Journal of Plant Physiology and Breeding
Volume:9 Issue: 1, Winter-Spring 2019

Determining appropriate deficit irrigation regimes and varieties under these conditions is necessary to optimize the use of available water in arid and semi-arid regions. In this regard, field experiments were carried out for two years (2014-2015) at the Moghan plain, Iran. The experimental design in each year was split plot based on randomized complete blocks with three replications. The main plots consisted of four irrigation levels: normal irrigation, 80% of maximum daily crop evapotranspiration (ETc), 70% ETc and 50% ETc. Three maize hybrids (SC704, SC703, SC705) were arranged in the sub-plots. Mean comparisons showed that deficit irrigation caused a significant decrease in grain yield and other agronomic traits, physiological characteristics (chlorophyll a, b and relative water content) and growth parameters (leaf area index, crop growth rate, relative growth rate). On the other hand, leaf rolling percentage increased due to the water deficit stress. By increasing deficit irrigation intensity (especially at 50% ETc), chlorophyll a, b and relative water content decreased in SC705 more than the other two hybrids (SC703, SC704) and the leaf rolling percentage at the severe stress condition reached to 60% in SC705. The highest grain yield (8.51 t/ha) and biomass (19.36 t/ha), averaged over two years, were observed under normal irrigation for the SC705 hybrid. However, this hybrid had minimum grain yield and biomass at 50% ETc. By increasing water deficit from normal irrigation to 50% ETc, significant decrease was observed for leaf area index, plant growth rate, relative growth rate and net photosynthesis rate of SC705. Due to the sensitivity of physiological characteristics and growth parameters to the deficit irrigation and the influence of grain yield from these traits, it seems necessary to prevent the occurrence of water deficit at critical stages of maize growth. In conclusion, due to the sensitivity of the SC705 to water shortage, this hybrid is not recommended to water deficit conditions and it would rather be planted when enough irrigation water is available. On the other hand, SC704 seems suitable for the water deficit environments, especially at the severe water stress condition (50% ETc).

Seed storage at unfavorable conditions of high humidity and temperature is a difficulty which decreases seed vigor and/or seed viability. Current experiment was conducted to evaluate the activity of antioxidant enzymes and seed germination characteristics after ageing on maize seeds (Zea mays L.) in the research laboratory of Razi University, Kermanshah, Iran. A three-factorial experiment was performed with completely randomized design with three replications, using three maize hybrids (SC704, SC647, SC260), and three levels of accelerated ageing (non-aged, artificially aged for 3 and 6 days at 45 oC temperature and 98% relative humidity). The hydro-priming was performed at different durations (0, 12 and 24 hours). Results indicated that germination characteristics of maize seeds were considerably affected by priming time periods. The germination characteristics of deteriorated seeds were significantly enhanced by hydro-priming, especially in 24 h priming. The highest germination characteristics and seedling length were obtained in the control (non-aged) seeds which were primed for 24 h. The lowest germination performance was obtained for the non-primed seeds after 6 days of ageing. The catalase, peroxidase and glutathione reductase activity and malondialdehyde (MDA) concentration of aged maize seeds were restored partially by hydro-priming. In fact, ageing-associated MDA decreased by priming. The results suggested that hydro-priming could improve deteriorated seed performance.

Two field experiments were conducted as factorial based on randomized complete block design to study the effects of soil covering (black, white, control), location (Sarab and Shabestr, Iran), and Stimplex foliar application levels (0, 2, 4 and 6 ml L-1) on growth and physiological traits of Coriandrum sativum. The highest values for essential oil, flavonoids and nitrogen contents were recorded for black covering at 2 ml L-1 foliar application of Stimplex. For phenolic compounds the highest values were observed with black covering at 2, 4 and 6 ml L-1 of foliar spray. In the city of Sarab, maximum values of root dry weight and essential oil content were obtained with 6 and 2 ml L-1 Stimplex spray, respectively. The best IC50 belonged to the white and black soil covers in Shabestar (1.6 and 1.7 mg ml-1, respectively). Foliar spray had significant effects on the above-ground biomass, plant height, axillary brunch number, umbel number, total soluble solids (TSS), phosphorus and potassium contents. Sarab had higher values than Shabestar for the nitrogen and potassium contents, axillary brunch number and TSS. Black soil cover had positive effects on K (%), P (%), TSS, chlorophyll a, umbel number per plant, plant height, axillary brunch number and above-ground biomass. In total, the results revealed that using black soil cover and foliar application of algal extract (2 ml.L-1) improved the growth and physiological responses of C. sativum plants.

