مجله علوم گیاهان زراعی ایران
سال چهل و چهارم شماره 1 (بهار 1392)

Proper sowing date along with providing normal growth rate in rape oilseed plants significantly leads to higher seed and oil yield via decreasing cold damages. The experiment was conducted as factorial with two factors including sowing dates with 4 levels (12 and 23 September, 2 and 12 October) and genotypes with 5 levels (Modena, Licord, Okapi, Opera and Zarfam) in three replications. The study was carried out in East Azarbaijan Research Center for Agriculture and Natural Resources (46º and 2˝ E, 37º and 58˝ N) during 2007-2008. The results indicated that genotypes at late sowing date had significantly lower leaves and rosette diameter, because at that time average air temperature was below rape oilseed base temperature (5 ºC) and indicated higher cold damage. Plants in the first and the second planting dates in compare with two late planting dates, indicated significantly higher values of plant height, pods per plant, seed and oil yields. Late planting was accompanied by decreasing pods per plant and seed yield reduction in plants. It seems that 12- 23 September could be suitable period to cultivate fall genotypes of rape oilseed in Khosrov Shahr and areas with similar climate (cold and semi-arid, according to Koppen climatic classification). Among studied genotypes, Modena and Licord had lower amounts of leaves per plant and rosette diameter. Also Opera had the longest pod length. Finally genotypes indicated similar seed and oil yields and therefore could be suitable for cultivation in Khosrov Shahr and areas with similar climate. It seems that induced effects of environmental factors such as drought periods and increasing temperature, could affect growth rate via primary differences (such as leave numbers) amonge genotypes. It is possible to investigate these traits by repeating the experiment.

Common bean (Phaseolus vulgaris L.) is one of the most important food legumes worldwide. The development of a core collection could facilitate easier access to bean genetic resources and enhance their applications in crop improvement program. In this article development of a core collection from 1425 accessions of common bean germplasm available from the National Plant Gene Bank of Iran (NPGGBI) was described. Accessions were clustered by Ward`s method based on geographical origin and 17 qualitative morphological traits data. Some accessions randomly selected from each cluster according to origin of construct core collection. Mean comparisons using Mann-Whitney U test, variances comparison by Leven's test and comparison of frequency distribution by X2 test indicated that core collection was similar to whole collection. The Shannon-Weaver diversity index (H (were also confirmed the similarity of collection and core collection based on different traits.

In order to investigate the effects of on-farm seed priming and sowing dates on seedling emergence, yield and yield components of a local genotype bean called Pach Baghala-Red strain (Phaseolous vulgaris L.) as a double crop after rice, an experiment carried out in the Rice Research Institute of Rasht. Experimental design was laid out in a split plot based on a randomized complete block with three replications. Sowing date was set out as the main plots including 11th, 21st and 31st August and priming treatments including four levels (no primed, priming using zinc sulfate, urea solutions and tap water) used as sub-plots. Time for priming was 5 hours soaking in each treatment. Results showed that primed seeds had higher speed and percentage of emergence especially by zinc sulfate solution. Also emergence percentage in the third planting date was decreased by 16% compared to other dates. In the first sowing date, all priming treatments and in the second sowing date, zinc sulfate solution led to higher grain yield while priming had no effect on the yield in the third sowing date because of severe reduction in growing season. Also harvest index was reduced significantly in the third sowing date. Priming with zinc sulfate solution significantly increased the 100 seeds weight but delay in planting decreased it. 100 seeds weight and number of seed per pod had the highest correlation with grain yield, meanwhile no correlation was detected between grain yield and pod number per square meter.

