Evaluation of the Effect of Day and Night Temperature Fluctuations in different Seasons of the Year on the Fruit Formation of Sweet Pepper (Capsicum annuum L.) Lines

Introduction Capsicum is a plant sensitive to temperature fluctuations at day and night, and temperature changes strongly affect the quality of the fruit. Identification of tolerant genotypes to temperature fluctuations that naturally produce parthenocarp and marketable fruit is important for use in breeding programs and the production of hybrids with appropriate fruit weight and size and high marketability. Materials and Methods In order to evaluate the reaction of the lines related to three populations of sweet pepper (A: red fruit, B: orange fruit and C: yellow fruit) obtained from five generations of self-polination (by generation management by single-seed bulk method), a greenhouse factorial experiment was conducted based on a completely randomized design with three different temperature conditions including optimal day and night temperature (day temperature 25± 2 and night temperature 20 ± 2 °C), low night temperature (day temperature 25± 2 and night temperature 11± 2 °C) and high day temperature (day temperature 40± 2 and night temperature 20 ± 2 °C). For this purpose, 100 lines from each population were planted in three separate greenhouses with the mentioned temperatures. Percentage of seedless fruit lines per population or Parthenocarp fruits (including seedless fruits that had at least 50% by weight of seeded and natural fruits and other seedless fruits that were deformed and small in size (knot) were removed), height Plant, day to ripening and number of fruit lobes per 100 lines of each population were measured in three different temperature conditions. Due to the fact that the lines within each population were different from the other population lines, so the data analysis was performed as a complex sequential-factorial design. Also, due to the importance of fruit characteristics in seedless fruit lines and seeded fruits, analysis of variance of these lines in a completely randomized design (15 treatments in 3 replications) using SAS v software 9.2 was performed and the comparison of the mean of the evaluated traits was performed using Duncan's multiple range test at 5% probability level.   Results and Discussion The results showed that under optimal temperature conditions, all lines had good growth and no parthenocarpic plants were observed in the evaluated populations, but day and night temperature fluctuations outside the optimal temperature range caused significant changes in plant growth, fruit development. And seeds were formed. The effect of high day temperature on the evaluated characteristics was less than low night temperature. With a sharp drop in night temperature, population A produced the highest percentage of seedless fruit plants. The percentage of parthenocarp lines of populations B and C were significantly lower than population A at low night and daytime temperatures. Population C was less affected by adverse day and night temperatures than the other two populations. Fruit size, fruit weight and fruit shape index, which are the most important determinants of fruit marketing, were strongly affected by day and night temperature fluctuations. In all three populations evaluated, fruit length was significantly negatively affected by low night temperature more than high day temperature, which resulted in distortion of fruit shape index. Fruit shape index, which is the result of the ratio of length to diameter of fruit, in marketable fruits is 1-1.02. As the fruit length increases and the fruit diameter remains constant or decreases, the shape index increases from 1.02, and as the fruit diameter increases with decreasing fruit length, which is usually achieved under cold stress conditions, this number decreases below one. Based on the results, the three populations evaluated had different fruit lengths under optimal temperature conditions, which, with the proportion of fruit diameter to length, the fruit shape index was normal and produced marketable fruits. By decreasing the night temperature below the optimum growth temperature, fruit length decreased sharply in the three evaluated populations, and this decrease was greater in seedless fruits. According to Table 2, the highest percentage of fruit length reduction at low night temperature was observed in population A and in seedless fruits. In this temperature condition, fruit length decreased by 43% in seedless fruits and 17.5% in seeded fruits. The lowest decrease in fruit length at low night temperature was related to population C. Fruit length in seeded and non-seeded fruits of this population decreased by 12 and 24%, respectively. However, the percentage of fruit reduction in the total populations evaluated was 13.90 and 33.69% on average in seeded and seedless fruits, respectively. Although the length of the fruit was less affected by the high temperature during the day than the low temperature at night, but the trend of fruit length changes in these temperature conditions was similar to the low temperature at night. The average decrease in fruit length in the total population in seeded and seedless fruits was 10.41 and 31.52%, respectively, with population C having the least and population A having the most effect from unfavorable daytime temperature. Fruit weight was also affected by the unfavorable temperature of day and night, but the negative effect of low night temperature on fruit weight was more than the unfavorable temperature of the day. According to the results, the percentage of fruit weight loss in seeded and seedless fruits at low temperature at night was 21.19 and 50.06%, respectively, and at high temperature at day, 15.98 and 50.12%. As the results show, seedless fruits had the same effect of unfavorable temperature day and night and showed the highest percentage of weight loss. Also, fruit weight in population C showed the least effect of adverse temperature day and night and no significant difference was observed between populations B and A. Expression is associated with undesirable traits that can be due to the coherence of traits or pleiotropic effects of parthenocarpic genes or physiological or molecular changes. Although in population C the number of lines with Parthenocarp fruit was 1%, but Parthenocarp fruits consisting of size and shape index are more suitable than the other two populations. The C population also showed a low percentage of Knot fruits as well as slight differences in fruit weight and shape at low temperature at night and high temperature at day. Based on the results, the three populations evaluated have different potentials in terms of reacting to adverse low temperatures at night and high temperatures during the day, and this potential can be used in future research and breeding programs to produce hybrids that tolerate temperature fluctuations