Potato is considered as a drought sensitive plant. To study the effect of drought stress and hormone on agro-morphological and physiological traits of potato, an experiment was carried out as split plot design based on randomized complete blocks with three replications in 2015 and 2016. The irrigation levels were control (well-watered), mild stress, severe stress and extreme stress, which were arranged in main plots. The second factor included four spaying treatments that were arranged in sub-plots. The foliar applications were as follows: no foliar application (control), gibberellic acid, epibrassinolide and acetyl salicylic acid. Results showed that drought stress and hormones had significant effect on most of the agro-morphological and physiological traits of potato. Leaf dry weight, shoot dry weight, tuber dry weight, plant height, number of stolons, number of tubers, leaf area index (LAI), relative water content (RWC), net photosynthesis rate, transpiration rate, intercellular CO2 concentration and stomatal conductance decreased, while amount of water saturation deficit (WSD) increased by the drought stress. It seems that the negative impact of drought stress on physiological traits, such as RWC, adversely affected the agro-morphological traits of potato. Except for chlorophyll index, hormones significantly affected agro-morphological and physiological traits of the potato plants. Epibrassinolide improved RWC, WUE, intercellular CO2 concentration, tuber dry matter, plant height, number of stolons, leaf dry weight, shoot dry weight and tuber dry weight, while application of gibberellic acid had better effects on LAI, WSD, transpiration rate and number of tubers as compared to epibrassinolide. In fact, these hormones mitigated the negative effects of drought stress in potato.

To study the effects of methanol and ethanol foliar application (0, 10 and 20 % v/v) and NaCl salinity stress (0, 75 and 150 mM) on yield and some physiological traits of geranium (Pelargonium graveolens L.), a factorial experiment was conducted based on completely randomized design with three replications. Salinity showed significant effect on all characteristics, except root dry weight, chlorophyll b and Fe content. Effect of foliar application of methanol and ethanol was significant on proline, protein, chlorophyll a, essential oil, Fe and K content, root dry weight and IC50. The results also revealed the significant interaction of salinity by foliar application of alcohol in relation to the chlorophyll a and protein content. The greatest protein and chlorophyll a contents were recorded by the NaCl0 + methanol20% treatment, which was significantly different from the corresponding control. Dry weight of aerial parts, K/Na ratio, essential oil, K, P, Fe and Zn contents were negatively affected by the salinity stress. With increasing salinity stress the amounts of malondialdehyde and H2O2 were elevated. Among alcohol treatments, methanol foliar application was more effective than ethanol. Methanol had better effect on IC50, root dry weight, Fe, K and essential oil content, while ethanol20% increased the proline content significantly as compared to the methanol and control treatments. Overall, the results indicated that foliar application of methanol ameliorated the negative effects of salinity in geranium, when averaged over the salinity levels under study.

The grapevine (Vitis vinifera L.) is a native of central Asia and has been propagated by various methods, including in vitro propagation. Present research was conducted to study the effect of plant growth regulators (BAP, IBA), carbon sources (sucrose, glucose, fructose, table sugar) and their concentrations (30, 60 and 90 g/l) on the proliferation, root induction, protein, chlorophyll and carotenoid contents of the grape (Vitis vinifera L. cv. Shahroudi) in in vitro conditions based on a completely randomized design with three replications, using nodal explants. The result showed that the highest rate of proliferation (3.04 shoots per explant) occurred at MS medium, containing 1.5 mg/l BAP plus constant amounts of GA3 (0.3 mg/l) and IBA (0.1 mg/l). The highest rate of root induction (88.88%) was obtained at 1/2 MS medium at 0.5 mg/l IBA. Type and concentration of carbon source had a significant effect on some of the measured characteristics. The highest plantlet height was obtained in MS medium supplemented with 30 g/1 table sugar and sucrose. Also, the highest number of shoots per explant (3.5 shoots) belonged to the use of 30 g/l sucrose in the culture medium, followed by 30 g/l table sugar (3.23 shoots). The highest value of chlorophyll a was observed for 90 g/l glucose, followed by 30 g/l sucrose and 60 g/l table sugar. The highest chlorophyll b contentwas obtained for 60 g/l table sugar, followed by 30 g/l table sugar and sucrose. In general, with regard to most of the characteristics under study, it could be inferred that the propagation efficiency of 30 g/1 sucrose or table sugar was better than other carbon sources. Considering economic reasons and time, these treatments can be recommended for the commercial micropropagation of the Shahroudi cultivar of grapevine, instead of traditional methods of propagation.

