مجله تولید گیاهان زراعی
سال هفدهم شماره 3 (پاییز 1403)

Sugar beet is one of the major industrial crops that has a major contribution to sugar production worldwide as well as in Iran. Suitable economic performance in sugar beet is dependent on proper vegetation growth in early growing season and appropriate allocation and distribution of assimilates to the roots, therefore, the time of cultivation of this plant will be important. The growth of sugar beet can be accelerated by planting in the transfer container and transferring it to the main land at a time when the risk of late winter and early spring cold and the problem of water scarcity are removed. Considering the economic importance of sugar beet, especially in Khorasan Razavi province, and adapting this plant for cultivation in Mashhad area, this study was carried out to determine the most suitable planting date and types of transplanting.

This experiment was conducted in research farm of the Faculty of Agriculture, Ferdowsi University of Mashhad in 2017-2018 growing season. The experiment was carried out in a randomized complete block design with 3 replications and 6 treatments. Treatments included: Direct planting in 11 April, Direct planting in 22 May, transplanting with leaves in 5 June, transplantation without leaves in 5 June, transplantation with leaves in 15 June and Transplanting without leaves in 15 June. Sampling and harvesting operations were carried out in late November. Measured indices included root dry matter percentage, root yield (RY), sugar content (SC), sodium content (NA), potassium (K), nitrogen (N), root Alkalinity (ALC), white sugar content (WSC), extraction coefficient sugar (ECS), molasses content (MS), water use efficiency (WUE) and water productivity (WP).

The highest sugar content was obtained in direct planting in 22 May (12.55%) but no significant difference was observed with other treatments. Amongst anti-quality traits, direct planting in 11 April contained highest sodium concentration, also the highest potassium content was observed in leafless transplanting in 5 June. The highest root nitrogen content and alkalinity were obtained in direct planting in 11 April. The highest white sugar content (%) and sugar extraction coefficient (%) were obtained in transplanting with leaves in 15 June treatment. The highest root yield (90.7 t. ha-1) and white sugar yield (5.96 t. ha-1) was obtained in transplanting with leaves in 5 June treatment. The results showed that the highest water use efficiency and water productivity were recorded in transplanting without leaves in 15 June and the lowest were observed in direct planting treatments.

The results of this study showed that transplantation of sugar beet in proper time can increase root and white sugar yield and also improve water use efficiency and economic water productivity in Mashhad conditions. In addition, direct seed sowing in 11th April and transplanting with leaves in 5 June showed the highest root and white sugar yield. Therefore, it may be suggested that sugar beet transplanting with leaves extended in sugar beet production areas after arrangement of local trails.

The canola plant (Brassica napus L.), containing 40 to 44 percent oil, is considered one of the most important edible oilseeds and is the third most significant annual oilseed crop in the world after soybean and oil palm. The global demand for food is rapidly increasing due to the growing population. This demand is expected to rise by 60 percent by the year 2050, which poses a significant challenge, especially in the context of climate change. Human activities since the industrialization era have led to an increase in greenhouse gas emissions, which are expected to alter regional rainfall patterns and temperatures. The most critical feature of global climate change is the significant increase in temperature and uneven distribution of precipitation, which are limiting factors for sustainable development. The ultimate goal of assessing climate change risks is to identify adaptation strategies to achieve sustainable development in a specific region. Adaptation strategies vary depending on agricultural systems, regions, and climate change scenarios. The aim of this study is to examine adaptation strategies to enhance drought resistance in rapeseed plants concerning future climate conditions in the country.

The present study aims to predict the impact of climate change on the growth and development of rainfed canola in Iran using two general circulation models, HadGEM2-ES and IPSL-CM5A-MR, derived from the CMIP5 project under two emission scenarios, RCP4.5 and RCP8.5, as reported in the fifth assessment report of the IPCC for the future period from 2040 to 2069. The downscaling of climatic parameters generating weather data was conducted using climate scenario generation tools within the AgMIP project and implemented in R software. After simulating the future climate and producing the necessary parameters (minimum temperature, maximum temperature, precipitation, and solar radiation), the growth and development simulation of rainfed canola was carried out using the SSM-iCrop2 model under current and future climate conditions. Additionally, the results of the growth and development simulation of rainfed canola under future climatic conditions in Iran were evaluated with increased drought resistance.