The effects of bio-priming with different isolates of biological agent of Trichoderma spp. and Pseudomonas fluorescens on morphological and physiological characteristics of a bean cultivar (Yaas) as well as their effects on controlling of Rhizoctonia solani were investigated in two separate experiments. In the first experiment, different isolates of Trichoderma including Trichoderma harzianum bp4, Trichoderma virensAs10-5, Trichoderma atroviride Cs2-1 as well as one bacteria isolate of Pseudomonas fluorescens (UTPF5) were applied on bean seeds primed with zinc sulphate and salicylic acid. In this experiment using a randomized complete block design with 3 replications, several characteristics like root, shoot and seedling length and dry weight, leaf area, chlorophyll content, ‎percentage of nitrogen and iron content, and antioxidant enzymes were measured. In the second experiment, the effects of aforementioned seed treatments on controlling of pathogen was considered. Seeds primed with zinc sulphate which treated with Trichoderma harzianum bp4 had superior growth characteristics like seedling dry weight and nitrogen percentage. The highest iron content (‏256.6 mg/kg (‏detected in seeds which primed with zinc sulphate and treated with UTPF5 bacteria isolate. The seedlings of primed seeds with salicylic acid and treated with UTPF5 had the maximum activity of ascorbat peroxidase (17.4 U.mg-1proteins‏). This seed treatment also had the best control effect (77.33%) on Rhizoctonia solani.

In order to locate QTLs controlling some agronomic traits associated to drought stress and to determine their relationships with grain yield, an experiment was conducted at the Research Farm, College of Agriculture, University of Zabol in 2011. The experiment was arranged in two complete block designs with 3 replications. 72 barley double haploid lines including their parents (Steptoe×Morex) were planted under normal and drought stress conditions. Agronomic traits such as spike length, awn length, plant height, 1000 seed weight, number of tiller per plant, number of spike per plant, number of seed per spike and seed yield were measured. Simple statistics, combined analysis of variance and phenotypic correlation were calculated after averaging of data. QTL analysis was conducted separately by composite interval mapping (CIM) method for each trait in each condition and mean of two conditions. The main effect of genotype was highly significant for all the studied traits and tansgrasive segregation in both directions (positive and negative) was observed. Forty QTLs controlling different studied traits were identified. Phenotypic variance explained by these QTLs varies from 8.02 to 25.66%. The highest LOD scores were obtained for the spike length on 3H chromosome. High value of R2 and small confidence interval for these QTLs shown high linkage between markers and QTLs that can be used for breeding programs.

Climate Changes due to global warming is affecting world agriculture adversely. Heat stress due to global warming has turned to one of the most important factors reducing quantity and quality of plants production such as tomato. Despite of wide cultivation of tomato and high temperature effects on its production, unfortunately; research in this area is scarce. This study was conducted to investigate the response of tomato genotypes to heat stress. Stress tolerance of 11 tomato genotypes was investigated. Plant materials were evaluated at two experiments over one year under normal and heat stress conditions in a randomized complete block design with three replications in the greenhouse of College of Agriculture and Natural Resources, Persian Gulf University, Bushehr, Iran. Plant height, shoot length, days to flowering, yield per plant, fruit weight, fruit length and diameter, days to physiological maturity and days to harvest maturity were measured. Combined analysis of variance results indicated high significance differences among genotypes for all traits. The genotype × temperature interaction for all traits was also highly significant. Heat stress resulted in significantly changes in all studied traits. Mean of yield reduction affected by heat stress was 72.33%. The highest reduction in fruit yield affected by heat stress was 90.58%. The highest positive (0.35) and negative (-0.67) correlations with fruit yield per plant under normal condition were detected for shoot length and days to harvest maturity, respectively. Under stress conditions, the aforementioned correlations were identified for plant height (0.37) and days to harvest (-0.67), respectively. Positive and significant correlation (0.49) was found between yield per plant under normal and stress conditions. This issue indicated that selection under normal condition could be used for selecting of stress tolerant genotypes. Generally, based on calculation of heat stress tolerance index (HTI), principal component analysis, correlation between HTI and components, yield per plant, days to harvest and other morphological traits, T629 and E26.34095 with acceptable yield under both normal and stress conditions were the best genotypes for Bushehr fields. The highest HTI (0.63) and components values under normal and stress conditions were found for E26.34095. Significant differences between normal and stress conditions for fruit morphological characteristics showing that heat stress reduces fruit quality significantly.