Seeds are an important part of the canola plant, and similar to other parts are affected by salt stress. Understanding the underlying mechanisms that take place in seeds of canola under salt stress is essential from the perspective of improving quality. In this study, we attempted to identify differentially expressed proteins of canola seeds in the Hyola308 cultivar under 350 mM NaCl using two dimensional (2D) gel electrophoresis. Effect of salt stress was significant on 100-seed weight and number of seeds per plant (p≤ 0.01), and it changed the proteome of the seeds. From a total of 548 reproducible protein spots, 28 protein spots showed significant changes in abundance, of which seven spots showed downregulation. The “Gene Ontology” analysis classified differentially expressed proteins into six biological processes: oxidation-reduction (28.5%), response to abiotic stress (28.5%), response to hormones (21.4%), catabolic process (21.4%), nucleoside diphosphate phosphorylation (17.8%) and glycolytic process (14.28%). In conclusion, salt stress induced canola seeds to upregulate proteins that mostly involved in the antioxidant activity and the proteins with nutrient reservoir activity.

Iranian seedless barberry is a species with high degree of contamination in in vitro culture. The current study was aimed to investigate the effects of mercuric chloride (HgCl2), sodium hypochlorite (NaOCl) + HgCl2, HgCl2 + 8-hydroxyquinoline, cefotaxime + streptomycin, HgCl2 + shoot type, HgCl2 + explant position and HgCl2 + shoot color on the reduction of contamination. The results showed that the combined use of NaOCl and HgCl2 was more effective than their single use, but the contamination rate was relatively high. Interestingly, the results showed that explants sterilized with 100 mg/L HgCl2 and cultured in the medium containing 150 mg/L 8-hydroxyquinoline exhibited the lowest fungal contamination (15%), while those treated with 50 mg/L HgCl2 and cultured in the 8-hydroxyquinoline-free medium showed the highest fungal contamination (96%). Furthermore, treatment of 75 mg/Lcefotaxime + 70 mg/L streptomycin exhibited no bacterial contamination compared to the control with 58% bacterial contamination. Explants prepared from suckers and treated with 150 mg/L HgCl2 showed the lowest rates of fungal (16%) and bacterial (13%) contamination. The results also showed that explants collected from upper position had the lowest rates of fungal (20.87%) and bacterial (18.4%) infection. Explants taken from pinkish-colored shoots showed surprisingly the lowest rates of fungal contamination (13.33%), bacterial contamination (10%) and bud mortality (36.47%). In general, choice of explants from upper position of pinkish-colored suckers, sterilization of them with 100 mg/L HgCl2 for 5 min and their culture in medium containing 150 mg/L 8-hydroxyquinoline can be recommended for reducing the contamination.

Molecular studies have shown that several genes with various functions are induced by drought stress and various transcription factors are involved in the regulation of the stress-inducible genes. To evaluate the effects of drought stress on gene expression, CRTBF2, DREB6 and DBF transcription factors as well as the expression pattern of Acyl, SuT5 and SuT4 genes were studied using qRT-PCR. The experiment was carried out as factorial based on completely randomized design. One factor included drought stress levels of -1, -2, -4 and -6 bar imposed by polyethylene glycol plus a control. The second factor consisted of four wheat cultivars as follows: Qaboos and Koohdasht (as drought tolerant), and Ehsan and Morvarid (as drought sensitive). Assessing the seedling morphological traits, such as germination percentage, plumule length and radicle length showed that with an increase in drought stress, the tolerant cultivars of Qaboos and Koohdasht showed lower decrease for these traits compared to the sensitive cultivars of Ehsan and Morvarid. The results of evaluating the gene expressions demonstrated that the DREB6 gene expression was higher in the tolerant cultivars of Qaboos and Koohdasht as compared to the sensitive cultivars of Ehsan and Morvarid, indicating the possible role of the product of this gene, as a transcription factor, in inducing promoters of drought tolerance genes and transcribing such genes. However, the CRTBF2 and DBF genes acted as repressor transcription factors in expressing the genes involved in the drought stress tolerance in the cultivars under study. The expressions of the Acyl and SuT5 genes were greater in the tolerant cultivars compared to the sensitive cultivars. The SuT4 gene expression was lower in both tolerant and sensitive cultivars than the expression of this gene in the corresponding control treatment. Therefore, it seems that the Acyl and SuT5 genes, through lipid decomposition and carbohydrate transport pathways, respectively, increased the tolerance of Qaboos and Koohdasht cultivars in this study.

