جستجوی مقالات مرتبط با کلیدواژه « کم‎آبیاری » در نشریات گروه « زراعت »

The economic importance of quinoa is not only due to the possibility of using the seeds as a food product characterized by a similar composition and use as consumer cereals but the species can also be managed as a leafy vegetable with high nutritional value and similar uses, such as, for example, spinach. Drought is another environmental stressor for plants subjected to severe water stress, especially in semi-arid and arid environments. Water scarcity poses a considerable challenge to crop production, leading to a notable reduction in crop yield. Quinoa, however, boasts low water requirements and demonstrates resilience in drought conditions. Even during dry periods, quinoa can effectively sustain leaf area and regulate photosynthetic activity. This resilience is facilitated by structural characteristics such as small, thin-walled cells, tissue flexibility, low osmotic potential, and controlled leaf area reduction through dehiscence. Other quinoa features for sustaining turgor pressure through osmotic adjustment during drought stress include inorganic ion buildup (e.g., Ca, K, and Na) and improved organic element synthesis (carotenoids and proline). Quinoa genotypes have several drought-resistance mechanisms, enabling this crop to grow and develop under severe drought conditions. 

To evaluate the effect of moisture levels on some quinoa cultivars biochemical traits, four separate experiments were conducted in a factorial layout based on randomized complete block design with three replications in two regions (Birjand and Sarbisheh) and two planting dates (March and July/August) in 2018-2019. The experimental factors included five moisture levels (25, 50, 75, 100, and 125% of crop water requirement) and three quinoa cultivars (Titicaca, Giza1, and Redcarina). Some quinoa physiological and biochemical traits were evaluated by composite analysis at the 50% flowering stage and the effects of planting date and location were considered fixed.

The results showed that in August/July cultivation, the characteristics of RWC, electrolyte leakage, sodium percentage, potassium percentage, chlorophyll a, carotenoids, proline content, and total soluble carbohydrate of leaves were increased by 17.10, 74.62, 95.51, 31.9, 3.53, 38.65, 94.19 and 9.30% respectively and chlorophyll b content decreased by 13.15% compared to March culture. Also, in Sarbisheh, RWC, electrolyte leakage, potassium percentage, and leaf carotenoids are respectively 3.53, 38.65, 94.19 and 9.30% more than Birjand, but sodium percentage, chlorophyll a, chlorophyll b, proline and total soluble carbohydrates of leaves were 4, 1.88, 15.67, 51.02 and 30.41% less than Birjand, respectively. In most of the studied traits, the Giza1 cultivar had higher quality traits. Severe water scarcity resulted in an elevation of certain biochemical traits in quinoa leaves. Specifically, as moisture levels decreased from 125% to 25% of the water requirement, there was a significant increase in electrolyte leakage, sodium and potassium percentages, chlorophyll a and b, carotenoids, proline, and total leaf soluble carbohydrates by 24.50%, 37.84%, 35.89%, 24.83%, 59.12%, 48.75%, 51.58%, and 36.71%, respectively. However, the relative water content (RWC) decreased by 17.70%. Notably, there were no significant differences observed between the 125% and 100% levels of water requirement for most of the analyzed traits.

In general, with the significance of the triple interaction of planting date × location × cultivar, as a result, the reaction of each variety depends on the planting date and location of its planting. But in general, most of the quinoa leaf physiological and biochemical traits increased in August/July cultivation. In Birjand, due to the higher average temperature and other climatic parameters compared to Sarbisheh, and probably understanding the heat stress, traits such as photosynthetic pigments, proline, and soluble carbohydrates had higher values. In this research, the Giza1 was superior to the other two cultivars, and moisture stress caused a significant decrease in the water content of the leaves and a significant increase in quinoa leaves quality traits.

The effect of magnetic and superabsorbent water was investigated on some morphophysiological traits and performance of cumin under a low irrigation regime.

An experiment was conducted in the agricultural year of 1399-1400 in the research fields of the Faculty of Agriculture of Shahrood University of Technology in two districts of Rahnjan and Garman of Shahrood city in a factorial format in the form of a randomized complete block design with three repetitions. Irrigation water type treatment at two levels (normal and magnetic) and locations (Rahanjan, Garman) with different climatic conditions and altitude above sea level as the main factor and superabsorbent treatment at three levels (zero, 100 and 200 kg/ha) as a secondary factor. Was considered. In all treatments, irrigation was applied based on 100% of plant water needs.

The results showed location, type of irrigation and different concentrations of superabsorbent had a positive and significant effect on the growth characteristics. In the Rahnjan region, due to the climatic conditions and higher average annual temperature and the treatment of 100 and 200 kg/ha of superabsorbent and the use of magnetic water, the highest amount of plant height, percentage and yield of essential oil and protein, soluble carbohydrates were observed.

According to the results, most of the traits in the Rahnjan region had higher values than in the German region, and plant cultivation in the Rahnjan region is economical.

The interaction of genotype with the environment provides the possibility of selecting stable genotypes for a wide range of environments. Evaluation of the interaction of genotype with the environment is necessary to increase the efficiency of selecting varieties with high and stable performance in a wide range of different environments. The objectives of this paper are: (1) evaluating the stability of 60 potato genotypes for tuber yield in two years using parametric and non-parametric stability methods, (2) identifying genotypes with good and stable performance when evaluated in variable environments and (3) investigating the relationship and correlation between stability statistics of tuber performance under water deficit conditions in Iran.

