فصلنامه اکوفیزیولوژی گیاهان زراعی
پیاپی 49 (بهار 1398)

Relationship, between seed yield and it morphological characteristics and their relative importance in 25 bread wheat genotypes under both rain-fed and supplementary irrigation conditions studied using a randomized complete block design with three replications were evaluated during growing seasons of 2014 and 2016 at the Kermanshah’s Sararud Rainfed Agricultural Research Station. Analysis of variance showed that all traits under study, except spike length, exhibited significant differences in rainfed and supplementary irrigation condition. In supplementary irrigation conditions, these traits showed higher values as compared to those of rainfed condition. The application of supplementary irrigation resulted in reduced leaf and canopy temperatures. The coefficients of simple correlation between the traits, for both of the rain-fed and supplementary irrigation systems, indicated that cell membrane stability, flag leaf length, straw yield, relative water content, 1000 seed weight, chlorophyll content, leaf and canopy temperatures were maximally correlated with the seed yield. Traits like straw yield and flag leaf length were inserted into the regression model of rainfed irrigation condition and traits such as the straw yield, flag leaf length, relative water content and spike yield were also inserted into the regression model of supplementary irrigation condition the results demonstrated that the former traits accounted for 0.741 of the seed yield variations and the latter traits explained 0.899 of the seed yield variation. Path coefficient analysis showed highest positive direct effect on seed yield in rain-fed condition, and straw yield and flag leaf length, relative water content, flag leaf length and spike yield in supplementary irrigation condition. Based on the results of this study, straw yield was found to be the most important indicator to select for higher yielding varieties of wheat under both rainfed and supplementar irrigation conditions.

To study the effect of electrical conductivity (EC) andsodium adsorption ratio (SAR) on the yield and physiological indices of two varieties of rapeseed, an experiment was carried in pot condition. Treatments were EC with 3 levels (0.35, 6 and 12 dSm-1), SAR with 4 levels (0, 6, 12 and 18 from NaCl and CaCl2) and varieties with two levels (Talayeh and Okapy). Traits measured were RWC, concentration of Na, K and Ca, leaf water potential, biomass and seed yields. The result of the analysis of variance showed that the interaction effect of variety by EC on Na concentration, biomass and seed yield were significant. With increasing EC levels, seed yield decreased, but yield reduction in Okapi variety was less than that of Talayeh variety. Seed weight per plant in Talayeh was 2.99 g. and that of Okapi was 3.13 g. In both of varieties, with increasing of EC, concentration of Na increased, but its concentration in Okapy was more than Talayeh. The interaction effect of EC by SAR showed that with increasing treatment levels, leaf water potential, biomass and seed yield decreased, while carbohydrates increased. With increasing SAR from EC1SAR1 to EC1SAR4, yield decreased by 7%, while it was 13.7% from EC2SAR1 to EC2SAR4 and 25% from EC3SAR1 to EC3SAR4. Although EC and SAR causes negative effects on rapeseed growth indices, but their negative on Talayeh variety was less than that of Okapy. Increasing calcium proportion against salinity reduced the effects salinity in all traits. Since, high saline water has higher calcium ion, it would have poper quality for to use it in agriculture.

To investigate the effect of different seed primings on quantitative and qualitative characteristics of two sugar beet cultivars a factorial experiment based on randomized complete block design (RCBD) with three replications, was carried out in both laboratory and field at the Agricultural and Natural Resources Research Center of West Azarbaijan province in 2015-16. The factors were two cultivars (Ekbatan and 7233) and five kinds of seed primings (seed hardening, priming with nano fertilizer, priming with pigeon manure extract, hydropriming and control). The results of combined analysis of variance showed that there were significant differences between genotypes for root yield and white sugar content. It was also, revealed that primings for all traits, except percent of sugar extraction, alkalinity and white sugar content, were significant. In this study, cultivar 7233, as compared with Ekbatan, produced higher root yield and sugar content. Furthermore, hydropriming produced higher germination percentage (96.50%), speed of germination (9.56 seeds/day), root yield (80.33 t.ha-1), sugars content (23.11%), sugar yield (18.38 t.ha-1) than other seed primings. Based on stepwise regression analysis, four traits, like sugars content, root yield, sugar extraction percentage and molasses sugar, justified 98% of white sugar yield variations. Thus, these four traits were identified as the most effective ones for white sugar yield. It can be, therefore, concluded that hydropriming would be a proper seed priming to improve the quantitative and qualitative characteristics of sugar beet.

