جستجوی مقالات مرتبط با کلیدواژه « Cut-off Irrigation » در نشریات گروه « کشاورزی »

Drought is one of the most important environmental stresses in the ecosystem of crops. In order to select potato tolerant genotypes to drought stress.

This experiment was conducted in the form of a randomized complete block design with the method of strip chopped blocks in three replications during the two cropping years was performed in Ardabil region. Two levels of non-stress and stress irrigation were compared as vertical factor and 20 potato genotypes were compared as horizontal factor.

The results showed that all measured traits were affected by stress treatments. Under stress treatment, genotype 905675 had the highest tuber yield and tuber weight per plant. The lowest tuber yield and tuber weight per plant were obtained from Marfona cultivar. In addition, with the application of stress, the activity of enzymatic and non-enzymatic antioxidants increased. The highest amount of reducing sugar with 122%, vitamin C with 63%, proline with 106% The percentage of catalase enzyme with 249% increase compared to non-stress conditions was observed in genotype 905675. The highest activity of superoxide dismutase and polyphenol oxidase with 214 and 42% increase belonged to genotype 901375, respectively.

In general, considering the amount of changes in tuber yield, tuber weight per plant, increasing the activity of enzymatic and non-enzymatic antioxidants, genotypes 905675, 901575 and 901375 were selected as tolerant and high yield potential genotypes in both stress and non-stress conditions, respectively, and Milva, Jelly and Marfona cultivars can be introduced as susceptible cultivars.

Sesame (Sesamum indicum L.) is one of the important oil crops that get attentions due to its relatively high oil content and tolerance to drought. Drought is one of the most important causes of crop products reduction and can affect plant phenology, growth and yield depending on the severity, time and stage of plant development. Superabsorbent polymers are suitable materials for increasing soil water retention capacity that can provide better conditions for crop growth, especially under water deficit conditions. The importance of useing chemical fertilizers in addition to their nutritional role, is to support the crop in tolerating environmental stresses such as drought and preventing yield loss which potassium has such role in plant life and survival under stress conditions. Potassium fertilizers, especially potassium sulfate, can play an important role in reducing the negative effects of water stress. Potassium is the third main nutrient for plant growth and plays a special role in the survival of plants under environmental stress and increasing their resistance to drought, high temperatures, cold, disease, salinity, weeds and maintaining osmotic potential.

In order to investigate the effect of superabsorbent polymer, potassium sulfate and water deficit on growth, yield and yield components of sesame (Sesamum indicum L.), an experiment was conducted out on factorial arrangment based on randomized complete block design with three replications in Research Field of Agricultural College, at Birjand University in 2018. Experimental factors included three levels of irrigation (full irrigation in the whole growing season, irrigation up to 50% flowering stage and cutoff irrigation until maturity, and irrigation up to 50% capsules appearance and cutoff irrigation until maturity), potassium fertilization at three levels (No potassium application, fertilizing at optimum recommendation using 100 kg.ha-1 potassium fertilizer and fertilizing 50% higher than optimum recommendation using 150 kg.ha-1 potassium fertilizer) and superabsorbent at two levels, including no application and 100 kg.ha-1 application. The studied traits were plant height, number of lateral branches, seeds per capsule, capsule per plant, 1000-grain weight, grain yield and days to maturity.

Results showed that irrigation levels had a significant effect on measured traits except for number of lateral branches. The highest grain yield (2316.61 kg.ha-1) was obtained under full irrigation conditions and the lowest seed yield (667.89 kg.ha-1) was observed at 50% flowering cutoff irrigation. The effect of superabsorbent on all traits was significant. The results showed that superabsorbent moderated the effects of drought and improved sesame growth indices. Interaction effect of potassium and irrigation on grain yield was also significant. Although, under water deficit conditions, grain yield was significantly reduced, but potassium sulfate application under these conditions partially prevented the yield loss. Due to the role of potassium in the plant, the presence of this element in water deficit conditions can be effective in tolerance and crop yield increment. The highest number of days to maturity (124.77 day) in interaction effect of water deficit and superabsorbent was obtained from full irrigation and 100 kg/ha superabsorbent treatment and the least amount (109.55 day) was obtained from50% flowering cutoff irrigation and non-superabsorbent treatment.The increase in soil moisture caused by the use of soil moisture absorbers can increase the duration of the day to maturity.

