نشریه نهال و بذر
سال بیست و دوم شماره 1 (بهار 1385)

In order to analyze karyotype of wormwood (Artemisia vulgaris L.), plants and achene's specimens were collected from different ecological regions of East Azarbaijan. Root tip meristems obtained from germinated achene's were pretreated with saturated solution of ?-bromonaphthalene, fixed in Lewitsky solution and stained in aceto-iron- hematoxylin. Ten metaphase plates were used to analyze karyotype parameters. C-banding was carried out according to conventional methods. The karyotype of A. vulgaris consisted of 2n=16 chromosomes. Size of chromosomes changed from 7.13±0.19 ? (the largest chromosome) to 4.54±0.11 ? (the smallest chromosome). All of them were metacentrics except the chromosome 6, which was subtelocentric with arm ratio = 3.33. Pairs 3 and 4 were satellite chromosomes. Size of satellites was 0.58 and 0.38 ? respectively. In one of investigated plants, telomeric fusion of two chromosomes was observed so that these joined chromosomes were found in all of cells in the slide at the metaphase and prophase stages. It is thought that basic number of chromosomes x=8 by this mean was originated from x=9 in evolution of genus Artemisia. In some plants B-chromosomes significantly smaller than somatic chromosomes were found. Several plants had only one B-chromosome which usually was met centric. Others had two B-chromosomes areocentric. Giemsa C-banding detected heterochromatin distribution in centromeric regions of all chromosomes.

Stalk rot is one of the main diseases of maize, causing stalk lodging and trouble for harvesting. The most effective way for controlling the disease is cultivation of resistant hybrids. In order to determine the susceptibility of maize hybrids, to stalk rot, an experiment was conducted with 60 hybrids arranged in RCBD at Karaj and Sari Research Stations in 1998. Inoculation was carried out by using Drill/ toothpick method in the first extentded internode of maize plants at tasseling stage. Inoculated Plants were cut at the third internode after physiological maturity and vertical stalk sections of each hybrid were used for disease assessment using disease severity index based on the discoloration of pith tissue. Significant differences in response to stalk rot were observed among the hybrids. The majority of the hybrids were highly susceptible to stalk rot. The most susceptible hybrids were K1263/14-2 K1264/1 and B73 K12641. A few hybrids such as K3153 KC103/8 and K3153 K582/1-22 were moderately resistant. The overall results demonstrated that, early-maturing hybrids are more succeptible to stalk rot disease compared with late-maturing hybrids.

Prunus mahaleb L. and Prunus avium L. are the principal rootstocks used in Iran and many other countries for sweet and sour cherries. This study was conducted at Agricultural and Natural Resources Center of Khorasan with the main purpose of investigation of genetic diversity and identification of mahaleb dwarf genotypes for cherry rootstock breeding. Morphological characters of 17mahaleb populations were evaluated. One-way analysis of variance was performed for determination of genetic diversity of different regions which indicated significant differences for most traits. Factor analysis revealed that in the first factor, crown height, size index, crown width, trunk circumference and crown volume had highest factor loading, bark to wood ratio, internode and chlorophyll content were the second most important and third factor was leaf area. These factors contained 57.9 percent of total variance. There were significant correlations between tree vigor, crown width, and crown volume and size index. Results also showed that mahaleb seedlings had vigor variation. Therefore, mahaleb seedlings were classified into four groups, very dwarf, dwarf, semi dwarf and standard at the basis of size index.

Nine new early maturing maize hybrids along with KSC301 as the check, were evaluated in six locations Karaj, Isfahan, Ardebil, Kermanshah, Sari and Khoramabad for two years 2001 and 2002. The experiments were conducted in a randomized complete block design with four replications. Each experimental unit was four rows spaced 75cm apart and 36cm within the row. Combined analysis of variance was carried out and stability statistics were also determined based on ten environments. Effects of environment, genotype and genotype environment interaction on grain yield was significant at 1% probability level. The stability parameters of ecovalance (W2i), stability variance (σ2i), regression coefficient (bi) and deviation from regression (S2di) were calculated. Comparison of mean yield using Duncan’s test showed that maximum grain yield belonged to hybrids (K1264/5-1 K 615/1) and (K 1263/17x S 61) with 10.25 and 9.98 tha-1, respectively. Hybrids (K 1728/8 K 615/1) and (K 2331
K 1263/2-1) both with grain yield of 9.73 tha-2 did not show significant difference with other hybrids. Overall stability analysis showed that hybrid (K 2331 K 1263/2-1) had acceptable mean yield and stability compared to the check hybrid and the other hybrids across the ten environments.

