Among the nutrients used by the plant for the growth of nitrogen due to its participation in the structure of proteins, amino acids, coenzymes and nucleic acids are the main factors involved in plant growth and fertility. In recent decades, a group of soil bacteria in the rhizosphere has been introduced as plant growth-promoting bacteria that have been able to improve crop growth. In addition to the positive effects on soil properties, these bacteria are economically and environmentally beneficial and a good alternative to chemical fertilizers. Azotobacter and Azpirillum are the most important Plant growth-promoting rhizobacteria (PGPR) in plants that, in addition to bio-stabilizing nitrogen, produce growth-promoting hormones such as auxin, gibberellin, and cytokines. Modification of root system architecture by PGPR implicates the production of phytohormones and other signals that lead to enhanced secondary root branching and development of the root system. Since accessible water is the main factor limiting growth in rainfed agriculture, so one of the ways to improve nutrition and plant growth is to use PGPR. Therefore, this study was carried out on the role of Azospirillum + Azetobacter on root traits of new wheat cultivars in Ilam province.

In order to investigate the effect of growth-promoting bacteria on root system criteria in wheat under dryland conditions, a field experiment was carried out as a factorial arrangement based on a randomized complete block design with three replications at the farm station of Sarablah Agricultural Research Center during 2019-2020 cropping season. Experimental treatments include different wheat cultivars (Sardari, Karim, Koohdasht and Rijaw) and treatment of different fertilizer sources, including control (without fertilizer treatment), 50% urea chemical fertilizer (50% of required), Azospirillum + 50% 50% urea chemical fertilizer (50% of required), Azetobacter + 50% N fertilizer, Azospirillum + Azetobacter + 50% urea chemical fertilizer (50% of required) and 100% urea chemical fertilizer (100% of required). Each experimental plot consisted of eight planting rows with a row spacing of 20 cm and a length of 4 m. Nitrogen fertilizer (120 kg.ha-1) was applied at planting and stalking stage based on soil test. Phosphorus fertilizer was applied from triple superphosphate source at the recommended rate of 50 kg.ha-1at planting time. In this study, root length, root fresh and dry weight, root volume, root surface, root diameter, specific root length, root length density, root specific mass, root tissue density and root surface area density were evaluated. Experimental data were analyzed using SAS statistical program. Comparison of means were done by Duncan test and graphs were drawn with Excel software.

The results of this study showed that the interaction between cultivar × fertilizer sources was significant in root characteristics of dryland wheat, so that the maximum root length (115.6 cm), root volume (13.3 cm3), root surface (137.2 cm2), specific root length (46.9 cm root length.g-1 DW root), specific root mass (0.0045 g of DW roots.cm-3 soil volume), root length density (0.214 cm root length.cm-3 soil volume), root tissue density (32.4 g root.cm-3 soil volume) and root surface area density (127.5 cm2.cm-3) was obtained in Rijo cultivar × Azospirillum + Azetobacter + 50% 50% urea chemical fertilizer (50% of required) compared to control treatment (without fertilizer sources).

The results showed that due to the lack of rainfall in most rainfed fields of the province and also due to the positive effect of fertilizer biofertilizer in maintaining soil moisture, improving the physical and chemical quality of soil, to achieve proper grain yield in rainfed conditions of biofertilizer with chemical fertilizer Used nitrogen. In this study, it was observed that in the combined system of biochemical and chemical fertilizers, the rooting system increases so that the maximum root length, root volume, root area, root-specific volume, root length density, root tissue density and root surface density was observed from Rijaw cultivar × Azospirillum + Azetobacter + 50% N chemical fertilizer.  Bacteria increase plant growth by affecting the plant by improving physiological and biochemical conditions to increase resistance to adverse environmental factors in rainfed agriculture. Therefore, the results of this study can be concluded that in rainfed conditions where the intensity and fluctuations of rainfall are not predictable, having a strong root system can greatly reduce the harmful effects of water deficit against environmental stresses in the region and cause an acceptable increase in the yield of dryland wheat grain.

Two different propagation procedures including aeroponics and soil systems were compared for the minitubers production in potato. The minitubers were evaluated for several quality characters. The plant materials were from three cultivars, Agria, Marfona and Savalan. The plantlets were grown in aeroponics and soil production systems at a plant density of 100 plants per m-2 and stem length, root length, stem diameter and yield were measured in both experiments. In the other experiment, germination, stem length and yield were measured for minitubers which were produced in aeroponics production system. Analysis of variance indicated that the main effects of cultivar and production system were significant for stem length, root length, stem diameter and yield. Also cultivar by production system interaction was highly significant at 0.01 probability level for stem length, root length and minituber yield of the plants. The aeroponics system led to increase in stem length, root length, stem diameter and yield. Cultivars Agria in terms of stem length and Marfona in terms of root length, stem diameter and minituber yield were the most favorable genotypes obtained from aeroponics production system. Minitubers of Marfona had more yield and better quality characters. It seems that cultivar Marfona could be considered as the most favorable genotype due to high performance in minituber production and having quality characters after planting.

