نشریه فیزیولوژی محیطی گیاهی
پیاپی 48 (زمستان 1396)

Models that predict the timing of weed seedling emergence are used to optimize weed control schedules. This study was carried out with the aim to predict the time of seedling emergence of three weed species, namely, Datura stramonium, Solanum nigrum, and Amaranthus retroflexus in field conditions using soil temperature and moisture. Three planting dates including first of June, first of July, and first of August were studied with three irrigation regimes including every other two, three, and four days and with three weed species. To express the changes in the emergence process, hydrothermal time model () was used. MPa - °C - days required for the emergence was calculated with the base temperature and water potential that was calculated by hydrothermal time model and soil moisture and temperature. Cumulative emergence percentage was plotted with hydrothermal time model and the sigmoid three-parameter model was fitted on it. Then the maximum germination percentage and MPa - °C - days required for 50% seedling emergence was calculated. Results showed that seedling emergence of three weed species was the highest and lowest in the first regime of irrigation in August and third regime of irrigation in June, respectively. Three species seedlings were emerged higher and faster in August than in June and July. Hydrothermal time required for the seedling emergence of these species was varied. D. stramonium had the lowest and S. nigrum had the highest hydrothermal time for 50% seedling emergence. The optimum temperatures for A. retroflexus, S. nigrum, and D. stramonium were 30-35, 37-30, and 29-34 °C respectively in all water potentials.

­In order to investigate the effects of different nano-fertilizers of Iron, manganese, and Nitrogr on some agronomic and physiological traits of sesame (Sesamum indicum L.) cultivars, a factorial experiment was conducted based on a randomized complete block design (RCBD) with three replications in a farm in Northwestern Dehloran. Experimental factors included three cultivars of sesame (Dehloran landrace, Dashtestan 2, and Darab 1) and four levels of nano-fertilizer foliar application (control, Fe, N, and Mn). Based on the results, the interaction of cultivar × nano-fertilizer on number of seeds per capsule, 1000 seeds weight, biological yield, and harvest index were significant (p≤0.05). Carotenoids and also soluble sugars content were affected only by the foliar application of nano-fertilizers and the highest amount of carotenoids and soluble sugars was observed in iron nano-fertilizer treatment. The highest amount of biological yield (1305 g.m-2) was observed in Dashtestan 2 with manganese application whereas the lowest biological yield (357 g.m-2) was in Darab 1 with control treatment. The highest seed yield (215 g.m-2) was observed in Dashtestan 2, and the difference between this cultivar and the other cultivars was significant. Application of different nano-fertilizer had positive effects on seed yield but only the effect of manganese nano-fertilizer on this trait was significant. Manganese resulted in the highest amount of seed yield (186 g.m-2) which was significantly different from the treatment with iron fertilizer and control (123 g.m-2). Based on the findings, Dashtestan 2 is recommended as the best cultivar for plantation in the region. Also, application of Manganese nano-fertilizer had a remarkable performance in yield improvement in sesame cultivars. Therefore, manganese nano-fertilizer is recommended for nourishing sesame while more studies are suggested on the effects of this fertilizer.

In order to study the effect of drought stress and application of potassium on seed yield, some biochemical characteristics, and the content of micronutrients such as copper (Cu), zinc (Zn) and manganese (Mn) in cowpea, a factorial experiment was carried out in randomized complete block design with three replications in the greenhouse of the Faculty of Agriculture, University of Maragheh, Iran in 2016. Treatments were water stress at two levels (normal or 100% and 50% field capacity) as the first factor and potassium at five levels (0, 30, 60, 90, and 120 mg/kg) as the second factor. Results showed that drought stress reduced the growth parameters and the concentration of the elements in plants while application of different levels of potassium increased shoot dry weight, yield, and carbohydrate by adjusting the effects of drought stress. Also, application of 120 mg potassium in stress conditions caused an increase in the concentration of Cu, Zn and, Mn. Findings seem to suggest that potassium improves growth characteristics in cowpea by decreasing the undesirable consequences of drought stress. Therefore, application of potassium sulfate is recommended as a strategy to mitigate the effects of draught stress in cultivation of cowpea.

