JWSS - Journal of Water and Soil Science

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Growth and grain yield of irrigated barley cultivars (Valfajr, Binam and Raihaneh) was investigated at 4 sowing dates (6, 22 Oct. and 14, 20 Nov.) in Karaj region. The effect of sowing date, genotype and their interaction on grain yield were statistically significant. Early and late sowing enhanced cold damage. However, the damage was more in late sowings. It was estimated that the optimum sowing date would be about 50 days (600 GDD) prior to freeze-up and maximum cold damage would occur when sowing was delayed until some 22 days (230 GDD) before freeze-up but any more delay in sowing would cause less damage. Highest grain yield was obtained from Raihaneh at 22 Oct. sowing. Binam showed good yield stability and relatively high yield, especially in unfavorable sowing dates. In the relatively favorable sowing dates (6 and 22 Oct.), grain weight showed positive correlation with linear grain filling rate, storage and translocation of reserves. LAI, LAR, RGR, CGR and LAD of each cultivar were higher in the second sowing date compared to the first one. The “ratio of post anthesis growth to maximum TDM” showed a high correlation with the harvest index. Raihaneh was the highest cultivar in resistance to lodging, harvest index, storage and retranslocation of assimilates, and linear grain filling rate. It is suggested that at favorable sowing dates, Valfajr and Binam had source limitation or disturbed translocation and Raihaneh had sink limitation.

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Soil loss due to erosion is a common problem in most parts of Iran. Reduced soil organic matter and lack of proper agricultural management have intensified the problem in recent years. Conservation tillage systems are becoming more widely used in corn production in other parts of the world because of soil losses due to wind and water erosion and energy inputs. Changes in tillage methods, however, create different environments for the germination, development and maturation of corn plants. Most corn hybrids have been selected and developed under conventional tillage systems but these hybrids mayor may not be well adapted to both systems. This study aims to evaluate the performance of five locally grown corn hybrids under zero and conventional tillage methods. The experiment was conducted for 2 years on a plot of land specified for this study. Experimental design was a split plot with randomized complete block arrangement and four replications.

Seedling and juvenile plant growth were not affected by tillage method and were similar for all hybrids. Plant dry matter was affected significantly by the cropping system and was lower in no-till method. Plant leaf area index and stem diameter reduced significantly in the no-till system. Reduction was greater in the second year of the experiment. Also grain yields were significantly different among years, tillage method and plant genotypes. Yield reduction was highest in the second year of the experiment under no-till cropping system. There was no interaction between tillage method and corn genotypes, indicating that, usually genotypes perform similarly with regard to grain yield under both tillage methods. The results suggest that corn production under no-till system in Isfahan is probably associated with yield reduction.

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In order to investigate the best planting time and rice cultivars for the conditions in Khuzestan Province, seven high quality cultivars of rice namely Domsiah, Binam, Ramasanali Tarom, Sang Tarom, Hasansarai, Tarom Mahalli, Daylamani and Anboori were selected and studied in 4 planting dates starting in Mid-May, with intervals of 15 days. The experiment was conducted as a split plot design in randomized complete blocks with 3 replications for 2 years from 1995 in Shavoor Agricultural Research Station. Main plots were planting dates and subplots were allocated to cultivars.

Results of this experiment showed that significant differences existed among planting dates on grain yield only in the second year. Grain yields were different among cultivars in the two years of study. Simple and combined analyses indicated that there were significant interactive effects between planting dates and cultivars. Tiller number was different between planting date and cultivars in the first year. Interactive effect between planting date and cultivars on tiller number was not significant. Maximum grain number in spike obtained early June planting date (76 grains per spike) and lowest grain number in spike obtained early May planting date (28 grains). Among cultivars, Anboori with 152 and Daylamani with 17 grains had maximum and minimum grain numbers in spike, respectively. One-thousand grain weight was maximum in the early June planting date. Among cultivars, Binam and Daylamani had maximum and minimum grain weights, respectively. Highest fertility percentage was obtained in early June planting date compared to other planting dates. Fertility percentage of cultivars depended on temperature at growth stages before and at anthesis, which was early June for all cultivars. Among environmental factors affecting plant growth, temperature was relatively more important than other factors, particularly than the photoperiod. Even under Khuzestan conditions, there is a wide range of temperature levels for rice planting (from early March to early November) however, even this wide temperature range may not be enough to provide favourable conditions for planting all the cultivars.

