مجله علوم گیاهان زراعی ایران
سال چهل و یکم شماره 2 (تابستان 1389)

To study the effects of intercropping fodder sorghum with pearl millet at different row proportions and plant densities, an experiment was conducted at the research farm of University of Tehran in 2005. The experimental design was a split plot with three replications. Three different densities of 200000, 270000 and 340000 plants per hectare were as main factor and seven different planting proportions of pure stand of sorghum, pure stand of pearl millet, 75% sorghum + 25% millet, 75% millet + 25% sorghum, 50% sorghum + 50% millet, 100% sorghum + 20% millet and finally 100% millet + 20% sorghum constituted the sub-factor. Taking into consideration the fodder yield on a dry weight basis, the pure stand of sorghum had the highest fodder yield in the first harvest, whereas during the second harvest the highest fodder dry weight obtained from pure stand of pearl millet. Evaluation of the two harvests together revealed that the highest fodder dry yield obtained from pure stand of pearl millet. In the first harvest, the highest sorghum fodder yield obtained in a combination of 75% millet + 25% sorghum and the highest pearl millet fodder yield resulted in a combination of 75% sorghum + 25% millet. However, in the second harvest a similar fodder yield for each of sorghum and pearl millet obtained in the combination of 75% sorghum + 25% millet. Evaluation of land equivalent ratio (LER) indicated that the highest ratio (LER=1.43) belonged to the combination of 75% millet + 25% sorghum.

In order to determine the cytotypes of 67 accessions of Aegilops crassa from Iran, two flow cytometry and cytogenetics methods were applied. The nucleus of the young leaves was colored using DAPI and the intensity of fluorescent determined by flow cytometry. By comparing the intensity of the fluorescent of the Ae. crassa samples with Ae. tauschii (as an standard sample), two cytotypes 4x and 6x were identified. Cytogenesis study through flow cytometry confirmed the existance of two cytotypes, 4x and 6x, in the Iranian accessions. In tetraploid cytotypes the size of chromosomes ranged from 13.88±0.65 to 8.75±0.43 µm with a mean size of 11.21±0.20 µm per chromosome and a total genome size of 156.88 µm. All the chromosomes in these cytotypes were metacentrics except choromosome 4, 8 and 13 which were submetacentric with arm ratio of 1.70±0.10, 2.16±0.17 and 1.84±0.12 µm, respectively. Moreover pairs 4 and 10 were satellited chromosomes with the sizes of 1.33 and 2.19 µm, respectively, while, in hexaploid cytotypes the size of chromosomes ranged from 12.95±0.56 µm to 7.53±0.23 µm with a mean of 10.35±0.23 µm and total genome size of 217.39 µm. All the chromosomes in these cytotypes were metacentrics expect choromosome 3, which was submetacentric with arm ratio of 1.76±0.02 µm. Chromosome pairs 3, 6 and 10 were satellited ones with the sizes of 1.09, 2.09 and 1.54µm, respectively. The results of comparing of two cytotypes for evaluated morphological characteristics indicated that plant height, flag leaf length, color and wooly glums were significantly different between 4x and 6x cytotypes which could be employed for distinguishing these two cytotypes.