Catharanthus roseus is an important multipurpose medicinal plant. In this study, in vitro proliferation and root induction of periwinkle were optimized and regenerated plants were subsequently surveyed for genetic homogeneity using the inter simple sequence repeat (ISSR) markers. Shoot tips and nodal segments were cultured in Murashige and Skoog (MS) medium supplemented with different concentrations of benzylamino-purine (BAP), gibberellic acid (GA3), and indol-3-butyric acid (IBA) hormones. ISSR profiling of regenerated plants as well as the mother plant were surveyed with five primers. The highest establishment rate (80.67%) was obtained in the MS medium containing 1.0 mg L-1 GA3 and 1.0 mg L-1 BAP. Highest proliferation rate (5.20 shoots/explant) and average shoot length (6.30 cm) were observed in 1.5 mg L-1 BAP + 0.5 mg L-1 IBA. Moreover, the best rooting response (85.30%) was observed on half strength MS containing 1.0 mg L-1 IBA. Genetic fidelity analysis using ISSR markers showed the monomorphic banding pattern of the micro-propagated plants and the mother plant, which highlighted their genetic uniformity. This implies that periwinkle micropropagation through shoot tip is the most reliable method for true-to-type production of C. roseus in a large scale.

Cannabis sativa L. is an important plant with various uses in pharmaceutical and paper production industries. Due to the higher priority of female and male Cannabis plants for pharmaceutical uses and fibre industry, respectively, reduction of the quality of products after pollination, and also for detection of better genotypes before pollination for breeding purposes, early determination of sex in Cannabis is one of the major concerns of researchers and farmers. Seeds of 26 accessions from different regions of Iran along with one accession from Afghanistan were planted in the field based on randomized complete block design with 10 replications. Five female and five male plants were sampled from each accession for molecular and morphological analyses. Thirteen ISSR primers and two SCAR markers were used. Also, morphological differences, which possibly related to sex were measured in the Cannabis populations under study. The results showed significant differences among the accessions within female and male plants for plant height, number of days to flowering, days after full bloom and height of the first flowering node. Male plants were generally, but not always, taller than female plants and had a shorter life cycle. The highest expected heterozygosity was found in the ISSR3 primer and the lowest in the UBC825 primer. In total, 143 polymorphic bands and one polymorphic band were amplified using ISSR and SCAR primers, respectively. Out of 143 polymorphic ISSR bands, only 10 markers had significant relations with the gender of this plant. MADC6 SCAR marker was monomorph across the accessions. On the other hand, MADC5 was a polymorphic marker and showed a significant relation with gender. These markers, especially MADC5, have the potential to be used in sex determination of C. sativa.

Salinity stress is one of the most harmful abiotic stresses that affect agronomical, physiological and biochemical processes in crop plants. In order to evaluate the effect of salinity stress on alfalfa (Bami ecotype) leaf proteins based on two-dimensional gel electrophoresis, an experiment was conducted with two salinity treatments (0 and 200 mM NaCl) and six replications under hydroponic cultural system. Salinity stress decreased fresh and dry weight of alfalfa about 24.5 and 39.5 percent, respectively. Proteome analysis was carried out on the leaf tissue using three replications. Fourteen repeatable protein spots had significant change in expression under salt stress. Probabilistic identification of proteins from the data bank was performed by isoelectric point and molecular weight. Nine proteins showed significant up-regulation and five proteins had down regulation. Candidate proteins were among the proteins involved in the defense system, regulation, metabolic pathways, nitrogen fixation and canalization. Higher abundance of trehalose-phosphate phosphatase 2, involved in regulation, and also uracil phosphoribosyl transferase lastic and β-hydroxyisobutyryl-CoA hydrolase 1, involved in the energy metabolism, demonstrated the important function of these proteins under salinity stress. It seems that the alfalfa plant manages to reduce the adverse effects of salinity through the candidate proteins identified in this investigation.