جستجوی مقالات مرتبط با کلیدواژه « rapeseed » در نشریات گروه « زراعت »

Salinity is one of the major abiotic stresses and the most limiting factor in agricultural production worldwide, affecting the growth, development, and final yields of crops. Rapeseed is one of the most important sources of oilseeds in the world, and its seeds contain more than 40% of oil. Moreover, the meal obtained from oil extraction has more than 35% protein, hence it currently ranks third among oil crops in the world after soybean and oil palm, making it necessary to identify the genotypes that tolerate salinity stress. The development and improvement of rapeseed cultivars with salinity tolerance and acclimation offer promising prospects for improving sustainable production in this area. Therefore, the current study aimed to investigate the responses of rapeseed genotypes to salinity stress through analyses of agronomic and biochemical traits.

The genetic diversity between rapeseed lines in terms of agronomic, morphological, and physiological traits in saline soils was investigated in an experiment based on a randomized complete block design with 17 autumn rapeseed genotypes with three replicates in the research farm of East-Azarbaijan Agricultural and Natural Resources Research and Education Center. The measured traits were plant height, the number of fertile pods, number of seeds per pod, pod length, pod area, plant growth rate, 1000-seed weight (TSW), seed yield, oil content, and oil yield. The relationships between yield, yield components, and morphological traits were explored using the analysis of variance (ANOVA), comparison of averages, correlation analysis, cluster analysis, and biplot to understand the relative importance of traits affecting the yield of the studied genotypes.

The studied genotypes were significantly different from each other in pod length, pod area, number of fertile pods, number of seeds per pod, plant growth rate, seed oil percentage, plant height, TSW, grain yield, and oil yield. However, there were no significant differences between the studied genotypes in terms of harvest index and number of actual pods to potential pods. According to the mean comparisons, genotypes 5, 11, and 15 can be introduced as salinity-tolerant lines, and genotypes 2, 4, 6, 9, and 12 can be considered salinity-sensitive lines. According to the other traits, genotype 11 produced a high pod length, number of fertile pods, oil percentage, and oil yield, genotype 5 had a high growth rate and oil percentage, and genotype 15 presented a high height and number of fertile pods. According to the cluster analysis, the second and third groups contained tolerant and susceptible genotypes, respectively. The genotypes in the second group had the highest percentage of positive deviation from the overall mean for grain yield, plant height, harvest index, seed oil percentage, pod length, pod area, and number of fertile pods. Based on the biplot analysis, Karaj 8 and 14 genotypes had a strong relationship with the number of  fertile pods, number of seeds per pod, pod length, pod area, and plant growth rate. Based on the obtained results, the plant height, TSW, seed yield, and oil content traits were closely correlated with Karaj 5, 7, 11, 10, and 15 genotypes. Based on the results of correlation analysis, the correlation coefficient of seed yield was positive and significant for three traits, i.e., plant height, oil percentage, and number of fertile pods, and the highest correlation coefficient (r = 0.879) was obtained for seed yield with seed oil percentage. Positive and significant correlations were measured for the number of seeds in pods with pod length (r = 0.699), pod area (r = 0.555), number of fertile pods (r = 0.678), and number of actual pods. Therefore, genotypes characterized by longer and more abundant pods play a crucial role in improving seed quantity, a key component of grain yield in saline environments. Consequently, the size and number of pods per plant serve as indicators of high-yield potential under such conditions. Based on the results of the principal component analysis (PCA), the first and second components had the highest relative variances, accounting for 44.66% and 31.22% of the total variance, respectively. Together, these two components accounted for 75.88% of the total variance. Factor loadings showed that traits such as number of fertile pods, seed yield, oil yield, and seed oil content had the highest factor loadings in the first component. Similarly, the plant growth rate had the highest factor load in the second component among all the studied traits. Cluster analysis divided the genotypes into four groups, and its dendrogram showed that all the studied genotypes were divided into four separate groups based on all the measured traits. The first group comprised three Karaj 1, 13, and 16 genotypes, the fourth group (like the first group) contained three Karaj 5, 11, and 15 genotypes, and the third group had five genotypes, namely Karaj 3, 7, 8, 10, and 14. The remaining genotypes were assigned to the second group.

