نشریه پژوهشهای زراعی ایران
سال نوزدهم شماره 3 (پیاپی 63، پاییز 1400)

Drought is undoubtedly one of the most important environmental stresses limiting the productivity of crop plants around the world. An optimal partitioning of dry matter between root and shoot, therefore is of crucial importance for crop yield under drought stress. Deficit irrigation strategy and planting crops with low water requirements and low expectations, for example, Kochia is very important under drought stress. Kochia is a salt- and drought-tolerant species that can be grown on drought soils, yielding fodder in quantities approaching that produced by alfalfa. The aim of this greenhouse study was investigating root and shoot growth of Kochia under drought stress conditions.

To study the effects of drought stress on root and shoot growth of kochia, a pot experiment was carried out as completely randomized design with three replications in University of Ferdowsi in 2013. There were 9 treatments included control (no stress) (NS-NS=100% field capacity (FC)), moderate drought stress (70% FC) during the vegetative phase (MS-NS), severe drought stress (30% FC) during the vegetative phase (SS-NS), moderate drought stress during the reproductive phase (NS-MS), severe drought stress during the reproductive phase (NS-SS), moderate drought stress during the vegetative phase and severe drought stress during the reproductive phase (MS-SS), severe drought stress during the vegetative phase and moderate drought stress during the reproductive phase (SS-MS), moderate drought stress during total growth period (MS-MS) and severe drought stress during total growth period (SS-SS). At the beginning of anthesis, plant height and branch number were recorded. Then plants were harvested and leaves, stems, and roots were separated. The fresh weight of the organs was recorded. Root volume was measured. Leaf area measured using a leaf area meter (LI-COR model) and root area was measured by Atkinson method. Then, leaves, stems, and roots dried in an oven at 75°C for 48 hours until mass reached and dry weight was recorded. For statistical analysis, analysis of variance (ANOVA) and LSD test were performed using SAS ver. 9.1 software.

Results showed that the highest and lowest plant height, leaf area, leaf, stem and total fresh and dry weight observed in control and severe drought stress during growth period, respectively. Significance of traits related to plant aerial parts due to morphological changes of root plants, which is actually a plant response to drought stress. Also, effect of drought stress was significant on root length, area and volume, fresh and dry weight, root length ratio to plant height. The highest and lowest of these traits were observed in control and severe drought stress during growth period, respectively. Drought stress thereby mostly reduced plant height and increased at least root length, leading to higher root/shoot ratio. Most importantly, the length of root was greater in the moderate drought-treated plants than the control plants at the end of the drought and recovery periods. Number of lateral branches and root dry weight/shoot dry weight ratio did not differ significantly with control. Generally, root and shoot growth under drought stress conditions is reduced that the amount of reduction depends on the growth stage of the plant, intensity and duration of the stress.

Finally, this study showed that the maximum amount of Kochia forage was obtained when the water is 100% FC to increase the number and size of the cells and, consequently, increase the yield. However, Kochia forage decreased 19% by decreasing 30% of irrigation water in treatments of moderate stress during total growth period in compared to the control plants. In addition to saving water, more land can be cultivated.

Proper planting date and irrigation rate are the most important factors for better use of rainfall and soil moisture and thus increase crop yield. Production of medicinal and aromatic plants and the demand for natural products in the world is increasing, so that the twentieth century has been named as a return to nature and the century of using herbal medicines. Proper growth and development of medicinal plants in agricultural conditions requires knowledge of the ecological characteristics of these plants, careful study of planting techniques and the use of agricultural inputs, especially irrigation, fertilizers, suitable planting and harvesting times and their management. Such factors also affect the amount of secondary metabolites in medicinal plants. The aim of this study was to investigate the effect of four planting dates and four irrigation rates on the yield traits of isabgol in Sarakhs.

In order to investigate the effect of irrigation levels and planting dates on the growth characteristics and yield of isabgol (Plantago Ovata L.) as a medicinal plant, a field experiment was performed in Research station, Sarakhs, Khorasan Razavi province during growth season 2015-16. This experiment was performed as strip plots based on a randomized complete block design with three replications. Irrigation treatments at four levels of 40, 60, 80, and 100% of the water requirements were placed in horizontal plots and four planting dates were on March 5, 2016, March 20, 2016, April 3, 2016 and April 18, 2016 in vertical plots. Irrigation was applied as furrow system at every 7 days. Irrigation treatments were applied at the time of complete establishment of seedlings in 3-4 leaf stage and continued until physiological maturity stage. The amount of irrigation water in each irrigation turn was calculated by AGWAT software. Measured traits included leaf area index, crop growth rate, dry matter accumulation, plant height, number of spikes per plant, number of seeds per plant, 1000-seed weight, grain yield, biological yield and harvest index.