The results indicated that the average temperature during the canola growing season in the future is expected to increase by an average of 2.3 degrees Celsius for the RCP4.5 emission scenario and by 3.1 degrees Celsius for the RCP8.5 scenario compared to current conditions. Additionally, the results showed that the distribution of precipitation among the growth seasons would vary between the two models. The simulation results under climate change for both RCP4.5 and RCP8.5 scenarios revealed that, with the increase in average temperature, the length of the growing season would decrease in both models studied. However, it is predicted that water productivity will increase under both emission scenarios. It is anticipated that the average yield of canola in the country in its main cultivation areas will increase by 5% and 8% under the RCP4.5 and RCP8.5 scenarios, respectively, compared to current conditions. By implementing adaptation strategies to enhance drought resistance, it is expected that under both RCP4.5 and RCP8.5 scenarios, the average yield changes will increase by 8% and 9%, respectively, compared to a future without adaptation strategies.

The results of this study indicate that, on average, the yield in most of the main canola cultivation areas in the country is expected to increase under both emission scenarios. By implementing adaptation strategies to enhance drought resistance in the future climate, it is predicted that the average yield will increase compared to a future without adaptation strategies.

Due to the extensive climate changes and environmental pollution, along with the heavy use of toxins and chemical fertilizers in industrial farming, addressing topics concerning sustainable agriculture is deemed essential in today's world. A key strategy for sustainable plant cultivation involves enhancing diversity by practicing intercropping. This technique aids in erosion control, soil and water protection, nitrogen biological fixation, boosting both the quantity and quality of yields, and managing weed growth.

To investigate the impact of humic acid on the yield of wheat and lentil in both sole and intercropping systems under dryland conditions, an experiment was conducted during the 2018-2019 growing season in Qahavand city, Hamedan, Iran. The experiment followed a factorial design based on randomized complete blocks design with three replications. The factors included different cropping patterns at four levels: wheat sole crop, lentil sole crop, strip intercropping with 6 rows of wheat and 3 rows of lentil (6W:3L), and strip intercropping with 12 rows of wheat and 6 rows of lentil (12W:6L). Additionally, humic acid was applied at three levels (0, 6, and 12 kg.ha-1). Yields, yield components, and land equivalent ratio were measured and evaluated.

The results indicated significant effects of intercropping on various parameters in both wheat and lentil crops. In wheat, intercropping influenced traits such as seeds per spike, spikes per square meter, 1000 seed weight, grain yield, biological yield, harvest index, and protein percentage. For lentil, intercropping impacted the number of pods per plant, 1000 seed weight, grain yield, biological yield, protein yield, and harvest index. Additionally, the application of humic acid significantly affected most traits, except for the lentil harvest index. The interaction between the intercropping and humic acid influenced wheat grain yield, 1000-seed weight of lentil, lentil grain and biological yield, and the total yield of lentil and wheat. The land equivalent ratio (LER) in all intercropping treatments was greater than 1, indicating the benefits of wheat and lentil intercropping over sole cropping.

The application of 12 kg.ha-1 of humic acid resulted in increased yields and yield components for both wheat and lentil crops, along with a higher land equivalent ratio ( LER) index. The intercropping of 6 rows of wheat and 3 rows of lentil (6W:3L), combined with this application, is optimal for achieving maximum yield and benefits in the intercropping of wheat and lentil.Keywords: Cereal, harvest index, land equivalent ratio, organic fertilizer, pulses