This study was conducted to determine the appropriate irrigation interval on the basis of cumulative water evaporation from Standard Evaporation Pan (Class A) and to find out the effects of irrigation regimes on growth indices and on qualitative and quantitative yields of sugar beet. The experiment was conducted in 2005 at the Lavark Agricultural Experiment Station Fields, Isfahan University of Technology located near Nejaf-abad using a randomized complete block design with four replications. The study included four irrigation regimes of: I1, I2, I3, and I4, namely, irrigation after 70, 85, 100 and 115 mm of cumulative pan evoporation up to September while afterwards, irrigation at 85, 100, 115 and 130 mm of cumulative pan evaporation, as the main plots along with two monogerm cultivars (Zarghan and Shirin) as subplots. Total dry weight decreased by about 45% as water regime was held from I1 to I4 treatment, while the effect of cultivar on total dry weight being non significant. The effect of irrigation treatments on leaf area index (LAI) was significant in all the samplings, being reduced with hold in water. The effect of cultivar on LAI was non significant in some samplings, but LAI in Zarghan was higher than that in Shirin cultivar. Crop growth rate decreased as irrigation was held from I1 to I4. However, moisture stress further than I2 negligibly affected net assimilation and relative growth rate. The effect of water regime was significant on root yield. Maximum root yield (77.5 t ha-1) was obtained from I1 treatment while the minimum (54.37 t ha-1) obtained from I4. Cultivars did not significantly differ for root yield. Maximum (17.19%) and minimum (15.02%) sugar content was obtained from I3 and I2 irrigation treatments, respectively. The highest and the lowest sodium, potassium as well as harmful nitrogen contents were found in I1 and I4 irrigation treatments respectively. The highest extractable sugar content (13.47%) was obtained from I3 irrigation treatment. The highest (8.45 t ha-1) and the lowest (6.99 t ha-1) white sugar yield were obtained from I3 and I4 irrigation treatments, respectively. From the obtained results, it can be concluded that to economize in irrigation water and at the same time to obtain optimum yield, irrigation of the crop (at the beginning of the growing season, namely months of April an May) must be on the basis of I3 while later on the irrigation should be based upon I1 treatment.

Water and soil salinity are two of the most important limiting factors in crop production. Phosphatase enzymes are widely found in plants. Phosphatase enzymes are responsible for de-phosphorylation of organic phosphate and altering it to mineral phosphate. Germination experiments were conducted using two bread wheat cultivars, namely, Iniya66 and Ghods along with application of different NaCl potentials. Salt stress significantly reduced all the germination traits. For assessing phosphatase enzymes activities in salt resistant and salt sensitive cultivars, an experiment was done under salinity stress conditions. The experiment was conducted using a completely randomized design of three replications. Treatments included cultivar, salinity and imbibition time. Results indicated that salinity stress enhanced phosphatase enzymes activities (Acid & alkaline) and by increase in stress level to -12 bars, phosphatase enzymes activities increased. Enzyme activity was higher in salt resistant cultivar (Iniya66) than in the sensitive one (Ghods). Acid and alkaline phosphatase activities in both cultivars (salt resistant and non resistant) increased with increasing of seed imbibition time. The greatest activity of the enzyme was detected after 18 hours of seed imbibition.

Source limitation during grain filling is important for both management and breeding strategies of grain crops. There is little information on the sensitivity of grain yield to various source-sink ratios in various wheat (Triticum aestivum) cultivars. The objective of the current study was to evaluate the response of grain yield as well as yield components to different source-sink ratios during grain filling in wheat cultivars improved for contrasting environments. Pot experiment was carried out outside, under natural conditions in greenhouse areas of College of Agriculture, University of Tehran, Karaj, in 2007-08 cropping season. Treatments consisted of 7 cultivars of bread wheat (new and old cultivars from moderate, cold and warm climates of Iran) and 7 defoliation treatments were carried out at the late joining stage and at 20 days after anthesis. Treatments were arranged in a 3-replicated factorial combination based on RCBD design. In general, defoliation treatments improved soil water content. The results indicated that defoliation increased photosynthesis and transpiration rates, stomatal conductivity and chlorophyll stability in flag leaf as compared to control. There was no significant interaction between cultivars and defoliation treatments regarding yield and yield components. Although severe defoliation treatments reduced grain yield, other defoliation treatments (2L and 3L) did not much affect grain yield. The number of grains in spike was affected by defoliation treatments, while it didn’t significantly affect the 1000-seed weight.

This study was performed to investigate the photosynthetic partitioning pattern of materials to aerial parts of bread wheat in dryland conditions. It was as well to study its relationship with bread wheat resistance and grain yield in drought conditions. Seven genotypes including two cultivars (Azar2, Sardari) and five lines were investigated in a field experiment through a randomized complete block design with four replicates and in rainfed conditions during the 2 years of 2006 and 2007. Samplings were carried out in anthesis as well as in physiological ripening stages. Results showed that there are significant and positive phenotypic correlations between yield and most of the traits except percent of dry matter partitioning to stem during anthesis. As well no phenotypic relationships were observed between grain yield and percent of dry matter partitioning to leaf. Results also showed that the amount of spike dry matter in anthesis, biomass and harvest index had a positive and significant, phenotypic correlation with grain yield. Therefore, these traits can be employed in the selection of genotypes with high yields as the effective traits.