The results of the present study demonstrate acceptable genetic diversity among rapeseed genotypes in terms of the evaluated traits in saline lands. This shows the importance and the possibility of using these genetic resources to achieve promising and superior genotypes in breeding programs.

Rapeseed with the scientific name (Brassica napus L.) are one of the most important oilseed crops in the world. Considering the country's increasing need to import oil and the importance of rapeseed among oilseeds plants, increasing the yield and percentage of oil is very important. Therefore, identification the traits that increase seed yield, play an important role in the success of breeding programs. Yield is a complex trait that is affected by many factors. direct selection of a variety for yield is not often very effective, so investigating the relationships between grain yield and other traits for indirect selection may be effective. In such a situation, correlations may not clarify the relationships well, therefore, multivariate statistical methods and path analysis can help in understanding the nature of the relationship between traits for direct or indirect selection and improve the efficiency of selection in breeding programs plants become useful.

In this study, eight genotypes of spring rapeseed (SPN-202, SPN-204, SPN-206, SPN-207, SPN-217, SPN-225, SPN-227, SPN-182) along with 56 rapeseed hybrids (F1) were planted in a randomized complete block design with three replications in 2019-2020 crop years in the research farm of Gorgan Agricultural Research Station. During the experiment, phenological, morphological traits, yield and yield components were recorded. The normality of the data was evaluated based on the Kolmogorov-Smirnov method. In order to understand the relationships between traits and to identify the traits affecting on grain yield, at first, correlation coefficients were estimated, then stepwise regression were done. Then, path analysis based on correlation coefficients was used to determine the direct and indirect effects of traits. Finally, all traits were grouped based on principal component analysis.

The results of analysis of variance indicate a significant difference for all studied traits at the probability level of one percent. The coefficient of variation (C.V) for the traits varied from 1.37 (physiological maturity) to 10.31 (number of sub-branches), which indicates that there is sufficient accuracy in conducting the research. The results of correlation evaluation showed that number of pod per lateral branches (0.864), number pods per Plant (0.865), number of lateral branches (0.466), physiological maturing (0.329) and number of grain per pod (0.358) had a positive and significant correlation with grain yield (P<0.01). Stepwise regression analysis showed that the traits of number of pods per plant, number of grain per pod and 1000-grain weight has a decisive role on grain yield. Based on the results of path analysis, number of pods per plant had the most direct effect (0.881) and number of grain per pod had the most indirect effect (0.053) through the number of pods per plant on grain yield. In order the results of principal component analysis, four components were able to explain 75.91% of the changes in the measured data of 64 rapeseed varieties.

Results of the path analysis showed that number of pods per plant, number of grain per pod and 1000-grain weight had a direct positive effect on grain yield. Also, the stepwise regression analysis showed that the stated traits have the highest regression coefficients. Therefore, selection for these traits can be very effective in achieving high performance

In order to investigate the effect of silica and calcium content and harvest dates on yield and yield components of rapeseed as a factorial split in a randomized complete block design with three replications in experimental farms in Aftab region of Tehran province in two cropping years 2018-2019 and 2019-2020 were implemented. Experimental factors include harvest date in three levels one week after the start of yellowing of pods, two weeks after the beginning of yellowing of pods and time of complete yellowing of pods, silica in three levels of zero (control), 3 and 6% of the source was sodium and calcium silicate at three levels of 2, 4 and 6% of the source of calcium sulfate. The results showed that the effect of year on plant height, number of pods per plant, number of seeds per pod and anthocyanin was significant and the second year had the highest amount of these traits. It was observed that the best grain yield of 2477.02 kg / ha and harvest index of 24.83% was related to harvest one week after the start of yellowing of pods and with delay in harvest, 1000-seed weight, grain yield, Biological yield and harvest index decreased and anthocyanins increased. According to the results, silica foliar application with 32.81% increase in plant height, 11.8% number of pods per plant, 31.48% number of seeds per pod, 17.2% weight per thousand seeds, 24.31% grain yield, Biological yield and harvest index and reduction of anthocyanin and electrolyte leakage were associated. The most positive effect on physiological characteristics and yield and yield components was obtained in 6% silica spray. With increasing calcium concentration, plant height, number of pods per plant, number of seeds per pod, 1000-seed weight, grain yield, biological yield and harvest index decreased and anthocyanin and electrolyte leakage decreased, the maximum positive effect on these traits in foliar application 6% calcium was observed. The results showed that silica and calcium had an additive effect on yield and yield components and the best grain yield was obtained by consuming 6% silica with 6% calcium and harvesting one week after the start of yellowing of pods.