To evaluate the performance stability and adaptability of the 60 potato genotypes, two cultivars and 58 advanced clones, 17 parametric and non-parametric statistics were evaluated for tuber yield across eight environments during the 2018-2019 growing seasons. The genotypes were evaluated under normal and water deficit conditions in Karaj and Ardabil. In this study, the parametric analysis for yield was determined by such parameters as regression coefficient (bi), environmental variance (Si2), coefficient of variation (CVi), deviation from regression (sdi2), and Wricke’s ecovalence (Wi2), The non-parametric analysis included Nassar and Huhn's statistics (S(1) and S(2)), Huhn's equation (S(3) and S(6)), Shukla’s stability variance (σ2i), Plaisted and Peterson’s (θi), Thennarasu’s non-parametric (NP(1), NP(2), NP(3), and NP(4)), and Kang’s rank-sum (KR) parameter. Parametric and non-parametric statistics are used by agronomists and plant breeders. Currently, researchers are interested in applying several stability statistics to obtain the desired results, crucial for the selection of stable varieties

Composite variance analysis showed that the effect of place and year as well as the effect of genotype are significant. The interaction effect of year × location × genotype was significant at the probability level of 1%. The genotype effect was also significant at the 1% probability level. The interaction effect of genotype x location and genotype x year was not significant, which indicates that the average performance of genotypes is not different in different locations and years. Grouping of genotypes based on average performance and parametric and non-parametric stability statistics showed that genotypes are divided into four main groups. In general, based on the average rank of parametric and non-parametric stability parameters, genotypes G31, G21 and G36 had the least changes and were recognized as the most stable genotypes, and therefore they can be introduced as stable genotypes. The results of stability statistics and cluster analysis showed that G31, G21 and G36 genotypes can be introduced as stable and compatible genotypes.

Our results showed that G21, G31 and G36 genotypes contributed the least to the genetic × environment interaction (G*E) and were considered as stable genotypes under water deficit conditions. The different parametric and non-parametric stability procedures can be proposed to select drought tolerant genotypes under different environments conditions; these procedures could be useable for recognition of the best genotypes under drought stress conditions. Therefore, the analysis of yield stability could be utilized in combination with parametric and non-parametric methods to evaluate and identify drought tolerance genotypes. Dendrogram results confirmed each other with the results of parametric and non-parametric statistics. While G49, G51, G53 and G56 genotypes with the highest values were the most unstable genotypes.

This experiment was conducted in order to evaluate the effect of water deficit irrigation on the agronomic characteristics of fodder sorghum cultivars in Kerman province. This experiment was carried out as a strip split-plot in a complete randomized block design with four replications in a research farm of agricultural research center of Jirof and Kahnooj, Kerman province, in 2019 and 2020. Drought stress as a vertical factor in four levels including without stress (irrigation after 80 mm evaporation from evaporation pan) as control, mild stress (irrigation after 110 mm evaporation from the evaporation pan), medium (irrigation after 140 mm evaporation) and sever (irrigation after 180 mm evaporation) and four sorghum cultivars including Spidfeed, Sugar graze, Jumbo and Pegah as a horizontal factor. The highest yield of fresh forage yield under non-stressed conditions (control) was observed in Spidfeed and Pegah (121.60 and 118.79 ton.ha-1, respectively). Also, Spidfeed and Pegah had the highest dry forage yield under non-stressed conditions (control) as 22.50 and 20.69 ton.ha-1, respectively. Also, the highest yield of dry forage in mild drought stress was observed in Pegah and Speedfeed varieties (15.30 and 14.88 ton.ha-1, respectively) and under medium drought stress in Pegah (11.12 ton.ha-1), whereas Spidfeed variety was superior to others for dry forage yield (7.42 ton.ha-1), in severe drought stress. Based on MP and STI indices, Spidfeed and Pegah cultivars with higher average of dry fodder yield were selected as the most suitable genotypes under drought stress conditions in Jiroft region of Kerman province.

Drought is considered one of the most important factors limiting crop performance worldwide. Consumption of humic acid on plants, in addition to soil fertility, increases plant tolerance to drought and soil water holding capacity. Chitosan is also a natural biopolymer modified from chitin and non-toxic, biodegradable, and environmentally friendly substances that acts as a potential stimulant in agriculture. Chitosan and humic acid reduce the negative effects of abiotic stresses. Accordingly, due to the drought crisis in arid and semi-arid regions, in this study, the modulating effect of humic acid and chitosan foliar application on wheat tolerance to drought stress at the end of the season was investigated.

This experiment was performed to study the effect of foliar application of chitosan and humic acid on improving drought tolerance of wheat genotypes in the form of split split plots based on a randomized complete block design with three replications. The main plot includes irrigation treatments at two levels (full irrigation and cessation of irrigation in spike stage), sub-plots including three wheat genotypes including Mihan, CD-93-9, and CD-93-10, and sub-plots including humic acid and chitosan foliar application levels (Zero, 2 g.L-1 of humic acid, 3 ml.L-1 of chitosan and the combination of humic acid and chitosan). The experiment was carried out on a field in Ardabil Agricultural Research Station. Sowing was done in October 2020 with a planting density of 450 seeds per square meter. Chemical fertilizer based on NPK soil test at 50, 100, and 20 kg.ha-1, respectively was added to the soil before planting. Each genotype was planted in 1.5 cm by 7 m plots. The length of each row was 7 m and the distance between the rows was 20 cm and the seeds were sown at a depth of 5 cm. STAR 2.01 statistical software was used to analyze the data including data analysis of variance and comparison of means by LSD method at a 5% probability level.

