فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 43 (پاییز 1396)

Seed filling in wheat is controlled by the availability of substrate (source strength), the capacity of the organs to utilize it for seed growth (sink strength). The aim of this research was to study source-sink relations in wheat, through seed weight and grain number in new and old wheat cultivars. The experiment was performed at Moghan College of Agriculture and Natural Resources, Research Farm (University of Mohaghegh Ardabili) during 2010-2011 growing season. The plant materials (81 wheat cultivars) were evaluated using a simple lattice design with two replications under well-watered condition. The results showed that there were significant differences for measured agronomic and physiologic traits among wheat cultivars tested. Overall, new wheat cultivars showed high values of seed yield as compared with the old ones. This trend was also observed in the cases of harvest index (HI) and grain number per square meter. There were no significant differences in biological yield and 1000-grain weight between old and new cultivars. Spike dry weight measured at anthesis and physiologic maturity and also partitioning photoassimilates to the spike during anthesis-physiologic maturity phases increased more in new cultivars than old ones. Increased grain number in new wheat cultivars and the lack of significant changes in 1000-seed weight suggests that seed yields of the cultivars used under the condition tested are controlled more by sink than source strength. Under conditions tested, it seems that increased grain number, either in plant level or in square meter, might be considered as a way to assess increased seed yield.

Growth analysis is a valuable method to quantify crop growth, development and production. Because, parameters of nonlinear regression models have significant physiological meanings, it was decided to study the effect of topping and variety on crop growth indices by using a logistic nonlinear regression model in a factorial experiment, based on randomized complete block design with 3 replications, at the Research Farm of Gonbad University during 2014-2015. The first factor consisted of five faba bean verities (Zohreh, Shami, Sheshband, Sarazeri and Barkat) and the second factor of two levels, topping and control. Results showed that using this molel described well the variation pattern of dry matter accumulation and LAI by time. It was also revealel that the difference between verities for the time to reach maximum leaf area index and the time required to reach 50 percent of maximum dry matter were not significant. The effect of variety on leaf area index was significant at the 5% level. The maximum and minimum leaf area index, total dry matter and crop growth rate of Barkat, Zohre and the Saraziri were higher than Shami and Sheshband varieties, and thus this was resulted in higher yield. Leaf area index in all varieties was the critical leaf area index. The average critical leaf area index in varieties was 1.37. The maximum and minimum relative growth rate at the beginning of the growing season belonged to the Saraziri and Barkat with 0.066 and 0.055 g/g.day, respectively.

Decision Support System for Agrotechnology Transfer (DSSAT) model is able to simulate plant growth, development, and yield that are grown on a uniform surface under simulated management conditions, including changes in soil water, soil carbon, soil nitrogen contents and nitrogen leaching. This study was aimed to investigate the effects of nitrogen on yield and yield components of maize variety SC704 by using this model, and to calibrate CERES-Maize model under 4 levels of nitrogen fertilizer: N1: 25% less than the recommended level, N2: recommended level (200 kg/ha), N3: 50% less than recommended level (260 kg/ha), and N4: 50% more than the recommended level (310 kg/ha). To evaluate the applicability of this model an experiment based on randomized complete block design with three replications was conducted during 2013 at the Research Field of Agriculture Faculty of Islamic Azad University – Karaj Branch. The measured traits, and their simulated values for ear and biomass yields, leaf area index (LAI) and stem dry matter content were compared. The results of the biomass simulation showed that Root Mean Square Error (RMSE) of the four fertilizer levels ranged 2496.48, 2159.24, 2302.43, and 3289.19 kg/ha respectively. For the ear yield, the highest coefficient of determination (R2 = 0.98) was obtained by N4. In fact, this treatment provided highest accuracy for predicting the yield of maize by the model. For leaf area index, the Willmott Agreement Index (d) varied between 0.77-0.94. This indicates that the model has successfully predicted the variation of leaf area index. Therefore, the model is considered appropriate for simulating growth, development and yield of maize under 4 levels of nitrogen fertilizer. In this case, it is recommended that the model is calibrated and verified, and then, it is applied for research purposes in Karaj climatic conditions.

