فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 55 (پاییز 1399)

Drought stress, as an important constraint to reduce crop yields in Iran. To identify rice genotypes tolerant and sensitive to drought stress during flowering 15 genotypes were studied under two environments (stressed and non–stressed conditions) in a randomized complete block design with three replications at Abbas Abad and Katalom regions during 2018 growing season. To evaluate the susceptibility or tolerance of genotypes to drought stress, traits like yield under non-stress (Yp) and drought stress (Ys) and average yield of all genotypes under stress and nonstress (Ȳs), stress tolerance indicators, arithmetic mean (MP), geometric mean (GMP), harmonic mean (HM), tolerance (TOL), stress tolerance (STI), yield index (YSI), yield index (YI) and sensitivity to stress (SSI) were evaluated. Among the genotypes under study, sixty (54.62) and Ali Kazemi (46.92) showed the highest values for HM index. Shastack based on MP and GMP, shastack (61.04) and Tarom genotype (3.15) and STI index with similar trend to shastack (1.54) and Ali Kazemi (1.08) genotypes, respectively. Stress sensitivity (SSI) and yield stability index (YSI) values were similar for both genotypes of Shirudi (0.32) and Caspian (0.76). Cluster analysis based on 10 indices under drought stress resulted in two groups. Based on the results of principal component analysis, the first two components accounted for more than 92.6% of total information. The first component explained 58.76% of the total variation. According to the drought tolerance index of Shastak, Ali Kazemi and Sang Tarom genotypes are recommended as tolerant genotypes having the highest yield in both environmental conditions and having high stress tolerance index.

To study essential oil components of Dracocephalum moldavica in response to mycorrhiza fungus inoculation under drought stress condition, a factorial experiment based on completely randomized design with three replications was carried out under greenhouse condition. The factors of the experiment were three levels of drought stresses [control, 0.75 maximum allowable depletion (MAD) and 0.5 MAD] and inoculation with mycorrhiza fungi in two levels (no mycorrhiza inoculation as control and Glomus verciforme inoculation). Essential oil components were recognized via gas chromatography (GC) and gas chromatography-mass spectrometric (GC/MS). The result showed that about 36 components in D. moldavica were identified through inoculation with mycorrhiza under drought stress. Concentration of 13 compounds of these were higher than the rest. Compositions of geranial (18.3%), geraniol (30.98%), geranyl acetate (26.78%) and neral (11.94%) had high quantities in essential oil. Drought stress and mycorrhiza inoculation increased the percentage of major essential oil components. The highest essential oil percentage (1.24%) was obtained by mycorrhiza inoculation treatment and drought stress at 0.75 MAD. Drought stress reduced the uptake of nitrogen, phosphorus and potassium elements, while mycorrhiza inoculation increased their uptake. The highest uptake of potassium was in non-stress and mycorrhiza inoculation conditions. It can be concluded that mycorrhiza inoculation under drought stress increased the uptake of nutrients and essential oil composition of dragonhead.

Melissa officinalis L. (Lamiaceae) is a well-known herb used to give fragrance to different food and beverage products. It has also been used as a medicinal plant for the treatment of headaches, gastrointestinal disorders, nervousness, and rheumatism. To study the effect of organic fertilizers and mycorrhizal symbiosis on yield components percentage of essences Melissa officinalis, factorial experiment in a randomized complete block design with 8 treatments and 4 replications was conducted in Sari, in 2014. The experimental treatments were mycorrhizal fungi (Glomus mosseae) with two levels (0, 10% of each pot), vermicompost with two levels (0، 10% of each pot) and compost tea with two levels (0, 1.5 liter for pots marked). Traits measured were leaf area, plant high, number of seeds per plant, 1000 seed weight, and essence content. The results showed that organic fertilizer and mycorrhizal symbiosis treatments had a significant effect on all traits as compared to the control. Highest leaf area produced by the use of tea compost (207.93 cm2) and lowest from control treatment (52.63 cm2). Highest plant dry weight due to tea compost treatment along with mycorrhizal symbiosis (3.07 g) and lowest from control treatment (0.51 g). Highest essence percent was produced by mycorrhizal symbiosis treatment (0.73 %) and lowest from control treatment (0.23 %). It seems that increase in traits under study was due to the beneficial effects of organic fertilizers and mycorrhizal symbiosis of fungus used in this study.