To study the effects of integration of mechanical control with herbicides on yield and yield components of soybean (Glycine max) a field experiment was conducted during 2003-2004 at the research farm of Agronomy Department, Agriculture Campus of Tehran University, Karaj. A Randomized Complete Block Design (RCBD) of 18 treatments was applied, each treatment being replicated 3 times. Treatments included 5 groups, viz: 1-tifluralin pre planted (960 gr ai/ha), alachlor pre emergence (2400gr ai/ha), bentazon (1200 gr ai/ha) and oxyflourfen (360 gr ai/ha) both post emergence, 2-trifluralin and alachlor plus cultivation or tank mixed with bentazon and/or oxyflourfen, 3-trifluralin and alachlor, plus cultivation and a reduced dose of bentazon (960 gr ai/ha) and/or oxyflourfen (288 gr ai/ha), 4-Trifluralin (1920 gr ai/ha) applied with irrigation water (herbigation) separately, and tank mixed with bentazon or oxyflourfen, and finally 5-weed free check. There were significant differences between treatments regarding weed dry weight at the physiological maturity stage of soybean crop. Trifuralin + oxyfluorfen and alachlor with 95 and 56% control were among the most efficient treatments. Treatments varied significantly with number of lateral branches, 100 seed weight, number of pods/plant, biological yield and harvest index at P=0.01 and number of seeds/pod at P=0.05. The highest (10148 Kg/ha) and the lowest (2981 Kg/ha) biological yields were obtained when applying bentazon at 1200 g ai/ha and alachlor + cultivation + reduced dose of oxyfluorfen at 288 + 2400 g ai/ha, respectively. The highest (2940 Kg/ha) and the lowest yields were obtained when applying trifluralin + bentazon at 1200 + 960 g ai/ha and trifluralin + oxyfluorfen at 360 + 960 g ai/ha, respectively. Best treatments in terms of weed control and optimum yield are considered to be tank mixes of trifluralin and bentazon (1200 + 960 g ai/ha), trifluralin, (plus cultivation), plus a reduced dose of bentazon (960 + 960 g ai/ha).

In order to deliberate karyologic and cytogenetic parameters, fifteen Aegilops populations, collected from different regions of the country, were studied. These populations included 3 diploids of Ae. tauschii, 6 tetraploids of either Ae. triuncialis or Ae. cylindrica species. The resultant data were analyzed according to a 2-factorial experiment on the basis of a completely randomized design (CRD) with 5 replicates of cells. The factors considered were populations (3 and 12 levels) and chromosome (7 and 14 levels) for diploids and tetraploids, correspondingly. The ANOVA results indicated conspicuous between-diploid differences for L, S, TL and r-value, between-tetraploid differences for RL%, and between-chromosomes either diploid or tetraploid differences for L, S, TL, RL% and F%. Mean comparisons were carried out, using LSR test. Both type populations differed in satellite number, ranging from 0 to 2 pairs. The most chromatin length was detected in pop. 11 (152.18 µm), while pop. 2 bore the least (70.52 µm). Among 15-population karyotypes, 10 were determined in 1A class of Stebbin's classification vs. 5 in 1B class. According to Levan's chromosome nomenclature, the chromosomes of 5 pops. were identified as medium region " m " and those of 10 pops. as both medium region " m " and sub medium region " sm ". Chromosome banding has proven to be a valuable tool for karyotype analysis and for rapid detection of gross chromosomal rearrangements, including large deletion and insertion mutation as well as transpositions. This research was carried out towards an establishment of a procedure, OR-banding, for the detection of the Aegilops chromosomes. Chromosomes OR-banding technique was investigated on 3 Iranian pops. of Ag. tauschii. Chromosome slides were prepared via squash technique in different intervals (24 h to one week) after being slained with 1% aceto-orcein dye. Chromosomal banding pattern was observed 3 d after staining. It was shown that the number of the bands decreased from prophase to metaphase stages of mitosis. The best time for observation of the OR-Banding pattern in Aegilops samples was a long-term (one week) past remaining of the root meristems in dye. This method can be empolyed for an identification of metaphase chromosomes in wild relatives of wheat.