Ajowan is one of the most important medicinal plants in Zahedan region. Salinity and drought are the main causes of yield reduction of plants in Sistan and Balochestan. To evaluate the effect of salinity on yield and quality of ajowan a factorial experiment with randomized complete block design with three replications was conducted at the greenhouse of the Payam Noor University of Agriculture in Zahedan in 2016. Treatments were two populations of ajowan: C1: local and C2: Pakistani which were considered as the first factor and five salinity levels 0, 2, 4, 6 and 8 d/ms as the second. The results of this experiment showed that highest root length, stem height, plant fresh weight and plant dry weight and yield of essence belonged to local population under saline condition. Increasing salinity levels beyond 4 ds/ms decreased quantitative traits significantly but increased essential oil content and concentrations of osmotic regulants (prolin and carbohydrate) as compared to that of control. This may indicate that ajowan is tolerant to salinity.

Cold and drought stresses are considered as the most important factors limiting crop production. To evaluate the effect of these tow stresses on yield and yield components of corn hybrids, a field experiment was implemented in split plots based on a randomized complete block design in 3 replicates during 2014 at the Research Greenhouse of Ferdowsi University of Mashhad. In this research, chilling stress in two levels (i.e. non-stress, and cold stress) is considered as the main factor and three levels of drought stress (i.e. irrigation equivalent to 100% of plants water requirement, non-stress as control, irrigation equivalent to 75% of plants water requirement, and irrigation equivalent to 50% of plants water requirement) as sub factor and three hybrid corn (i.e. single-cross 704, single-cross 400, single-cross 260). The results showed that the effects of drought and hybrids on traits under study were significant. Cold and drought stresses interaction of different corn varieties on the traits under study (seed number per ear, 100-seed weight, yield, biological yield and harvest index) was also significant. The highest seed yields of hybrid 704 and hybrid 400 under 100% water requirement were 7887 and 6862 kg.ha-1 respectively. Single-cross 400 variety had the highest water productivity in line with the 704 variety with the highest grain yield and water consumption efficiency, water consumption efficiency for biomass production in water-limited conditions increased. Finally, it shows that cold and drought stress interaction resulted in highest water consumption efficiency in the treatments of non-chilling stress and 100% water requirement.

To evaluate theeffect of different ratios of animal manure and super absorbent polymer on some physiological characteristics of fennel under drought stress conditions, an experiment was conducted as spilt-plot based on a randomized complete block design with three replications in 2015 at the University of Shahrekord. Different levels of drought stress consisted of three levels of: control (50 mm), 100 mm and 150 mm evaporation from class A pan assigned to the main factor and different ratios of animal manure and super absorbent polymer in six levels including: D1: lack of manure and super absorbent polymer, D2: 10 t.ha-1 manure 150 kg.ha-1 super absorbent polymer, D3: 20 t.ha-1 manure 100 kg.ha-1 super absorbent polymer, D4: 30 t.ha-1 manure 50 kg.ha-1super absorbent polymer, D5: 40 t.ha-1 manure and D6: 200 kg.ha-1 super absorbent polymer to the sub-factor. The results showed that the drought stress and animal manure and super absorbent polymer and their interactions had a significant effect on proline, chlorophyll b, and carotenoid contents, seed and essential oil yields. Also, the highest seed yield (146.66 g.m-2), essential oil yield (2.99 g.m-2) and carotenoid were obtained from control with D6. The highest proline content was obtained from 150 mm with the use of D4. The highest chlorophyll b was obtained from control and D3. The highest relative water content and total chlorophyll were obtained from control and D6, while the highest chlorophyll a was achieved from control and D4 treatment. In general, the highest seed and essential oil yields were obtained from 50 mm evaporation and 200 kg/ha superabsorbent polymer treatments. On the other hand, the effects of drought stress on seed and essential oil yields decreased by application of 40 t/ha manure at 100 mm evaporation conditions. Also, at 150 mm evaporation and use of manure and superabsorbent polymer (30 t.ha-1 and 50 kg/ha, respectively), the effects of drought stress on seed and essential oil yields decreased as compared to the other treatments.

