N2-fixation by ammonium-excreting Azospirillum brasilense in auxine-induced root tumours of wheat (Triticum aestivum L.)

Summary Wheat seedlings, treated with the auxine 2,4-dichlor-phenoxy acetic acid (2,4-D) during germination developed only a residual root system. Root elongation was extremely restricted and root tips were deformed to thick club-shaped tumours. When 2,4-D was added in a later stage of plant growth the plants developed additional nodule-like knots along primary roots. Root and shoot dry-matter production was slightly repressed in all 2,4-D treatments and N translocation from roots to shoots was repressed as well. When transferred to an auxine-free growth medium, the 2,4-D-affected roots were not capable of complete recovery. In plants inoculated gnotobiotically with Azospirillum brasilense, either with the wild type or with the NH ₄ ⁺ -excreting mutant strain C3, a 2,4-D addition increased rhizosphere acetylene-reduction activity at pO₂ 1.5 kPa. The O₂ sensitivity of root-associated nitrogenase activity tended to be reduced. The number of root-colonizing bacteria, at approximately 10⁸ colony-forming units (cfu) per g dry root, was similar in the 2,4-D treatments and untreated controls. Plant treatment with high concentrations of the chemical isomer 3,5-dichlor-phenoxy acetic acid (3,5-D) did not have comparable effects, either on plant development or on rhizosphere-associated nitrogenase activity. Root-tumour tissue inhabited by A. brasilense showed purple staining when subjected to a tetrazolium chloride solution, which may indicate intensive local nitrogenase activity in this tissue. Exposed to an ¹⁵N₂-enriched atmosphere, plants treated with 2,4-D and with A. brasilense incorporated significantly higher amounts of ¹⁵N than untreated controls. In all cases the highest values of ¹⁵N enrichment were found following inoculation with the NH ₄ ⁺ -excreting mutant strain C3. Present address: F. A. Janssens Laboratory of Genetics, Catholic University of Leuven, Willem de Croylan 42, B-3001 Heverlee, Belgium     

Macronutrient accumulation in wheat crop (Triticum aestivum L.) with Azospirillum brasilense associated with nitrogen doses and sources

Abstract

New studies are needed to optimize the nitrogen (N) amount that can be applied to utilize the Azospirillum brasilense benefits. In addition, information regarding the interaction between the urease inhibitor and biological nitrogen fixation (BNF) and how they affect the macronutrients accumulation are also needed. We evaluate the effect of N sources and doses associated with A. brasilense regarding the macronutrients accumulation in straw and grains and wheat grain yield in tropical conditions. A randomized block experimental design was used with four replications in a 2?×?5?×?2 factorial arrangement as follows: two N sources (urea and urea with urease enzyme inhibitor NBPT; five N doses (0, 50, 100, 150, and 200?kg ha^?1) applied in topdressing; with and without A. brasilense inoculation. We found that an increase in N doses positively influenced the accumulation of macronutrients in straw and grains and the wheat grain yield. N sources have similar effects. Inoculation with A. brasilense increased accumulation of Mg and S in straw and P, Ca, and Mg in grains, regardless of the N dose. The inoculation with A. brasilense associated with 140?kg ha^?1 of N increased wheat grain yield. The inoculation can contribute in a more sustainable way to wheat nutrition and optimizing N fertilization.     

Assessment of terminal drought tolerance among elite wheat (Triticum aestivum L.) genotypes using selected agronomic and physiological traits

ABSTRACT

The selection response of wheat (Triticum aestivum L.) under water-limited condition can be enhanced through breeding novel genotypes possessing drought-adaptive and yield-related agronomic and physiological traits. The objective of this study was to evaluate terminal drought tolerance among bread wheat genotypes and select superior parents for breeding. Agronomic and physiological responses of 28 wheat lines were assessed under well-watered (WW) and terminal drought (TD) treatments using a 7?×?4 alpha-lattice design under rainout shelter (RS) and glasshouse (GH) environments. Significant (p?≤?0.05) genotype?×?environment interaction effects were observed for number of days to heading (DTH), number of days to maturity (DTM), number of productive tillers per plant (TN), grain yield (GY), thousand kernel weight (TKW), stomatal conductance (SC), leaf canopy temperature (LCT) and chlorophyll content index (CCI) suggesting varied genotypic response under WW and TD treatments. Correlation analysis revealed significant associations TN and GY (r?=?0.67; p?≤?0.001), TKW and GY (r?=?0.72; p?≤?0.001), CCI and GY (r?=?0.39; p?≤?0.05) under TD treatment. Drought tolerant wheat genotypes such as LM100, LM72, LM22 and LM95 are useful for direct cultivation and for developing breeding populations with enhanced yield performance.     