Early vigor, stress resistance, uniformity, high yield, and breeder right protection have turned hybrid cultivar development into the most successful breeding strategy in rapeseed (Brassica napus L.). The goals of this research were to develop the first CMS based rapeseed hybrids in Iran and to evaluate their performance and fertility. The effect of different traits on yield increasing of hybrids was also studied. Seven CMS lines were crossed with R2000 (a restorer-line) and the seed yield of hybrids was tested using a randomized complete block design with three replications in 2019-2020 and 2020-2021. Three of hybrids with 4.64, 4.40, and 4.38 tons per hectare, showed considerable yield and were significantly different than Nilufar, Neptune, and Nima (3.44, 3.37, and 3.30 tons per hectare, respectively), as check cultivars. R2000×A8 demonstrated the highest heterosis (34.71%) to high-check cultivar. All hybrids obtained were normal in terms of fertility, having no male-sterile flowers. Based on the results of principal component analysis and cluster analysis, the simultaneous increase in the number of pods per plant and the thousand seed weight, together with crossing the more distant parents will lead to more high yielding hybrids. The promising hybrids with high yield and remarkable fertility could be released as new cultivars after passing adaptability and stability experiments.

Environmental stress, especially drought stress, is one of the most important factors that reduce the growth and development of oil plants such as rapeseed in arid and semi-arid regions. The purpose of this research is to investigate the effect of biochar and biosulfur on seed yield and some ecophysiological traits of rapeseed under drought stress conditions in winter cultivation.

This research was carried out in form of a factorial split-plot with randomized complete block design having three replications in 2019 in Karaj. In this experiment, irrigation treatment witnessed three levels of 30%, 60%, and 100% of crop capacity as main plots, while biochar treatment saw three levels of no application and application of three and six tons per hectare and biosulfur treatment, two levels of application and non-application as plots. Subsidiaries were considered.

It was found that drought stress had a significant effect on the seed and oil yield of rapeseed. Thus, the amount of these traits in drought stress showed a decrease of 50% and 52%, respectively, compared to the control. Also, the use of six tons per hectare of biochar had increased by 49% and 36% in terms of its number of pods per plant and the number of seeds per pod. Also, the interaction effect of biosulfur application and the use of six tons of biochar had the greatest effect on the traits of the number of pods per plant and harvest index.

The results showed that the use of biofertilizers can be used as a suitable method to increase the yield of rapeseed. Increasing oil percentage and grain yield will ultimately increase the field and economic yield (oil) of the rapeseed plant.

This experiment was carried out as split plot factorial based on complete block design with three replications during 2018-2019 cropping season in two regions including Qazvin and Karaj, Iran. Irrigation regimes including three levels of full irrigation, irrigation interruption from flowering stage and irrigation interruption from silique stage and four levels of micronutrients including zero (control), foliar application of Zn, Fe and Zn + Fe as factorial in main plot and two cultivars of rapeseed namely Sarygol and RGS300 in sub plot comprised experimental treatments. The greatest number of secondary branch per plant (7.72), number of silique per secondary branch (125.80), 1000-seed weight (5.46 g), biological yield (23760 kg/ha), seed yield (5668 kh/ha) and oil yield (5668 kg/ha) obtained in RGS300 cultivar under full irrigation and foliar application of Zn + Fe conditions that showed no significant difference with Sarigol cultivar under similar condition. In this experiment, irrigation interruption from flowering stage showed the greatest loss of seed yield in rapeseed and under water deficiency from flowering stage, foliar spraying of Zn + Fe enhanced seed and oil yield of RGS300 and Sarigol cultivars equal 107 and 153 percent in comparison with control, respectively.Integrated application of Zn + Fe as foliar application increased seed yield through improving of vegetative and reproductive growth of rapeseed plants in different irrigation regimes. Hence, combined foliar application of Zn + Fe micronutrients both with four per thousand concentrations could be recommended to enhance quantitative and qualitative yield of rapeseed under similar climatic condition