The results showed that irrigation levels decreased sesame growth and yield. Water deficit at flowering and encapsulation stages reduced grain yield compared to full irrigation treatment. Therefore, it is necessary to irrigate the crop according to water requirement during these stages. Due to the necessity of conserving available water resources as well as optimum consumption of water, the use of superabsorbent and potassium can be effective in increasing crop yield and drought resistance. Obviously, it is necessary to provide sufficient water requirement in order to achieve higher grain yield. Therefore, it seems that hydrogels reduce the negative effects of drought by absorbing water and making it available for the crop. Potassium application in environments with different levels of drought can be considered as a practical method to reduce drought damage and prevent yield loss.

Safflower (Carthamus tinctorius L.) is one of the world’s oldest cultivated crops. It is traditionally grown for its seeds and used for coloring and flavoring foods and for making red and yellow dyes. The total area of safflower harvested in Iran was 490 thousand ha, and in South Kerman was 7000 ha in 2017. Safflower is an oilseed crop, from the Asteraceae family, not very popular compared to other oil crops such as soybean, sunflower and peanut because it is not widely cultivated around the world. Safflower is a C3 plant tolerant to drought, salinity stress and highly adaptable to various environmental conditions because of having deep rooting ability, water uptake from soil, and different osmolyte accumulation. Drought stress is one of the most limiting factors in agricultural productivity because of its highly negative effect on photosynthesis, growth of plants and productivity worldwide. Water deficiency usually promotes the degradation of chlorophyll, caused by photo-inhibition, reduction of photosynthetic efficiency or other processes, such as cell division and expansion. Fernanda et al., (2017) reported that water stress decreased photosynthetic pigments, chlorophyll a, chlorophyll b, grain yield, oil content, oil yield, and increased electrolyte leakage. Nabipour et al., 2007. Water stress decreased 1000 seed weight, seed in capitul, capitul in plant, seed yield and oil content in safflower. Also, plant density is an important crop management that affects the seed yield. However, increasing plant density can be decreased grain yield, due to the competition for water and nutrients between the roots of the neighboring plants. The purpose of the present study was to investigate the response of safflower yield and yield component to water deficit and plant density.

In other to study the effect of plant density and water stress on grain yield, yield components and oil content safflower. An experiment was conducted in Agricultural Research and Education Center Jiroft, Iran during 2012- 2013. This experiment was carried out as strip plot based on randomized complete blocks design with three replications. Treatments were water stress as vertical factor in four levels including normal irrigation (control), cut-off irrigation in capitul emergence stage before flowering (code 50 BBCH-scale), cut-off irrigation in 50 percent flowering (code 65 BBCH-scale), cut-off irrigation at the end of flowering and begins to expand as fruits develop (code 71 BBCH-scale), and density plant as horizontally factor in four levels including 30, 35, 40 and 45 plant/ m2. Traits were measured including plant height, 1000 seed weight, capitul number in plant, grain number in capitul, grain yield and oil content. The data were statistically analyzed using combined variance of analysis and the differences among mean values of the treatments were compared by LSD test (p≤0.05) using SAS 9.1 software.

The results showed that water stress, plant density and water stress × plant density had significant (p < 0.05) effect on 1000 seed weight, capitul number in plant, grain number in capitul, grain yield and oil content. Plant density had not significant effect on plant height, while water stress had significant effect on plant height. Water stress decreased plant height, 1000 seed weight, capitul number in plant, grain number in capitul, grain yield and oil content significantly. The highest grain yield and oil content were obtained when applied treatment of cutoff irrigation in capitul emergence stage plus 40 plant/ m2, by 2852 and 884 kg ha-1 respectively. The lowest grain yield and oil content achieved when applied treatment of cut-off irrigation in the end of flowering plus 45 plan/m2, by 718 and 204 kg ha-1 respectively. Also, application of treatment normal irrigation (control) plus 40 plant/ m2 had the highest grain yield and oil yield by 4101 and 1239 kg ha-1 respectively.