Application of Bio-fertilizers are the most important sustainable strategies for reduction of chemical fertilizers. To study the effect of mycorrhiza and azotobacter bio-fertilizer on quantitative and qualitative characteristics of rapeseed cultivars, a factorial experiment based on a randomized complete block design with four replications were conducted in two temperate and semi temperate regions of Khorramabad and Aleshtar, Iran. The bio-fertilizer application consisted of application of mycorrhiza, application of azotobacter, combined application of mycorrhiza and azotobacter, and non-application of bio-fertilizer as control. Cultivars used in this study were: Gabriella, Nepton, X-Power and Okapi. Results showed that the average seed yields in two locations are 4265.7 and 4168.0 kg.ha-1 in Khorramabad and Aleshtar area, respectively. The highest seed and oil yields, were belonged to Gabriella (4599.7 and 1923.0 kg.ha-1, respectively) and the least to Okapi (3849.6 and 1591.0 kg.ha-1, respectively). The highest seed yield was attributed to the combined application of mycorrhiza and azotobacter (4408.0 and 1831.8 kg.ha-1, respectively) and the least to the non-use of biological fertilizers (3849.6 and 1650.1 kg.ha-1, respectively). As a whole, according to interaction of three factors, Gabriella cultivar with combined application of bio-fertilizers mycorrhiza and azotobacter and X-Power cultivar with azotobacter bio-fertilizer recommended to Khorramabad temperate region and Aleshtar semi temperate region, respectively.

Delayed planting of sugar beet, use of nitrogen fertilizer and growth promoting bacteria are important in accelerating growth and compensating time loss. To study this subject, a split split plot experiment was conducted in a randomized complete block design with 3 replications and 8 treatments in 2018 at the Research Farm of Ferdowsi University of Mashhad. The factors under study consisted of planting date with two levels (regular planting, D1, and delayed planting, D2) as the main factor, nitrogen fertilizer with two levels (use of nitrogen fertilizer based on recommended rate, N1 and 25% less than recommended rate, N2) as a subfactors and bacterial growth stimulant with two levels (bacterial inoculation, B2, and without its use, B1) were considered as sub-sub- factors. Growth indices under study were leaf area index, total dry matter, crop growth rate, relative growth rate and net assimilation rate. In this study, highest leaf area index (3.5) and dry matter accumulation (2898 g.m-2) in thermal unit, as well as growth rate, relative growth rate and net assimilation rate under regular and delayed planting dates were due to the use of recommended rate of nitrogen fertilizer and bacterial inoculation treatments. The least amounts of these traits were obtained at both planting dates and use of nitrogen fertilizer, 25% less than the recommendation, and without using bacteria. Root yield and sugar content sugar beet under treatment of bacterial and nitrogen use, based on recommended rate, showed 8 to 10% higher than other treatments, under both regular and delayed planting date. It seems that the combined use of chemical and biological fertilizers is useful in delayed sowing, to compensate delayed time loss planting of sugar beet.