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Although safflower is known to be a cool-season crop, it is usually planted as a summer crop in Isfahan. Thus, an experiment was conducted in 2000 at the Agricultural Research Station, Isfahan University of Technology, to study the effects of date of planting on growth, yield components, and seed yield of safflower. Five planting dates (March 12, April 12, May 10, June 8, and July 12) and four safflower genotypes (Arak 2811, local variety Koseh, Nebraska 10, and Veramin 295) were evaluated using a randomized complete block design with split-plot layout in three replications. Date of planting was considered as the main plot and cultivars were randomized in sub-plots. Delay in planting from March 12 to may 10 reduced plant dry weight per unit area, number of heads per plant, number of seeds per head, seed yield per unit area, harvest index and petal yield. The above traits increased as planting was further delayed from May 10 to June 8. Highest seed oil and lowest seed protein contents were also obtained for this planting date. Plants of July 12 planting date did not reach physiological maturity. Among the genotypes evaluated and over planting dates, the highest and lowest number of heads per plant, 1000-seed weight, and seed yield were produced byArak 2811 and Veramin 295 (mean of the first and second planting dates), respectively. Highest seed yield (4512 kg ha

^-1) was produced by local variety Koseh in June 8 planting date. It might be concluded that this variety has adapted to the summer planting conditions of Isfahan by natural selection.

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Safflower (Carthamus tinctorius L.) is one of the multi-purpose oilseed crops which has a high adaptation to different conditions such as resistance to drought and it is suited to be grown in arid and semi-arid regions such as Isfahan province. Root rot disease is an important soil-borne disease of safflower in Isfahan, which can be caused by different pathogens. The objective of this study was to determine the causal agent of safflower root rot and to evaluate different genotypes for tolerance to the disease. Different species of Fusarium were isolated from sample collections. Laboratory and greenhouse inoculations indicated that F. solani was the only pathogenic species. In this experiment, 60 genotypes of safflower including breeding lines selected from various Iranian local populations and foreign cultivars were evaluated for reaction to the disease in a randomized complete block design with three replications in greenhouse. Artificial inoculation via injection of spore suspension of F. solani (10⁶ spores/ml) was conducted on 8-week plants and then development of necrosis and death percentage were recorded. The results showed that there were significant differences among the genotypes in terms of reaction to the disease. The most resistant and susceptible genotypes were breeding lines of IUTE14310 and IUTC121 with mean necrosis of 9.67 and 28.33 mm, and death percentage of 32 and 74, respectively. Based on the means of necrosis and death percentage, the genotypes were significantly classified in 5 distinct groups including resistant (7 genotypes), moderately resistant (19 genotypes), tolerant (29 genotypes), moderately susceptible (3 genotypes), and susceptible (2 genotypes). The commercial foreign cultivars of AC Sunset, AC Sterling belonged to tolerant and moderately susceptible groups, respectively. However, Saffire was classified as a tolerant genotype. The local landrace of Kooseh which is widely grown in Isfahan province was classified as susceptible genotype. Phenotypic and genetic coefficients of variation (23.85 and 18.32 %, respectively) and a relatively high broad-sense heritability (59%) for necrosis and also the phenotypic and genetic coefficients of variation (25 and 21 %, respectively) and a high broad-sense heritability (73%) for death plants indicated that there was sufficient genetic variation for resistance and selection can be effective for producing resistant genotypes to Fusarium root rot disease.