Yield response of spring wheat cultivars (Triticum aestivum and T. turgidum) to inoculation with Azospirillum brasilense under field conditions

Summary Eight commercial Israeli spring wheat cultivars (six Triticum aestivum and two T. turgidum) grown with 40 and 120 kg N/ha were tested for responses to inoculation with Azospirillum brasilense. At the low level of N fertilization (40 kg/ha), five cultivars showed significant increases in plant dry weight measured at the milky ripe stage; however, by maturation only the cultivar Miriam showed a significant increase in grain yield. Two cultivars, which had shown a positive inoculation effect at the earlier stages, had a significant decrease in grain yield. No significant effect of inoculation was found at the high N level. To confirm those results, four wheat (T. aestivum) cultivars were tested separately over 4 years in 4 different locations under varying N levels. Only Miriam showed a consistently positive effect of Azospirillum inoculation on grain yield. Inoculation increased the number of roots per plant on Miriam compared with uninoculated plants. This effect was found at all N levels. Nutrient (N, P and K) accumulation and number of fertile tillers per unit area were also enhanced by Azospirillum, but these parameters were greatly affected by the level of applied N. It is suggested that the positive response of the spring wheat cultivar Miriam to Azospirillum inoculation is due to its capacity to escape water stresses at the end of the growth season.     

Response of selected drought tolerant wheat (Triticum aestivum L.) genotypes for agronomic traits and biochemical markers under drought-stressed and non-stressed conditions

ABSTRACT

Genetic improvement of wheat for drought tolerance can be achieved by developing suitable ideotypes with enhanced yield-response associated with agronomic traits and biochemical markers. The objective of this study was to determine drought response of elite drought tolerant wheat genotypes using agronomic and biochemical traits to select promising lines for breeding. Fourteen wheat genotypes selected from the International Maize and Wheat Improvement Center’s heat and drought tolerance nursery and one standard check variety were evaluated under drought-stressed (DS) and non-stressed (NS) conditions using a randomised complete block design in three replications. Significant (P?<?0.05) genotype, drought condition and genotype?×?drought condition interaction effect were detected for the tested traits suggesting differential response of genotype for selection. Grain yield positively correlated with sucrose (r?=?0.58; P?<?0.05), fructose (r?=?0.52; P?<?0.05) and total sugar (r?=?0.52; P?<?0.05) contents under NS condition and with sucrose (r?=?0.80; P?<?0.001), total sugar (r?=?0.84; P?<?0.001) content, proline content (r?=?0.74; P?<?0.001) and number of grains per spike (r?=?0.58; P?<?0.05) under DS condition. Genetically unrelated wheat genotypes such as SM04, SM19, SM29, SM32, SM45 and SM97 possessing key agronomic and biochemical traits were selected for cultivar development for drought-stressed environments.     

Peculiar effect of Azospirillum inoculation on growth and nitrogen balance of winter wheat (Triticum aestivum)

Summary Wheat plants (Triticum aestivum) grown in pots and in the field under the Mediterranean climate of the south of France were inoculated with a strain of Azospirillum brasilense. Comparisons with non-inoculated plants grown under the same conditions showed significant responses to inoculation with an increase in the number of fertile tillers, shoot and root dry weight, and root to shoot biomass ratio. The roots of inoculated plants attracted relatively more assimilates than those of the control plants until a late stage of growth (heading stage) but the rhizosphere respiration expressed per unit of root growth was not increased by inoculation. Nitrogen yield, both total and in grains, was also enhanced; however, N percentages of all aerial parts of the plants grown in pots were always statistically lower after inoculation than in the control. At maturity, the N % in seeds was 1.81 and 2.45, respectively. The possible mechanisms of this effect of inoculation under the experimental conditions of this study are discussed.     

Effects of P fertilization level on phosphorus uptake and agronomic traits under deficit irrigation in winter wheat (T. aestivum L.)

