جستجوی مقالات مرتبط با کلیدواژه "کمبود آب" در نشریات گروه "منابع طبیعی"

Allocation of surface water resources is considered as a solution to deal with water stress, especially in low rainfall areas, but the existence of high uncertainty as well as the lack of water. This allocation has always caused problems and this issue has become one of the main problems of governance in low rainfall areas of the world. Hence, in this research, a fuzzy interval probabilistic planning model was designed for the allocation of surface water resources by considering ecological factors and water scarcity. In so doing, after analyzing and validating the model, parametric sensitivity analysis was performed on the ecological and economic factors in the Simineh River, which is one of the important rivers of the Urmia Lake catchment. The results showed that an increase of 10 to 50 percent of water shortage led to a drop in the values ​​of the objective functions. Also, a 50% increase in the pollution production rate has led to a decrease in all economic and ecological goals from 2.5 to 3.5%, and a 50% increase in the removal of pollutants has also led to a 2-3% improvement in economic goals. In conclusion, it can be argued that the water scarcity is one of the consequences of the pollution of this crucial resource, and for this reason, a significant part of water resources are left out of the allocation cycle. With a 100% increase in uncertainty, the ecological goal has dropped by 2.7% and other goals have changed in the range of 1.5% to 2.0%. Considering the variables of water scarcity and water pollution can also affect the output of the developed model and provide more reliable answers, therefore, it is recommended to consider these two factors in future studies.

The aim of this study was to investigate the response of anise to the occurrence of drought stress in different stages of growth of this plant and also the effect of humic acid in reducing the negative effects of drought stress and improving plant growth characteristics in climatic conditions of Quchan city. For this purpose, an experiment was conducted in the form of split plots based on randomized complete block design with three replications in the 2019-2020 cropping year. The irrigation treatment in four levels was as the main factor of the experiment and consumption of Humic acid was considered as sub-factor in three levels. According to the obtained results, stopping irrigation at the seeding stage and nonuse of humic acid in comparison with full irrigation and consumption of 4 kg of humic acid reduced the 1000-seed weight of anise by 23.45%. Also, cessation of irrigation at the stages of stemming, flowering and seeding reduced the grain yields by 7.80, 29.46 and 24.08%, respectively, compared to the control. The use of humic acid at both levels of 2 and 4 kg/ha increased grain yields by 5.01 and 10.64%, respectively, compared to the control. According to the results obtained in this study, despite the problem of water shortage in the study area, one solution to solve this problem is to stop irrigation in the pre-shoot stage, which can reduce water consumption in the production of anise. Also, the application of humic acid at the rate of 4 kg/ha will significantly compensate for the negative effects of drought stress during vegetative and reproductive growth stages.

In order to evaluate the seed and essential oil yield and harvest index of cumin, a factorial experiment based on randomized complete blocks design was conducted with three replications, at the research farm of the faculty of agriculture of Urmia University in 2010. Treatments were four irrigation regimes (irrigation after 50, 100, 150 and 200 mm of evaporation from a class A pan) and different amounts of superabsorbent polymer (0, 60, 120, 180, 240 and 300 kg/ha). The highest biomass yield (3640 kg/ha), seed yield (1226 kg/ha) and essential oil (36.5 kg/ha) belonged to irrigation after 50 mm of evaporation and 60 kg/ha superabsorbent polymer application. Increasing in irrigation distances to 100, 150 and 200 mm of evaporation needs to 180 and 120 kg/ha polymer to produce maximum yield (biomass and seed), but they were 60 and 300 kg/ha polymer for essential oil yield and harvest index, respectively. The maximum harvest index of seed for irrigation after 100, 150 and 200 mm of evaporation belonged to 180 kg/ha superabsorbent treatment. Application of superabsorbent at irrigation after 50 mm of evaporation (non-stress condition) does not have efficiency for essential oil production compared with the control (without polymer in this irrigation). In conclusion, increasing irrigation intervals from 50 to 200 mm of evaporation from pan lead to reduce the yield (biomass, seed and essential oil), that application of superabsorbent polymer A200 compensate part of this reduction.

Drought stress is one of the most important limiting factors which can affect crop production in semi-arid regions. To investigate the effects of water stress on some of the morphological characteristics of fenugreek and to identify the best landraces, a factorial experiment was conducted in a completely randomized design with three replicates as potted in the Ferdowsi University of Mashhad in 2014. Experimental treatments were combination of eight fenugreek landraces of Isfahan, Tabriz, Hamedan, Sari, Challous, Amol, Mashhad and Yasooj with four levels of moisture stress (1- no stress (100% of field capacity), 2- mild stress (75% of field capacity), 3- moderate stress (50% field capacity) and 4- severe stress (25% field capacity). The results showed that the main effect of drought stress was significant for all traits studied. The comparison of means revealed that the number of days till flowering, till maturity, plant height, root length and yield components (number of pods per plant, seeds per pod and seed weight) in the highest level of drought compared to control decreased 45.20, 9.08, 14.82, 32.39, 29.96, 27.13, 4.69, 30.36 %, respectively. Comparison of landraces also showed that the highest performance belonged to the landraces of Challous and Mashhad. Following the results of the current study, these two landraces could be utilized for modifying landraces with high potential yield in context of water stress.