To study the effects of drought stress and foliar application of nano iron chelated on photosynthetic pigments, yield and yield component of thirteen genotypes of chamomile, a factorial experiment was conducted in a randomized complete block design with three replications at the Research Greenhouse of Zabol University in 2014. The experimental treatments were: drought stress at 2 levels (control or irrigation at 90% of field capacity and irrigation at 70% of field capacity), foliar application of nano iron chelate at 2 levels (control and 2 mg/l) and 13 genotypes of chamomile consisting at: Isfahan, Mashhad, Shiraz, Kerman, Arak, Ardestan, Gachsaran, Nain, Khozestan, Safashahr, Kazeroon, Germany and Hungary. The results showed that besides the main effects of stress×genotype, the genotype×nano iron chelated and stress×nano iron chelated interactions and the triple effects were also became significant. Mean comparisons showed that the condition of genotypes at any level of stress and nano iron chelated had different trends. Using nano iron chelated in drought stress decreased chlorophyll a in Shiraz, Khozestan, Nain, Hungary and Germany genotypes, decreased chlorophyll b in genotypes of Isfahan, Kazeroon, Ardestan, Khozestan, Nain and Germany, decreased total chlorophyll in genotypes of Isfahan, Shiraz, Ardestan, Khozestan, Nain, Hungary and Germany and decreased anthocyanin content in Isfahan, Shiraz, Safashahr, Kazeroon, Khozestan and Germany genotypes. Using nano iron chelated in drought stress also caused a decrease in flower yield of Mashhad, Arak and Nain and a decrease per plant yield of Isfahan, Mashhad, Arak, Safashahr, Khozestan and Nain genotypes. The highest per plant yield (0.665 g.) belonged to Kerman genotype, were achieved through non-stress and use of nano iron chelate treatments and the lowest per plant yield (0.164 g.) to Arak genotype through the stress and non-spray treatments. Totally the interaction of chamomile genotypes to drought stress were different. Among the genotypes under study the Shiraz genotype were more resistant to stress compared to others. The effects of application of nano iron chelated were different depending on the genotype and for most of the genotypes it increased the photosynthetic pigment contents and yield components of Chamomile. This shows the effectiveness of low rate application of nano iron chelate.

To study the effects of spraying manganese sulfate on some physiological characteristics and seed yield of tetraploid and hexaploid varieties of wheat under different irrigation regimes a factorial split plot experiment based on completely randomized design with three replications was conducted at the Research Station of Faculty of Agriculture, Islamic Azad University, Tabriz Branch, Iran, in the fall of 2013. Irrigation regimes were considered as main factor in three levels, including irrigation at every 7 days (control), cutting off of irrigation at stem elongation (code 30 scale Zadoks) and cutting off of irrigation at booting stage (code 45 scale Zadoks), manganese sulfate fertilizer as sub factor including not spraying, spraying with 50% and 100% concentrations of recommended rate based on soil analysis (with 0.005 concentration) and sub sub factor in four levels, including two levels of each hexaploid (Pishgam and Alvand) and tetraploid (Cheheldaneh and Saji) wheats. The results showed that irrigation regimes significantly affected translocation of dry matter of flag leaf internode, leaf relative water content, duration and rate of seed filling, leaf proline content, water use efficiency and seed yield. Cutting off of irrigation at both stages and also not spraying of manganese sulfate reduced seed yield, rate and duration of seed filling.Cutting off of irrigation at stem elongation stage reduced leaf relative water content (by 33%) as compared to control treatment. Also, cutting off of irrigation increased praline content of leaf, cutting off of irrigation at stem elongation stage increased amount of leaf proline content from 5.35 to 8.34 micro moles per gram. Irrigation at 7 day intervals increased seed filling duration in comparison of cutting irrigation, by 36 days. The highest water use efficiency (0.0018 kg/m3) with total volume water use (2.4 m3) was achieved with the irrigation at 7 day intervals.