Canola is one of the most important crops in the world and ranked as the third most important oil seed crop. Adverse environmental storage conditions including high temperature and relative humidity could affect canola seed quality. The aim of this study was to evaluate the seed quality of canola seed under various seed moisture content, temperature and storage time using Okapi cultivar. Also, electrical conductivity of seeds was measured. Moreover, seed viability constants were estimated using germination responses. Seeds with various moisture contents (5, 9, 13, 17%) were kept under five temperatures (5, 15, 25, 35, and 45°C) for six months. Every month, seeds were taken and transferred to 20°C for viability test. Germination test last for seven days. Analysis of variance indicated significant differences for all interaction effects. According to the results, seeds with 5% moisture content stored at 5°C had the highest germination percentage and the least deteriorated state even after 6 months. High temperatures along with higher moisture content resulted in more deterioration. Electrical conductivity increased under aforementioned conditions. Estimates of KE = 5.65359, CW = 2.49975, CH = 0.04387, CQ = 0.00001438 were derived for prediction of storage length

To characterize the distribution of melanin producing Medicago-nodulating rhizobia in western and north-western of Iran, 982 Sinorhizobium isolates were trapped from a combination of three alfalfa populations (Hamedani, Nikshahri, Kodi) and soil samples from eight sites across Kurdestan, Kermanshah, Eastern Azarbayjan and Lorestan provinces. All rhizobial isolates were examined for their ability to produce melanin (Mel+). According to the results, 24.1% of them were Mel+, as well as the reference strain S. meliloti GR4. Analysis of melanin production revealed more melanin producing isolates among different sites in comparison of different cultivars. Therefore, it can be concluded that the influence of field soil type in dominance of melanin producing strains is more than the host cultivars. The presence of 456 bp amplified fragment using primers designed from the mepA gene in 30 strains of rhizobial strains and its absence in 20 other strains was in accordance with the results of melanin production in the medium, showing that all strains producing melanin contained mepA gene. Multiple sequence alignment revealed that the sequence of mepA gene in S. meliloti is conserved, while this sequence in S. medicae had limited changes.

Drought stress, especially drought at terminal stages, plays an important role in reduction of yield in field crops such as common beans. 50 genotypes of common bean including 3 control genotypes (Dehghan, Bahman and Naz) were used to evaluate and identify the tolerant genotypes. This experiment were performed in a randomized complete block design (RCBD) with three replications under two conditions (stress and non-stress) using stress indices. MP, GMP, HARM and STI indices were introduced as the best indices for screening genotypes because of their high correlation with yield under stress and non-stress conditions. Based on the results of principal components analysis, the first component, which explained 65.96 percent of data variations, was considered as a component of yield stability and drought tolerance, and the second component, which explained 31.53 percent of the data variation, introduced as component of sensitivity to stress. Based on a biplot analysis, genotypes 1, 16, 18 and 49 were introduced as tolerant genotypes with high yield potential. Cluster analysis based on MP, GMP, HARM and STI indices and yield under stress and non-stress were classified genotypes in four clusters. Drought tolerant genotypes were located in the first cluster and the most drought-sensitive genotypes with the largest gap were located in the fourth cluster.

To study the effects of foliar application of common and nano-sized iron sulphate on five sunflower cultivars (Alster, Olsion, Hysun36, Yourflour and Hysun33) under two levels of salinity (0 and 100 mM NaCl), a pot experiment in factorial based using a randomized complete block design with three replications was conducted. Plant height, leaf area, shoot weight, chlorophyll content and the concentration of K and Fe in shoots were decreased and the concentration of Na was increased under salinity. Foliar application of iron sulphate in either forms increased plant height, leaf area, shoot dry weight, quantum yield, chlorophyll content, Fe concentration and also decreased Na concentration. Foliar application of nano-sized of iron sulphate increased plant height, leaf area, shoot dry weight, chlorophyll a and total content up to 4, 9, 7, 30 and 13% in comparison with foliar application of common form. The effects of salinity and cultivar interaction was significant on leaf area, shoot weight and K/Na ratio. The percentage reduction of these parameters in Olsion cultivar was lower than other cultivars at saline stress. In Yourflour cultivar the absorbance of iron was significantly higher in the nano form than in common form. The results of this experiment showed that the nano form of iron sulphate compared to the common form had greater positive effect on the biomass production of sunflower. However, under the conditions of this experiment, the application of nano-sized of iron sulphate showed no significant advantage over common form in terms of the alleviation of salinity effects.