In order to determine drought stress in the final stages of flowering up to 50% pods and pods until harvest tolerance in canola genotypes via yield-base stress tolerance indices, a split plot experiment has been conducted based on the randomized complete block design with three replications at the research farm of department of plant production and genetics, Agricultural Sciences and Natural Resources University of Khuzestan, Iran during 2020-2021. The main plots include three irrigation treatments: the control (without any interruption of irrigation), interruption of irrigation in the beginning of flowering stage (phenology code 60) to the formation of 50% pods (phenology code 75), and  interruption of irrigation in the stage of formation of pods until harvest (Phenology code 99) in the main plots. Also, the genotypes (Long pod, Aram, RGS 003, Jankom, Solar, Hayola 4815, Mahtab, Julius, Agamax, and Sala) are arranged in sub-plots with respect to irrigation treatments. They are reliable indices to identify drought tolerant rapeseed cultivars. Indices MP, GMP, and STI are the most suitable ones to evaluate drought stress tolerance in different treatments. The highest grain yield of control treatment belongs to Hayola 4815, Long pod, Solar genotypes (2093.8, 1791 and 1700 kg / ha), and the lowest to Jankum genotype (832.1 kg / ha), in flowering Stress up to 50% pods. The highest grain yield is observed in Hayola 4815 (1563.9 kg / ha) and Lon gpod (1150.9 kg / ha) and the lowest grain yield in Jankum and Mahtab genotype (540, 935.5 kg / ha).

Rapeseed is one of the most important oilseed plants in the world. Therefore, the selection of high-yielding genotypes is especially important in this plant. Production of high yielding hybrid cultivars is the main objectives of breeding programs in rapeseed. Also, study on relationships between yield and other agronomic traits will improve the efficiency of a breeding program with appropriate selection criteria. Therefore, the objectives of this research were to the selection of new rapeseed hybrids and to find interrelationships among traits.

In this research, 21 rapeseed hybrids (yielded crossing between 3 restorers with 7 cytoplasmic male sterile lines) along with four cultivars Okapi, Ahmadi, Nima and, Nafis were evaluated in a randomized complete block design with three replications in Seed and Plant Improvement Institute (SPII), Karaj during the 2018–2020 growing seasons. The phonological, morphological characteristics and yield and its components including days to flowering starting, days to end of flowering, flowering period, days to physiological maturity, plant height, number of lateral branches, number of pods per plant, number of seeds per pod, and head, thousand seed weight, oil content, seed yield, and oil yield were measured. In this study, the selection index of ideal genotype (SIIG) and factor analysis were used to select rapeseed genotypes and study the relationships between the traits.

Based on the SIIG index, the genotypes G15, G3, G10, G5, G22, G8, G4, and G25 with the highest SIIG values (0.706, 0.680, 0.667, 0.665, 0.647, 0.641, 0.610, and 0.607 respectively) were the superior genotypes. On the other hand, G23, G18, G1, G24, G21, G7, and G13 genotypes with the least amount of SIIG value (0.219, 0.315, 0.334, 0.383, 0.397, 0.398, and 0.402 respectively) were the weakest genotypes for most studied traits. The genotypes G15, G5, G22, G3, and G10 with high SIIG values as well as higher oil yield that total averages were recognized as superior genotypes from the point of yield and other agronomic traits. Also, the results of factor analysis indicated a positive relationship between thousand seed weight with seed yield and oil yield.

Generally, the results indicated that the genotypes of G15, G5, G22, G3, and G10 were recognized as superior genotypes from the point of oil yield and other agronomic traits. Also, the trait of thousand seed weight could be used as a suitable criterion in selecting for increased yield in rapeseed breeding programs.