The effect of electromagnetic field and ultrasonic waves on the seed germination, seedling characteristics and essence percent of thymes investigated by using two separate factorial experiments, based on completely randomized design with three replications, at the Seed Science and Technology Laboratory of Faculty Agricultural Sciences of Islamic Azad University of Mahabad in 2017. In the first experiment, the seeds were exposed to electromagnetic field with 5, 50 and 100 milli tesla for 5, 15 and 30 minutes, and in the second experiment, the seeds were exposed to ultrasound intensity of 20, 40 and 60 kHz for 4, 8 and 12 minutes. Results of analysis of variance showed that the effects of electromagnetic field intensity by ultrasound intensity interactions were significant on all traits and indices. In this research, the highest germination percentage (97.66%), speed of germination (0.20), root length (8.70 cm), stem length (9.67 cm), root dry weight (41.5 mg), stem dry weight (44.75 mg), seedling dry weight (86.21 mg), plant dry weight (0.82g), and lowest mean germination time (4.84 days) belonged to the seeds treated with electromagnetic field intensity of 50 milli tesla for 15 minutes. The results also revealed that highest germination percentage (90.66%), germination speed (0.21), root length (7.78 cm), stem length (6.65 cm), root dry weight (41.21 mg), stem dry weight (53.60 mg), seedling dry weight (94.80 mg) and plant dry weight (0.55 g) and the lowest mean germination time (4.96 days) were related to 60 KHz ultrasound intensity for 16 minutes. The highest essence percent was produced from seeds treated with electromagnetic fields of 5 milli tesla for 30 minutes (3.44 percent) and 60 KHz ultrasound waves for 16 minutes (2.95 percent). Thus, these treatments are recommended to improve thyme germination and its seedling properties.

Chitosan is one of the bio-elicitors that cause physiological and morphological changes in plants. To this end, two separate experiments were carried out to investigate the effect of chitosan on morphological and physiological traits of lemon verbena under in vitro and field conditions. 12.5, 25, 50 and 100 ppm concentrations of chitosan were added to MS culture medium and their effects on lemon verbena growth indices were evaluated. The results showed that chitosan had a significant effect on all traits, except for the normal plantlet percentage, lateral shoots and chlorotic leaf numbers evaluated. Increasing chitosan concentrations up to 50 and 100 ppm under in vitro condition increased longest shoot length, chlorophyll content and plantlet length in lemon verbena explants but it reduced node numbers of the longest shoot when all concentrations of chitosan were used. Increasing the effect of chitosan on rooting percentage and root numbers were positive and reached the highest levels at concentrations of 50 and 100 ppm. It was also found that the shoot fresh weight, the leaf number and longest root have a positive effect on chitosan and had a better effect on concentrations less than 100 ppm. However, the use of chitosan showed irregular changes in the amount of citral. The effect of chitosan with 12.5, 25, 50 and 100 ppm concentrations were evaluated on growth indices of lemon verbena under field condition. The positive effect of chitosan concentration of 50 ppm was observed for inflorescence number, inflorescence length and leaf fresh weight. Because of positive effects of chitosan concentrations of 50 and 100 ppm, on most growth characteristics of lemon verbena in field and tissue culture conditions their applications could be recommended in plantations of this tree.

To compare yields of mung bean under different nutrition (Chemical, Biological and Integrated) and tillage systems a split plot experiment based on a randomized complete block design with three replications was conducted in 2015. Treatments consisted of 3 levels of tillage systems (no-tillage, conservation tillage and conventional tillage) and 4 levels of plant nutritions (inoculated with mycorrhiza + 50% nitrogen, 50% nitrogen without mycorrhizal inoculation, mycorrhizal inoculation +100 percent nitrogen, without inoculation with mycorrhiza + 50% nitrogen). The results showed that plant nutrient sources affected yield significantly. The highest grain yield (1510.03 kg.ha-1) was obtaind by using conservation tillage, 50% nitrogen and mycorhizal seed inoculation. This yield was 50% more than conventional tillage and nitrogen fertilizer and mycorrhizal seed inoculation which was 934.1 kg.ha-1. The highest protein yield (24.99 kg.ha-1) belonged to conventional tillage, 50 percent of nitrogen use and mycorrhizal inoculation, which is 100% (13.33 kg.ha-1) more than conventional tillage and nitrogen fertilizer with 50 percent of mycorrhizal inoculation. In general, the results showed that the use of tillage did not have significant effect on most of the traits. This result could be different if this experiment would be continued for several years. These results indicated that mycorrhizal seed inoculation reduced the need for nitrogen fertilizer, while increased seed yield.