Studies of Microbiota Dynamics Reveals Association of “Candidatus Liberibacter Asiaticus” Infection with Citrus (Citrus sinensis) Decline in South of Iran

Citrus Decline Disease was recently reported to affect several citrus species in Iran when grafted on a local rootstock variety, Bakraee. Preliminary studies found \u201cCandidatus Phytoplasma aurantifoliae\u201d and \u201cCandidatus Liberibacter asiaticus\u201d as putative etiological agents, but were not ultimately able to determine which one, or if an association of both, were causing the disease. The current study has the aim of characterizing the microbiota of citrus plants that are either asymptomatic, showing early symptoms, or showing late symptoms through amplification of the V1\u2013V3 region of 16S rRNA gene using an Illumina sequencer in order to (i) clarify the etiology of the disease, and (ii) describe the microbiota associated to different symptom stages. Our results suggest that liberibacter may be the main pathogen causing Citrus Decline Disease, but cannot rule out the possibility of phytoplasma being involved as well. The characterization of microbiota shows that the leaves show only two kinds of communities, either symptomatic or asymptomatic, while roots show clear distinction between early and late symptoms. These results could lead to the identification of bacteria that are related to successful plant defense response and, therefore, to immunity to the Citrus Decline Disease

(Brief report) Etiological Study of Gladiolus Wilting Disease in Jiroft

Introduction: Gladiolus belongs to the family Iridiaceae. It is commercially cultivated in all parts of the world. This plant is mainly affected by wilt disease caused by Fusarium oxysporum Schlecht Fr f .sp. gladioli (Massey) Snyd. and Hans. It results in death of plant and rotting of corms. Fusarium disease of gladiolus is commonly known as yellows, wilt or corm rot. The wilt disease of gladiolus is known to occur in almost all gladiolus growing areas. Wilt disease is one of limiting factors of cultivation and development of gladiolus in Jiroft, Kerman, Iran. Different fungi such as Fusarium oxysporum f.sp. gladioli, F. moniliforme, F. sporotrichiella, F. hetrosporium and Penicillium gladioli, P. rubrum have been reported as causal agents of gladiolus wilt, root and corm rot disease in many countries. The disease symptoms, including yellowing of leaves, weakness of plant, flower imperfect, root and corm rot, browning of infected root and corm, wilting and finally death of infected plants which observed in infected samples. No research has been carried out in Jiroft, therefore, this research aims to study and identify the causal agent of wilt disease on gladiolus. Materials and Methods: During survey, characteristic symptoms of wilt disease were recorded and also samples were collected for isolation of pathogens that infect on Gladiolus. The infected corms showing typical symptoms of wilt disease were used for the isolation of pathogen. The standard tissue isolation procedure was followed to isolate the pathogen. To identify the causal agent of gladiolus wilt, infected tissues from symptomatic plants were first surface disinfestations, dehydrated and cultured on Potato Dextrose Agar Medium and incubated at 25± 2oc. Isolated fungi identified using morphological and microscopic characters. To pathogenicity test, corms were inoculated using the dip method in conidial suspension and then planted in pots containing sterilized soil. Inoculated plants were checked for disease symptoms. Distilled water used for inoculation of plants as a control. Observations were made regularly for the appearance and development of symptoms. After symptom development, re-isolation was done from the artificially infected corms. Results and Discussion: The disease symptoms, including yellowing of leaves, weakness of plant, flower imperfect, root and corm rot, browning of infected root and corm, wilting and finally death of infected plants observed in infected samples. The type of disease symptoms was similar to others which have been reported before. A fungus with white aerial mycelium and little dense colony recovered from infected cultured samples. The produced micro conidia were single, sometimes two cells, oval to ellipsoid in shape, in diameter 3.75-5 * 8-10 micrometer which formed on single and short phialides. Macroconodia were mostly 3-4 celled, in diameter 3-5 * 18-35 micrometer and formed on spordochia. Chlamidospores were spherical to round shape, mostly single, sometimes in the short chain and formed intercalary and terminal. 10 to 14 days after inoculation the symptoms of the disease were seen as yellowing, plant weakness, and wilt. Based on morphological and pathogenicity test, the isolated fungus identified as Fusarium oxysporum f. sp. gladioli and confirmed by the Iranian Research Institute of Plant Protection. Infantino and Rumine (1993) reported that the F. oxysporum f .sp. gladioli infected other members of the Iridiaceae family. Other Fusarium species associated with the corms of gladiolus are Fusarium solani (Mart) Sacc., Fusarium subglutinans (Woolenweb and Reinking) Fusarium heterosporum. Nees ex Fr and Fusarium sporotichoides Sherb. ( Georgieva and Peikova, 1976). This is the first report of Fusarium wilt of Gladiolus on three different cultivar (White, pink and red) in Jiroft, located in the south part of Kerman, Iran. Few resistant cultivars are available in the world. It found that Australian fair and Monsoer were tolerant to F. oxysporum. f .sp. gladioli. Conclusion: based on this research project, the causal agents of gladiolus wilt disease in Jiroft is Fusarium oxysporum f. sp. gladioli. Disease incidence was different on three gladiolus cultivars which cultivated in this area. Field observation showed, the white cultivar was more tolerant in comparing to red and pink gladiolus cultivars. In gladiolus wilt disease control managements, more emphasis should be focused on disease resistance. The more resistant cultivars should be tested for resistance to several Fos isolates