In order to investigate the effect of intensity (40 and 59 kHz), power (60, 80 and 100 watts) and duration (2, 4, 6, 8 and 20 minutes) of ultrasound waves on germination, growth and physiological characteristics of canola (Ekapi cultivar), a factorial experiment was carried out as completely randomized design in the Seed Technology Laboratory of the Faculty of Agricultural Sciences of Shahed University in 2019. Germination percentage, germination rate, average time required for germination, weight and length index of seedling vigor, seedling length, seedling dry weight and some physiologic parameters including chlorophyll a, chlorophyll b, total chlorophyll, carotenoid content and relative water content were measured. The interaction of intensity, power of the device and duration of application of ultrasound waves affected all studied traits except germination rate, seedling dry weight and relative water content. The highest germination percentage of rapeseed seeds in the treatment composition was related to 59 kHz waves, 100 watts and 6 minutes with an average of 88.33%. The content of carotenoids, total chlorophyll, chlorophyll a and chlorophyll b were observed with an average of 22.57, 49.08, 22.62 and 26.47 μg/g fresh weight in the application of 40 kHz ultrasonic waves with a power of 80 watts for two minutes. Based on the results, it can be concluded that the use of ultrasound was able to improve the germination, growth and physiologic characteristics of rapeseed. Therefore, according to the conventional time-consumed seed dormancy breaking methods, the use of ultrasound as a new technology to break dormancy as an alternative to older methods is recommended.

The purpose of this study is to use meta-analysis to combine the results of experiments conducted in Iran on the effect of drought stress due to irrigation cessation at different stages of development, on yield and yield components of canola. The studied traits include grain yield, oil and dry matter, number of pods per plant, number of seeds per pod, 1000-seed weight, and grain oil content. Results show that all traits under the influence of stress at different stages of development are significantly affected by drought stress. Irrigation interruption in different stages on average cuts grain yield by 34.5%, oil yield by 36%, oil content by 4.7%, dry matter by 25.8%, number of pods by 35.4%, seeds per pod ratio by 18.5%, and 1000-seed weight by 17.5%, while raising the proline content by 49.9%. The highest reduction rate in grain and oil yield belongs to the irrigation cut-off treatment, in turn leading to a reduction of 41% and 46% of these two traits, respectively. Also, regarding the yield components, the highest reduction in the number of pods per plant, number of seeds per pod, and 1000-seed weight is observed in the cut-off treatments of stem, flowering, and podding, respectively.

MicroRNAs(miRNAs) are a group of small non-coding RNAs of approximately 18 - 24 nucleotides that play a negative role in post-transcriptional changes in eukaryotes. The miRNAs are then loaded onto the argonate family proteins (AGO) to form a protein complex (RISC). The primary activity of the RISC complex is to direct the mature miRNA to the target RNA and to stop protein production (Megah et al., 2018). miRNAs are involved in response to abiotic stresses in plants such as drought; several miRNA families have been reported in response to drought stress in rice, tomato, Arabidopsis, Medicago truncatula, peach, barley and wheat (Akdogan et al., 2015). The purpose of this study was to identify new microRNAs and their role in suppressing and preventing expression of some of their target genes in rapeseed.

A total of 38589 known mature miRAN sequences were downloaded from the miRBase database. The miRNA sequences were used as known sequences to find conserved miRNAs based on homology search for miRNAs with rapeseed GSS sequences.103369 GSS for rapeseed was downloaded from NCBI database. Mature miRNA sequences were uploaded to the BLASTn algorithm to search for homology with rapeseed GSSs in Linux. The miRNA sequences as known sequences and the GSS sequences as sequences were compared with each other for homology search. GSSs with mature miRNA sequences up to four mismatches were selected as candidates (Zhang, 2005). GSS sequences were used instead of EST sequences because miRNAs can generate GSS sequences in addition to EST sequences. Consequently, GSSs were sequenced between the BLASTx miRNA sequences and the GSS coding sequences were deleted and only non-coding GSS sequences remained (Karimi et al., 2017). Mfold software was used to predict the secondary structure of candidate miRNAs (Vivek, 2018). ath-miR5021 and ath-miR8175 from Arabidopsis, bol-miR9410 and bol-miR9411 from wild cabbage and cas-miR11592 from Camelina sativa were selected from the psRNATarget website (Dai and Zhao, 2011.

For miR5021: The NST1 target gene encodes a protein called Stress response protein NST1, which plays a role in regulating secondary wall thickness in plants and preventing its destruction against a variety of stresses (Mitsuda et al., 2005). For miR9410: The HST gene is one of the target genes that encodes an enzyme called Shikimate O-hydroxycinnamoyltransferase in plants, which participates in the phenylpropanoid biosynthesis and heat stress control in plants, propanoids as secondary metabolites during developmental stages. The plant is synthesized in response to stress conditions (Lukasik et al., 2013).