The results of growth indicators showed that the maximum leaf area index (3.4 and 3.3), the crop growth rate (22.12 and 22.18 g m-2 d-1) and the accumulation of dry matter (444.9 and 445.4 g m-2) were obtained in the treatments of 100% and 80% of the water requirements, respectively. Also, the maximum leaf area index and crop growth rate were observed in the treatments of April 18 and April 3 (1.86 and 2). The treatments of March 20 and 5 also had the highest crop growth rate (14 and14 g m-2 d-1) and dry matter accumulation (270 and 261.3 g m-2). The results also showed that the interaction effects on plant height, number of seeds per plant, 1000-seed weight, grain yield, biological yield, and harvest index were significant at the 1% level of probability. Maximum plant height (24.57 cm) was obtained in the 100% of the water requirement and planting date of March 20 treatment. The highest number of seeds per plant (1210.36), grain yield (1891.4 kg), biological yield (5607.8 kg), number of spikes per plant (29.67) and 1000-seed weight (2.05 g) were obtained in the treatments of 80% of water requirement and planting date on March 20.The highest harvest index (36.4%) belonged to the treatment of 100% of water requirement and planting date on March 5.

general, it can be concluded that different characteristics of isabgol plant were affected by planting date and irrigation water amount so that with a delay in planting date and also reducing the amount of irrigation water, growth and yield characteristics were significantly reduced. As a result, deficit irrigation at 80% of the crop water requirement and planting date of March 20 were more effective in saving irrigation water along with a good yield of the isabgol plant compared to 100% of the crop water requirement treatment in the study area.

Environmental condition and appropriate planting date are the most important factors in producing optimal yield. Different planting dates lead to adaptation of plant vegetative growth period to different temperatures, daytime, and solar radiation. Therefore, it affects the development, production of biomass and ultimately plant yield. The effect of environmental factors on phenological stages of the plant makes the planting date differ from region to region and between genotypes in one region. Determining the optimal time for planting an herb is very important and it is a major factor to achieve potential yield. Furthermore, vermicompost plays an effective role by making available the necessary nutrients. Despite many studies on the positive effects of Vermicompost on the growth of different plants, few studies have investigated the use of vermicompost for Dracocephalum moldavica at different planting dates. Therefore, this experiment aimed to examine the effects of different amounts of vermicompost on the growth, yield, and essential oil of Dracocephalum moldavica at different planting dates.

This study was conducted byfactorial experiment based on completely randomized block design. The first factor included different planting dates at four levels (20 February, 5 March, 20 March, and 3 April) and the second factor included vermicompost at three levels (control and 5 and 10 t.ha-1 of vermicompost). Samples were taken from plants in the field at 50% flowering stage to measure the concentration of leaf elements and physiological traits. At the end of the growth period, were measured the height, the number of lateral branches, dry weights of aerial organs, and root dry weight. To measure the percentage of essential oil, were harvested aerial organs in different treatments at the flowering stage. Analysis of data variances was performed using SAS software version 9.1. Duncan’s Multiple Range test was used to a comparison between means at p ≤ 0.05. It should be noted that the results of mean comparison were only presented for the traits that the effect of experimental factors on them was statistically significant.

The results indicated that the highest nitrogen and phosphorus content of leaves and dry weight of Dracocephalum moldavica were obtained in a treatment of 10 t.ha-1 of vermicompost. The delayed planting changed physiological traits, including chlorophyll content and relative water content of leaves. Delayed planting due to the higher heat and drought stress decreased root growth and thus caused low water absorption from the soil. Therefore, the delay in planting reduced some growth indices of Dracocephalum moldavica Because of improved absorption of nutrients such as nitrogen, vermicompost resulted in further synthesis of the photosynthesis pigments. Regarding the results of this experiment, the greatest shoot dry weight, dry weight root and essence percentage were obtained by applying 10 t.ha-1 of vermicompost, while the lowest one was observed in control treatment without applying vermicompost fertilizer. There was an increase in essential oil percentage and yield by the use of 10 t.ha-1 of vermicompost. Furthermore, the planting date of 3 April reduced the yield of essential oil compared to the planting date of 20 March.