Numerical investigation of the effect of cross-section shape, mortar strength, and number of textile layers on the cyclic behavior of RC columns

Repairing and strengthening of structures are unavoidable. The main reasons for repairing and strengthening concrete structures are improper design or construction, weakness of the structural elements, changing the usage of the building and damages that happen in structural elements. There are various ways for strengthening the vulnerable structures. In recent years, usage of high strength concrete reinforced with textile meshes (Textile Reinforced Concrete (TRC)) for strengthening the concrete structures has become a proper alternative for retrofitting the buildings. Using reinforced concrete with TRC is one of the new methods for strengthening the concrete structures. This method has become popular in recent years due to its light weight, high strength, no changes in the dimensions of reinforced concrete elements, and ease of use. The aim of this study was to evaluate the efficiency of this method in strengthening concrete columns with a low reinforcement ratio that need reinforcement. In this investigation, after verifying two models simulated by finite element software (ABAQUS) with experimental results, eight models were studied numerically. The models consisted of columns and supporting beams and they were categorized into four groups by different parameters which are effective in strengthening the concrete columns. In this paper, various parameters such as geometry of cross-section, mortar strength, and number of textile layers were investigated. The columns and their connections to supporting beams were strengthened with TRC. Models strengthening were carried out using vertical layers plus horizontal layers of textile meshes in cement mortar. Lateral force capacity, crack, and stress pattern on concrete and mortar surfaces and yielding of rebars in reinforced concrete columns were compared and evaluated. The cyclic behaviors of all TRC strengthened models were improved compared to non-strengthened ones

Important phytoplasma ribosomal subgroups distributed in Iran

So far, phytoplasmas enclosed in ribosomal groups and associated with phyllody, virescence, proliferation and sterility of flower, yellowing, little leaf, dwarfing, decline and witches’ broom symptoms were identified in Iran. These groups are 16SrI, 16SrII, 16SrIII, 16SrVI, 16SrVII, 16SrIX, 16SrX, 16SrXI, 16SrXII, 16SrXIV, 16SXXIX and 16SrXXX. The most widespread phytoplasmas belong to 16SrI, 16SrII, 16SrVI, 16SrIX and 16SrXII groups, whilst the 16SrII phytoplasma group is the one with most numerous associated diseases. The most economically and environmentally spread phytoplasma ribosomal subgroups in Iran are reviewed

Diversity, distribution, and status of phytoplasma diseases in Iran

In Iran, although phytoplasmas and their associated diseases have been observed in sesame since 1965 as “green flowering of sesame” the agent associated with the disease and its insect vector were reported for the first time in 1992 by electron microscopy, transmission assays, host range, and symptomatology studies of sesame phyllody samples collected from Darab, Fars province. Since then, many phytoplasma diseases have been identified on various plant species in the country. Among them, several new phytoplasma strains and host species have been reported for the first time worldwide. Some of these phytoplasma diseases are very destructive and have a great economic importance. So far, phytoplasma strains enclosed in 12 ribosomal groups have been identified or are being studied across at least 29 plant families. Identified phytoplasma groups are 16SrI, 16SrII, 16SrIII, 16SrVI, 16SrVII, 16SrIX, 16SrX, 16SrXI, 16SrXII, 16SrXIV, 16SXXIX, and 16SrXXX. Among these, the 16SrII is the most important and widespread and lime and alfalfa witches’ broom are examples of destructive and economically important phytoplasma diseases in Iran

Metagenome analyses reveal microbiota changes in Citrus sinensis affected by citrus decline disease in Iran

Citrus decline disease was recently reported in Iran, affecting several citrus species grafted on Bakraee a local rootstock. Preliminary studies identified \u2018Candidatus Phytoplasma aurantifoliae\u2019 and \u2018Candidatus Liberibacter asiaticus\u2019 as putative etiological agents, but were not ultimately able to determine which one, or if an association of both pathogens, were causing the disease. The current study had the aim of characterizing the microbiota of citrus plants that were either asymptomatic, or showed either early or late symptoms, through the amplification of the V1-V3 region of the 16S rRNA gene, using an Illumina sequencer in order to: (i) clarify the etiology of the disease, (ii) describe the microbiota associated with different symptom stages. Our results suggest that liberibacter may be the main pathogen causing citrus decline disease, but cannot entirely rule out the possibility that a phytoplasma be involved as well. The characterization of microbiota described very different situations in the aerial part of the plants and in the roots, or between rootstock and scion: the leaves showed only two kinds of communities, either symptomatic or asymptomatic, while the roots showed a clear distinction between early and late symptoms. These results could lead to the identification of bacteria that are related to successful plant defense response and, therefore, to immunity to citrus decline disease