Types of microRNAs and their role in suppressing target genes during live and abiotic stresses in barley, wheat, soybean, cucumber, alfalfa, olive, rice have been reported (Ozhuner et al., 2013). In this study, we tried to identify new microRNAs and their role in suppressing target genes for the first time in rapeseed. The results of this study showed that among the newly identified microRNAs, miR5021 and miR9410 families play an important role in suppressing NST1 and HST target genes, respectively, especially during stress in canola.. Therefore, identifying the molecular mechanism of these microRNAs and their target genes can help us in selecting drought and heat resistant varieties for rapeseed. A study of microRNAs for boron stress tolerance in leaves and roots of barley showed that of the four new microRNAs identified, miR408 was more involved in regulating cell signaling in leaves than the other three microRNAs (Ozhuner et al., 2013). Also, no response has been reported in hybrid and maize inbred lines for miR172 under drought and salt stress conditions (Kong et al., 2010). Therefore, understanding the cellular regulation mechanism for new microRNAs, including how to regulate the activity pathway of antioxidant enzymes such as superoxide dismutase in organs such as leaves, roots and shoots of canola, requires further investigation.

MicroRNAs can be used as a new molecular tool alongside existing classical breeding methods to improve the genetic status of plants to promote tolerance to a variety of biotic and abiotic stresses in plant breeding.

in oIn order to investigate the quantitative and qualitative response of autumn rapeseed cultivars to nitroxin biological fertilizer in drought stress conditions, a split plot factorial experiment was conducted based on complete randomized blocks design with 4 replications in the research farm of Agricultural Research and Training Center And the natural resources of Bojnourd city in 2015-2016 and 2016-2017. Factors were: drought stress at three levels (low, medium and serve) as the main plot and Nitroxin application (non-inoculation, inoculating with nitroxin), 3 rapeseed cultivar Natalie, Okapi and Neptune in factorial arrangment as the sub plot. Severe stress reduced the plant height (62.5%), the number of laterl branches (76.3%), the number of pods per plant (45.56%), the number of seeds per pod (1.3%), and the weight of 1000 seeds (11.52%), seed yield (19.2%), seed oil percentage (5.5%) and seed oil yield (90.45%) compared to low stress conditions. Maximum plant height (156 cm) and number of laterl branches (8.1), seed number in pods (24.8) and weight of one thousand seeds (3.44 gr) were observed in Neptune cultivar, grain yield (2062 kg.ha-1) and seed oil yield (933 kg.ha-1) in Natali cultivar and protein yield (321 kg.ha-1) in Natalie and Neptune cultivars. Overall, the results showed that the Natali was more tolerant to drought stress than other cultivars. Nitroxin also increased the tolerance of rapeseed to drought stress.

In order to investigate the interaction between sodium nitroprusside and drought stress on photosynthetic pigments and their relationship with yield and yield components of rapeseed, an experiment was conducted during two cropping years (2015-16 and 2016-17) at Hamedan Agricultural and Natural Resources Research Center. The experiment was carried out as a factorial in randomized complete block design with three replications. Experimental factors were irrigation levels including full irrigation (control), irrigation termination from beginning silique stage and irrigation termination from grain filling stage, and four treatments of foliar application of sodium nitroprusside with concentrations of 0, 100, 200 and 300 μM. The results showed that irrigation termination significantly reduced the amounts of studied traits. Sodium nitroprusside foliar application increased the amounts of photosynthetic pigments, yield and grain yield components under drought stress and non-stress conditions. The highest and the lowest grain yield were obtained in the combination treatments of plant foliar application with 300 mM sodium nitroprusside and full irrigation (5129 kg/ha) and non-foliar application and irrigation interruption at the beginning silique stage (3396 kg/ha), respectively. The experiment indicated that sodium nitroprusside application can have positive effects on photosynthetic pigments, yield components and grain yield of rapeseed under drought stress and non-stress conditions, and therefore its application can greatly mitigate the adverse effects of drought stress in water deficit conditions.