In general, the highest quantitative and qualitative yields of Dracocephalum moldavica were seen in the treatment of 10 t.ha-1 of vermicompost. We recommend the planting date of 20 February and 10 t.ha-1 of vermicompost for Dracocephalum moldavica planting. Providing a suitable growth medium, vermicompost increased the growth of Dracocephalum moldavica Therefore, organic fertilizers can be used to improve the quantitative and qualitative yield of herbs, and they are useful for medicinal applications in the perspective of this plant.

One of the important factors in the adaptation of plants to new environmental conditions is the appropriate response of development stages to temperature and photoperiod regimes. The thermal time, growing degree days (GDD) or heat unit concept is commonly the basis for modeling phenological development in crop models for different common crops and under-utilized crops. The GDD concept describes crop development as a function of temperature accumulation above the base temperature (lower limit) and in some cases below a cut off temperature (upper limit). Evaluation of plant photoperiod sensitivity is often beneficial help to use appropriate cultivars which in turn to ensure cultivation success. Considering that adaptation of quinoa to new regions demands acclimation to appropriate temperature range also day-length, this study aimed to investigation of quinoa response to Yazd weather condition as an arid region to assess the possibility of quinoa cultivation under these conditions.

This research was conducted through 10 separate experiments and were based on a randomized complete block design with three replications. The experimental treatment consisted of five lines (1, 2, 3, 4 and 5), and one cultivar (Titikaka) which belong to different maturing groups including early, middle and late maturing. Ten planting dates selected to be serial as following: March 29, April 29, May 28, June 28, July 26, August 23, September 6, September 20, January 29, and February 29. Every three days, phenological stages of each line including planting distance to each stage of development including emergence, four leaves, flower bud, panicle formation, pollination, seed filling, seed hardening and ripening were recorded accordingly. Using local weather data and equation 1 the needed GDD for every development stage was calculated:GDD= (Tmax-Tmin)/2-T(1)MS-Excel Ver. 15 was employed to arrange recorded data and required calculating. Fitting equations and plotting the graphs were done using Slide Write Ver. 2 and Minitab Ver. 20 software.  

The results showed that the mean of flowering temperature up to seed formation stage was between 25 and 30 °C for five lines and was between 20 and 25 °C in cultivar 6. The mean length of photoperiod for flowering and seed formation stage of these lines was between 12 and 12.5 hours. The relationship between temperature and day length was inversely related to the number of days of flowering stage, i.e., with decreasing day length and increasing temperature, the number of days for flowering stage was increased. The time required for flowering stage, between 20 to 30° C, for the early maturing cultivar was about 35 days, for the middle maturing lines including 1, 2, 3 and 6 was about 40 days and for the late maturing line 4 was about 45 days. At temperatures higher than 30 °C, a decreasing trend was observed in the number of days required for flowering stage. From the budding stage to the end of the growth period, a significant difference in the GDD was observed for the quinoa lines. The GDD of quinoa was the highest (2530 °C) for late maturing line (4) and was the lowest (1805 °C) for the early maturing cultivar. The effect of planting date on the GDD of quinoa lines showed that moving from March planting date to July, there was an increasing trend on the GDD of quinoa lines and by moving from July planting date to October, a decreasing trend was observed.

In general, quinoa is a short-day plant which is affected by the day length from flowering to seed maturity stages. Line 6 responded qualitatively to day length; however, the other lines responses were quantitatively. The study of the simultaneous effect of temperature and day length showed that temperature has a compensatory effect for day length during flowering stage. According to the results, it seems that the most suitable planting date for early lines suggests in September, for middle maturing lines suggests in August and for late maturing lines suggests in August. The results also showed that line 6 is more suitable than other lines for cultivation in cold regions.

The high nutritional value of quinoa and its ability to grow under adverse environmental conditions have led to an increase in the area under cultivation globally. Quinoa has attracted particular attention in recent years due to its ability to grow under adverse environmental conditions and its high nutritional value.  Water scarcity stress is one of the non-bioenvironmental stresses that has destructive effects on crops' development and yield. Morphological, physiological, and biochemical reactions of plants to water deficiency depend on several factors, including stress intensity, duration of stress, and plant growth stage. Increased proline content, glycine betaine, total carbohydrates, and decreased yield under water stress conditions have been reported in various quinoa studies. The low cost of growing quinoa and its relatively high price, on the one hand, and the need for low water and adaptation to difficult climatic conditions, on the other hand, have made quinoa cultivation very economical. Due to the lack of water resources in different parts of the country and the fact that few studies have been done on quinoa cultivation in our country, the present study was conducted to investigate the effect of different irrigation regimes on some biochemical parameters and quinoa yield.