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To determine yield stability and to evaluate genotype interaction with environment interaction, 18 genotype of barley (Hordeum vulgare L.) and a control group were evaluated in a randomized complete block design with 4 replications in 3 successive years (1997-2000) at 10 research stations. Simple and combined analysis of variance revealed significant genetic differences between yield genotypes for grain yield. The results of combined analysis of variance indicated that genotypic and genotype were significant through interaction with environment. Therefore, different stability parameters including, environmental variance (S²_i), environmental coefficient of variation (C.V_i), mean of variance of interaction (θ_i), interaction variance (θ_i), equivalence ( W²_i), stability variance (σ²_i), linear regression coefficient (b_i, β_i), mean of squares of deviation from regression (S² _di) and years within location MS for a genotype, averaging over all locations (MS_y/l) were determined. Based on all the stability parameters, genotype 18 was known as the most stable one and genotypes 17 and 11 ranked lower. Genotype 5 with the highest yield was known to be the most adaptable one at fertile environments and is recommended for these locations. In addition, genotype 9 with good yield and low yield variance (1.58) and regression coefficient of less than 1 is suggested for unfertile locations.

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In this study, the an AMMI analysis (additive the main effects and the multiplicative interaction effects) was used to evaluate the yield stability of nine oats genotypes (4 Canadian cultivars and 5 Turkish breeding lines) and Makoi barley (as ckeck) in the 6 environments (3 dates of planting of Oct.12, Oct.31 and Nov.21 and 3 sowing densities of 300, 375 and 450 seeds/m²). The experiment was conducted at the Research Farm of Isfahan University of Technology in 2001. For each environments, a randomized complete block design with the 3 replications was used. According to the results obtained, the main effects of genotypes, environment and genotype X environment interaction effects were statistically significant (p<0.0 1) and 70% of sum of squares was explained by the first two interaction principal components (IPCI). Biplots of genotypic and environmental components of the first and second interaction principal components and the mean yields of the genotypes and environments, pattern analysis of the two significant and also stability statistics of AMMI model (EV2 & SIPC2) revealed that Boyer and Line No. 28 were the most stable genotypes. Boyer had the lowest IPC1 and Pacer and Lines No.2 and 17 were the least stable genotypes with specific adaptation to sowing density of 300 seed/m². Lines No.32 and 28 indicated the specific adaptions to first planting date (Oct.12) Makoi and Pacer had the specific adaptation to second and third planting date and the second sowing density.

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To facilitate the interpretation of data from a genotype by environment experiment (GE), a cluster method is proposed to group genotypics according to their response to the environments especially when the GE interaction is large. The interaction structure of two-way classification data often can be identified if the data stratified into homogeneous subsets. In this paper four GE interaction cluster methods are proposed for this purpose. The stability of the 10 maize hybrids including 9 hybrids that were the best hybrids in yield trials and KSC 301 (check hybrid) were evaluated for 2 years in 4 locations of Iran. The randomized complete block design with 4 replications was conducted for each environment with different layouts. Simple analysis of variance revealed significant genetic differences between hybrids for grain yield. The results of combined analysis of variance indicated that genotype × year, genotype × location, and genotype × year × location interaction effects were significant (P < 0.01). Results also showed that models 1 and 3 and models 2 and 4 had the same responses. Hybrids 8 (K1263/1 × KE8212/12) with high yield stability in both models 1 and 3 were in one group and other hybrids were in another group. In models 2 and 4 results led to 3 groups: Group1 included hybrids 3, 7 and 9 that were very stable and had high yield group 2 included hybrid 1 alone that had medium stability and yield and group 3 included other hybrids that had low stability and yield.