agriculture in Iran is the largest consumer of water resources, reducing water availability due to climate change is the most significant limiting factor for agricultural production. Therefore, increasing water productivity and optimising these limited water resources are essential. Considering the constraints on water resources, especially during the summer when sesame cultivation and growth occur in the country, it is necessary to conduct practical studies on optimal water use in sesame farming and the possibility of replacing native varieties and old cultivars with new ones. Hence, it is hypothesised that introducing sesame varieties and lines through reduced plant access to water (increasing irrigation intervals or accelerating irrigation cut-off at the end of the growth period) can achieve greater water use efficiency with minimal seed and oil yield losses. The present research was designed and implemented to address this hypothesis.The experiment was conducted over two years, 2022 and 2023, at the research farm of the Seed and Plant Improvement Institute, located in Alborz Province, Karaj. The experiment investigated the effect of irrigation intervals, including irrigation after consuming 40% (full irrigation) and 80% (deficit irrigation) of available soil moisture, and the timing of the last irrigation, including irrigation cut-off at the beginning of flowering, irrigation cut-off at the beginning of capsule formation, and irrigation cut-off during mid-capsule formation, on the yield, yield components, oil percentage, and water use efficiency of two sesame genotypes, Ultan and Sesame Line 2. The experiment was laid out in a split-split-plot design )treatment of irrigation intervals as the main plot, the time of the last irrigation as the sub-plot and the genotype as the sub-sub-plot) within randomised complete blocks with three replications. Compound data analysis assuming the random effect of year and using the GLM procedure in SAS software was employed. To compare the means of main effects, LSD test (means statement) was conducted at a 5% significance level, and in case of significant interaction effects, slicing and comparison were performed using the lsmeans procedure (slice and pdiff statements).Results showed that, in both genotypes, irrigation cut-off at the beginning of capsule formation compared to mid-capsule formation had no significant effect on the number of capsules per plant under full irrigation conditions. The results showed that under full irrigation conditions, there was no significant difference in grain yield between the two irrigation cut-off timings (early and mid-capsule formation). In other words, continuing irrigation after the early stage of capsule formation did not increase sesame grain yield. Additionally, results revealed that although the yield of both genotypes was approximately equal under full irrigation conditions (871 and 890 kg per hecta, respectively, in Oltan and Line 2), the yield of Line 2 was 51% higher than Ultan under deficit irrigation conditions. In Ultan, accelerating irrigation cut-off was accompanied by significantly reducing water use efficiency. In contrast, in Line 2, irrigation cutoff at the early stage of capsule formation not only did not decrease water use efficiency but also insignificantly increased it. In conclusion, it can be inferred that by substituting native masses and old varieties with new varieties and lines in sesame cultivation, savings in water consumption can be achieved, increasing water use efficiency in sesame farming while preventing yield reduction.In general, it can be concluded that in low irrigation conditions, postponing the time of cutting irrigation until the mid-capsule formation and in full irrigation conditions, cutting off irrigation at the beginning of capsule formation can be a suitable management for sesame production. Also, the replacement of newer cultivars, including the line 2, can be effective in increasing the yield and efficiency of water consumption in sesame cultivation.