Abstract

Enhancing the phosphorus (P) use efficiency is critical for the sustainable cultivation of winter wheat. In this study, we investigated the effects of P fertilization level on plant P-uptake and agronomic traits under deficit irrigation, by using two wheat cultivars sharing contrasting water responses (i.e., Jimai 585 and Shimai 22). The high P level treatment (P120) improved plant biomass and P accumulation at each growth stage, grain yields, P remobilization amount to grain (PRA), P remobilization rate (PRR), and P contribution rate (PRR) of the cultivars with respect to the low P treatments (i.e., P90 and P60). Compared with Jimai 585, a cultivar acclimated to affluent water, the drought tolerant cultivar Shimai 22 exhibited similar behaviors on plant biomass, P-associated traits at each stage, and agronomic traits at maturity under P120. However, Shimai 22 was more improvement on P-associated and agronomic traits than Jimai 585 under P60 and P90. P contents were increased whereas moisture contents decreased in soil profile treated by P120 with respect to those by P60. Meanwhile, the soil profile cultivated by Shimai 22 displayed reduced moisture and P contents under P deprivation (i.e., P90 and P60) respect to that by Jimai 585, suggesting the contribution of more consumption of soil P and water storage to improved agronomic traits of Shimai 22. Together, our investigation suggested that suitable P input management positively mediates plant P-associated traits and grain formation capacity under deficit irrigation by improving supply and internal translocation of P across tissues in winter wheat plants.     

Comparative growth and physiological responses of two wheat (Triticum aestivum L.) cultivars differing in salt tolerance to salinity and cyclic drought stress

Two cultivars of wheat (Triticum aestivum L.) with differential salinity tolerance were compared by evaluating the growth attributes, pigment composition and accumulation of Na⁺, K⁺, Zn²⁺, Fe ²⁺, Mn ²⁺ and proline. Wheat cultivars Al-Moiaya (AM) (salt tolerant) and Habbe-Druma (HD) (salt sensitive) were subjected to four levels of salinity (1.21 dS m^?1, 4.4 dS m^?1, 8.8 dS m^?1 and 13.2 dS m^?1) in factorial combinations with three drought stress (FC 30%, FC 60% and FC 90%) treatments in a randomized complete block design. Plant dry weight, leaf area ratio (LAR), soluble protein and total chlorophyll (Chl) content were higher in AM than HD. Salt-tolerant AM maintains a higher K⁺/ Na⁺ ratio and thereby is able to grow better than the salt-sensitive HD under both the stresses. The lower foliar Na⁺ in AM resulted in retention of higher Chl content, reflected in the strong positive correlations between plant ion status and Chl contents (Na⁺-Chl r² = 0.83; Chl- Fe²⁺ r² = 0.76; Zn²⁺ r² = 0.93 and Mn²⁺ r² = 0.88). In conclusion, our results suggested that the K⁺/Na⁺ ratio, exclusion of Na⁺ and ion homeostasis play much more important roles in the tolerance to salinity and drought stress than the compatible osmolyte, proline.     

Auxin production by rhizobacteria was associated with improved yield of wheat (Triticum aestivum L.) under drought stress

Drought tolerant rhizobacteria of the genus Bacillus, Enterobacter, Moraxella and Pseudomonas colonizing the root system of Acacia arabica were isolated to mitigate the drought stress of wheat (Triticum aestivum L.). In vitro auxin production by rhizobacteria was quantified by Ultra High Performance Liquid Chromatography (UPLC). Analysis of the crude extracts detected the indole-3-acetic acid (IAA), indole-3-carboxylic acid (ICA) and indole-3-lactic acid (ILA). Highest IAA production of 25.9 µg ml^?1 was observed for Bacillus amyloliquefaciens S-134. Pot trials were conducted to evaluate the role of rhizobacteria to enhance the growth of wheat at different water regimes. At highest water stress i.e. 10% field capacity (FC), significant improvement of shoot length was observed with B. amyloliquefaciens S-134. For yield parameters, B. muralis D-5 and E. aerogenes S-10 recorded 34% and 1 fold increases for spike length and seed weight, over respective control at 10% FC. Mixed culture combinations of M-2 (B. thuringiensis S-26, D-2, B. amyloliquefaciens S-134, B. simplex D-11) and M-3 (M. pluranimalium S-29, B. simplex D-1, B. muralis D-5, P. stutzeri S-80) showed significant improvement for tillers and number of spikelets. In conclusion, application of the drought tolerant rhizobacteria can help to overcome productivity losses in drought prone areas.     