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This experiment was conducted to evaluate drought tolerance of selected lines from local populations of safflower (Carthamus tinctorius L.) at the Research Farm of Isfahan University of Technology in 2002. In this study, the 12 selected safflower lines from different local populations along with two exotic cultivars and a local population were evaluated at two different irrigation regimes, using a randomized complete block design with three replications. The first and second irrigation regimes were based upon the depletion of 50% and 85% of soil moisture content, respectively. The results showed that there were significant differences (p<0.01) among the genotypes for seed yield in both irrigation regimes. Also, the interaction between genotypes and irrigation regimes was significant (p<0.05). Based upon the genotype by environmental interaction analysis (method of Sneller and Dombek), the genotype H27 had the highest tolerance to drought stress, and its seed yield in the first and second irrigation regimes was 3353 and 3072 kg/ha, respectively. The growing variety in Isfahan province (Koseh population) was the most sensitive genotype to the drought stress and had a seed yield of 3525 and 2394 kg/ha in the above irrigation regimes, respectively. The assessment of different water stress indices (SSI, STI, TOL, GMP and MP) revealed that STI seems to be the most suitable index for recognizing the more tolerant genotypes to drought conditions and based on this index, E2428 was the most tolerant genotype, and the exotic cultivar of Ac-Sunset (from Canada) was the most sensitive one. The seed yield for genotype E2428 was 4174 and 3458 kg/ha, and for the genotype Ac-Sunset was 2004 and 1438 kg/ha in the first and second irrigation regimes, respectively.

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This research was conducted at Rsearch Farm of Isfahan University of Technology to evaluate yield stability of 9 Oat (Avena sativa L.) genotypes and Makooi barley, to determine the contribution of each environmental factor to genotype × environment interaction, and to find the most stable yield component in these genotypes. Four Canadian cultivars and 5 Turkish breeding lines were included in this experiment. Three dates of planting (12 Oct. 31 Oct. and 21 Nov.) and three sowing rates (300, 375 and 450 seed m²) were used as 6 environments. In each environment a randomized complete blocks design with 3 replications was used. Grain yield, No. of panicle/m², No. of seed/ panicle, and 1000-grain weight were measured. Result of combined analysis of variance showed highly significant (P < 0.01) difference among genotypes for all the studied traits. Significante differences were observed among environments for all the characteristics except for 1000-grain weight. Grain yield and its components showed highly significant genotype × environment interaction ffects. The ratio of genotype × environment interaction sum of square to total sum of square for grain yield (22.37%) was higher than other traits. Stability analysis based on regression coefficient showed that Boyer cultivar and Line No.28 with nearly b=1 and more than average yields were the most stable genotypes. Pacer cultivar and Makooi Barley had specific adaptations with suitable and unsuitable environments, respcctively. Based on deviation mean square, Boyer cultivar was the most stable one among high yielding genotypes. Tai’s path analysis of genotype × environment interaction showed that V₃ genotypic component (Seed weight) was the most effective component of stability and yield. Boyer with the highest V₃ score was the highest yielding and stable genotype. According to environmtntal component of path analysis, fertilization stage and grain filling period were the most sensitive growth stages to environmental conditions. Therefor, it is not effective to evaluate genotype stability according to V₂ component (seed/panicle). Finally, according to the result of this experiment Boyer with grain yield of 5.8 t/ha and stable response in all environments was selected as a suitable cultivar for breeding programs or introduction for commertial production.

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This research was conducted in order to select male genotypes of pistachio with good performance. The study was performed on 10 genotypes in regard to their flowering time, pollen quantity and quality. The results indicated that flowering times of P1, P2 genotypes were simultaneous with Kallehghochi P3, P4, P5 genotypes with Ahmad Aghaii P6 and P7 genotypes with Ohadi and P8, P9, P10 genotypes with Akbari. Inflorescence weight showed big differences between them, ranging from 4.5gr for P6 to 1.66gr for P8. The amount of pollen per inflorescence also showed big difference, ranging from 71mg for P2 and 267mg for P5. In order to determine the percentage of pollen germination, a medium consisting of sucrose, agar and boric acid was used. The percentage of pollen germination also showed big difference, ranging from 30%for P3 and P4 and 85% for P10. Stored pollen at 4°C temperature showed 30% germination after one month and 0% germination after three months. The results also indicated that the percentage of pollen germination in culture medium without boric acid was lower, compared with other treatments. The viability of pollens collected from cutting inflorescences kept in water bottle was higher than that obtained from dried inflorescences maintained in room condition.