An experiment was conducted to investigate the effect of irrigation intervals and amounts on the quinoa's physiological traits and yield at the University of Kurdistan research farm, located in Dehgolan plain. The experiment was arranged in a split-plot scheme based on randomized complete blocks design with three replications. Four irrigation intervals (4, 8, 12, and 16 days) were considered the main factor, and four irrigation levels (100%, 75%, 50%, and 25% of plant water requirement) were considered secondary factors. Giza1 cultivar, which was obtained from the Seed and Plant Improvement Institute, was used for cultivation. Traits such as the content of proline, glycine betaine, soluble carbohydrates, insoluble carbohydrates, catalase activity, peroxidase activity, and grain yield were studied. Data analysis of variance was performed using SAS 9.1 statistical software, and means were compared using the Duncan test at 5% probability level. Excel software was also used to draw the graphs.

The effect of irrigation intervals and levels were significant on all studied traits. The study results showed that by reducing the plant's available water and increasing the irrigation intervals, the amount of proline, glycine betaine, soluble carbohydrates, insoluble carbohydrates, peroxidase activity, and catalase activity were increased, but the grain yield was decreased. Increasing the irrigation intervals from 4 to 8 days did not significantly affect grain yield, but increasing the interval to 12 and 16 days reduced grain yield by 24.4 and 44.8%, respectively. The highest grain yield was observed at full irrigation treatment (1866.5 kg.ha-1) but there was no significant difference with the treatment of 75% of the plant water requirement. The rate of yield reduction in the treatment of 25% of plant water requirement compared to the control was about 56.5%.

The results showed that quinoa produced acceptable levels of yield even under severe drought stress, i.e., when the irrigation interval increases or the water availability decreases. Based on our results, one reason for this is stress reduction mechanisms by the quinoa plant, such as increasing the content of compatible osmolites and increasing antioxidant enzymes' activity.

Rice (Oryza sativa L.) is one of the most important staple food crops in the world. However, rapid increase in world population and adverse effects of climate change, such as prolonged drought, has resulted in challenges in food security. One of the important factors in reducing rice yield can be the emergence and poor establishment of seedlings in the field. Seed treatment before sowing is the foundation for activation of seed resources that in combination with external ingredients could contribute to the efficient plant growth and high yield. Various physiological and non-physiological techniques are available for enhancing seed performance as well as to combat environmental constraints. Pre-sowing seed treatment such as seed coating and seed priming could improve the seed germination and vigor particularly under unfavorable environmental conditions.

In order to investigate the effect of priming and seed coating on emergence characteristics, yield and yield components of rice, a field experiment was conducted in the 2020 growing season, Rice Research Institute of Iran (RRII). The experiment was performed as a factorial in a randomized complete block design with three replications. Experimental factors include rice cultivars (Hashemi and Gohar) and treatment of rice cultivars in seven levels including 1- Priming with calcium chloride (-1.25 MPa in 24 hours), 2- Priming with potassium chloride (1.25 MPa in 24 hours), 3- Priming with zinc sulfate (concentration of 0.5 mM in 12 hours), 4- Hydropriming (48 hours) + Coating the seeds with calcium chloride, 5- Hydropriming (48 hours) + Coating With potassium chloride, 6- Hydropriming (48 hours) + coating with zinc sulfate and 7- Hydropriming (48 hours as control).

The results showed that the highest emergence percentage with 87% and 94% and the emergence rate with 0.17 and 0.19 (1.day-1) were obtained in Hashemi and Gohar cultivars, respectively. From these results, it is inferred that Gohar cultivar has higher genetic potential and physiological quality than Hashemi cultivar. The results of mean comparison showed that the highest height of rice plant with 147 and 143 cm was observed in coating and priming with potassium chloride in Hashemi cultivar, respectively. The results of this study attributed the increase in height to the effect of pretreatment on increasing the rate of emergence and better establishment of seedlings due to better plant use of related resources. The results showed that seed pretreatment with calcium chloride, potassium chloride and zinc sulfate increased the panicle length by 27, 24 and 12% under priming and 37, 34 and 17% under seed coating, respectively. The results of the mean comparison table showed that the highest panicle weight with 1.35 and 1.32 g was observed by seed coating with potassium chloride and calcium chloride, respectively. However, priming with calcium chloride, potassium chloride and zinc sulfate also increased the cluster weight by 12, 17 and 5%, respectively, compared to the control treatment. The results showed that the highest 1000-seed weight was obtained among the two cultivars with 24.63 g in Gohar cultivar. Also, the findings of this study showed well that pretreatment of rice seeds can increase the 1000-seed weight. Pretreatment of rice seeds with calcium chloride, potassium chloride and zinc sulfate 10, 12 and 5% under priming and 18, 22 and 10% under seed coating, respectively, increased 1000-seed weight. The results of mean comparison showed that grain yield in Hashemi and Gohar cultivars were 3046 and 4929 kg.ha-1, respectively. Pretreatment of rice seeds with calcium chloride and potassium chloride 14 and 20% under priming and 19 and 23% seed coating respectively, increased rice grain yield. In general, the increase in grain yield can be due to the improvement of antioxidant properties, proper establishment and optimal use of environmental factors such as light, soil moisture and nutrients.