The result of our study showed that there is a strong relationship between time cut-off irrigation and reduce of seed yield and yield component. The highest seed yield under water stress condition achieved when applied cut-off irrigation at the end of flowering, cut-off irrigation in 50 percent flowering and cut-off irrigation in capitul emergence respectively. 

Plant growth regulators (PGRs) are used to prevent reduction in rapeseed grain yield under limited moisture conditions. A field experiment was conducted to investigate the effect of paclobutrazol (0, 50, 100, 150 and 200 mg L-1) on canopy surface temperature and some quantitative and qualitative characteristics of two rapeseed cultivars (Okapi and Natalie) under full irrigation and late season drought stress conditions at Research Station of College of Agriculture and Natural Resources of Payam Noor University of Fereydunshahr, Isfahan, Iran, in 2016-2017 growing season. The experimental design was split split plot based on randomized complete block design with three replicates. Results showed that all the treatments including late season drought stress, paclobutrazol and cultivar had significant effects on number of seeds per pod, pod length, seed weight, canopy temperature and seed yield. Both cultivars were highly sensitive to late season drought stress at flowering, so that drought stress led to a nearly 40% decrease in grain yield of both cultivars. In both cultivars the application of 100 mg L-1 paclobutrazol under full irrigation and 200 mg L-1 under late season drought stress produced the highest grain yield. Both cultivars had similar responses to drought stress and paclobutrazol, while Natalie (5346 kg ha-1) produced higher yield than Okapi cultivar (4910 kg ha-1). Also, in both cultivars the application of paclobutrazol reduced canopy temperature under drought stress conditions. According to our results, although drought stress suppresses rapeseed grain yield and yield components, the examined plant growth regulator could be harnessed to compensate, at least in part, for the yield suppression imposed by the late season drought stress. Therefore, use of paclobutrazol could be recommended to alleviate the drought stress effect on rapeseed.

Irrigation planning caused to achieve high crop yield and economic benefit. Regarding that, AquaCrop model was used to determine canola irrigation scheduling. At first, optimum depth of irrigation (Iw) and irrigation depth for maximum yield (Im) were determined. Then, these two irrigation depth (Iw and Im) were used to simulate 12 scenarios (T1-T12) for each Im and Iw using calibrated AquaCrop model. The results showed that Im and Iw were 53 and 45 cm, respectively. The highest values for yield and biomass in both Iw (2432 ton.ha-1) and Im (2496 ton.ha-1) irrigation depths were obtained in scenario FI. The highest WUE values using Im were obtained for T8, T11, and T6 as 0.65, 0.63, and 0.58 kg.m-3, respectively. For Iw irrigation depth, the highest WUE values were obtained for T11, FI, and T8 as 0.33, 0.37, and 0.38 kg.m-3, respectively. To put in nutshell, Treatments T8, T11 and T6 are recommended for achieving high WUE and acceptable yield (1832, 1566, 1876 ton.ha-1 using Im and 1264, 1169 and 1189 ton.ha-1 using Iw) in this region.