Wheat stem reserves can be an important contributor to grain filling particularly under drought conditions. Knowledge concerning genetic variation in stem reserve could be empolyed to develop wheat genotypes more adapted to harsh environments. The aim of this research was to study the ability to store assimilates in stem and their re-mobilization to the grain in all the 81 Iranian wheat cultivars. The plant materials were evaluated using two simple lattice designs with two replications under irrigated and drought conditions at University of Tehran Research farm during 2007-2008. Drought stress was imposed by the plants being withheld from being watered at the heading stage. The level of dry matter stored and mobilized was estimated by measurement of changes in masses of internodes from anthesis to maturity at 8 day intervals. Relationships among internode's length as well as specific weight and accumulation and re-mobilization of stem reserves were determined. The results revealed that dry weight of lower internodes was higher than that of the upper ones. Maximum release of stored carbon, on the average, was found in lower internodes followed by penultimate and peduncle. Release of dry matter from internodes was decreased by drought stress in some cases, while in some other cases the reverse trend was observed. The same pattern was observed for re-mobilization efficiency. Relationship among internodes characteristics and accumulation and re-mobilization were not the same for stem segments and in all experimental conditions. Release of dry matter from internodes was not correlated with grain yield in well watered conditions. Dry matter mobilized from lower internodes was significantly correlated with grain yield in drought affected plants. Significant genotypic variation for accumulation and re-mobilization was observed under both conditions indicating that these traits can be advantageously manipulated in breeding programs.

This research was carried out in the Research Field of Aboureyhan Campus, University of Tehran during 2006-07 growing season to investigate the effect of Sinapis arvensis L. interference on yield and growth indexes of different canola (Brassica napus L.) varieties. The experimental design was a complete randomized block arrangement in factorial with three replications. Eight canola varieties namely: Elite, Ebonite, Okapi, Zarfam, SLM046, Orient, Licord and Opera were planted in either pure or mixed cultivation with the weed. Trend of Dry Matter (TDM) accumulation, Leaf Area Index (LAI), Crop Growth Rate (CGR) and grain yield were investigated in the canola varieties. In general, the weed reduced growth indexes in canola varieties, but the response of canola varieties were different. Elite and Okapi were recognized as the most resistant and sensitive varieties in competition with the weed, respectively. Elite variety produced the highest grain in mix treatment while the lowest one belonged to Okapi variety, but in pure canola cultivation Ebonite and Opera yielded the maximum and minimum grain, respectively.

To evaluate allelic diversity at loci encoding low molecular weight glutenin subunits (LMW-GS) among 62 genotypes of bread wheat, nine specific primer pairs for Glu-A3, Glu-B3, Glu-D3 loci were employed. PCR products were separated on 2% agarose gels. Two pairs of specific primers, at amplified Glu-A3 locus, 8 alleles were detected the c allele of which was the most abundant with a frequency of 0.311.Seventeen alleles were detected at Glu-B3 loci by through specific primers, the f allele of which was the most abundant with a frequency of 0.145. For Glu-D3 loci; in total 22 alleles were detected by four specific primers the h allele of which was the most abundant with a frequency of 0.174. Using Nei’s genetic variation index (H), the genetic diversity for Glu-A3, Glu-B3 and Glu-D3 loci, were estimated as 0.818, 0.914 and 0.915 respectively. The mean genetic diversity (H) for Glu-3 loci was 0.894 among the genotypes. Genetic variation index (H) for each primer revealed that Glu-D3.3 primer exhibits more polymorphism than the other primers. Related analysis of quality and molecular data through use of stepwise regression method indicated that the highest number of informative markers belong to dry and wet gluten. The results revealed that there is a considerable diversity among Iranian bread wheat genotypes which could be employed as a valuable source for improving the quality of wheat final products.