The results showed that the interaction effect of cultivar × stress × foliar application was significant in all studied traits including plant height, number of seeds per spike, number of spikes, spike length, and grain yield, except the number of tillers per plant and 1000-seed weight. Regarding the number of tillers per plant, the interaction of cultivar × foliar application was significant and for 1000-seed weight, the interaction of cultivar × stress and stress × foliar application was significant. Although there were differences in the response of wheat genotypes to the foliar application under both stress and non-stress conditions, in most traits such as number of tillers, number of seeds per spike, spike length, plant height, and 1000-seed weight, the best result was the simultaneous use of chitosan and humic acid. Was obtained. Also, both under non-stress and under stress conditions, the highest grain yield of the studied genotypes was obtained in simultaneous foliar application of chitosan and humic acid. In general, it can be concluded that the combination of chitosan and humic acid (2 g.L-1 humic acid and 3 ml.L-1 chitosan) significantly showed the best results in increasing the yield and yield components of wheat compared to the control treatment in both non-stress and the end of the season drought stress conditions.

Foliar application of humic acid and chitosan increased and improved the studied traits, both under drought stress and non-stress conditions in wheat genotypes compared to non-foliar application. The maximum number of tillers, number of seeds per spike, number of spikes, spike length, 1000-seed weight, and grain yield were obtained by foliar application of chitosan and humic acid under both full irrigation and stress conditions. Therefore, it is recommended to use simultaneous spraying of chitosan and humic acid to increase tolerance and achieve higher performance. Also, the study of different concentrations of these two substances in combination with each other and at different stages of wheat growth can determine the best dose and time of their consumption in this strategic crop, which is recommended to conduct studies in this regard.

The lack of irrigation water resources in the country in recent years has reduced the yield of crops and threatened food security; Therefore, it is necessary to think of ways to produce crops while saving water. One of the ways to increase production with limited irrigation water resources is the cultivation of drought-tolerant crops with high water use efficiency. Sorghum is known as one of the most important crops in arid and semi-arid regions of the world with its unique characteristics (including tolerance to environmental stresses, especially drought and heat, deep and extensive root system, C4 photosynthetic pathway, etc.). The use of appropriate irrigation methods is also known as another way to increase the production of crops with limited water resources. In this regard, the irrigation methods of alternate furrow irrigation and drip irrigation have been used as new irrigation management solutions in the country with favorable results. This study aimed to evaluate the effect of different irrigation regimes and methods on yield, morphological characteristics, water productivity, and drought tolerance of open-pollinated and hybrid forage sorghum cultivars.

This experiment was conducted as a factorial split-plot based on a randomized complete block design with three replications at the Seed and Plant Improvement Institute, Karaj, Iran, during the 2019 and 2020 cropping seasons. The factorial combination of four irrigation methods (CFI, conventional furrow irrigation; FFI, fixed alternate furrow irrigation; AFI, variable alternate furrow irrigation; and drip irrigation) and three levels of drought stress (full irrigation, moderate stress, and severe stress; including the supply 100, 75, and 50% of soil moisture deficit, respectively) as the main factor and two sorghum cultivars (Speedfeed and Pegah) as sub-factor were investigated. In this study, traits including silage yield, dry matter yield and percentage, irrigation water use efficiency, benefit per drop, net benefit per drop, leaf-to-stem ratio, plant height, and drought stress tolerance indices were evaluated. Due to the homogeneity of the variances of experimental errors over two years, the data were subjected to combined analysis of variance using SAS 9.1 statistical software, and Tukey's test (P≤0.05) was used to compare the means. In addition, IPASTIC online software was used to calculate stress tolerance indices and principal component analysis (PCA) based on these indices.
Research

The results showed that drought stress in all investigated irrigation methods decreased the silage yield, dry matter yield, and plant height and increased water use efficiency for silage and dry matter production, dry matter percentage, and leaf-to-stem ratio. The highest silage and dry matter yields (79.11 and 17.19 ton ha-1, respectively), and the maximum net benefit per drop (18854 Rials m-3) were obtained by cv. Pegah under full irrigation and drip method, whereas the maximum water use efficiency for silage and dry matter production (34.53 and 7.88 kg m-3, respectively) and the highest benefit per drop (60542 Rials m-3) were recorded in hybrid Speedfeed under severe stress and drip method. The highest leaf-to-stem ratio (0.715) was obtained in the FFI method under severe stress and the amount of this trait in cv. Pegah was about 8.6% higher than that of hybrid Speedfeed. Based on the stress tolerance indices, cv. Pegah under the CFI and drip methods and hybrid Speedfeed under the FFI method had more drought tolerance. In contrast, there was no significant difference between the cultivars under the FFI method.

In order to save water while achieving suitable forage yield and water productivity, the drip irrigation method and supplying 75% of soil moisture deficiency is recommended. If it is impossible to implement the drip irrigation system, the variable alternate furrow irrigation method can produce suitable forage yield while reducing the amount of water consumed.