The assessment of water deficit stress and timing of nitrogen fertilizer application effects on seed yield and its components in bread wheat cultivars were carried out in a an split split plot experiment based on RCB design with three replications was carried out. Experimental factors consisted of different levels of irrigation (full irrigation, stopping irrigation at heading and anthesis stages) that were assigned to main plots, and four levels of nitrogen fertilizer applications (F1: 20 and100 kg/ha at sowing and tillering stages respectively, F2: 20 and 100 kg/ha at sowing and booting stages respectively, F3: 20, 50 and 50 kg/ha at sowing , tillering and booting stages respectively, F4: 20 , 50 and 50 kg/ha in sowing, tillering and heading stages, respectively) to sub plots and five bread wheat cultivars (Zarrin, Pishgam, Urum, Zare and Mihan) to the sub sub plots. The results showed that mean yield of cultivars was 7.5 t/ha and it was decreased to 6.5 t/ha at stopping irrigation. The highest and lowest yield belonged to Mihan (8.1 t/ha) and Zarrin (5.7 t/ha) cultivars, respectively. Highest yield belonged to Mihan cultivar (9.4 t/ha) under full irrigation and F4 fertilizing treatments. Under deficit water stress condition at heading and flowering stages, the Mihan cultivar produced the highest yield with 8.3 and 8.6 t/ha at F3 and F4 treatments, respectively. Pishgam, Zare and Mihan cultivars responded properly to F2, F3 and F4 fertilizing treatments when irrigation stopped at heading stage, in comparison with F1 fertilizing treatment. Based on drought tolerance indices, Mihan and Pishgam identified as high performance cultivars under both stress and non-stress conditions.

To evaluate the effects of Zn application on seed yield and some qualitative properties of wheat in a calcareous soil an experiment was carried out in factorial randomized complete block design (RCBD) with three replications at the Faculty of Agriculture, University of Maragheh, Iran, during 2014 growing season. The first factor consisted of four durum wheat genotypes and the second factor of levels two zinc sulfate application (control and foliar application of Zn on soil at stem elongation seed filling stages). The results showed that application of zinc sulfate could increase biological and seed yields of RCOL genotype by 2 and 4 times compared to control respectively. The effects application of zinc sulfate on biological and seed yields of other genotypes were not significant. Based on the results obtained from this study the highest increase in seed weight was 20.7% in the RCOL genotype by Zn application. The highest reduction in phytic acid to zinc molar ratio was observed in Ege-88 genotype and this ratio was decreased by 52.2 percent in the control to 8.4% due to Zn application. This may indicate different responses of durum wheat genotypes to the zinc deficiency in the soil. The results also showed that the number of seed per spike was increased by 22.7 percent and phytic acid was decreased by 62.3 percent due to the application of zinc sulfate. Also, application of zinc sulfate increased Zn concentration in seed from 29.9 mg.kg-1 to 64.7 mg.kg-1 in control. In general, however, the application of zinc was not the reason of seed yield improvement of all genotypes studied but it improved seed yield qualities. It can be concluded that use of Zn is an appropriate method to improve the qualitative and quantitative traits of seed yield. To confirm these results other studies are needed.

Application of proper rates of nitrogen fertilizer and plant density are important factors for medicinal plants yield. To study the effect of nitrogen rates and plant densities on yield and yield components of coriander, an experiment was carried out in split-plot based on randomized complete block design with three replications at the Research Field of Islamic Azad University of Birjand, Iran, in 2013. The main plots were nitrogen rates with four levels (0, 40, 80 and 120 kg N per ha) and the sub-plots with three levels (30, 40 and 50 plants per m2). The results showed that nitrogen rate had significant effect on number of umbel per plant and per m2, fruit number per umbel, fruit yield, biological yield, fruit weight of single plant, biomass yield of single plant and percent and yield of essential oil. Changes in plant density, also had significant effect on all traits except fruit number per umbel, 1000-fruit weight and percent of essential oil. Moreover, interaction effect between nitrogen rate and plant density affected all traits except umbel number per plant, fruit number per umbel and percent and yield of essential oil. Mean comparisons showed that as N fertilization rate increased from 0 to 80 kg N ha-1, umbel number per m2, fruit yield, biological yield and essential oil yield increased by 62.5, 74.1, 74.3 and 186.8%, respectively. Results also revealed that increasing plant density from 30 to 50 plants per m2, increased these traits by 25.6, 31.4, 21.8 and 37.4%, respectively. The conclusion is that application of 80 kg N ha-1 and use of 50 plants/m2 produced highest fruit and essential oil yield for coriander in Birjand region.