Drought stress has osmotic and physiological effects on plants, resulting in reduced growth, metabolic disorders and oxidative stress in plants. Different plants use several strategies to cope with drought stress. External application of different compounds such as organic solvents and minerals is a solution to increase drought tolerance in plants. Salicylic acid is recognized as a plant hormone and its role in defense mechanisms against biological and non-biological stressors is well defined. The purpose of this experiment was to evaluate the effect of salicylic acid on reducing the effects of drought stress on yield, water use efficiency and some physiological characteristics of the barely. This experiment was carried out as factorial experiment based on randomized complete block design with three replications in the Kizor fields located in the city of Sabzevar in 2017. The altitude of this area is 1195 m above sea level and is 36° 5 N latitude and 44° 3' E longitude. The treatments included irrigation at two levels of cut-off irrigation (irrigation cut from booting to harvesting stage) (Z39) and non-cut-off irrigation and salicylic acid spraying treatment at four levels of zero (control), two, four and six mM at stage of shoots on barley. Data were analyzed with the SAS software ver 9.1 and the means were compared with LSD test. The results showed that in both conditions of non-cut-off irrigation and cut-off irrigation, the highest number of spikes, number of seeds, seed yield and biological yield per m2 were obtained in two to six mM of salicylic acid, respectively, and the lowest was related to control treatment. The lowest water use efficiency (0.38) was obtained under non-cut-off irrigation conditions without salicylic acid and with the consumption of salicylic acid up to six mM, water use efficiency increased. Also, salicylic acid spraying in cut-off irrigation conditions compared to non-cut-off irrigation led to increase water use efficiency. In both conditions, non-cut-off irrigation and cut-off irrigation, the highest and lowest grain yields were obtained from 6 mM salicylic acid and control treatments (without salicylic acid spraying), respectively. Under non-cut-off irrigation and cut-off irrigation, spraying with 6 mM of salicylic acid increased the grain yield by 44% and 48% compared to control (without salicylic acid spraying). It seems that the effect of salicylic acid spraying in cut-off irrigation conditions was more effective than non-cut-off irrigation conditions. The cause of higher water use efficiency in cut-off irrigation conditions in comparison with non-cut-off irrigation was high waste of water due to evapotranspiration and deep penetration in non-cut-off irrigation treatments. Spraying with salicylic acid by stimulating the growth of hair and sub-roots plays an effective role in increasing water use efficiency. In cut-off irrigation conditions, salicylic acid consumption has reduced the amount of electrolyte leakage so that the spray at a concentration of 6 mM of salicylic acid compared to the control (without salicylic acid spraying) decreased electrolyte leakage about 38 %. The reduction of membrane damage due to the use of salicylic acid is related to the production of antioxidants. Spraying with salicylic acid increases the stability of the membrane against oxidative stresses. Water deficit at first affecting the structure of the cell membrane, increased the permeability of the membrane relative to the ions and macromolecules and at second stage decreased the photosynthesis by decreasing the chlorophyll index, which finally reduced the yield and its components. Also, salicylic acid alleviate drought stress by reducing ion leakage, increasing proline concentration and chlorophyll index resulting to improved wheat grain yield under cut-off irrigation conditions compared to non-cut-off irrigation.

Wheat is the oldest and most important cultivated crop in the world and has fundamental role in human food security. Drought is one of the most common environmental stresses that affect growth and development of plants. Most parts of Iran’s cultivation land are located in arid and semiarid regions and because of water deficiency, plant stress appear and wheat performance reduces severely in these regions. In such circumstances, the production of drought tolerant varieties has special importance. Understand the genetic basis of yield and yield related traits is necessary in breeding programs. One of the best approaches to determine genetic parameters is generation means analysis method, due to it allows breeders to predict epistasis. In order to estimate genetic parameters and evaluation of gene action controlling agronomic traits in bread wheat under moisture stress, F4 families derived from cross between Roushan and Kavir along with F2, F3 and parents, were evaluated under moisture stress.
Field experiment was carried out in research field of Shahid Bahonar University of Kerman, during growing season of year 2013-2014 using Augmented design with 5 known check cultivars (Roushan, Falat, Mahdavi, Karchia and Shahpasand). Stress treatment was cut off irrigation at heading stage. Grain yield and some agronomic traits were measured. Generation means analysis method was used to determine genetic parameters including additive effect (d), dominance effect (h), additive × additive [i], and dominance × dominance effect [l] were evaluated for different traits. Generation means analysis was carried out using equation 1.
Y= mα[d]β[h]α2[i]αβ[j]β2[l] (1)
Broad and narrow sense heritability of evaluated traits were estimated according to equation 2 and 3.
The study revealed a complex genetic control for studied traits. Genetic variation in F2, F3 and F4 was more than parents. Five-parameter model including m, [d], [h], [i] and [l] explained genetic variation for plant height, awn length, grain number per plant, 1000-grains weight, biology and grain yield. While, a four parameter model including m, [h], [i] and [l] were explained genetic diversity of grain filling period and a four-parameter model including m, [d], [h], and [l] was valid for explaining genetic variation of number of spike per plant and harvest index. A three parameter model including m, [d], [i] made the significant contributions to the inheritance of spike length. The additive genetic variance was detected as the most important genetic effect in controlling grain yield, biologic yield, harvest index, 1000-grian weight, awn length, spike length and grain filling period. Therefore, selection in early generations is effective for these traits. High narrow sense heritability of these traits proposes that the most part of genetic variance could be fixed in segregating generations. Broad and narrow sense heritability of studied traits in the present population were 0.46 to 0.96 and 0.16 to 0.93, respectively. 1000-grian weight, grain yield, biologic yield, grain filling period and harvest index had the highest narrow sense heritability, respectively. Therefore in the present population, selection based on these traits could result in good genetic gain. While, dominant effect was more important for plant height, number of spike per plant and grain number per plant. Significant differences between broad and narrow sense heritability of these traits has confirmed the fact that the dominance effect is very important. Therefore, selection should be made in later generations until desirable genes are fixed. Low narrow sense heritability was observed for number of spike per plant (0.16). Therefore, selection based on this trait can not have good genetic gain in present population. In this study, environmental variation was less than additive and dominance variance that show accuracy of the estimations and low impact of the environment on evaluated traits. Plant height, number of spike per plant and grain number per plant showed one degree greater than of dominance. These result showed over dominance of genes controlling mentioned traits.
Based on the results obtained in this experiment, it can be concluded that there is a considerable genetic diversity in the population F2, F3, F4 derived of Roushan and Kavir cross which can be used as a high potential population for genetic improvement of evaluated traits. The Results showed that additive variance was more important than dominance in genetic control of evaluated traits. So, selection during early generations is recommended in wheat breeding program of this population.