In order to evaluate the effect of drought stress on some characteristics of germination and seed set of commercial soybean cultivars under water stress in the research farm of Karaj Seedling and Seed Breeding Research Institute, an experiment was conducted in 1400 using a standard germination test in the laboratory. The seed analysis of Karaj Seed and Seedling Registration and Certification Research Institute was carried out factorially in the form of randomized complete block design with 4 replications. The treatments include applying 4 levels of dry stress of polyethylene glycol 6000 with potentials of 0 (no stress), 3-, 6-, and 9-MPa, on the seeds of 4 commercial soybean cultivars, Williams, Hamilton x Essex, TMS, and Bunty, produced at 3 levels. The low irrigation stress of the mother plant, irrigation after the values of 50 (optimal irrigation and control), 100 (mild stress) and 150 (severe stress) mm of evaporation from the evaporation pan were class A). The examined characteristics include: percentage of final germination, percentage of normal seedlings, percentage of abnormal seedlings, percentage of hard seeds, percentage of rotten seeds, average daily germination, average germination time, seedling length and index The length and weight of the seedlings were. The results showed that the mutual effect of drought stress, low irrigation stress and variety had a significant effect on all the examined characteristics. In the treatment of 9-MPa drought stress and without water deficit stress, the Williams variety compared to the treatment without drought stress and without water deficit stress, the average germination time was 0.90 days, the percentage of rotten seeds, hard seeds and abnormal seedlings were 0.18%, 750 respectively. 5.5% and 0.60% increase and average daily germination of 1.28 days, final germination and normal seedling decreased by 1.28% and 4.92%, respectively. In general, among the studied cultivars, Williams variety showed the best and Bunty variety showed the weakest response to low irrigation and drought stress.

A field experiment was carried out at the research field of Payame Noor university of Shadegan, Khuzestan province during 2021-2022 growing season to evaluate the grain and oil production of sesame under deficit irrigation in response to vermicompost application. The experiment was conducted as split-plot in three replications, where irrigation treatments (I1: full root zone irrigation and I2: partial root zone irrigation) were allocated to main plots and vermicompost (0.0, 5.0, 10.0, 15.0 and 20.0 t ha-1) were assigned as sub plots. Results indicated that oil percentage, grain and oil yield of sesame were reduced 3.0%, 17.7% and 23.9% under partial root zone irrigation, respectively. Significant reduction (P≤0.01) of grain number and grain weight under partial root zone irrigation (30% and 11.2%, respectively) showed that grain yield of sesame was affected by both components of grain yield. However, grain number was more sensitive to water shortage compared with grain weight. Water consumption in the limited irrigation treatment was reduced by 49.2%, and this caused the water productivity for seed and oil production to increase by 61.7% and 49%, respectively, compared to the full irrigation of the root system. The use of vermicompost fertilizer led to the improvement of sesame grain and oil yield and their related traits, so that with the consumption of 20 t ha-1 of fertilizer, the grain and oil yield increased from 791 to 1248 kg ha-1 (57.8% increase) and 374 to 657 kg ha-1 (75.7% increase), respectively. Therefore, the use of vermicompost fertilizer can help to improve the yield of sesame seeds and oil under limited irrigation conditions.

The aims of this study is evaluate AquaCrop in simulating rapeseed yield, biomass and water use efficiency under different irrigation amounts (E1, E2, E3 and E4, indicating water supply of 50, 75, 100 and 125 mm from the evaporation pan, respectivly) was performed in three cropping years (Y1, Y2 and Y3 representing the first, second and third years, respectively). In order to calibrate this model, the data collected from the first year used for calibration and data for the second and third year were used for validation. The results showed that AquaCrop had an overestimated error (MBE< 0) to simulate all three parameters studied. The accuracy of AquaCrop was excellent for simulating yield and biomass (NRMSE <0.1) and good for water use efficiency (NRMSE <0.2). The mean differences between simulated and observed yield, biomass and water use efficiency water were 0.19 t.ha-1, 0.78 t.ha-1 and 0.05 kg.m-3, respectively. Based on the results, use of AquaCrop to simulate rapeseed yield, biomass and water use efficiency is recommended.

The purpose of this field was to study the effect of biochar application and different planting patterns in different irrigation regimes on the growth and yield of thyme essential oil. The studied treatments include irrigation (irrigation of all furrows, irrigation of furrows as one in constant and one in variable (biochar (non-application of biochar and application of biochar at 8 tons per hectare) and planting pattern (single row cultivation) Thyme and cultivation of two rows of thyme) on the growth and yield of the thyme plant. This experiment was carried out in two cropping years of 1397 and 1398 in the form of split plots based on a randomized complete block design with three replications. The results showed that the highest yield of flowering branches was obtained in the treatment of irrigation of all furrows + application of biochar with mean of 1701 kg. ha-1. In this study, the highest yield of essential oil with 24.7 kg. ha-1 was obtained in the treatment of furrow irrigation as a constant interval + application of biochar + cultivation of two rows of thyme. Based on the results of this study, the application of biochar and two-row cultivation caused a significant increase in the yield of thyme essential oil. In general, despite the decrease in growth and yield of thyme dry matter, furrow irrigation treatments as one-to-one variables increased essential oil yield by significantly increasing the percentage of essential oil and reducing water consumption. Biochar treatment also had a positive effect on all vegetative and functional traits of thyme.

