نشریه نهال و بذر
سال بیست و دوم شماره 2 (تابستان 1385)

In order to estimate heritability of seed yield and yield components in cotton, a diallele cross method was attempted. Ten genotypes including 6 F1 progenies and parents were grown in Kashmar Cotton Research Station (non-saline location) and Saadaldin region, 50 kilometers far from Kashmar (Saline location), in a randomized complete block design with three replications in 2003. Diallel analysis was done based on Griffing method II for seed cotton yield, boll seed cotton weight, percentage of earliness and the number of plants in plot. Results showed that the variance of genotypes was significant only for boll seed cotton weight in non stress environment and for seed cotton yield and number of plant per plot in stress condition. The effect of general combining ability of boll seed cotton weight was significant in non-stress environment. Seed cotton yield and plant number per plot, were significant in salinity condition.The effect of specific combining ability for boll seed cotton weight in non-stress environment and the plant number per plot in stress condition were significant. It was also significant for seed cotton yield in stress condition. Diallel analysis showed that both additive and non additive genes effect had a role in controlling the mentioned traits. Combining diallel analysis indicated that additive variance was important for boll seed cotton weight, seed cotton yield and the number of plant per plot. Broad sense heritability was high for all traits in both conditions, whereas narrow sense heritability varied from low to mediate in both conditions.

The effects of ten citrus cultivars including Sweet lime (Citrus limettioides Tanaka), Mexican lime (C. aurantifolia Swingle), Lisbon lemon [C. limon (L) Burm F.], Sweet orange [C. sinensis (L.) Osbeck], Clementine mandarin (C. reticulata Blanco), Grapefruit (C. paradisi Macfadyen), Kara mandarin (Satsuma King mandarin), Bakraei (C. reticulata C. limettioides), Volkamer lemon (C. volkameriana Ten. and Pasq) and Sour orange (C. aurantium L.) as rootstocks were studied on vegetative growth, dry mater and mineral concentrations of Mexican lime scion, grown on calcareous soil in greenhouse. The experiment was arranged in a compeletely randomized design with ten treatments (rootstocks) and five replications. Results showed that, type of rootstock highly affected the vegetative growth and mineral components of Mexican lime scion. Vegetative growth and mineral contents in scion differed with different rootstocks. The highest scion length were on Mexican lime, Lisbon, Bakraei and Volkamer lemons and the lowest on Kara mandarin. Leaf analysis of eleven elements showed significant differentes among rootstocks. The highest N content obtained from scions on Bakraei, P on Volkamer lemon and Bakraei, K on Kara mandarin, Ca on Sour orange, Mg on Sweet orange and Clementine, Na, Fe and B on Grapefruit, Cu on Volkamer Lemon, Zn on Mexican lime and Clementine and Mn on Lisbon lemon. General conclusion that, scion on Volkamer lemon rootstock caused faster vegetative growth and higher mineral content compared to the other rootstocks.

An experiment was conducted to determine a suitable planting date and density for B73 line, using a randomized complete block design (RCBD) in split plot arrangement with four replications in Zarghan for two years (2002-2003). Five planting dates (5 May, 20 May, 4 June, 19 June and 4 July) were assigned to main plots and three different spaces between plants in maternal rows consisted of 15, 18 and 21 cm were considered as sub plots. Yield and yield components were assessed in each plot. Combined analysis of variance showed the significant effect of planting dates on yield and yield components, such as kernel number/ear row, row number/ear, 1000 kernel weight and kernel depth. The best planting date was 4 June that produced 4.604 tha-1 of seeds with 14% moisture. Results showed that the plant density of maternal line had significant effect on yield (P=0.01), and the highest yield was obtained from the highest density of maternal line. Intreraction of planting date and density was not significant on seed yield, but the highest seed yield was obtained from those with 15 cm plant spacing on maternal rows on 4 June planting date. B73 inbred line rows that were closed to MO17 inbred line rows had higher seed setting and more seed yield than the others. Maize Rough Dwarf Virus epidemic occurred in Zarghan in 2003, affected the seed yield of plots planted in 5 May and 20 May so that the first planting date (5 May) which had the highest yield in 2002, produced the lowest yield in 2003