To investigate the effect of plant density on agronomic traits of winter rapeseed (Brassica napus L.) cultivars under foliar application of salicylic acid a factorial split-plot arrangement in randomozide complet block design with three replications was carried out in Karaj, Iran, in two cropping seasons (2015-2017). Plant density at three levels of 40, 50 and 60 plants.m-2 and salicylic acid at two levels of 0 (non-application) and application with a concentration of 1‰ in two stages of 6 leaf and stem elongation were assigned in main plots and rapeseed genotypes; HW118, WPN6, HL3721, L14, Tassilo and Natali were randomized in sub-plots. The Plant density × salicylic acid × genotype interaction effect was significant (P≤0.01) on plant hight, number of silique on the main stem and branches, seed number of silique on the main and branches, 1000-seed weight, seed yield, oil yield, biological yield and total chlorophyll content. This interaction effect was also significant (P≤0.05) on seed oil content. All rapeseed genotypes showed positive responses to foliar  application of salicylic acid at different plant densities, and L14 and Natali genotypes in 40 plants.m-2 and application of salicylic acid had the highest seed yield (5629 and 5448 kg.ha-1), oil yield (2444 and 2352 kg.ha-1) and 1000 seed weight (5.3 and 5.1 g), respectively. Therefore, for rapeseed production, especially in low densities (40 plants.m-2), foliar application of salicylic acid is suitable for increasing seed yield.

Over the past decades, the economic benefit has prompted farmers to grow rapeseed. Consequently, the global rapeseed production increased considerably, and today the crop is grown in shorter rotations than ever before. Rapeseed crops usually yield more if grown after other species than when grown after rapeseed. Crop rotation is a succession of crops grown on the same land. Pulses in crop rotations can improve the productivity of subsequent crops due to increased soil available N and other agronomic benefits. Also, Legume plants can promote C storage by enhancing the formation and stabilization of soil aggregates that protect soil organic C from mineralization. In order to evaluation of rapeseed growth and yield under nitrogen fertilizer and pre-cropping with corn and chickpea crops, an experiment was conducted.

A factorial experiment was designed based on randomized complete blocks with three replications and implemented on a sandy clay soil during 2012-13 and 2013-14 growing seasons, at the Agricultural Research Station, Faculty of Agriculture, University of Bu-Ali Sina, Hamedan, Iran. The first factor consisted of chickpea and corn (forage) and the second factor was urea fertilizer levels of 0, 40, 80, 120, 160 and 200 kg/ha. Harvest operation was done in July 2013 and 2014. Random samples 2 m2 areas were harvested by cutting the stems near ground level to determine the crop grain and straw yield. Evaluated traits include plant height, grain yield components, biological and grain yield, harvest index, chlorophyll index and percentage of grain protein and oil. SAS procedures and programs were used for the analysis of variance (ANOVA) calculations.

The results showed that all of the evaluated properties of rapeseed affected by pre-cropping and nitrogen fertilizer treatments. But, none of the rapeseed traits do not affect by pre-cropping × nitrogen fertilizer. The highest biological yield and grain yield and protein percentage were observed in chickpea pre-cropping treatment (about 924 and 263 g m-2 and 22.29%, respectively). Chickpea pre-cropping treatment increased rapeseed biological yield and grain yield and protein percentage about 14, 13 and 15 percent in comparison to corn pre-cropping treatment. Pay attention to the improved physicochemical conditions of the soil after cropping legumes such as chickpea, it is normal to improve the growth and yield characteristics of the next crop (in this study, rapeseed). Among the nitrogen fertilizer levels, the lowest rapeseed biological yield and grain yield and protein percentage (about 567 and 125 g m-2 and 19.05%, respectively) were achieved at 0 kg ha-1 N fertilizer consumption. Also, the highest rapeseed biological yield and grain yield and protein percentage (about 1311 and 342 g m-2 and 21.06%, respectively) were observed at 200 kg ha-1 N fertilizer consumption, but it had no significant difference with 160 kg/ha treatment. One of the most well-known effects of nitrogen fertilizers increased the properties of crop growth. In this study, rapeseed growth and yield characteristics such as plant height, chlorophyll index, grain yield components, biological and grain yield, harvest index, and percentage of grain protein and oil increased due to urea application.

It seems that in rapeseed farming, legumes pre-cropping such as chickpea pre-cropping is a good solution to reduce the use of nitrogen fertilizers and to contribute to environmental health. Also, attention to optimum fertilizer levels and non-overuse of fertilizers will contribute to agricultural sustainability.