Now-a-days, in addition to the quantity of production its quality, stability and sustainability are taken into account. This research was conducted in a split plot experiment based on randomized complete block design with three replications at Ramhormoz region in 2016-2017. The main treatments consisted of phosphorus fertilizers and bio-fertilizers with four levels (without using phosphorus fertilizer as control, bio-fertilizer, phosphorus bio-fertilizer + 150 kg.ha-1 superphosphate fertilizer and 200 kg.ha-1 superphosphate fertilizer) and foliar application of micro-nutrients (zinc, iron and manganese) with three levels (without application of micro-nutrients as control, spraying of micro-nutrients with 0.002 and 0.004 concentrations) assigned to sub plots. The analysis of variance of data showed that the combined effect of chemical and biological phosphorus fertilizer and foliar application of micronutrient on seed yield, its components, protein yield and its percentage, plant height and spike length were significant. Mean comparisons indicated that phosphorus bio-fertilizer + 150 kg.ha-1 superphosphate fertilizer produced highest number of spike per m2, seeds per spike, 1000-seed weight, harvest index, protein percentage, protein yield, plant height and spike length. The highest seed yield belonged to phosphorus bio-fertilizer + 150 kg.ha-1 superphosphate fertilizer and foliar application of micro-nutrients with 0.004 concentration and the lowest to the control treatment. Generally, to reduce the use of chemical fertilizers, cost of production and the prevention of soil contamination use of phosphorus bio-fertilizer +150 kg.ha-1 superphosphate fertilizer and spraying micronutrients with 0.004 concentration can be recommended to the farmers of the region.

To study the effect of planting dates on yields, yield components and protein contents of seeds of millet varieties in Birjand region, an experiment was carried out as a split-plot based on randomized complete block design with three replications at the Research Field of Islamic Azad University, Birjand Branch, Birjand, Iran, in 2013. Planting dates with three levels (May 12rd, June 2nd and June 23rd) were assigned to main plots and millet varieties with 5 levels (Bastan, Chomaki, Pishahank, White Gavars and Yellow Gavars), to sub-plot was. The results of variance analysis showed that the effect of planting date× variety interaction significantly affected tiller number per plant, seed number per panicle, number of days to physiological maturity, seed yield, biological yield, harvest index and protein yield. Means comparison of simple effects showed that the highest of panicle number per m2 (736.97) obtained at planting date of June 2nd and highest 1000-seed weight (3 g) obtained at planting date of June 23rd. Also, the highest number of panicles per m2 (742.2) belonged to White Gavars and highest 1000-seed weight (4.2 g) to related to Pishahang varieties, respectively. Means comparison of simple effect showed that the highest seed and protein yields (323.2 and 37.1 g.m2) were obtained from Chomaki variety at planting date of June 2nd respectively, but the highest biological yield (1207.2 g.m2)belonged to Yellow Gavars variety at planting date of May 12rd. As a whole, results of this research showed that planting date of Jane 2nd for Chomaki variety and planting date of June 23rd for Yellow Gavars variety were found to be proper planting dates to grow these two varieties in Birjand.

Maize is one of the important cereal crops in Iran. Moghan, in Ardabil province, is an appropriate region to grow it in the country. Redroot pigweed (Amaranthus retroflexus L.) is one of the major noxious weed in maize fields worldwide and also in Iran. To study the interference of effect of this weed on maize seed yield and its morphological characteristics, a factorial experiment based on randomized complete block design with three replications was carried out at the research field of Agricultural and Natural Resources Research Center of Ardabil (Moghan) in 2012. The experimental factors were maize plant densities with four levels (70000, 75000, 80000 and 85000 plant.ha-1) and redroot pigweed densities with four levels (0, 4, 8 and 12 plant/m per row). The results showed that increasing density of maize and redroot pigweed, grain yield, biological yield and chlorophyll content of maize leaves were significantly reduced. The highest grain yield (11.88 t.ha-1) at density corn of 80000 plants.ha-1 of maize under weed free condition and lowest grain yield (7.92 t.ha-1) at maize density of 75000 plants.ha-1 with the presence of the 12 plant/m per row of redroot pigweed. The highest biomass of redroot pigweed (497.8 g/m per row) was produced at density of 85000 plants.ha-1 of maize with the presence of the 12 plant/m per row of redroot pigweed. Generally, the results of this research showed that 80000 plants.ha-1 of maize resulted in highest control of redroot pigweed and grain yield.

To study the efficacy of rimsulfuron, as a postemergent herbicide, on potato tuber yield (c.v. Agria), its components and control of weeds, a factorial field experiment based on randomized complete block design with 3 replications was conducted at Ardabil in 2014. The first factor consisted of seven different levels of rimsulfuron dosages (0, 5, 10, 20, 30, 40 and 50 g. a.i /ha), and second factor was its applications at three different potato growth stages (emergence, stolon initiation and tuber bulking). A weed free treatment was also considered as control. Statistical analysis showed that 50 and 40 g. a.i/ ha rimsulfuron applications reduced weed densities by 55.38 and 49.47 percent respectively, but their difference was not statistically significant. Among rimsulfuron application times, its application at potato emergence, resulted in highest reduction of weed density. The results also, showed that rimsulfuron application of 50 g. a.i/ha to the weed free condition, increased number of medium and large sized tubers and total tuber yield by 53.04, 59.45 and 20.51 percents respectively and decreased small sized tubers by 61.03%, but its effect on the number of tubers per plant was not significant. According to result of this research it can be concluded that rimsulfuron is an efficient herbicide to increase potato yield and control weeds of potato fields in Ardabil, and probably in Iran. Further research is needed to substantiate these results.