Rice is one of the most important crops in Asian countries, which is cultivated in more than half of the continent's agricultural lands. Environmental conditions are different and uncontrollable even in different parts of an area, so the response of rice cultivars to these conditions will be different. Therefore, it is necessary to perform performance comparison experiments to achieve high quality, quantity, consistency and stability in different regions. More than 50 percent of human food is supplied from cereals, and rice is a cereal that has a high crop after wheat, but more than wheat and others in terms of energy production per hectare Cereals are important. By using the GGE biplot method, by using multivariate methods, in addition to proper data analysis, the work facilitates the interpretation of the results. The aim of this study was to evaluate the stability of the lakes by using GGE biplot analysis and selecting and introducing superior lanes for stability and response in underwater stress conditions and flooding.

In this experiment, the eight lines with the control cultivar of the region and IR29 cultivar during 2014 and 2015 with the desirable qualitative and qualitative characteristics and suitable growth period in a completely randomized block design with three replications in two regions of Gonbad Kavous and Ali-Abad were cultivated. Ten plants of 15 cultivated plants were randomly selected and separated from the soil at a depth of 50 cm. After removing the bushes from the soil using the shovelomics method, the plants were first immersed in water for seven days. Then the root and part of the air organs were separated. To record the root characteristics, each root of the plant is separated and the number of roots is less than 5 cm, the number of roots is 7-6 cm, the number of roots between 20-8 cm, the number of roots 21-30 cm and the number of roots greater than 30 cm, root volume and root dry weight were measured. Using the aerial parts, related traits such as panicle number, plant height, stem weight, straw weight, panicle length, number of filled grains, weight of grains and cluster number were recorded.

The results of analysis of variance showed that the difference between locations for days to days of traits, number of roots, total length of roots, root number between 7 to 20 cm, stem weight, panicle weight, root dry weight, straw weight and seed number Poke was significant, and the difference between years was significant for number of pancakes, root number was significant. Comparison of mean of studied sites and years showed that grain yield per hectare had no significant difference, but the mean comparison of this trait in terms of waterlogging and stress conditions indicated that flooding conditions had a higher yield than tension. Separation of the interaction of location × planting time × irrigation conditions with different cultivars by biplot method showed that the cultivar 87.5.103 in all states related to Aliabad city had the highest yield. In irrigation stress conditions, IR55411, IR70360, 87.5.21, IR66424 and 87.110 lines had lower yields, but in terms of flooding, IR55411, IR70360, 87.5.21, IR66424 and 87.110 lines had the highest yield, respectively. In both cases, all of the cultivars had a higher yield than IR-29

Separation of the interaction of location × planting time × irrigation conditions with different cultivars by biplot showed that cultivar 87.5.103 in all states related to Aliabad city has the highest performance. In general, the cultivar 87.5.103 among all cultivars and the floodplain dome in the first year was the best environment for all the environments in terms of day.

This study was conducted to investigate the effect of drought stress and plant density on yield and some yield components of wheat cultivars in Boroujerd Agricultural Research Station in 2019-2020. The experiment was performed as a split factorial in a randomized complete block design. The main plots belonged to drought stress treatments (at three levels of control, irrigation to flowering, and irrigation to grain filling). The sub-plots consisted of plant density treatments (300, 400, 500, and 600 plants m−2) and cultivars (Mihan and Baharan). The results showed that drought stress, density, and cultivar treatments influenced grain yield components, and the interaction of stress ×plant density significantly affected plant height and spike length. The interaction of cultivar × stress significantly influenced plant height, 1000-seed weight, grain yield, and flag leaf area index. The interaction of cultivar × density was also significant on plant height, spike length, and internode diameter. The highest plant height (87 cm) was obtained in the treatment of 600 plants/m2 without applying drought stress. The highest plant height among all treatments belonged to the Baharan cultivar cultivated at a density of 600 plants/m2. The spike length was higher in full irrigation treatment and at the level of 500 plants/m2 than in the other experimental treatments. The dry weights of flag leaves were 2.8 and 3 g in Mihan and Baharan cultivars, respectively. The highest 1000-seed weight (43.7 g) in the Mihan cultivar at the level of complete irrigation treatment increased by about 12% compared to that in irrigation....

The occurrence of water shortage and drought stress during plant growth, is caused yield loss as well as the grain quality of rice genotypes. Hence, this experiment was conducted to determine eefects of different irrigation methods on rice grain yield and several important grain quality traits such as amylose percentage, degree of milling and gelatinization temperature in Rice Research Institute of Iran (Mazandaran Branch, Amol) in 2017. Experiment carried out as split plots using randomized complete blocks design with main factor of irrigation methods in three levels of flooding irrigation, alternate wetting and drying method up to 10 (AWD10) and 20 (AWD20) cm below the soil surface and sub-factor with ten rice genotypes. The results showed that different irrigation treatments were statistically significant on garin lenghg before cooking, crash grain, amylose content and gelatinization temperature. Among the genotypes, Neda with average of 6901.7 kg.ha-1 had the highest grain yield, harvest index 44.2%, milling efficiency, degree of milling 72.3% and healthy garin 65.3%. The highest degree of milling (90%), grain length after cooking (13.2 mm), elongation ratio (2 mm) and Gelatinization temperature (5.6) belong to Vandana, IR74428-153-2-3, Firozan and IR70416-53-2-2 genotypes, respectively. In general, considering to the important quantities and qualities traits of genotypes in irrigation regime treatments were not different from flooding method, therefore, the studied genotypes are recommended for planting in areas with lack of irrigation water. It should be noted that Neda genotype is introduced as a superior genotype due to increase of sevral important quantities and qualities traits compared to other genotypes.