Information on variations in concentration, accumulation, and allocation of phosphorus (P) in different species is important for improving the absorption and use efficiency of mineral nutrients, especially in poor soils. Hence, this experiment was conducted in order to study the variations in P concentration, accumulation, and allocation to various parts of plants in a number of gramineae crops and weeds in stem elongation and anthesis growth stages. The experiment was carried out in a completely randomized design with a factorial arrangement with three replications in an open field condition in Gorgan University of Agricultural Sciences using a low (4.85 mg kg-1) available P soil during 2015-2016 growing season. Treatments in the pot experiment included 7 crop and weed species of poaceae family including bread wheat, durum wheat, common barley, naked barley, triticale, wild oat, and canary grass and application and non-application of recommended N, P, and K chemical fertilizers. Based on the results, with fertilizer application, the concentration and accumulation of P significantly increased in all parts of plants except for root in both stages of stem elongation and anthesis. Under non-fertilization conditions, the average P concentrations of the aerial part of the plant at stem elongation and pollination stages were 3.9 and 1.9, respectively, which increased to 4.5 and 2.1 g kg-1 as a result of fertilization. Also, as a result of fertilization, the average P concentration accumulated in the aerial part of the plants increased from 0.92 to 3.2 mg plant-1 at the stem elongation and from 2.45 to 2.9 mg plant-1 at anthesis stage. During anthesis, the effect of plant species on P concentration in all parts of the plants was significant while during stem elongation, this effect was significant only for P concentration of stem and aerial parts of the plants under study. However, at both stages, accumulation of P in all parts and in the whole plant was significantly affected by plant species and the interaction effects of the species and fertilization. The average concentration of P in the aerial parts of the species varied from 2.9 to 4.7 g kg-1 at stem elongation and from 1.4 to 2.7 g kg-1 at anthesis stage. The results of the mean comparisons of the interaction effects showed no significant difference of P accumulation in different parts of the plant at stem elongation stage under unfertilized conditions, and that at anthesis stage, differences of P accumulation under non-fertilization conditions between species were much less than those of fertilization conditions.

To evaluate the effect of various application methods of zinc (Zn) and silicon (Si) on some physiological traits of rice (cv. Tarom Hashemi), a field experiment was carried out as factorial based on randomized complete block design with 16 treatments and three replications in Nour in 2016. The experimental treatments included T1: Control, T2: Calcium silicate soil application, T3: Zinc sulfate soil application, T4: Calcium silicate Zinc sulfate, T5: Nano-Si foliar application, T6: Nano-Si Calcium silicate, T7: Nano-Si Zinc sulfate, T8: Nano-Si Calcium silicate Zinc sulfate, T9: Nano-Zn oxide foliar application, T10: Nano-Zn oxide Calcium silicate, T11: Nano-Zn oxide Zinc sulfate, T12: Nano-Zn oxide Calcium silicate Zinc sulfate, T13: Nano-Si Nano-Zn oxide, T14: Nano-Si Nano-Zn oxide Calcium silicate, T15: Nano-Si Nano-Zn oxide Zinc sulfate and T16: Nano-Si Nano-Zn oxide Calcium silicate Zinc sulfate. Results showed that straw protein, zinc and silicon in grain and straw were affected by experimental treatments, but the evaluated treatments showed no significant effect on grain protein and chlorophyll content of flag leaf. Among evaluated treatments, the combined application of silicon and zinc improved nutrient absorption compared to separate application of each element and control. This indicates the aggregation of Zn and Si compounds and their synergistic effects. Combined application of silicon and zinc by both methods of NP foliar application and soil application (T16) improved nutrients uptake in grain and straw of rice, but among the methods used, the NP foliar application had a more positive effects in improving physiological characteristics of rice plants than the treatments of soil application of elements.