Prediction of weed emergence timing would help minimize crop yield loss and reducing herbicide use by optimization of the timing of weed control. Therefore, seedling emergence evaluation was conducted in different irrigation levels (40, 60, 80, 100 percent of crop water requirement and furrow irrigation) to develop a thermal time seedling emergence model for Amaranthus retroflexus L. in sunflower field. Weed seedling emergence was monitored in plots from late-May through mid-September during growth season. Cumulative seedling emergence for A. retroflexus was described against thermal time using the Gompertz and Weibull functions. The Weibull model predicted seedling emergence of this species in different irrigation level with reasonable accuracy. The RMSE values of the model were ranged between 4.4– 9.7 percent showing that the predictions agreed closely with the observed seedling emergence. This species showed different patterns of emergence and thermal-time requirement for the onset of emergence in different irrigation levels. However, at 56 thermal-time unit, emergences occurred in different irrigation levels. In 80 and 100 percent of crop water requirement, there was an early peak of emergence followed by lower emergence later in the season. At thermal-time unit of 288, 90% of A.retroflexus seeds emerged in the furrow irrigation, suggested early emergence pattern of A.retroflexus in this irrigation system, while, seeds required 381- 413 thermal-time unit for 90% emergence in the tape system, indicating a late emergence pattern in tape system. Delay in seedling emergence could decrease weed competition ability against sunflower; however, late emergence could allow this species to escape weed control practices because most weed management strategies (e.g. cultivation and herbicide applications) are implemented early in the season.

To determine the effects of drought stress and Fe and Zn spraying on two annual medics, namely, Medicago polymorph cv Serena and Medicago scutellata cv Comertial, a field experiment as a split factorial based on a randomized complete blockdesign in 3 replications in Allborze Agricultural Research Center, in Karaj was conducted. Spraying treatments include distilled water (control), Fe, Zn and Fe+Zn, and drought stress include complete irrigation as control, irrigation until 10 days before flowering, irrigation until %50 flowering, and irrigation until maturity of first pod from the lower part of plant. For laboratory experiments, osmotic treatments of -3, -6 and -9 bars using polyethyleneglycol 6000 and distilled water as control were used to evaluate produced seed response to drought stress. The result showed that Fe content of seed in spraying treatment of Fe and Fe+Zn increased by 68% and %13, respectively. Amount of Fe in spraying treatment of Zn, was lower than control (by %15). Fe content in Scutellata seed was 181 mg/kg lower than Polymorpha and Zn content was %10 higher than Polymorpha. Significant and negative correlation between Zn and Fe in seeds (r=-62**) was achieved. Interaction of genotypes and spraying in different levels of drought stress showed that Fe content in Scutellata seeds in the second, third and fourth levels of drought were 8, 6 and %33 higher than complete irrigation, respectively. Percentage of seed hardness in the second, third and fourth levels of stress under spraying treatments of Zn, Fe+Zn and Fe+Zn was 28, 30 and %22, respectively. By increasing osmotic potential from -3 to -9 bars, seedling growth was increased under Fe+Zn spraying up to 0.5-15 fold in all level of stress in compare to control treatment. Moreover, under the aforementioned conditions dry weight of root was 10-48% higher in Scutellata than control. Also shoot dry weight increased by 20-60 % in spraying treatment of Fe+Zn under stress conditions. Seedling vigor in spraying treatment of Fe+Zn was 1.5 -3 fold better than control. Generally, iron plus zinc and iron spray treatments were valuable treatments to produce seedlings with high vigor and ability to withstand drought conditions.