The most effective approach for genetic improvement of grain yield as a polygenic trait is indirect selection by other traits and simultaneous selection based on the suitable selection indices. The objective of this research was to select the elite lines of bread wheat by selection indices approach. 305 pure lines of bread wheat derived from a cross between Roshan × Falat as well as four check varieties, Roshan, Falat, Mahdavi and Shahpasand, were evaluated as an augmented design at research field of Shahid Bahonar University of Kerman 2013-2014 growing season. In order to apply drought stress, irrigation was cut-off at the emergence stage of the spike and grain yield and other agronomic traits were measured. Among the studied traits, grain weight of main spike, grain weight of single plant, number of grain per plant, 1000- grain weight, number of spike per plant, main spike weight, flag leaf length, spike length and plant weight showed highly genetic correlations with grain yield. Direct and correlated response to selections for grain yield for these traits were calculated. The results indicated that number of spike per plant and number of grain per plant had the highest efficiency for indirect selection. The different selection indices constructed by these traits had the high genetic correlation with grain yield. Moreover, relative efficiency of selection and expected gain of selection index using the Smith-Hazel index was higher than the Pesek-Baker index. Therefore, using the optimum index can be effective in breeding programs of wheat to improve grain yield under drought stress. Finally, 30 elite lines were selected based on each selection index and from their comparison, seven superior and promising lines were identified for further evaluations and introduction to farmers.

Wheat grain yield is adversely affected by post-anthesis drought stress conditions in most wheat growing areas of Iran. To evaluate the effect of late drought stress on wheat cultivars, a field experiment was conducted as split plot in a completely randomized block design with four replications at experimental farm of Collage of Agriculture, Shiraz University during 2009-2010 growing season. Irrigation regime (normal and cut off after flowering) and wheat cultivars were in main plots and subplots, respectively. There were ten bread wheat and five durum wheat cultivars. The result showed that post-anthesis drought stress reduced biological yield, grain yield, number of grain per spike, 1000 grain weight, and harvest index significantly. Maximum grain yield in the normal irrigation and late season drought stress was detected in Moghan2 and Shiroudi, respectively. Mean productivity (MP), geometric mean productivity (GMP) and stress tolerance index (STI) showed positive and significant correlation with yield in both stress and non-stress conditions. It appeared that MP, GMP and STI were appropriate indices for selection of cultivars resistant to late season drought stress conditions. In this experiment, Moghan2 and Adl cultivars showed higher potential yield as well as greater relative resistance to late season drought stress.