Tall wheat grass (Agropyron elongatum), as many other grasses, benefits from wide genetic bases in Iran. Estimation of genetic diversity and a selection of suitable genotypes is the initial step for developing adaptable synthetic varieties in many cool season grasses. In order to investigate production, variation and genetic similarity of 25 tall wheat grass genotypes, an experiment was conducted using clonally propagated material. Genotypes were evaluated for agronomic, phenological and morphological traits using a randomized complete block design during 2005 and 2006. Results indicated that there were significant differences between genotypes for all the traits examined indicating a broad genetic diversity in this germplasem. The highest estimates of heritability were observed for days to heading, days to pollination and plant height, while the lowest observed for crown diameter. Genotypic coefficients of variability were highest, for forage and seed yield while the lowest belonging to phenological traits and crown diameter. Applying cluster analysis on the studied attributes, three groups were obtained. Regarding all the assessed characters the least and the most similar accessions were identified to be used in the further future breeding projects. Finally, on the basis of the results it can be concluded that clonally evaluation trails can be useful in estimating the genetic variation and selection of appropriate parents for conducting advanced breeding programs.

Available genetic variation for ascochyta blight resistance in genus Cicer has prompted interest in the development and use of autumn sown resistant chickpea cultivars. A thorough understanding of the mode of inheritance of resistance to ascochyta blight in chickpea would assist the breeding efforts. In order to determine the number of genes, as well as to evaluate heritability and action of genes conferring blight resistance and leaf size in chickpea, two genotypes, Iranian local-Bivanij and ICC 12004 were crossed. Parents along with F1, F2 and F3 generations were sown in a Randomized Complete Block Design with three replications at International Center for Agricultural Research in the Dry Areas (ICARDA) under artificial infection conditions. Results showed that, in F2 and F3 generations, ratio of resistance to susceptible plants didnt show significant differences with the respective expected ratios of 9:7 and 5:3. There was a negative correlation observed between leaf size and blight score, meaning that, large leaf genotypes are more susceptible to ascochyta blight. Generation means analysis for resistance to blight revealed that, in this study, additive components played the main role in blight resistance variability, while dominant ones had a significant contribution in variation for leaf size. For these two traits, dominance effects (h) and dominance × dominance interaction (l) had opposite signs which may show the presence of a duplicate epistasis. With respect to these findings, genotypes of the resistant parents could be considered as R1R1R2R2. According to these results, breeding programs could be suggested which appropriately use additive variance for gene pyramiding that can lead to developing ascochyta resistant genotypes in chickpea.

Drought is considered as the most important constraint to world’s crop production. Furthermore arid and semiarid climate accounts for nearly most of terrestrial areas of Iran. Therefore in order to study the effect of irrigation regimes on growth, physiological attributes and grain yield as well as components of such a crop plant as safflower a 4-replicate split plot RCBD field study was performed at Lavark Reasrch Farm, Isfahan University of Technology, Isfahan, Iran in 2007. Three irrigation levels, including irrigation after 75 mm (I1), 105 mm (I2) and 135mm (I3) evaporation from a Standard Class A Pan served as main plots, while six safflower genotypes including Arak2811, Kooseh, Nebraska-10, C111, S149 and K12 constituted the subplots. Chlorophyll fluorescence parameters (F0, FM and FV/FM) at heading and at pollination, leaf area index (LAI) at %50 flowering, head/plant, seed/head, 1000 seed weight, grain and biological yield, oil content and harvest index were the traits assessed. LAI differed among irrigation levels and genotypes, amounting to 5.05 and 2.33 for I1 and I3 levels of irrigation and 4.42 and 2.99 for S149 and Nebraska, respectively. Among chlorophyll fluorescence parameters, FV/FM decreased under I3 level of irrigation at both stages. Grain yield decreased with drought, I1 outyielding I3 by 39%, due apparently to a greater seed/head (26%), head/plant (33%) and 1000 seed weight (10%) in the I1 as compared to I3 irrigation level. Among grain yield components, head/plant and 1000 seed weight indicated the highest (0.86**) and the lowest (0.62**) correlation with safflower grain yield. Irrigation level affected biological yield, with 37.18 and 24.65 g/plant for I1 and I3 respectively. It could be concluded that with genotypes employed in this experiment and the environmental conditions in 2007 in Isfahan, drought negatively affects grain yield and it’s attributes due apparently to decrease in photosynthetic quantum efficiency and photosynthetic surfaces in safflower. Chlorophyll fluorescence parameters proved useful in studying photosynthetic activity of safflower under drought stress.