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  Presence of genotype × environment interaction necessitates evaluation of genotypes in a wide range of environments to find desirable genotypes. This study was carried out to determine the stability and adaptability of grain yield of 17 chickpea genotypes, in RCBD with four replications at Kermanshah, Lorestan, Ilam, Gachsaran and Gorgan Research Stations during two seasons (2003-2004). The genotype × environment interaction effect analyzed using the additive main effects and multiplicative interaction (AMMI) statistical model was significant at 1% level of probability. The sum of squares of G × E interaction was partitioned by AMMI model into four significant interaction principal component axes (IPCA). The first four principal component axes (IPCA 1, 2, 3 and 4) cumulatively contributed to 94% of total genotype by environment interaction. A biplot generated using genotypic and environmental scores of the first two AMMI components also showed that genotypes FLIP 97- 79, X95TH1 and FLIP 97- 114 were selected as stable genotypes, among which the genotype FLIP 97- 114 was outstanding for high yield stability.

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One of the applications of Non-Parametric methods is determination of genotypes rank in different environments, which is also used as a measuring stability. A stable genotype shows similar ranks across different environments and has minimum rank variance in different environments. Non-Parametric Stability Statistics require no statistical assumptions about the distribution of the phenotypic values and are easy to use. This study was carried out to determine the ranks of 10 Lentil genotypes (Lens culinaris Medikus) across ten environments in 2002-2004, using a randomized complete block design with four replications. Analysis of Thennarasu non-parametric statistics showed that genotypes 8 and 9 had high stability by NP₍₁₎ statistic and genotypes 9, 8 and 1 had stable yield in NP₍₂₎ method. Result of the NP₍₃₎ statistic was similar to NP₍₁₎ statistic. NP₍₄₎ statistic selected genotypes 9 and 1 as the most stable genotypes and ultimately NP₍₅₎ statistic introduced 9 and 1 genotypes as stable genotypes in this experiment. Also analysis of Nassar and Huhn non-parametric statistics revealed that genotypes 1 and 2 were most stable and well adapted across ten environments. In addition, it was concluded that plots obtained by both mean yield (kg ha-1) vs.S_i⁽¹⁾ and mean yield (kg ha-1) vs. S_i⁽²⁾ values could enhance visual efficiency of selection based on genotype × environment interaction. According to these configurations, genotypes in section 1 can be considered as stable and well adapted to all environments, having general adaptable ability. For recognition a daptability,S_i⁽¹⁾ and  S_i⁽²⁾ take preferred over other non-parametric statistics.

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To study the effects of planting date and density on yield and its components in chickpea (Cicer arietinum L.) genotypes under dryland conditions of Khorram-Abad, an experiment was conducted during 2005-2006 growing season at the Agricultural Research Station of Lorestan Weather Department. Three sowing dates (March 6, March 21, and April 5) and two chickpea genotypes (Greet and Flip 93-93) with four plant densities (18, 24, 30 and 36 plants m^-2 ) were evaluated using a randomized complete block design with split-factorial design in three replications. Dates of planting were considered as the main plots, genotypes and plant densities were randomly distributed in sub-plots with factorial arrangement. The result showed that delay in planting from March 6 to April 5 significantly reduced number of pods per plant, number of grains per pod, 100-grain weight, grain yield and dry matter. Increasing plant density led to a significant decrease in number of pods per plant, number of grains per pod and 100-grain weight. However, grain yield and dry matter increased firstly with increasing plant density and then decreased. Planting date and density had no significant effect on harvest index, while genotype of Greet produced a larger number of pods per plant, grain yield as well as final dry matter. Also Flip93-93 produced a bigger number of grains per pod, greater grain weight and harvest index. The maximum grain yield was obtained with genotype of Greet at the first planting date in 30 plants m^-2 density. It could be concluded that due to thermal and drought stress occurring in late spring,, early planting of Greet genotype at 24-30 plants/m² may lead to a suitable increase in grain yield.