不同小麦品种生育期氮素效率差异的变化特征

以6个小麦品种(洛麦1、郑麦9023、豫麦18、小偃22、小偃6和小偃107)为材料,设置低氮和高氮两个处理,分别在小麦的4个生育期收获取样,研究了不同小麦品种生育期氮吸收和利用效率差异的变化特征及其与相关生理参数的关系。研究结果表明,氮吸收方面,洛麦1为低氮高效品种,小偃107为高氮高效品种;氮利用方面,豫麦18为低氮高效品种,洛麦1为高氮高效品种;小偃6在两个氮处理中无论是氮吸收还是氮利用均为低效品种。造成小麦氮吸收或利用效率差异的主要时期为灌浆期到成熟期之间的籽粒产量形成阶段。低氮条件下,氮利用高效品种灌浆期的地上部谷氨酰胺合成酶活性也较高,而根系生物量和根系活力与小麦氮吸收效率无明显相关。     

Azospirillum strains isolated from roots and rhizosphere soil of wheat (Triticum aestivum L.) grown under different soil moisture conditions

The present study deals with the isolation and characterization of Azospirillum strains isolated from roots and rhizosphere soil of wheat (at tillering and anthesis stages) plants grown under different moisture regimes in the field and in pots. The survival of Azospirillum isolates from plants of irrigated field and those from well-watered pots was higher than that of Azospirillum strains isolated from roots and rhizosphere soils of plants grown under arid and semiarid (14–8% soil moisture) field conditions and under water-stressed (8% soil moisture) conditions in pots. On the basis of carbon/nitrogen source utilization, the Azospirillum strains isolated from wheat under field and pot conditions were grouped in three groups. The unweighted pair group method with arithmetic means cluster analysis based on random amplification of polymorphic DNA showed that two groups of Azospirillum were similar. The strains isolated from plants (at tillering stage) grown under low moisture conditions either in pots or in field were genetically similar to strains isolated from plants grown under well-watered conditions in both pots and field. Inoculation of wheat with isolates from water-stressed plants induced tolerance to water stress in inoculated plants. Isolates from water-stressed conditions exhibited lower production of indole acetic acid, gibberellic acid, and trans zeatin riboside but a higher production of abscisic acid.     

Influence of Rhizobium/Azotobacter and Rhizobium/Azospirillum combined inoculation on mineral composition of faba bean (Vicia faba L.)

 Mixed inoculation of Vicia faba L. with four different Rhizobium/Azospirillum and Rhizobium/Azotobacter combinations led to changes in total content, concentration and/or distribution of the mineral macro- and micronutrients, K, P, Ca, Mg, Fe, B, Mn, Zn and Cu, when compared with plants inoculated with Rhizobium only. The effects varied to a great extent among the Azotobacter and Azospirillum strains selected for combined inoculation. Received: 6 June 1998     

Water stress effects on biochemical traits and antioxidant activities of wheat (Triticum aestivum L.) under In vitro conditions

Water stress is one of the major environmental stresses that affect agricultural production worldwide, especially in arid and semi-arid regions. This research investigated the effect of water deficit, induced by PEG-6000 on wheat genotypes (GA-2002, Chakwal-97, Uqab-2000, Chakwal-50 and Wafaq-2001) grown in modified MS medium solution. Osmotic stress caused a more pronounced inhibition in leaf relative water content and leaf membrane stability more sensitive (index in Wafaq-2001 and Uqab-2000) genotypes compared with the tolerant (Chakwal-50, GA-2002 and Chakwal-97) genotypes. Upon dehydration, an incline in proline, total soluble sugar, total soluble protein, superoxide dismutase, peroxidase, catalase and malondialdehyde activity content were evident in all genotypes, especially at osmotic stress of ?8 bars. The observed data showed that status of biochemical attributes and antioxidant enzymes could provide a meaningful tool for depicting drought tolerance of wheat genotypes. The present study shows that genotypic differences in drought tolerance could be likely attributed to the ability of wheat plants to induce antioxidant defense under drought conditions. In order to develop genotypes with stable, higher yields in dry farming conditions, it is necessary to characterise genetic resources based on drought adaptation, determine suitable genotypes, and then use them in breeding programmes.     