The sustainability of agricultural systems can be improved by practices such as intercropping and conservation tillage systems. This research aimed to investigate the intercropping of wheat with clover and vetch to increase the quantitative and qualitative yield and the beneficial use of environmental resources in conservation and conventional tillage systems. The experiment was carried out in the form of split plots in a randomized complete block design with three replications in the research farm of Ilam University in the crop year of 2018-2019. Tillage regimes as the main factor in three levels were assigned to the main plots, including conventional tillage, minimum tillage and no tillage. The sub-plots included different cultivation patterns at five levels (Wheat monoculture, monoculture clover, monoculture vetch, 100% wheat + 50% clover intercropping and 100% wheat + 50% vetch intercropping). The results showed that the grain yield of wheat in the intercropping of wheat+ clover and wheat + vetch in the system no-tillage was 29.7 and 19.4% respectively and in conventional tillage it was lower by 13.6 and 17.9% respectively compared to monoculture. In the minimum tillage system, wheat grain yield in the intercropping of wheat + clover was higher by 6.6% compared to wheat monoculture. The forage yield of vetch in the monoculture pattern in the system no-tillage, minimum tillage and conventional tillage was higher by 41.3, 73.4 and 54.3%, respectively, compared to the intercropping of wheat + vetch. In minimum tillage, the forage yield of clover was 24.7% higher than the conventional tillage system. Phosphorus concentration of wheat grain increased by 21.9% the intercropping of wheat + vetch compared to monoculture of wheat. The concentration of wheat grain protein in the intercropping of wheat+ clover and wheat + vetch was on average 8.5% higher than that of wheat monoculture. Calcium content of vetch forage in the system without tillage decreased by 16.81% compared to conventional tillage. Phosphorus of clover and vetch forage in minimum tillage was 34.5 and 15.1% higher than no-tillage. Phosphorus content of vetch forage in intercropping decreased by 11.40% compared to monoculture of vetch. In the intercropping of wheat+ clover and wheat + vetch forage protein was 14.06 and 6.71% less than the monoculture of these plants, respectively. The amount of neutral detergent fiber (NDF) in the monoculture of clover and vetch was on average about 11% lower than their intercropping patterns. The amount of ADF (acid detergent fiber) in monoculture of clover and vetch was 12.65% and 9.62% less than the intercropping patterns. The land equivalent ratio in all intercropping patterns of wheat with legume cover crops was more than one, indicating the advantage of intercropping patterns for land use and increasing the yield over monoculture. Calculating the aggressivity index showed that wheat was more dominate than legumes under different tillage systems. The intercropping of wheat with leguminous plants improved the quality of wheat and increased the percentage of phosphorus, nitrogen and wheat grain protein. In general, the results of this research showed that the intercropping of wheat with clover and vetch under conservation tillage system improves the forage production and increase the productivity of the land.

Early sowing date of sunflower in cold temperate regions can be a sustainable management strategy in areas with limited water resources. Field trials have shown that sowing sunflowers in late February to mid-March was the most effective strategy in terms of water efficiency and grain yield. so the present study was conducted to investigate grain yield and yield components of sunflower hybrids in the early sowing date, compared to the summer sowing date, and their effects on the physical and economic water productivity in the cold temperate regions of Kermanshah province. A two-year research (2022-2023) was conducted at the Mahidasht Agricultural Research Station of Kermanshah. The experiment was conducted as a strip plot with a randomized complete block design with four replications. The treatments included sowing dates as the first factor, including five levels: in the first year (March 16, March 30, April 14, April 30, and June 5) and in the second year (February 9, March 23, April 14, April 30, and May 20), and the second factor was sunflower cultivars including Shams, Golsa, Zarin and Lakomka. Data were analyzed using SAS statistical software (SAS 9.1). To investigate productivity of different sowing dates, physical and economic water productivity indices were calculated. The results of variance analysis showed that sowing date in both years had a significant effect on yield and yield components, except for the number of seeds per head in the second year. The cultivars also had significant differences for grain yield and yield components in both years. The highest seed yield in the first year with 3921 and 3720 kgha-1 belonged to sowing dates of April 30 and April 14 and in the second year with 3782 and 3711 kgha-1 belonged to sowing dates of March 23 and April 30. The results showed that sowing in spring (April 29) and summer (June 4) in both years led to an increase in the 1000 seeds weight compared to early sowing dates (Table 2). Decrease in 1000 seeds weight in early sowing dates was due to the coincidence of the seed filling period with the increase in temperature in late July. Lakomka cultivar, which is an open-pollinated cultivar, had the highest seed yield in the first and second year with 3927 and 3957 kgha-1, respectively, and the Golsa hybrid had the lowest grain yield with 3163 and 2941 kgha-1, respectively. Based on physical and economic productivity of water, results showed that the early sowing dates of February 28 and March 23 in the second year had 74% and 70% higher economic productivity than summer sowing date, respectively, due to saving water consumption. In general, the results showed that the sowing date of March 30 and March 16 had the highest grain yield, physical and economic water productivity, but early sowing on the dates of March 16, March 30 and April 14 with a reduction in water consumption also showed acceptable economic productivity. The importance of early sunflower sowing in drought conditions and also when the price of water used in agriculture is calculated in real terms becomes more apparent. In general, the results of this study emphasized that the early sowing of sunflower, although it may not be associated with a higher grain yield, but due to the optimal use of water resources and acceptable productivity, it can be a practical and effective solution in managing water resources and dealing with drought