Due to Iran's location in the arid and semi-arid region of the world, the possibility of drought is high. Therefore, implementing low irrigation technologies to increase the efficiency of limited water resources is a scientific solution to reduce water consumption. On the other hand, rice receives two to three times more water than other crops and drought in rice is the most important factor limiting production worldwide, which indicates the need for optimal use of water resources to determine the real water needs of rice plants. Therefore, development and introduction of drought tolerant genotypes, using new irrigation methods, is a useful method to improve water productivity and efficiency in the face of drought and water scarcity. The aim of this experiment was to evaluate rice genotypes by measuring traits related to photosynthetic pigments and yield in order to select drought tolerant genotypes.

The present study, evaluated physiological and qualitative traits of grain with 10 rice genotypes that were known as tolerant genotypes in seedling stage based on the measurement of traits and mechanisms of drought tolerance split-plot arrangement using randomized complete blocks design with three replications in 2016, in Research Institute Rice (Mazandaran), Iran. Experimental research include three different irrigation regime (submerged surface (A0), alternate wetting and drying method up to 10 (A1) and 20 (A2) cm below the soil surface) and 10 genotypes rice that respectively are located in the main plots and sub-plots. The studied traits include physiological characteristics such as chlorophyll a, b and carotenoids, harvest index, biological yield and grain yield. Photosynthetic pigments were measured by spectrophotometer and its concentration was performed by Welburn and Lichtenthaler (1994) method.

The results showed that the amounts of photosynthetic pigments in low irrigation treatments increased compared to flood irrigation. So that the ratio of chlorophyll a to b and carotenoid content in in AWD20 increased by 5 and 20% compared to flood irrigation treatment, respectively. Genotypes also showed a very significant effect on traits related to photosynthetic pigments and quantitative and qualitative grain yield. The AR8 genotype had the highest chlorophyll a and a / b (average of eight and two µgr.ml, respectively). The highest chlorophyll b and a+b were also observed in Vandana genotype with an average of 5.2 and 13 μg.ml. The highest grain and biological yields were related to Shiroodi and IR74428-153-2-3, respectively. The interaction of the treatments showed that Neda genotype among other genotypes during AWD20 water stress has a greater advantage over the studied traits.

The results of this study indicated the preservation of quantitative and qualitative traits of genotypes under drought stress. Also, genotypes showed different reactions to the studied traits. Neda, Vandana, AR8 and IR74428-153-2-3 genotypes were able to increase photosynthetic capacity and quantitative and qualitative grain yield by applying low irrigation treatments.

In confectionary sunflower cultivation, drought stress at the stage of vegetative growth and plant density are two important variables that determine grain yield. In order to increase the 1000-seed weight and marketability of sunflower seeds, farmers usually consider plant density less than oily sunflower, and on the other hand, for more root growth and dormancy resistance due to large heads, in the vegetative growth stage of sunflower they bring drought stress to the sunflower farm. In some regions of Kermanshah province, confectionary sunflower (local cultivar Songhori) is cultivated with very low density (1-3 plants per square meter). On the other hand, farmers, based on their experiences, in the vegetative growth stage (2-6 leaves), cut off the field irrigation, and this watering interruption may take 30-45 days. The purpose of stopping irrigation in such conditions is to grow more roots and prevent lodgings of plants due to the weight of the head. In the present study, the effect of cutting irrigation at vegetative stage and plant density on yield and other agronomic characteristics of local confectionary sunflower was investigated to identify the most appropriate treatments.

The present study was conducted using split plot experiment based on randomized complete block design with three replications in the farmers' farm of Kermanshah province in 2016. Drought stress was as the main factor at three levels including severe stress, moderate stress and non-stress. The sub-factor was three levels of plant density with changes in plant space on 60 cm planting rows in the form of 20, 40 and 60 cm. Important agronomic traits including number of days to star, number of days to full flowering, stem diameter, plant height, number of leaves, leaf area, head diameter, percentage of hollow, number of seeds per head, 1000 seed weight and yield were measured according to Schneider and Miller (1981). In order to measure the grain yield of each plot, the middle row plants were harvested after removing the marginal plants (one row and one plant from the beginning and end of each plot) and the grain yield was measured after threshing. Based on the harvested area, it was converted to kilograms per hectare. In order to statistical analysis, SAS Ver 9.1 statistical software was used to analyze the variance and the means of treatments was compared by Duncan’s multiple range test.