To study the relationship between different traits with grain yield in wheat under salinity stress, an experiment was conducted during 1999-2000 cropping season at the Roodasht Research Station of Isfahan. Forty two wheat lines and cultivars were planted in a triple rectangular lattice design. Plants were irrigated with saline water with EC = 12 dsm-1 (moderate salinity for wheat) throughout the growing season. Grain yield and 18 agronomic traits were studied. Correlation coefficients among traits and the linear stepwise regression of grain yield on the other traits were calculated. Grain filling period and number of spikes per m2 had the highest correlation with grain yield. In linear stepwise regression, grain filling period was the first trait that used in the regression model. Based on the variables that used in the stepwise regression model i. e. grain filling period, grain weight per spike, number of spikes per m2 and plant height, also using some other traits, path coefficient anlyasis was performed. Regarding to the results, grain filling period had the highest direct effect on grain yield, and indirect effects of flag leaf area duration and peduncle length via grain filling period were high and positive. Also number of spikes per m2 and number of kernels per spike had relatively high direct effects on grain yield. Finally, grain filling period, number of spikes per m2 and number of kernels per spike were the most effective traits on grain yield in this experiment. Genotypes Roshan, Barekat, DH2-390-1563 F3 Chds/5/Anza/3/Pi/Hys/4/ 1-66-75, Pishtaz, 1-66-22/Inia, 1-67-78/5/Cnn/Knakoy//Kc 66/3/Skp35/4/Vee"s" and Shiraz that produced about 4 tonha-1 of grain yield were determined as superior genotypes.

Forty-four barley (Hordeum vulgare) dryland promising lines, were tested for their reactions to four isolates of barley leaf stripe disease caused by Pyrenophora graminea in the greenhouse using seed inoculation method, and also in field conditions in four locations, Karaj, Gorgan, Marogheh and Miandoab, using infected seeds of susceptible cultivars as disease spreader. Because of non-conformity of flowering date between spreader and the experimental lines and/ or non-desirable environmental conditions, the disease did not develop uniformly and sufficiently on the materials in field, but in the greenhouse, lef stripe developed up to 100% on emerged seedlings. The lines were grouped into four reaction categories, based on percentage of infected seedlings. Analysis of variance of the data showed that the experimental lines differed in their reactions to the pathogen isolates, as 38% of lines were resistant, 51% moderately susceptible, 9% susceptible and 2% highly susceptible. The most susceptible lines were Pirat 1//Aljer/ceres 362-1-1 IC, T-2 (2R)//Lignee131/Arabia Abiad, Alpha//Gumhuriyet/ Ligkee 131 and Yesevi-93 and the most resistant ones 4697/105//Yea 132 TH/3/ Tipper followed by ICB-100974/Action, Alpha//Sul/Nacta/3/80-5001 and 132TH/Tokak Yia 147. Frequency of resistance reaction among lines with facultative spring and spring growth habit was higher than that of winter type lines. P. graminea isolates differed in pathogenicity at P>1% level based on the mean of percent infection of lines. This indicating physiologic specialization in population of P. graminea.

In this study eight forage sorghum cultivars KFS1, KFS2, KFS3, Pacific BMR, Chopper, Nectar, Sweet Jumbo and Speed feed were evaluated on a randomized complete block design in four replications at Karaj during 2003-2004 growing season to determine the most suitable cultivar with the highest forage yield. Ammonium phosphate on the base of P2O5 was applied at 115 Kgha-1 and a total amount of nitrogen 183 Kgha-1 at four times, was used. Six traits including green fodder, dry matter, protein yield, plant height, stem diameter and tiller number were measured in each cutting. Harvesting was conducted from 7.8 m2 area. Two years data were analysed in simple and combined analysis, and the means were compared with Duncan's multipl range test (DMRT) method. Analysis of variance showed significant differences between cuttings for all traits (except for plant height) in each year. The green fodder, dry matter, protein yield and tiller number at second cut and stem diameter at first cut ranked first in each year. Combined analysis of variance showed significant differences between years (except for dry matter and tiller number), cultivars and year cultivar interaction (except for stem diameter). The means comparison with DMRT showed, green fodder with 150.5 tha-1, protein yield with 2.80 tha-1 in the first year, plant height with 196.9 cm and stem diameter 15.48 mm in the second year ranked in first group. Nectar and KFS2 produced the highest and lowest green fodder with 164.6 and 130.4 tha-1, respectively. Sweet jumbo produced the highest dry matter (36.38 tha-1), protein yield (2.88 tha-1) and tiller number (3.61 tillers). The highest plant hieght with 214.4 cm and stem diameter with 17.99 mm were produced by Speed feed and KFS2 respectively. The lowest dry matter (32.41 tha-1), protein yield (2.58 tha-1), plant height (172.2 cm) and tiller number (2.11 tillers) were produced by chopper and the lowest stem diameter (11.61 mm) by Speed feed. Nectar and Sweet Jumbo cultivars were determined as the most suitable cultivars for forage production in this study.