Modern intensive agriculture has boosted crop yields through chemical inputs. However, this approach has caused decreased biodiversity, harm to human health, and environmental degradation. Developing sustainable agricultural practices that increase productivity while minimizing negative effects, especially in arid and semi-arid regions, requires strategies like deficit irrigation and environmentally compatible weed control methods such as intercropping. This study aims to assess the performance of an intercropping system comprising buckwheat and cowpea under deficit irrigation and minimal weeding. The research seeks to provide insights into the viability of this approach for sustainable agriculture in water-limited environments.

A field experiment was conducted in 2022 at the Agriculture and Natural Resources campus of the University of Tehran research farm in a randomized complete block design with split-split plot arrangements. The main plot factor included three levels of irrigation: 100% of the plant's water requirement (control), 85% of the water requirement and 70% of the water requirement compared to the control. The subplot factor consisted of five planting patterns: sole cultivation of buckwheat, sole cultivation of cowpea, and three intercropping patterns of buckwheat and cowpea with different row ratios (1:1, 3:1, and 1:3). Timing of weed removal, as the sub-subplot factor, was implemented at five levels: no weeding (control), weeding until the second, fourth, sixth, and eighth weeks after cultivation.

The highest grain yield of buckwheat (2436.9 kg ha-1) and cowpea (2495.5 kg ha-1) was observed in the sole cultivation plot with eight weeks of post-planting weeding under full irrigation. These results are attributed to higher planting densities in sole cultivation compared to intercropping. The 1:1 intercropping pattern with eight weeks of post-planting, exhibited the best cowpea leaf area index (3.36), and buckwheat (4.1) and similarly, this intercropping pattern with six weeks of post-planting resulted in the highest number of branches per plant (16). Sole cowpea plot under 85% deficit irrigation exhibited the highest weed dry weight (145.7 g m-2). The highest Land Equivalent Ratio (1.08), was observed in the 1:1 intercropping pattern with two weeks of post-planting weeding under full irrigation. Interestingly, the 1:1 intercropping pattern also showed the lowest weed biomass (12.1 g m-2) without specific weed management under 70% irrigation.

Most intercropping treatments achieved a land equivalent ratio greater than one, highlighting the superior efficiency of this planting method compared to sole cultivation. Specifically, the 1:1 intercropping pattern successfully controlled weed biomass, increased grain yields under deficit irrigation, and some for both crops. Therefore, intercropping offers a promising strategy to reduce reliance on herbicides and improve overall land use efficiency.

Black cumin is a medicinal and widely used plant worldwide. The seeds of this plant have significant economic value and contain compounds such as thymoquinone, thymol, tocopherol, trans-retinol, and selenium, which have multipurpose applications. Studies have shown that the delay in cultivation hurts the growth and performance of this plant. Since the sowing date is effective on plant establishment, control of weeds, diseases and pests, harvest time, and product quality, it is important to know the proper sowing date in each region to improve the quality and quantity of the product.

Therefore, to investigate the effect of sowing date and different varieties of black cumin on the yield and yield components, a field experiment was conducted in the agricultural year 2021–22 at the Golestan Agriculture and Natural Resources Research and Education Center. This experiment was factorial with a randomized complete block design with 4 replications. The treatments included the sowing date in three levels (6 November, 6 December, and 5 January) and the black cumin variety in three levels (Iranian, Syrian, and Indian). In this study, the traits studied include the number of sub-branches, capsules per plant, the number of pods per plant, the number of seeds per capsule, the number of follicles, the weight of capsules, the weight of 1000 seeds, seed yield, dry weight of a single plant, and biological yield.