The results of variance analysis showed that drought stress significantly reduced plant height, days to maturity, seeds per head and stem diameter and increased days to flowering. Effect of Density was significant on all studied traits except plant height and number of leaves. While increasing density, stem diameter, head diameter, number and weight of seeds per head and 1000-seed weight was decreased and the hollow percentage of head, the number of days to flowering was increased. Mean comparison of data showed that grain yield under severe and non-stress condition was 2749 and 4543 kg ha-1, respectively. The highest and the lowest grain yield was belonged to plant spacing of 40 cm and 20 cm with 4599 and 3538 kg ha-1, respectively.Given the water crisis in Iran, the real value of water consumption should be considered and water loss should be prevented by using different methods in crop production. According to the mean grain yield, it can be seen that the average yield of mild drought stress (two less irrigations) is slightly different from the average yield in non-stress irrigation. The two removed irrigations in the mild stress treatment coincide with the time of grain filling of crops such as wheat, barley and canola or the cultivation of some spring crops such as corn. Irrigation in these stages is important in the grain yield of these plants. So by eliminating two irrigations after the establishment of the sunflower, the saved water can be used to irrigate other crops. On the other hand, low and high density treatments both had lower grain yield than intermediate density treatment. Plant spacing of 40 cm with high 1000-seed weight had higher grain yield than plant spacing of 20 and 60 cm, so that a plant distance of 40 cm can be recommended in confectionary sunflower. It can also be recommended that, after the establishment of the sunflower plant, by eliminating two irrigations before reproductive growth, without effective reduction of grain yield, water resources can be used for other crops such as wheat, barley and canola.

Lack of irrigation water resources has been identified as the most important problem in forage production. Therefore, to increase the productivity of crop production using limited water resources, it is necessary to pay attention to the cultivation of drought-tolerant crops. Sorghum has a high resistance to abiotic stresses and can perform well in comparison with other summer crops. Irrigation and fertilization are not only costly but also are of the most important factors affecting the quantity and quality of forage crops. Therefore, the present study was conducted to evaluate the effects of different levels of drought stress and nitrogen fertilizer on the sorghum forage yield and quality, and water use efficiency.

This study was conducted as split-plots based on a randomized complete block design with three replications in Karaj, Iran, during the 2018 growing season. Drought stress at three levels (no-stress, moderate and severe stress; including the supply of 100, 75, and 50% soil moisture deficit, respectively) as the main factor and nitrogen fertilizer application from urea source at four levels (0, 150, 300, and 450 kg ha-1) as the sub-factor were evaluated. In all experimental treatments, nitrogen fertilizer was applied in two equal parts, at planting and 5-6 leaf stage. In the present study, drip tape irrigation approach was applied (with a diameter of 16 mm and drip distance of 10 cm). Irrigation cycle was considered constant for all plots and different levels of irrigation water were applied. In order to properly establish the sorghum crops, deficit irrigation regimes were started after 2-4 leaf stage. Sorghum forage was harvested at the milky-dough stage. Data were subjected to two-way analysis of variance (ANOVA) and the difference between treatment means was separated using LSD test. A significance level of 95% was applied by GLM procedure of SAS 9.1.

The results of ANOVA showed that the main effect of drought stress and nitrogen fertilizer on the forage yield, irrigation water use efficiency (IWUE), plant height, and quality characteristics of sorghum forage (except hemicellulose) was significant (p≤0.01). Also, the interaction effect of drought stress × nitrogen fertilizer on the forage yield, IWUE, plant height, and crude protein content at the probability level of 1%, and on other quality characteristics of sorghum forage (except hemicellulose) at the probability level of 5% was significant. The highest dry-matter and protein yield (40.03 and 3.48 t ha-1, respectively) and the maximum plant height (224 cm) were obtained with full irrigation and application of 450 kg nitrogen ha-1, whereas the maximum IWUE for dry matter and protein production (6.793 and 0.672 kg m-3, respectively) was obtained under moderate stress and with the application of 450 kg nitrogen ha-1. By increasing the nitrogen fertilizer application from 0 to 450 kg ha-1 under full irrigation, moderate stress, and severe stress conditions, the dry matter yield increased by 167, 181 and 101%, respectively, protein yield increased by 238, 284 and 174%, respectively, forage protein content increased by 27, 36 and 39%, respectively, and relative feed value increased by 8, 6 and -2%, respectively. Overall, in order to achieve the maximum quantity and quality of forage and the highest water use efficiency in full irrigation and moderate drought stress conditions, application of 450 kg nitrogen ha-1, and in severe stress conditions, application of 300 kg nitrogen ha-1 can be recommended.

Generally, the results illustrated that the treatment of moderate drought stress (supply of 75% soil moisture deficit) with the application of 450 kg nitrogen ha-1, along with saving water and producing high forage yield, among the studied treatments resulted in the highest water use efficiency, DMD, NEL, and RFV, and the minimum ADF and NDF, can be recommended as the superior treatment for sorghum forage. In case of severe limitation of irrigation water resources, supply of 50% soil moisture deficit (severe drought stress) along with application of 300 kg nitrogen ha-1 can be recommended.

Sugar beet has long-growth period and high-water use. Thus, managing to reduce water consumption and decline growth period causes to increase the crop productivity. Sugar beet provides more than one-half of sugar produced in the United States and about 40% of sugar production in the world. The root of this crop contains 13- 22% sugar content. In general sugar beet also has a major role in the human diet and it is the mainstay parts of the agriculture economy in Iran. The leaves of sugar beet comprise the main light receptor organ for a crop. Leaf area development early during the season causes more efficient use of sunlight since it is important to the formation and expansion of the canopy. Sugar beet in the primary growth stages needs a warm and sunny climate and optimum water supply for optimal photosynthesis and photoassimilate partitioning.