Evaluation of bread wheat (Triticum aestivum L.) genotypes for yield and related traits under drought stress conditions

ABSTRACT

Drought is a major factor threatening crop production worldwide. Developing wheat varieties that are adapted to drought prone environments is a sustainable strategy to improve wheat production and productivity. The aim of this study was to evaluate and select bread wheat genotypes for yield and yield components, and for stability under drought stress and non-stress conditions. One hundred and twenty genotypes were evaluated at five test sites in the 2018/19 cropping season using a 10 x 12 alpha lattice design with two replicates. The level of drought stress was imposed using different sowing dates (early planting representing non-stressed, while late planting as drought stressed conditions) following the onset of the main rain at each site. Grain yield and yield components were recorded, and drought indices were calculated for each genotype. Among the drought tolerance indices, GMP, MP, HM, STI and YI were found to be the most suitable for predicting drought tolerance because they had significant and positive correlations with yield under drought stress and non-stress conditions. Rank sum analysis identified the most drought tolerant genotypes as ‘YS-34', ‘YS-85' and ‘YS-82’. The selected wheat genotypes are useful genetic resources for future drought tolerance breeding programmes in Ethiopia or similar agro-ecologies.     

Effects of biofertilizers and cycocel on some physiological and biochemical traits of wheat (Triticum aestivum L.) under salinity stress

In order to study the effects of biofertilizers and cycocel on some physiological and biochemical characteristics of wheat (Triticum aestivum L.) under salinity condition, a factorial experiment was conducted based on randomized complete block design with three replications under greenhouse condition in 2015. Treatments were included salinity in four levels [no salt (control or S₀), salinity 30 (S₁), 60 (S₂) and 90 (S₃) mM NaCl equivalent of 2.76, 5.53 and 8.3 dS m^?1, respectively], four biofertilizers levels [no biofertilizer (F₀), seed inoculation by Azotobacter chrocoocum strain 5 (F₁), Pseudomonas putida strain 186 (F₂), both inoculation Azotobacter + Pseudomonas (F₃)] and three cycocel levels [without cycocel as control (C₀), application of 600 (C₁) and 1000 (C₂) mg L^?1]. Results showed that salinity severe stress (90 mM) decreased chlorophyll content, relative water content (RWC), total chlorophyll, photochemical efficiency of PSII and yield of wheat. Whereas, soluble sugars and proline content, electrical conductivity (EC), the activity of catalase (CAT), peroxidase (POD), polyphenol oxidase (PPO) enzymes were increased. Similar results were observed in CAT, POD and PPO activities due to inoculation by biofertilizers and cycocel. Salinity at 30 mM increased the photochemical efficiency of PSII and chlorophyll content in plants grown under biofertilizer and cycocel treatment but with increasing salinity up to 90 mM mentioned parameters were decreased. The highest proline and soluble carbohydrate at all salinity levels were observed in plants treated in the highest cycocel level and Azotobacter+ Pseudomonas application. Generally, it was concluded that biofertilizers and cycocel can be used as a proper tool for increasing wheat yield under salinity condition.     

Differential allelopathic potential of sunflower (Helianthus annuus L.) genotypes on weeds and wheat (Triticum aestivum L.) crop

Studies were conducted to screen eight sunflower (Helianthus annuus L.) genotypes for their allelopathic potential against weeds and wheat crop, which customarily follows sunflower in Iraq. All sunflower genotypes significantly inhibited the total number and biomass of companion weeds and the magnitude of inhibition was genotype dependent. Among the eight genotypes tested, Sin-Altheeb and Coupon were the most weed-suppressing cultivars, and Euroflor and Shumoos were the least. A subsequent field experiment indicated that sunflower residues incorporated into the field soil significantly inhibited the total number and biomass of weeds growing in the wheat field. Sunflower genotypes Sin-Altheeb and Coupon appeared to inhibit total weed number and biomass more and significantly increased wheat yield compared with the least-suppressive genotypes (Euroflor and Shumoos). Chromatographic analyses by HPLC revealed the presence of 13 secondary metabolites in residues of the tested sunflower genotypes. All the isolated compounds appeared to be phenolic, with the exception of terpinol, which is a terpenoid derivative. The total concentration of Phytotoxins (phenolic compounds) was found to be higher in the most-suppressive potential genotypes compared with the least-suppressive genotypes.     

Comparison of protein quality and mineral element concentrations in grain of spelt (Triticum spelta L.) and common wheat (Triticum aestivum L.)