To determine the optimal plant population density and weed management method in irrigated spring sown chickpea, an experiment based on RCBD arranged in a split plot with four replications was carried out at research farm of University of Tehran (karaj) during 2010-2011. Main factor comprised nine treatments, namely, 1) trifluralin pre-plant (960 g ai/ ha), 2) pendimethalin pre-plant (825 g ai/ha), 3) imazethapyr pre-emergence (70 g ai/ha), 4) imazethapyr post-emergence (40 g ai/ ha), 5) mechanical weeding, 6) pyridate (1200 g ai/ha) along with mechanical weeding, 7) pyridate post-emergence (1200 g ai/ha), 8) complete hand weeding (weed free check), and 9) weedy check (no weeding). Sub factor included three densities of 35, 45 and 55 plants per m2. Results revealed that plant density and weed management had significant effects on chickpea characteristics. The highest seed and biological yield obtained at 55 plants per m2; however it showed similar results for these traits at 45 plants per m2. The weed biomass was significantly differed at various plant densities and it was the lowest at 55 plants per m2. After complete weeding (weedy check), pyridate + mechanical weeding and pendimethalin controlled effectively weeds. After complete weeding, the pendimethalin gave the highest chickpea seed and biological yield at Karaj prevalent conditions.

To study the growth and development of maize and mungbean in sole and intercropping systems, an experiment using replacement technique was conducted. Different planting ratios of intercropping in five levels (sole maize, sole mungbean, 25% maize + 75% mungbean, 50% maize + 50% mungbean, 75% maize + 25% mungbean) and three varieties of maize (KSC 260, KSC 301, KSC 302) arranged in a split plot experiment in the form of RCBD with three replications at the Research Farm of Agriculture Center of Zabol University (Iran) in 2011. Varieties of maize were assigned to main plots and planting ratios of intercropping were assigned to sub plots. The results showed that the maximum of forage yield was obtained at 75% maize + 25% mungbean intercropping. Quality of forage in the intercropping was higher than sole maize. The highest of DMD was obtained in 25% maize + 75% mungbean but no significant difference with 50% maize + 50% mungbean. Forage ADF at intercropping was lower than sole maize. The highest LER was detected in planting ratio of 75% maize + 25% mungbean with LER=1.42. The highest of forage yield was obtained in KSC 302 (15706.4 kg/ha). The results also showed that intercropping had the highest quantity and quality forage yield and the best planting ratio for forage was 75% maize + 25% mungbean compared to sole maize and sole mungbean.

A 7×7 complete diallel cross experiment was performed to study the genetic relationship of grain yield and some agronomic traits in rice. Analysis of variance showed significant differences among genotypes for all traits. Results of correlation analysis showed that rice grain yield was positively and significantly correlated with BY (rp = 0.81, rg =0.55), HI (rp =0.35, rg =0.79), NP (rp = 0.80, rg =0.67), PW (rp = 0.78, rg =0.83) and GSH (rp = 0.32, rg =0.81). Correlation between PH and GY (rp =-0.09, rg =-0.53) was negative at both type of correlation, but only rg was significant. The results of path analysis indicated that number of panicles (NP), panicle weights (PW) and plant height (PH) were strongly (92% of total variation) influenced grain yield (GY) as the predictor variables. Among these characters, PW reflected the highest direct effect (0.73) with grain yield; while minimum direct effect was indicated by PH (0.15). NP and PW can be used as effective selection criteria for grain yield increase. Factor analysis indicated that five important factors accounted for about 81.05% of the total variation among traits. The first factor assigned 23.0% of total variation between traits and was significantly related with grain yield, its components and flag leaf area. Other factors accounted for 18.65, 16.20, 14.20 and 9 percent of variation between traits. Applying genotype × trait (GT) biplot to the multiple trait illustrated that GT biplots graphically displayed the interrelationships among GY, PH, PW, HI, NP, GSH and BY. The results of this research indicated that use of NP and PW could be applied as a breeding strategy to obtain high yield rice cultivars.