This purpose study was performed in the research field of Hamedan in 2016. The experiment was conducted in a split-split plot based on RCB design with four replications. Experimental treatments were planting date at two levels as main plot (May 14 and June 28), irrigation at two levels as sub-plot (full irrigation and 75% of full irrigation or water requirement), and cultivar at 3 levels (two premature hybrids and the resistant cultivar to Rhizoctonia (Arya)) as sub-sub-plot at 2016 crop season. Studied traits were root yield, sugar content, sugar yield, and Enzyme activities such as SOD, PO, leaf chlorophyll, and some physiological and morphologic traits. SAS software version 9.1 was used to analyze the data. Also, the mean of the studied parameters was compared using the least significant difference test (LSD) at the level of 5 percent probability.

Based on the results of the analysis of variance, the difference between planting dates in terms of superoxide dismutase content, root yield, sugar yield, white sugar yield, and water use efficiency was significant at the level of 1% probability. There was a significant difference between irrigation levels in terms of superoxide dismutase and water use efficiency at 1% probability level and membrane lipid peroxidation content, peroxidase enzyme, chlorophyll a, chlorophyll b, and carotenoid content at 5% probability level. There was a significant difference between the studied genotypes in terms of root yield and sugar yield at a probability level of 1% and in terms of white sugar yield and water use efficiency at a probability level of 5%. The interaction effect of culture date on genotype was significant in terms of the effect on the percentage of white sugar and yield of white sugar at the level of 1% probability. The interaction effect of irrigation levels in genotype was significant only on water use efficiency at the level of 1% probability. The results showed that irrigation level 75% of plant water requirement compared to 100% level increased, hydrogen peroxide content, membrane lipid peroxidation, peroxidase activity and superoxide dismutase activity by 14.83, 25, 17.38, and 26%, respectively and reduced chlorophyll a, chlorophyll b and carotenoid content by 15%, 12%, and 14%, respectively. Also, the amount of superoxide dismutase activity and root yield on planting on May 14 was 33% and 26% higher than planting on July 28, respectively. Root yield in 33868 and 33872 hybrids was higher than Aria cultivar. The results also showed that the difference between the planting dates of May 14 and June 28 in the two hybrids 33868 and 33872 was not significant in terms of sugar content, white sugar yield, and water use efficiency. Also, the planting date of June 28 increased the percentage of white sugar in both hybrids. Finally, two hybrids, 33868 and 33872, obtained the highest water efficiency in the treatment of 75% of the required water.

In the conditions that there is a possibility of delay in the cultivation of sugar beet, planting two hybrids, two hybrids 33868 and 33872, is recommended.

Quinoa is a pseudo cereal from Amaranthaceae family, which is currently considered as a suitable alternative for plants with high water consumption due to its high nutritional value and stresses tolerance, especially drought and salinity. Meanwhile, reduction in crop yield caused by weeds competing for water, light and nutrients is well known. Hence, a study was conducted in Karaj to investigate the competitive capacity of quinoa with weeds under normal irrigation and drought stress and also to determine the required time for weed control. The experiment was arranged in split plot randomized complete block design with four replications consisted of irrigation levels (60, 80 and 100 mm evaporation from the evaporation pan) as main plots and weed control levels (0, 7, 14, 28 days of control and control in all seasons) as subplots. The highest quinoa grain (331 g/m2) and biological yields (1262 g/m2) were obtained under normal irrigation in weeds free treatment. Also, the lowest grain and biological yields were 139 and 723 g/m2, respectively that obtained under high drought stress in weeds infestation during growing season. In one month weeds free treatment under medium drought stress, grain and biological yields were 290 and 1010.25 g/m2, which show that despite the competitive potency of summer weeds, quinoa has good competitiveness in drought stress, and with one month of weed control, can achieve performance close to full control. In logistic model fitting to the grain yield, the maximum and minimum values of y0 and a, i.e. upper and lower limits, were observed in normal irrigation and high drought stress, respectively; although, the maximum and minimum values of GDD50 were obtained in high drought stress and normal irrigation, respectively.

In order to investigate the quantitative and qualitative response of three sesame cultivars (Sesamum indicum L.) to different irrigation and fertilizer treatments, an experiment was conducted in the research farm of Karaj Seed and Plant Breeding Institute during 2016 and 2017. The experiment was performed as split-factorial plots in a randomized complete block design with three replications. Irrigation treatments at two levels including low irrigation regime (irrigation after 80% of usable soil moisture) and full irrigation (irrigation after 40% of usable soil moisture) in main and factorial plots with different amounts of nitrogen (0, 60 and 120 kg N ha-1) and sesame cultivars (Oltan, Dashtestan 2 and Naz single-branched) were placed in subplots. The results showed that in full irrigation conditions, application of 120 kg N ha-1 increased sesame seed yield by 83% compared to non-application. In contrast, this increase in yield in response to the application of nitrogen in low irrigation treatment was 40%. In general, the results showed that in full irrigation treatment, the use of nitrogen fertilizer for all three cultivars can be justified. Maximum grain yield was obtained in Oltan (1106 kg ha-1), Dashtestan 2 (1012 kg ha-1) and Naz single-branched (634 kg ha-1) cultivars with 115, 117 and 100 kg N ha-1, respectively. In contrast, in conditions of low irrigation, in none of the cultivars, grain yield higher than 500 kg N ha-1 was not achieved even with high amounts of nitrogen (60 and 120 kg N ha-1).