According to the results of this study, priming and seed coating treatments with calcium chloride and potassium chloride in rice cultivars can increase rice yield by improving seedling characteristics. Therefore, farmers can be advised to use a simple and inexpensive crop management method to pre-treat seeds with calcium chloride and potassium chloride.

Introduction

Sustainable agriculture is necessary to tackling environment pollutions whilst protecting food security and reducing dependence to fossil fuels. Conservative agriculture is a sustainable system for crop production which improves crops production. No-till system is one of the methods of Conservative agriculture which decreases greenhouse gas emissions and soil erosion. Mulching is also one of the other methods of conservation agriculture which covers the soil surface with varied covering materials and decreases moisture losses and increases crops yield. Nitrogen is an essential element for plant and its deficiency causes plants growth and yield reduction. Grain legumes are a great source of protein for humans and livestock and recommended in areas under common agricultural systems within ecological focus. These crops have also the ability of biological nitrogen fixation through symbiotic bacteria with their roots, finally, produced nitrogen returns to the soil and reduces the nitrogen fertilizer demand for subsequent plants. However, only a fraction of nitrogen in their biomass will be available for the following crop. It is estimated that 41 to 50% of nitrogen fertilizer applied to Maize (Zea mays L.) has been lost to the environment. Thus, this experiment was conducted to evaluate the effects of faba bean cover crop-rotation on forage corn.Materials and MethodsIn order to study the effects of faba bean in rotation with corn, a field experiment was conducted in two growing seasons (2018-2019) at the research farm of the Agriculture and Natural Resources Faculty, University of Mohaghegh Ardabili, located in Babolan village, Ardebil, Iran. Experimental treatments included faba bean densities (25, 35, 40, and 80 plants per square meter) and different levels of nitrogen fertilizer in forage corn (0, 100, 200 and 300 kg ha-1). A local small-seeded variety of faba bean was used in this experiment and 80000 plants ha-1 -of corn- Single cross hybrid (201). Nitrogen fertilizer was applied as urea at the V5 stage of corn development by top dressing (in three stages). At maturity stage of faba bean, samples were taken by 0.5 × 0.5m quadrat for each plot. Grain yield was determined by harvesting seeds and dried in oven 65°C for 48 h and weighted by digital scale (0.01 g). Three plant of corn were cut randomly in each plot, thereafter were weighed to determine fresh forage yield. Shoot were dried in oven 75°C for 72 h and weighted for dry matter calculation (data converted to hectare). Statistical analysis of the data was performed by using of SAS software (version 9.4). Also, significant difference between the treatment means were tested with Duncan's Multiple Range Test at P<0.05.

Results indicated significant effects of faba bean plant densities on most of the traits. The maximum fresh and dry grain weight were obtained from densities of 80 and 40 plant per m2. Also, the maximum grain nitrogen and grain crude protein were observed from 25 plants per m2. 40 plant of faba bean per m2 had the highest amount of seed dry matter, protein yield, protein harvest index, and productivity effort. Also, results of interaction effects showed that various densities of faba bean and different levels of nitrogen fertilizer had significant effect on forage corn. So that, the maximum dry matter yield and production efficiency was obtained from 40 plant of faba bean per m2 and application of 200 kg niterogen per ha-1. 35 plant of faba bean per m2 without application of nitrogen fertilizer had the highest amount of nitrogen utilization efficiency.

Totally, results showed that faba bean rotation with corn could be a suitable alternative method for mono-cropped maize with high utilization of nitrogen fertilizer (density of 40 plant per m2 of faba bean and application of 200 kg nitrogen per ha is recommended).