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Because of many small florets and protandry, cross pollination in onion which is a biennial plant, by using polycross method for breeding is suitable and easy. To produce polycross seed, bulbs of 9 self onion genotypes were planted in the shape of equilibrium lattice design for 9 treatments with 10 replications on May 2002. To study some agronomical characteristicss, the polycross seeds produced from free pollination and original self-fed seeds (totally 18 genotypes) were planted in plots as a randomized block design with four replications. Samples were taken from each plot and different characteristics were measured. Results showed that polycross generally increased plant fresh and dry weight, plant height, percentage of off type bulbs and yield, with no effect on bulbing ratio and time to ripening. Although polycross increased most agronomical characteristics and yield in Kashan, Azarshahr and Kazeroon genotypes, in some genotypes little increase or even negative effects resulted due to interaction between genotype and polycross. With more assessment of polycross genotypes, good characteristics will be fixed and seeds with higher qualities will be produced.

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Onion thrips (Thrips tabaci Lind.) is one of the important factors which indirectly restrict the proper yield of onion (Allium cepa L.). Therefore, finding tolerant cultivars to onion thrips is important. Because of many small florets, cross pollination in onion which is a biennial plant by using polycross method for breeding is suitable and easy. To produce polycross seed, bulbs of 9 self pollinated onion genotypes were planted in the shape of equilibrium lattice design for 9 treatments in May 2002. To study tolerance to onion thrips and assess other agronomical characteristics, the polycross seeds produced from free pollination and self pollinated plant seeds (totally 18 genotypes) were planted in a randomized block design with four replications. The main plots were sprayed and not sprayed, and sub-plots were onion genotypes. From August to October 2003, samples were taken from each plot bi-weekly, and number of thrips, and percentage of injury on plants were recorded. As a result of this study, Azarshahr self pollinated genotype showed maximum population density of thrips (22.24) and injury, but Ghom and Abarkooh genotypes showed the lowest amount (2.65 and 5.68 respectively) among all genotypes. Among pollycross genotypes, Ghom and Kashan genotypes showed low population densities (4.3 and 4.24 respectively) and injury, but Azarshahr and Tarom showed high population densities (20.66 and 19.84 respectively) and percentage of injury. Generally, polycross reduced population density of thrips and percentage of injury.

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This experiment was conducted at the Agricultural Research Station of Isfahan University of Technolgy in 2006 to evaluate the effects of planting pattern and the level of soil moisture on two safflower cultivars. A factorial split plot arrangement was used in a randomized complete block design with three replications. Two planting patternS (flat and bed planting) and two levels of soil moisture (irrigation after 80 and 100 mm cumulative evaporation from Class A pan) were considered as the main factor and two safflower cultivars (IL 111 and Kosseh) as minor factor. Each plot in flat planting consistedof six rows, spaced 25 cm apart with plants 8 cm apart and in bed planting consisted of four rows, spaced 45cm apart with plants 5 cm apart. The duration from planting to button formation, 50% flowering, and 100% flowering stage were significantly shorter in 45cm bed planting than in 25cm flat planting. The duration from planting to all growth stages was less in IL 111, compared to Kosseh cultivar. The level of soil moisture did not affect the duration of any growth stages. Plant height, leaf area index, plant dry matter, number of buttons per plant, number of grains per button, grain weight, and harvest index were higher in flat planting, compared to bed planting. Plant height, plant dry matter, number of buttons per plant, number of grains per button, grain weight, and harvest index were reduced as the level of soil moisture was decreased. Leaf area index and plant dry matter were not significantly affected by the level of soil moisture at 50% flowering stage. Regardless of the level of soil moisture and cultivar, the grain yield was 36% more in flat planting than bed planting. The grain yield was more at higher level of soil moisture and also in Kosseh than in IL 111. The oil percentage and oil yield was higher in flat planting, compared to bed planting and also in Kosseh than in IL 111. The oil percentage was not significantly affected by the level of soil moisture. However, the oil yield was decreased as the level of soil moisture was reduced. The highest amount (1168 kg/ ha) of oil yield was obtained from Kosseh in flat planting and the lowest amount (417 kg/ ha) was achieved from IL 111 in bed planting. The results from this experiment show that to obtain the optimum yield from summer planting in areas with similar conditions to that of this study the 25cm flat planting compared to the 45cm bed planting, and Kosseh compared to IL 111 cultivar seems to be superior.