Drought stress is the main factor affecting on plant growth in dry and sub-dry regions and had the most importance than other abiotic stresses at seedling establishment. So، today''s، the great amounts of biological researches are about drought stresses. In this study، the effect of drought stresses (100، 75، 50 and 25% field capacity) on seedling survival، growth (height، basal diameter، leaf area، root length، root volume and root length/ height) and physiological activities (photosynthesis، transpiration، stomatal conduction، leaf surface temperature and gas exchange) of P. atlantica seedlings were investigated in greenhouse condition. The results showed that drought stress had significant effects on morphological and physiological characteristics of Pistacia atlantica seedlings. So that، drought decreased survival، height growth، basal diameter، leaf surface، photosynthesis، transpiration، stomatal conduction and gas exchange of P. atlantica seedlings. Drought stress hadn’t significant effects on root length، root/height and leaf surface temperature of seedlings.

External apical root resorption is a common iatrogenic consequence of orthodontic treatment. Much controversy exists in the literature about changes in root lengths at post treatment periods. Although many practitioners believe that resorption becomes stable after active treatment, quantitative data are scarce. The purpose of this study was to determine quantitative changes in root lengths of maxillary incisors during fixed orthodontic post treatment period, and to assess if it is influenced by gender and factors related to active treatment. This was a case cross over study, performed on 80 patients (52 females and 28 males) aged between 13 and 22 years. At debonding stage and beginning of retention phase of fixed orthodontic treatment, Hawley type retainer was fabricated for maxillary arch. Periapical radiographs of maxillary incisors using standard parallel technique were obtained immediately after debonding, and 3 and 7 months later. Crown and root lengths of maxillary incisors were measured using computer program. Changes in root lengths were calculated considering correction factors. Also associations between some factors and the change in root lengths during post treatment periods were assessed. These included gender, type of treatment plan (non extraction/extraction), technique (standard edgewise/straight-wire edgewise) and duration of active treatment (less than 2 years/2 years and more). T-test and 4-way ANOVA were used for statistical analysis with P0.05 as the limit of significance. No significant relation was found between apical root resorption of maxillary central incisors and time elapsed after treatment. Significant relation was observed between apical root resorption of maxillary lateral incisors and the length of post treatment period. No significant relation was found between root length changes of maxillary incisors during post treatment period and gender, type of treatment plan, technique, and the length of active treatment period (P 0.05). Considering the general process of root length reduction in maxillary lateral incisors during post treatment period, establishment of preventive measures is emphasized.

The aim of this study was to evaluate the biological and mechanical methods of priming on improving germination characteristics and growth of Haloxylon ammodendron seedlings. Cultivation was performed in two parts of seedling tray and Petri dish in a completely randomized design in the Plant Physiology Laboratory of Semnan University. The biological treatments were Pseudomonas fluorescens, Azotobacter chroococcum, Bacillus megaterium, Azospirillum lipoferum, and Flavobacterium F-40. Ultrasonic device with 24 kHz wavelength application for 5 minutes was considered as mechanical priming treatment. Traits related to seed and seedling germination were measured. Result of analysis of variance in laboratory (Petri dish) showed significant differences for radicle length, ratio of  radicle  length to plumule  length, seedling growth, radicle and plumule fresh weight, and plumule dry weight (p<0.01). In the seedling tray, the effect of treatments was significant in radicle and plumule length, ratio of  radicle  length to plumule  length, radicle and plumule fresh weight, plumule dry weight, leaf freash and dry weight and leaf areas (p<0.01). Based on the results obtained from the comparison of means, ultrasonic treatment caused an increase (33%) in fresh weight of Haloxylon ammodendron radicle compared with the control in the seedling tray test. Azotobacter significantly increased radicle length (19%), ratio of  radicle  length to plumule  length (13%), seedling growth (10%), radicle fresh weight (23%), fresh weight (18%) and dry weight (18%) of plumule as compare to control in petri dish. In addition, Azotobacter increased radicle length (16%), ratio of  radicle  length to plumule  length (60%), leaf fresh weight (26%) and dry weight (68%), leaf area (172%) compare with the control in the seedling tray. Flavobacterium was able to increase the plumule length (21%) of Haloxylon ammodendron compared to the control in the seedling tray experiment. Azospirillum increased plumule fresh (65%) and dry weight (156%) of the plant in the seedling tray compared to the control. In general, according to the present results, the use of Azotobacter, Flavobacterium and Azospirillum bacteria was evaluated as a positive bio-priming treatment and can be used for propagation and production of Haloxylon ammodendron seedlings.

