectively.

Control of floweing time in apricot trees is very important where spring frost damage is of high risk. Application of plant growth regulators during autumn has been suggested for controlling bloom date. This experiment was conducted during 1999-2001 to examine the effects of application of different concentrations of ethephon and gibberellic acid (0,50, 100,200,300 mglit-1 in 3 dates (end of August, September, and October) on delay of flowering in apricot Shahroudi cultivar. A factorial experiment was laid out in completely randomized-block design with 3 replications. Compared to the control, results showed that 100 mglit-1 of ethephon applied at the end of October, delayed full bloom approximately 3 days (2000) and 7 days (2001). Gibberellic acid applied at 300 mglit-1 at the end of August, delayed full bloom about 5 days (2000) and at the end of September, 10 days (2001). During both years, application of gibberellic acid and ethephon at the higher concentrations resulted in a lower percentages of flower opening and fruit set.

Androgenic ability of microspores of F3 populations obtained from crosses between salinity and heat tolerance (Afzal/Torkman/Kavir), coldand heat tolerance (Boyer/Rojo), salinity tolerance and disease resistance (Ashar/ Hebe), salinity and heat tolerance. (Arigashar/ Matico) and Igri cultivar as control, were studied after pretreatment with 0.3 M mannitol using L1 modified liquid medium supplemented with 3 mgl-1 Phenylacetic acid (PAA), 1 mgl-1 Benzylaminopurin (BAP), 1 mgl-1 Casein and 65 mgl-1 maltose as induction medium. Murashige and Skoog medium supplemented with 1 mgl-1 BAP and 0.5 mgl-1 Naphtalenacetic acid (NAA) was used as regeneration medium. Statistical analysis revealed a significant difference between F3 progenies and Igri cultivar for androgenic ability. Igri cultivar produced on average 566.75 embryos per microspores of 100 anthers and the F3 progenies of Afzal/ Torkman/ Kavir produced on average the highest number of embryos (141.5 embryos/ microspores of 100 anthers) among the progenies of F3 populations. For green plantlet production per microspores of 100 anthers there was also asignificant difference between progenies ofF3 populations and Igri cultivar. For this character Igri cultivar produced the highest number of green plantlets (65.5 plantlets/ microspores of 100anthers) and the progenies of Ashar/ Hebe and Boyer/ Rojo with 18.5 and 17.5 green plantlets respectively per microspores of 100 anthers on average produced more green plantlets than the progenies of Afzal/ Torkman/ Kavir. This means that the mechanisms of embryo induction and green plantlet production may be different. In this study Igri cultivar produced the green plantlet production may be different. In this study Igri cultivar produced the least number of a albino plantlets in comparison with other plant materials.

Lesser moth has been known as one of the major pests of date palm in Iran and its damage in some areas such as Barn has been increased up to 50-70 percent recently. This pest damages fruits in both orchards and stores. In this study, 30 Khuzestan native date palm cultivars were classified in to four groups based on percentage of infestations of the cultivars. The first group, highly infested cultivars, including Dagalsorkh, Bentalsabae, Diry, Raim, Jahromy, Sayer, Gantar, Dagalzard and Berhee. The second group, moderately infested cultivars, including Hamravi, Bobaki, Sovidani, Berim, Halavi, Belyani, ZaheQi, Khazravi, Fersi and Hadal. The third group, less infested cultivars, including Ashkar, Jozi, Khasab, and Amobahri. The fourth group, noninfested cultivars, including Hasavi, Liloei and Mashtom. The characters such as bunch number, bunch weight, pedicel length, fruits number, fruit length, fruit width and fruit weight showed significant correlation with lesser moth infestation. Other characteristics such as the smallest strand length, stone weight and flesh/stone ratio had not significant correlation with infestation.

Sclerotinia stem rot of rapeseed caused by Sclerotinia sclerotiorum (Lib.) DeBary is considered as one of the most important diseases of this crop in the north of Iran. Use of resistance, because of the compatibility with the other premonitoring and control ways, is paramountly important in integrated pest management of the disease. In this investigation, reactions of four lines and 21 cultivars of rapeseed were evaluated using the fungal mycelium coated wheat seeds method, in a single lattice design (5 x 5) at Bayekola Research Station of Neka (Mazandaran). Reactions were recorded before the harvesting time, on the basis of macroscopic symptoms. To assess relative resistance of genotypes quantitatively, a rating system of 1 (resistant) to 5 (very susceptible) was introduced and the disease index (DI) on the basis of mean rating score for each genotype was calculated. The results indicated that there were significant differences among the genotypes at 1% level of all tested genotypes, Foseto and Ebony had the highest and lowest resistance to the disease, respectively.

To study the inheritance of grain yield related traits in barley, F1, F2 and F3 generations derived from Afzal x Cwb cross, along with parents were planted in a randomized complete block design with three replications. Spike weight, spike length, number of spikelets per spike, awn length, thousand grain weight, grains per spike and straw yield per spike in different generations were recorded. Generation mean analysis was performed for all the traits. The results showed that additive, dominance and epistasis effects were significant for all the traits except awn length. Results also indicated that dominace variance was the most important in inheritance of all the traits. Average broadsense heritabilities were between 58%-82% for all the traits. The estimated number of genes for the traits were ranged from one to five.

The present study was conducted to determine the inheritance of resistance to Russian wheat aphid (RWA) in two Iranian resistant wheat cultivars, Azadi and amid. The resistant cultivars were crossed with each other and with a susceptible cultivar, Sholeh. Seedling of both parents, F1, F2, BCS and BCR were screened for resistance to RWA under greenhouse condition. Twenty one days after infestation, the damage of aphid was measured quantitatively (percentage of leaf rolling) and qualitatively (scale 0-3).Inheritance of resistance to RWA, based on leaf rolling, was studied by Mendelian segregation ratios as a qualitative method, and mean and variance analysis of generations as a quantitative method. Mendelian ratios showed that one and two major genes in Azadi and amid, respectively control leaf rolling. Quantitative variations of this trait and presence of epistasis (based on generation mean analysis) indicated that I some minor genes have significant role in its control. Additive and dominance components and duplicate interactions (i, j and I) had also significant effects on controlling leaf rolling in cultivar Azadi. In amid cultivar, only additive component had significant effect. Leaf rolling showed high and moderate heritability in Azadi and amid, respectiveley. No allelism relationship was observed between major genes of two resistant cultivars. These different genes therefore, can be incorporated into adapted wheat cultivars to provide a durable resistance.

To determine suitable pepper cultivars with high quantitative and qualitative characteristics adapted to the climate of Sistan, an experiment was conducted in Zahak Experimental Station, Zabol, using RCBD with four replications in two years. In this experiment, four sweet pepper, five green pepper and three salad pepper cultivars were evaluated individually. The results showed significant difference among cultivars at 5% level. Jupiter, local Khash and Crelit cultivars had the highest yields among the sweet, green and salad pepper cultivars, respectively.