Soil contamination with heavy metals would accumulate these elements in plant tissues and decrease qualitaty and quantity of agricultural producs and thus endanger human and animal healths. Previous crop residues and rates of fertilizers applications (especially phosphorus fertilizer) are the most important effective factors on accumulation of cadmium in crop tissues. Another influential factor affecting soil shrinkage is crop rotation which induces the solubility of cadmium. This research was aimed to assess the effects of conventional cropping system on cadmium concentrations in wheat at its different growth stages by using a split plot in time experiment based on completely randomized block design with three replications in the 2014-2015 growing season in Shavoor Agricultural Research Station (Khuzestan province). Main plot consisted of cropping system (rice-wheat, fallow-wheat) and sub plot of growth stages at three levels (tillering, flowering and ripening). Different wheat seed cadmium concentrations due to two cropping systems were different significantly at 1% probability level. Cadmium concentration in the seeds at rice-wheat cropping system (0.31 mg.kg-1) was higher than fallow-wheat system (0.27 mg.kg-1) which is higher than World Health Organization standards. Result of analysis of variance showed that the effect of cropping systems and different growth stages of wheat on root and stem cadmium concentrations were significant at 1% probability level. Rice-wheat cropping system resulted in higher cadmium concentration in root (1.09 mg.kg-1) and stem (0.73 mg.kg-1) compared to that of the fallow-wheat cropping system. Accumulation of cadmium in stem or root at different growth stages of wheat were not significant but it was totally additive, because range of variation of cadmium concentration from planting to harvest was low.

The effect of times of weeding on reducing herbicide dose in sugar beet was studied in 2011-2012 in Jovein. The experiment was conducted in split plot based on a randomized complete block design with three replications. The main factor was herbicide doses (0, 25, 50, 75 and 100% of recommended dose (Chloridazon 3.25 kg. a.i. ha-1 soil applied) and sub plot was times of hand weeding (0, one time hand hoeing, tow times hand hoeing, at 30 and 60 days after plant emergence). Traits like root yield and white sugar yields, impure sugar content, alkalinity coefficient, sodium, potassium, α-amino nitrogen and sugar content in molasses were evaluated. The result showed that the increased frequency of weeding reduced weed density, weed dry weight, α-amino nitrogen and percentage of impure and pure sugar contents, root yield and sugar yield. The least weed density and biomass of weeds were observed in recommended dose. Increasing the doses of herbicide increased impure sugar content (14.48%), α-amino nitrogen (57.86%), pure sugar (19.30%), root yield (77.67%) and sugar yield (111.17%) while it decreased potassium (18.77%), sodium (28.84%) contents and alkalinity coefficient (52.76%) as compared with that of control. For most of the traits, there were not statistically significant difference between the recommended dose and 75% of the recommended dose. Increasing the number of hand weedings reduced herbicide dosages. The, results finally showed that 25% dose reduction of herbicide in one time weeding and 50% dose reduction of it in twice weedings might produce desirable economic yield (root yield).

Forage crops are considered as important components of sustainable farming systems. Legumes have a specific role in farming systems. In order to assess the possibility of growing lupine in Tabriz plain, an experiment based on randomized complete block design with three replications was carried out at the East Azarbaijan Agriculture and Natural Research and Education Center, Iran. Three forage lupins varieties namely Dieta (Lupinus albus), Iris (L. angustifolius) and Pootallong (L. luteus) in this study were evaluated. The results indicated that establishment and survival percentage of varieties under farm condition were significantly different. The intraction effect of variety× days after planting on percentage of establishment among lupine speaces was significantly different. Seedling of Dieta and Iris varieties emerged 6 days after planting, but that of Pootallong could emergent after 9 days. Seedling of Iris and Pootallong varieties dried 27 and 18 days after planting, respectively. The trends of growth and establishment of Dieta variety in the farm was different from the other two varieties. It could achieve the peak emergence after 24 days. Although, Dieta lupine variety, by having 50.1% emergence in the field, was able to grow in the farm and produce seed, but it couldnt express acceptable seed yield and its component. Since the salinity of soil and water used in this experiment were 4580 and 5634 µs/m respectively, growth of these species, specially L. angustifolius and L. luteus (Iris and Pootallong varieties) came across sevrer limitations. More studies are needed to evaluate adaptability and planting time of Dieta cultivar in the region.