The results showed that the effect of sowing date, varieties, and their mutual effect on most studied traits was significant at the probability level of 1%. Based on the results, the highest number of healthy pus capsules and the highest number of follicles were observed in the Iranian variety. Also, the highest capsule weight, 1000 seed weight, and maximum seed yield were assigned to the Indian variety on the first sowing date with an average of 0.288, 2.38 g, and 994.75 kg/ha, respectively. In general, among the investigated varieties, the Indian variety had the highest value in most of the functional traits compared to the other two varieties due to its adaptability to the climatic conditions of the region.

In this research, the delay in sowing dates (December and January) caused a significant decrease in traits related to yield and yield components, and the first sowing date (2021/11/06) had the most positive effect on all three varieties. Therefore, the most suitable sowing date for black cumin in Gorgan climatic conditions is planting in November, which achieves the maximum grain yield in black cumin varieties, especially the Indian variety. As a result, to achieve maximum yield, this sowing date is recommended in the climatic conditions of Gorgan city.

Common bean (Phaseolus vulgaris L.) due to its high nutritional value has an effective role in ensuring food security of the community. In Iran, protein supply is mainly dependent on plant products, and any action to improve the yield and production of protein-rich crops, which are headed by legumes, is of particular importance. Increasing yields by optimizing production management and eliminating yield gaps is the most appropriate way to increase crop production and improve food security. Therefore, accurate estimation of potential yield and yield gap and crop production is essential for sustainable food supply. The present study aims to estimate the yield gap and production and water productivity of bean in its main climate zones in Iran based on the Global Yield Gaps Atlas (GYGA) project at the Gorgan University of Agricultural Sciences and Natural Resources was done in 2016. In order to estimate the beans yield gap and water productivity in Iran according to GYGA protocol, first the data related to farmers' yield (Ya) and bean harvested areas and production in the country in a period of 15 years from 2001 to 2015 from the Ministry of Agriculture of Iran was prepared. Then the distribution map of beans in the country was prepared. By combining the distribution map of the bean harvested areas and the climatic zoning map of the country, the main climatic zones (DCZs) of bean production were identified. Then, reference weather stations (RWSs) were selected according to the level of each climatic zone. In order to estimate the potential yield (Yp) and water productivity (Wp) based on weather data and major soil type and agronomic management meteorological in each of the selected areas, the SSM-iCrop2 simulation model was used, which was locally calibrated and evaluated. Finally, the bean yield gap (Yg) was calculated from the difference between the potential and actual yield of each RWSs was upscaled to DCZs and country-level. The results of comparing the average of beans actual yield reported by the Ministry of Agriculture of Iran with the actual yield calculated according to the GYGA protocol for the country with RMSE, CV and r values of 84 kg ha-1, 4% and 0.96 respectively, which indicated using This protocol can estimate the average yield of bean in the country with high accuracy. The average beans actual yield in Iran during the years 2001 to 2015 varied between 1.6 and 2.3 ton ha-1. Also, the average actual yield in the main climatic zones of production was 1.9 and between 1.1 (climatic zone 4202 in Germi) to 2.3 ton ha-1 (in climatic zone 3003 in Avaj). Bean potential yield was estimated from 3.4 (in climate zone 4202 in Germi) to 5.4 ton ha-1 (in climate zone 4103 in Hamedan and Bijar) with an average of 4.5 ton ha-1. Based on results, in the main climatic zones of bean production in Iran, there is a yield gap of 1.8 to 3.5 (average 2.6) ton ha-1, equivalent to 46 to 67% (average 57%). The average water productivity potential for bean in Iran was estimated to be 0.76 kg m-3. According to the results, if the factors causing the yield gap are eliminated by optimizing the management of bean production and cultivation and bringing the yield of bean fields to attainable yield (80% of potential yield), is increasing grain yield from the current value of 1.9 to 3.6 ton ha-1 with the same harvested areas, bean production in Iran will increase from the current 222,705 to 415,822 ton, which is equivalent to 46% increase in production and is considered an important step in improving food security.