The cultivation of Triticum spelta (spelt) has no tradition in Hungary. In recent years the interest towards this old species renewed in many countries. This high‐nutritional cereal, which has a high ash and fibre content, can be used in many health‐oriented grain‐based food products. Therefore, field experiments have been conducted for some years to test the performance of this species under home growing conditions. Here we report the results of analyses for some important quality parameters of grain samples from the 1996/97 season in comparison with those of older and new home‐grown bread wheat cultivars. Three common wheat cultivars and one advanced spelt line were grown on small plots fertilised with an NPK dose necessary to reach the highest yield and quality. Spikes were sampled weekly from the time of 70–77% grain moisture to full ripening. The grains were analysed for ash, N, P and K content and amino acid composition. Concentrations of 16 other macro + micro elements and in the ripe grains, baking quality parameters were also assessed. The grain development of spelt showed a remarkable time‐lag compared to that of the common wheat cultivars. However, the highest thousand‐grain‐masses, ash, N, and P concentrations were measured in this cultivar after milk ripening. The grains of spelt contained the macro‐nutrient Mg and four micro‐nutrients (Zn, Mn, Fe, Cu) in higher concentrations compared to those of the common wheat varieties. The total and essential amino acid concentrations measured in the ripe grains of spelt were also remarkably higher.

Although its wet gluten content (47.5%) was considerably higher than that of the bread wheat cultivars, its breadmaking quality was poor.     

纳米氧化铜对小麦根系生理生化行为的影响

为阐明纳米金属材料暴露对植物生长的影响及其作用机制,采用模拟土壤的琼脂培养方法研究了纳米氧化铜(CuO NPs)对小麦(Triticum aestivum L.)根伸长及相关生理生化行为的影响。结果表明:小麦根伸长与CuO NPs暴露浓度之间存在指数相关关系,在低浓度CuO NPs(10 mg/L)暴露下得到一定程度促进,而在高浓度(100 mg/L)下受到强烈抑制。小麦根内超氧化物歧化酶(SOD)活性随CuO NPs暴露浓度的变化趋势与小麦根伸长具有一致性。另外,在1~100 mg/L范围内,随着CuO NPs暴露浓度的升高,小麦根内丙二醛(MDA)含量不断增加,但植物蛋白含量急剧降低。以上结果说明CuO NPs对根伸长抑制主要是由于纳米材料暴露造成植物细胞膜氧化损伤,小麦能通过提高根系活力对CuO NPs暴露作出适应性应激响应以减少纳米材料毒性的伤害。     

Effect of certain herbicides on growth and pathogenicity of take-all fungus on wheat (Triticum aestivum L.)

Summary The effects of Spray Seed (diquat + paraquat), Roundup (glyphosate), Banvel-D (dicamba), Treflan (trifluralin), Glean (chlorsulfuron) and Dacthal (chlorthal dimethyl) at concentrations of 0–500 ppm product on the vegetative growth, vigour and pathogenicity of Gaeumannomyces graminis var. tritici (Ggt) on wheat were examined. All herbicides with the exception of dicamba and chlorsulfuron inhibited fungal growth on potato dextrose agar (PDA) at concentrations 10–500-fold of rates recommended for use in the field. The vegetative growth of the pathogen growing out of straw colonized on PDA supplemented with 100 ppm diquat + paraquat or glyphosate was reduced by 47.4% and 42.4%, respectively. When portions of these colonies were subcultured onto unamended PDA, their growth and the pathogenicity of straw pieces colonized by these subcultures were found to be unaltered. Straw colonized by Ggt on agar amended with concentrations of diquat + paraquat or at all concentrations of glyphosate produced less root disease in wheat seedlings in comparison to those colonized on unamended agar. It is proposed that the reduced pathogenicity of inocula prepared on agar amended with these two herbicides is due to poor colonization by the pathogen of straw on these media, and that a similar effect on saprophytic colonization in the field could lead to a reduction in the field inocula of the pathogen.     

Optimum rate of nitrogen application and seed rate for deteriorated wheat (Triticum aestivum L.)

In order to study the effect of seed quality (SQ), seed rate (SR), and nitrogen rate (NR) on yield and yield components of wheat, an experiment was conducted as a factorial-split plot based on the randomized complete block design with four replications in Golestan Province, Iran. Treatments included the combination of SR and NR (recommended rate, 15 and 30% higher than the recommended rate) as the main plots, and SQ (control, 15, 30 and 45?h of accelerated aging) as the subplots. The interaction of NR?×?SR was significant on 1000-seed weight, seed yield, plant height, the number of seeds, biological yield, and harvest index. There was a significant reduction in all traits with an increase in seed aging. Seed yield had a significant and positive correlation with yield components. Using higher density and applying higher nitrogen fertilizer than those of recommended could reduce the negative effects of seed aging in wheat.