The present study was conducted to investigate the response of durum wheat cultivars to different planting dates and densities under rainfed conditions during the years 2014-2016 in Sararood, Kermanshah, using a split plot factorial experiment based on randomized complete block design with four replications. Three durum wheat genotypes (SAJI, BCR and STJ) with three sowing dates, prior to effective rainfall (the amount and time of effective rainfall were 33.2 and 34.5 mm, and 26 October, and 5 November for two years of experiment, respectively). 15 days after effective rainfall and 30 days after effective rainfall were evaluated for four densities of 250, 350, 450 and 550 plant per square meter. Traits like number of spikes per square meter, 1000 kernel weight, seed and biological yield, harvest index and absorbed radiation percentage were measured. The results of mean comparisons of simple effects showed that the number of spikes per square meter in the planting date before rainfall was more effective than two other planting dates. Biological yield and absorbed radiation percentage were 26.9 and 12.9 percent higher respectively in second year of experiment as compared to the first year. Comparison of interactions means showed that STJ genotype under 250 seeding density and 15 days sowing date after effective rainfall, produced highest 1000 kernel weight, while SAJI cultivar at 550 seeding density and planting date before effective rainfall showed the highest kernel yield. The SAJI cultivar showed highest biological yield under 450 seeding density and planting date before effective rainfall. For all three genotypes, the highest percentage of radiation absorption was observed when sowing date used before rainy season using 450 and 550 seeding densities. In this study all genotypes showed the highest traits values at first planting date and under 450 seeding density. The highest values of protein and chlorophyll content were observed using 350 seeding density.

To study the effect of GDD and plant spacing on some agronomic, morpho-physiologic traits and qualitative traits of mungbean (Vigna radiate L.), cv. Gohar, a field experiment was conducted by using a factorial experiment based on a randomized complete block design with three replications in summer of 2016 in Ilam region. The first factor, planting date, consisted of three GDD of 1910 GDD, 1740 GDD and 1485 GDD (planting dates of 10 and 25 July and 5 July) and the second factor plant spacings on the row consisting of four levels (5, 10, 15 and 20 cm) with 50 cm between rows (40, 20, 13.3 and 10 plants.m-2,respectively). The results showed that leaf chlorophyll content, leaf area, relative water content, pods.plant-1, pods.m-2, grain yield, biological yield and harvest index were affected by planting date× plant distances on the row. The highest chlorophyll content (1.85 mg/g fresh weight), pods.plant-1 (44 pods), pods.m-2 (507 pods), grain yield (3149 kg.ha-1) and harvest index (50.2%) were obtained at 1740 GDD and 15 cm plant distances on the row. According to the results of this experiment, the highest grain yield and yield components belonged to the planting date of 1740 GDD (planting dates of 25 July) with 15 cm plant distances on the row (13.3 plants.m-2) in Ilam region.

Rapessed is one of the most important oilseed crops. Weeds, also are most important factors that limit the production of the oil crops and greatly affect the quantity and quality of their extracted oils. To investigate the effect of row spacing and herbicide application on photosynthetic pigments and rapeseed yield, a factorial experiment based on a randomized complete block design with three replications was conducted during 2017-18 at Bayekola Research Station, Neka, Mazandaran. Factors were planting arrangement in two levels )one and two-row plantings( and weed control in 7 levels of  application of herbicides consisting of Trifluralin (Treflan) 2.5 l.ha-1 before planting and mixed with soil, Quinmerac + Metazachlor (Butisan Star) 2.5 l.ha-1 pre-emergence, Trifluralin 2.5 l/ha before planting + Quinmerac + Metazachlor 2.5 l.ha-1 pre-emergence, Chlopyralid (lontrel) 1 l.ha-1 + Haloxyfop-R-Methyl (Super Gallant) 0.8 l.ha-1 at 2 to 4 weeds leaf stage, Paraquat (Gramaxon) 2 l.ha-1 at 4 to 6 weeds leaf stages, weed control and without weed control. The results showed that by changing the planting arrangement and using combination of Trifluralin with Quinmerac + Metazachlor and/or application of Paraquat (as a guided herbicide) in two-row culture, the rapeseed chlorophyll content increased by 38.06% and 34.11% as compared to without weed control. Also, weed dry weight decreased by 87.16% and 94.97%, and rapeseed grain yield increased by 73.4% and 76.79%, respectively, which resulted in increasing crops,s extracted oil. It can be concluded that by modifying the canola planting pattern we can increase canola,s oil yield, and application of guided herbicide or combination of Trifluralin with Quinmerac + Metazachlor, to control weeds.