This experiment was carried out to analyze some primary and secondary compounds in various organs of Lactuca serriola during phenological vegetative growth stage. After collecting aerial parts of L. Serriola from the farms in Vamenan village in Azadshar, various organs such as root, stem, and leaf were dried and powdered separately. Also, mixed organs were considered as another treatment for comparison. Then various organs of L. serriola and a mixture of them were analyzed qualitatively for primary metabolites like organic matter, raw ash, protein, proline, starch and soluble sugar as well as membrane stability index and some secondary metabolites like total phenols and anthocyanin. Results showed that various organs of L. serriola had a various content of primary and secondary metabolites as well membrane stability index. On the basis of the findings, the highest and lowest contents of organic matter and raw ash were obtained in leaf, respectively. The highest content of protein, starch and compatibility osmotic of soluble sugar and proline also were found in the leaf organ. The highest content of total phenols and anthocyanin were obtained in leaf showing a positive and significant correlation with membrane stability index. Regarding the high biomass generated from L. serriola, it is suggested to analyze the other chemical compounds in this plant. Complimentary studies are required to exploit the application of these compounds as bio herbicide.

RAPD and ISSR markers were used in the present study to determine genetic relationship and distance between some populations of Carum carvi. Amplification of genomic DNA all population using RAPD analysis yielded 126 fragments, where TIBMBA02 and TIBMBA08 had the minimum number of fragments (7) and TIBMBC05 had the maximum number of fragments, (22). ISSR marker yielded 79 fragments, where UBC112 and UBC809had the minimum (1) and maximum (15) fragments, respectively. The Diversity Index value of RAPD primers ranged from 0.8 (TIBMBA02) to 0.94 (TIBMBC05) and also Shanoon Diversity and Nei diversity were 0.57 and 0.38, respectively. In ISSR primers The Diversity Index value ranged from 0.0 (UBC112) to 0.92 (UBC809) and also Shanoon Diversity and Nei diversity were 0.57 and 0.39 respectively. According to ISSR and RAPD markers in combination, maximum genetic similarity (0.48) was observed between Kerman and Jandagh Carum carvi while the minimum similarity (0.115) was observed between Kerman and Neishabour Carum carvi with average 0.315. Also, cluster analysis segregated all populations into 3 groups according to geographical zone.

In order to investigate the effect of interaction of mycorrhiza and humic acid on morphological characteristics, seed protein percentage, and nutrients concentration of red beans, an experiment was conducted as factorial randomized complete block design in three replications. Research factors included mycorrhiza at three levels of control, Glomus intraradice, Glomus mossea, and also foliar application of humic acid at three levels of control, 15, and 30 mg/l. The experiment was conducted as pot and under normal and uncontrolled conditions. Measured traits included plant height, root length, number of plant pods, number of seeds in each pod, 100 seeds weight, seed protein, and nitrogen and phosphorus concentration of leaves. Application of mycorrhiza and humic acid increased measured traits except for the number of seeds in each pod and 100 seeds weight. There was no significant difference between the two strains and also levels of 15 and 30 mg/l humic acid in the studied traits. Generally, foliar application of 15 mg/l humic acid in the presence of mycorrhiza was more effective than other treatments.

Plants are always subjected to various environmental adverse factors such as salinity, drought, high/low temperatures, heavy metal toxicity, waterlogging, UV-B radiation, and ozone. Abiotic stresses cause hampering in the growth, physiology, and yield of crops and thus, are an important challenge for crop production and food security. Various strategies have been proposed to improve crop production under stress conditions, but attempts to enhance yield under these conditions have been largely unsuccessful. However, in recent years, exogenous application of phytoprotectants such as osmoprotectants (like proline and Glycinebetaine), phytohormones (for instance Abscisic acid, Salicylic acid, Gibberellic acid, Jasmonic acid, Brassinosteroids, and polyamines), antioxidants (including Ascorbic acid, Glutathione, and Tocopherol), micro nutrients (like Iron and Zinc), and trace elements (including Selenium and Silicon) have been found effective in mitigating the stress-induced damage in plant. This strategy has gained considerable attention because of its high efficiency, feasibility, and cost and labor effectiveness. Moreover, exogenous phytoprotectants show acceptable capacity to enhance plants’ growth, yield, as well as stress tolerance under adverse environmental factors. Regarding the importance of the application of exogenous phytoprotectants under stress condition, this article provides a review of the major responses of plants to these components in the presence of growth restriction factors.