In order to study the effects of irrigation, mist and plant density on quantitative aspects of vegetative and reproductive characteristics of buckwheat (Fagopyrum esculentum), an experiment was conducted in split split plot, based on RCBD with three replications, during 2001 in experimental station, College of Agriculture, Tehran University. Effects of three factors, including air humidity, irrigation and plant density were considered. Mist and non-mist were arranged in main plots and another three factors including soil moisture or irrigation levels (20 mm and 40 mm), planting density levels (100 and 33/3 plant per m2), were arranged in subplots.The effect of these factors and their interactions were studied on characters including: 1000-seed weight, yield of seed per plant, number of seed per plant, plant height and biomass dry weight. Results showed that the both main and interaction effects of main and subfactors were significant on some characters including number and amount of seed per plant, 1000-seed weight and plant dry weight.Treatment of mist, 40 mm water irrigation and density of 33/3 plant per m2 showed the highest effects on all characters

Choice of efficient breeding program depends on the knowledge of the genetic system controlling the character to be improved. To estimate the genetic parameters for yield, yield components and some other morphological traits in corn (Zea mays L.), B73×MO17 and B73×K74/1 crosses were studied by triple testcross method. The experiments were conducted at research field of Seed and Plant Improvement Institute (SPII) in 1999-2001. Significant differences were observed among means of F1 , P1 and P2 testcrosses for all of the traits in both crosses. The B73 testcrosses generally had greater means than MO17 and K74/1 testcrosses except for number of leaves in two crosses, cob weight in cross B73×MO17 and anthesis silking interval in cross B73×K74/1. B73 testcross seems to contribute significantly in the expression of positive epistatic effects. Epistasis effects were significant for all of the traits in both crosses. Partitioning of the epistasis effects into fixable and non-fixable components revealed that additive×additive effects (fixable) were not significant for the traits except for days to silking in both cross, anthesis silking interval and plant height in cross B73×MO17, but additive×dominance and dominance×dominance effects (non-fixable) were significant for all of the traits in both crosses.

Several samples of wheat leaves infected with powdery mildew were collected from Mazandarn, Golestan and Fars provinces in 2003 and 2004. After purification, 23 isolates of the pathogen were selected for pathotype determination. Seeds of 17 near-isogenic lines carrying the known Pm genes, were grown in pots in a greenhouse with 18-22 C, 95-100 RH and 12 hours light and darkness period. Each set of the isogenic lines were inoculated separately with pure condia of each isolate. Infection types of each line were recorded 12 and 16 days after inoculation. Twenty one different pathotypes were identified, having different virulence formula. Based on the results, 95% of the isolates were virulent on Pm3c and Pm5. Virulence for lines carrying Pm4b, Pm2,6, Pm1,2,9 and Pm2,4b,8 genes was rare among the isolates. This is the first report on the presence of virulence for Pm1,2,9 gene combination in Iran. Frequency of virulence for genes Pm4a, Pm8, Pm2,6, Pm1,2,9, Pm7 and Pm2,4b,8 was higher in 2004 than in 2003, but frequency of virulence for genes Pm1, Pm2, Pm3b, Pm3a, Pm6, Pm5, Pm3d and Pm9 was higher in 2003. No change in frequency of virulence for Pm3c was detected during two years. Pathotypes of Gharakhil in Mazandaran province, contained the highest number of virulence factors among the isolates.

To study the effects of different amounts of sulphur and boron fertilizers on grain yield and grain quality of bread wheat cultivar Pishtaz, an experiment was conduncted in Karaj during two cropping seasons 2001-2003. Three levels of sulphur (S0= 0, S1=250 and S2= 500 kgha-1) and three levels of boron (B0= 0, B1= 20 and B2= 40 kgha-1) were different treatments of the experiment arranged in RCBD with three replications in factorial. Analysis of variance on grain yield indicated significant differences among the treatments. The highest grain yield and grain protein percent were obtained from the treatment in which the highest levels of sulphur and boron had been used