In order to study the effects of nitrogen and planting time on vegetative traits and yield of Gladiolus (Gladiolus grandiflorus cv. Oscar) corms, an experiment was conducted as a factorial design in the base of RCBD with 3 replications in Horticultural Research Farm, College of Agriculture, Karaj. First factor was 3 nitrogen levels (10, 20 and 30 gm-2). As urea fertilizer and second factor was 3 planting times (May 13, May 23 and June 3, 2003). Results showed that in the first planting time, tallest plants and highest corm yield (dry weight percentage, fresh weight mean, corm diameter and number of cormlets) were obtained. In the second planting time, the highest amount of flower fresh weight was obtained. Planting time had no significant effect on some traits like leaf numer and amount of potassium, calcium and nitrogen contents of corm dry mass. Among nitrogen levels, 20 gcm-2N caused an increasing in leaf number mean, flower fresh weight and corm yield (fresh weight mean, corm diameter and cormlet numbers). Nitrogen had no effect on plant height, corm dry weight percentage and amount of potassium, calcium and nitrogen in corm dry mass.

In order to recognize and select Iranian onion cultivars with the best quantitative and qualitative characters such as yield, neck thickness, size, form, number of scales, storability, dry matter, total soluble solide, firmness and determine the relation of some characters on storability, this experiment was conducted at Karaj in 1999-2000. Field experiment was carried out based on Randomize Complete Block Design with four replications and five treatments Ghermez Azarshahr, Sefide Kashan, Sefide Qhom, Tarom Zanjan and Dorche Isfehan onion cultivars. For determination of the storage ability of Onion cultivars, a study was carried out in a factorial experiment based on completely randomized design with three replications in common storage conditions. Factors were cultivars with five levels and dates with eight levels. In a period of four months at 15 days interval, (8 distinct dates) losses were measured according to percentage of weight loss, sprouting and rotting. The rate of changes of some traits such as total soluble solids (T.S.S), dry matter (Dm), bulb firmness were also determined during storage. Results showed that in field experiment, the highest and lowest yields were obtained from Sefide Qum cultivar (60.82 tha-1) and Dorche Isfehan (32.03 tha-1) respectively. Sefide Qum cultivar had the lowest percentages of weight loss, sprouting and rotting during storage (15.33% and 11.72% respectively), which were not significantly different from those of Germez Azarshahr and Dorche Isfehan. Tarom zanjan cultivar had the highest weight loss, and Sefid Kashan had the highest bulb sprouting and rotting during storage period (23.06% and 55.46%, respectively). In storage period, some qualitative characters such as dry matter and total soluble solids increased slightly, but bulb firmness decreased. Sefid Qum cultivar had the highest total soluble solids, dry matter and bulb firmness (9.81%, 11.8%, 39.19 N, respectively), and Tarom Zanjan the lowest (8.37%, 9.29%, 34.3 N, respectively). A highly significant positive correlation (r =0.84) and linear regression equation (y = -2.472 + 1.424x) was found between total soluble solids and dry matter of bulbs. During storage, a significant negative correlation of (r = -0.592) and linear regression equation (y=101.515-1.863x) was found between bulb firmness and sprouting and rotting.

In Order to evaluated resistance to yellow rust in some doubled haploid lines and their parents in the spring hexaploid wheat, fourty doubled haploid lines together with their parents (Ghods, 9106 and 6605), and two cultivars Bolani (Susceptible check) and Triticum spelta var. album (Resistant check) in a randomized block design with three replications were tested in the greenhouse conditions in seedling stage to four races 134E134A+ , 38E2A- , 7E18A- and 230E62A+ of yellow rust. Resistance components measured were latent period (L. P.) and infection type (I. T.). The results showed that, some doubled haploid lines were resistant to the races of yellow rust, e.g. line (GH 91) DH3 was resistant (I. T. = 2) to race 134E134A+ , in spite of the susceptibility of both parents.