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To assess adaptability and stability of seed cotton yield in promising cotton genotypes, eight cultivars of cotton (Gukorova, Nazeli–84, Khordad, No: 200, Crema, Tabladila, Beli Izovar and Sepid), along with two controls (Sahel and Varamin), were studied in a completely randomized block design (RCBD) with four replications in six regions of Golestan and Mazandaran provinces in two successive years (2005 & 2006). Combined analysis of variance was done and means comparison of yield was conducted based on Duncan's multiple range test. Sepid, Beli Izovar, Varamin and Khordad varieties were superior for yield, earliness, boll weight and boll number, respectively. The result of combined variance analysis showed that, there are significant differences between genotypes and genotype × environment (G.E) interaction effect. Because of significant G.E interaction effect univariete stability parametric and non-parametric stability methods were used to determine genotype stability. The results of varied methods were different. The 43200 and Sepid cotton cultivars had a specific adaptation and were suitable cultivar for fertile lands in north of country, because of good reaction to production high yield. In contrast, Sahel cultivar with lowest yield had broad stability with non-fertile regions. Overall, three genotypes (Khordad, Tabladila and Gukorova) were determined with suitable stability and moderate yield (general stability) for most locations in north of country.

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Multi-environment trial data are required to obtain stability performance parameters as selection tools for effective cultivar evaluation. The interrelationship among several stability parameters and their associations with mean yield, along with the repeatability of these parameters in consecutive years was the objective of this study. Barley yield data of 18 cultivars, proprietary of Dryland Agricultural Research Institute, evaluated in 12 locations over 2005-2007 in three locations of Iran was used for the combined analysis of variance in three datasets. I: Across locations in a single evaluation year (dataset A), II: Across locations in each of two single evaluation year (dataset B), III: Across all locations in three years (dataset C). For each dataset, cultivar phenotypic variance and other statistics were appropriately partitioned in its components. The interrelationship among the parameters and their associations with mean yield based on Spearman rank correlation was studied in each of the three single evaluation years (dataset A). Rank correlation coefficients were also used as estimates of the repeatability of these stability parameters across two year combinations (dataset B). The parameters 2 σi Shukla and 2 Wi were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. The parameters bi , 2 Si and CV were consistently highly correlated with each other but not with mean yield in all single and pair evaluation years. Result showed that Shukla variance, Wricke ecovalence, SIPC1 and ASV AMMI stability statistics have high repeatability. Thus it is suggested that more stability statistics especially nonparametric methods be used for determination of repeatability methods.

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Gray mold, caused by Botrytis cinerea, is a serious disease of cut rose flowers (Rosa hybrida L.) in Iran. In order to elucidate the effects of different potassium and calcium levels in nutrient solution on susceptibility of cut rose flowers to gray mold, this experiment was carried out as factorial design in a randomized complete block with four replications at Safi Abad Agricultural Research center in 2008 for one year. In this experiment, rose plants were grown and subjected to three levels of potassium (1.0, 5.0 and 10.0 mM) in combination with two levels of calcium (1.6 and 4.8 mM) under hydroponic condition. Rose flowers from two consecutive harvesting periods were sprayed with the conidial suspension (104 spore/ml) of B. cinerea isolate. At the end of experiment the disease severity was recorded and analyzed. The results indicated that application of 10.0 mM K in the nutrient solution led to increasing rose disease severity to gray mold (30.4 % day-1) compared to 1.0 mM (24.8 % day-1) and 5.0 mM (26.2 % day-1) of K levels (P< 0.01). The increased susceptibility was associated with a decreased concentration of Ca in the rose petals. Correlation analysis revealed that susceptibility of rose flowers to gray mold significantly increased with K to sum cations ratio in the nutrient solution (r = 0.94*). The increase of Ca supply from 1.6 to 4.8 mM resulted in decline of disease severity from 29.6 to 24.6 % day-1 (P< 0.01). Therefore, balanced application of potassium and calcium (5.0 and 4.8 mM, respectively) is recommendable for preventing antagonistic effects between them and reducing of rose gray mold intensity under hydroponic conditions.