The response of root to water stress is one of the most important parameters for researchers. Study of growth and distribution of root under different irrigation managements helpsresearchersto a better understanding of soil water content, and the availability of water and nutrition in water stress condition. To investigate the effects of four levels of irrigation under two different deficit irrigation managements on the root length of maize, a study was conducted in 2009. Irrigation managements included fixed irrigation interval-variable irrigation depth (M1) and variable irrigation interval-fixed irrigation depth (M2). Maize plants were planted in 120 large 110-liter containers in a strip-plot design in a randomized complete block with three replications. Root data sampling was done after root washing in five growth stages. The results showed that the effect of irrigation levels on root length was significant (Punder both managements. The maximum root length was 4.61 and 4.64 Km per m3 of soil profile in M1 and M2, respectively in the depth of 0-70 cm of soil profile which was observed in full irrigation treatment at milk stage. The results indicated that root length in mild-deficit-irrigation level was more than root length in moderate and mild-deficit-irrigation levels. The response of root maize to water stress was more severe in variable-irrigation-interval management and the same amount of reduction in applied water resulted in more decrease in root length under variable-irrigation-interval than fixed-irrigation-interval management. Therefore, due to the importance of root length as one of the most important characteristics of growth indices in maize to determine the amount of water absorption, determination of the optimum level of water stress and selection of an appropriate deficit-irrigation management can increase water use efficiency as well as maize yield.

An experiment was conducted to investigate the effects of jasmonic and humic acids on some seed germination characteristics of Roselle under the salt stress condition in a factorial experiment, adopting a completely randomized design with three replications. Treatments included four different levels of salinity stresses: 0, 70, 140 and 210 mM; four levels of Jasmonic Acid: 0, 50, 150 and 200 mM and three levels of humic acid: 0, 40 and 80 mM. The results showed that the effect of salinity on all the traits studied was significant except the ratio of the length of root and shoot. With an increase in salinity stress condition from 70 to 210 mM, there were 39% decrease in germination percentage, 55% in germination rate, 45% in fresh and dry weight, 30% in root length, 42% in shoot length, 37% in seedling length, 67% in longitudinal index and 61% in the weighted power, as compared with the control. However, the longitudinal power index increased. In addition, the use of jasmonic acid and humic acids had a significant effect on the traits studied. The interaction of the salt and hormones had a significant impact on plant fresh and dry weight, the length of the root, germination percentage, power weight index and average time needed for 50 percent germination. Given that the highest rate of root length and plant fresh and dry weight belonged to the interaction of humic and jasmonic acid in the absence of salinity, that in the presence of humic acid (with 80 mM concentration), Rosselle can bear salinity up to 140 mM and maintain stamina root length and that the germination rate of Rosselle increases by adding jasmonic acid up to 200 mM, one can conclude that the interaction of jasmonic and humic acids not only improves germination rate, but it also contributes to root length because, with an increase in root length, Rosselle can bear water stress conditions.
Highlights: 1. Jasmonic acid and humic acid increase the Rosselle germination in salinity condition.
2.Jasmonic acid and humic acid increase Rosselle the root length in salinity condition.

To study the root structure and its morphological characteristics of winter and durum wheat cultivars, an experiment was carried out based on randomized completely design with four replications at faculty of Agriculture, Ilam University during 2013-2014. Experimental treatments consisted of six bread wheat cultivars (Sardari, Keras Sabalan, Nestor, Pistaz, Bahar and S83-3), four durum wheat cultivars (Karkheh, Dena, Sora and Saji). Traits under study were seminal roots, nodal roots, sub-nodal roots, number of total roots, seminal roots length, nodal and sub-nodal roots, total root lengths, root dry weight, root volume and root to shoot ratio. The results showed significant differences for root structure of bread wheat cultivars (Sardari, Keras Sabalan and Nestor). They had stronger root system than the other bread wheat cultivars.It was also found that Saji from durum and Sabalan cross from bread wheat cultivars had the highest number of total roots (seminal, nodal and sub-nodal roots), root length total (seminal, nodal and sub-nodal roots), root volume and root/shoot ratio as compared with the other cultivars under study. Orthogonal contrast for three groups of genotypes indicated that in terms of number and length of nodal roots, bread wheat cultivars showed higher values as compared to durum wheat cultivars.

To investigate the germination of perennial herbaceous Astragalus, six species in different accessions were selected to be studied in a randomized complete block design in which three treatments including control, scarification and chilling were applied for one week with three replications. The study was carried out in the laboratory of Gene Bank at RIFR. Germination percentage, germination rate, plumule and radicle lengths, vigor index and ratio of radicle to plumule length were measured. All data were analyzed and the studied species showed significant differences in terms of the mentioned germination parameters except radicle length and ratio of radicle to plumule while differences among treatments were significant for all traits except radicle length. Interaction effects of species*treatment were also significant except radicle length and vigor index. Maximum and minimum values of germination traits were recorded for A. vegetus and A. lilacinus, respectively and other species were classified as average. The values of germination traits in chilling treatment were less than that in control treatment and it can be concluded that the cultivation of these species in autumn and winter may cause unsuccessful establishment. According to the results, A. vegetus was identified as a suitable species for range improvement in terms of most germination traits.