In this experiment the effect of salinity on yield, yield components and other characteristics of three watermelon cultivars Charleston Gray, Crimson Sweet and Sugar Baby were studied in Birjand at Amirabad Experimental Station. The experiment was performed during 2001 and 2002 growing seasons, using three water sources of 1.4 (check), 5.5 and 10.5 dsm-1 electrical conductivity. The design of the experiment was split plot in randomized compelet block with three replications. The three electrical conductivities of irrigation water were the main plots and three cultivars as sub plots. The salinity treatments were applied after 2nd to 3rd leaves stage. Based on the results of combined analysis, the effect of salinity on fruit yield, fruit number per plant, fruit weight, fruit length, and flesh diameter were significant at 1%, and on sink diameter at 5% level. These parameters were decreased with increasing salinity. In severe salinity (10.5 dsm-1), compared to control, the percentages of decrease for parameters were 76, 60, 42, 26, 21.4 and 22.8 respectively. Decrease of fruit yield in Charleston gray, Crimson Sweet and Sugar Baby in 5.5 dsm-1, was 21.4,24.3 and 33.6% and in10.5 dsm-1 75,70 and 77% respectively. Charleston gray and Crimson Sweet had higher fruit yield than the Sugar Baby in saline conditions. The threshold tolerance to salinity for Charleston gray, Crimson Sweet and Sugar Baby was 8, 8.1 and 6.8 ds/m respectively. The correlations between fruit yield and fruit number per plant, fruit length, sink diameter, flesh diameter and friut diameter were significant with r = 0.5, 0.7, 0.43, 0.54 and 0.58 respctively. Based on the results, cultivars Charleston gray and Crimson Sweet cultivars seem to be more suitable for saline conditions than the Sugar Baby cultivar.

Stem borers (Sesamia cretica and S. nonagrioides) cause dead heart at tillering stage on sugarcane. In year 2001, 148 sugarcane cultivars were compared based on dead heart criterion. Screening for resistance was carried out under natural infestation in the field condition at two prominent Agro-Industries located in Khuzestan. Percentage of dead heart was deretmined on each cultivar at both stations. In order to unify the findings of two stations, a Dead Heart Index (DHI) was developed. Since the distribution of the data was in a normal pattern, an Interval of Standard Deviation from the Mean (ISDM) was developed to classify the cultivars. Following the classification, Canonical Discriminant Analysis (CDA) was used to assess the contribution of variables for separation, and also investigation of the effectiveness of the classification procedure. The results of CDA confirmed the accuracy of the classification procedure used, showing that 95.9% of the original data was correctly classified in the predicted group membership. Cultivars of sugarcane showed a wide spectrum of resistance to stem borers, therefore potential long-term breeding program should address this resistance problem. According to the results of this investigation, cultivars with less than 4.71% dead heart were resistant such as CP57-614 and more than 12.24 were susceptible such as NCO310.

Azalea is cultivated as a shrub plant with high capability of potting culture in greenhouse. Decrease in production cost and increase in plant growth affect highly the economic production of Azalea. Bed of cultivation and nutrition with nitrogen are two main factors affecting directly the economic production of Azalea. In 2000 an experiment was implemented in factorial effects of six levels of nitrogen, 0, 3.5, 7, 14, 28.5 and 57 mmoll-1 on three type of growth media consisted of peat, 1/3 peat + 1/3 tea waste compost + 1/3 sand and 3/4 tree bark compost + 1/4 tea waste compost were studied. Results showed that 14 mmoll-1 nitrogen in two growth media, peat and 1/3 peat + 1/3 tea waste compost + 1/3 sand, and 28.5 mmoll-1 nitrogen in 3/4 tree bark compost + 1/4 tea waste compost were the most effective treatments on growth indices of height, diameter, flower number, fresh weight and dry weight. The growth bed, 1/3 peat + 1/3 tea waste compost + 1/3 sand with respect to 66% decreasing of peat intake, could be suitable for production of Azalea.