Drought resistance is a very important characteristic needed for plant survival especially at germination stage, in arid and semi-arid lands. Phosphatase enzymes are widely found in plants. These enzymes are responsible for dephosphorylation of organic phosphate and altering it to mineral phosphate. Germination experiments were conducted in two bread wheat cultivars (Sardari and Alvand) under simulated drought conditions using different polyethylenglycol concentrations (0, -4, -8, -12, -16 bars). Drought stress decreased germination indices. For assessing phosphatase enzymes activities in drought resistant vs. susceptible cultivars, an experiment was conducted under osmotic conditions with three replications using a completely randomized design. Factors included cultivars, osmotic potentials, and seed imbibition times. Results indicated that drought stress caused the increasing of phosphatase enzymes (acid and alkalin). Also, along with increase in osmotic potential up to -12 bars, phosphatase enzyme activities increased. This increasing enzyme activity was much more pronounced in drought resistance cultivar (Sardari) than the susceptible one (Alvand). Acid and alkalin phosphatase activities in both cultivars (drought resistant and susceptible) increased with increasing seed imbibition time. In this experiment the highest activity for phosphatase enzymes was detected at 18 hours of seed imbibition. However, the activity of acid phosphatase was significantly higher than that for alkalin phosphatase.

Drought, specially in reproductive stage is one of the major constraints, limiting the productivity of crops, including chickpea (Cicer arietinum L.). To study the effects of drought during pod set and seed filling stages (terminal drought) on phenology, growth and seed yield of 5 Kabuli chickpea genotypes of: Arman, Jam, Hasham, Flip93-93 (Azad) and ILC482, an experiment was conducted during the 2006 growing season at the experimental field of the Agricultural Faculty of Bu-Ali Sina University. The trial was a split plot one on the basis of a randomized complete block design with three replications. The irrigation levels (irrigation at podding, at both podding vs seed filling stages and no irrigation) constituted the main plots while the chickpea genotypes constituting the subplots. The results revealed that growth duration, biological and seed yields were significantly decreased by drought stress but no significant difference was observed between harvest index among all the irrigation levels. Among the yield components, the number of pods per plant and seed weight exerted the most effect on reduction of seed yield in water stress conditions. Irrigation at podding increased seed yield of genotypes by 12 to 60% but there was no significant difference observed among the yield of genotypes in drought conditions as compared with irrigation at podding except in Jam and ILC482. A comparsion of seed yield of genotypes in drought conditions showed that Hashem and Jam cv's exhibited the least and the most reaction to drought stress, respectively.

To study yield and its relationships with yield components in 10 varieties of foxtail millet (KFM1 to KFM10), an experiment was carried out in Safiabad Agricultural Research Center in RCBD design with three replications for a period of three years (2003 to 2005). Vegetative and reproductive characteristics of each cultivar were recordered during the growing seasons. Three year results showed significant differences among cultivars for all the traits. KFM10 was found out as the most adaptable among the studied cultivars in Safiabad region due to its high seed and forage yield and less lodging because of its stem thicknes. Path analysis was employed to study the correlations among seed yield, dry forage yield as well as other traits. Results of path analysis for seed yield indicated that the number of tillers, stem diameter and days to 50% flowering positively and direct affected seed yield (respectively 0.564, 0.516, 0.472) while effected negatively (-0.323) spike length. Results of path analysis for dry forage yield indicated that the number of seeds per spike, number of leaves, number of tillers as well as days to 50% flowering had positive direct effect on the yield (respectively 0.247, 0.221, 0.3, 0.628). To improve seed yield in foxtail millet, it is finally recommended to select late maturity cultivars with high number of tillers, thicker stems and shorter spike lenght. In order to increase dry forage yield, the first priority should be firstly given to a selection of late maturity plants and then to plants with a higher number of leaves & tillers as well as higher number of seeds per spike. High residual effect for seed yield (0.67) and for dry forage yield (0.667) was indicative of the fact that lots of traits that affected seed yield and dry forge yield had not been dealt with in this research.