نشریه پژوهش های علوم کشاورزی پایدار
پیاپی 2 (تابستان 1400)

In order to evaluate the physiological and biochemical characteristics of rapeseed (Brassica napus L) cultivars in terms of irrigation interruption and delay planting date، an experiment was implemented in two crop years as a factorial split-plot in the form of a randomized complete block design with three replications in Karaj region. In the present study، irrigation in two levels including normal irrigation (80 mm evaporation from Class A evaporation pan) and irrigation cut-off from the stage of sowing and pod formation stages in two levels including Sep، 26 and Oct، 26 was placed in main plot and four winter rapeseed cultivars including Tassilo، Elvise، Neptune and Okapi were placed in subplots. According to the results، the highest content of chlorophyll in both planting dates (Sep. 26 and Oct. 26، respectively، with values of 1.59 and 1.88 mg. g-1 FW) and under normal irrigation conditions belonged to Elvise cultivar. The results showed that irrigation cut-off reduced the relative water content of leaves and increased leaf proline، soluble protein content and soluble carbohydrate content. Elvise and Neptune cultivars had the highest grain yield under normal irrigation conditions with 3346 and 3220 kg / ha، respectively، and under irrigation cut-off conditions، with a mean of 3211 and 3081 kg / ha، respectively. According to the Stress Tolerance Index (STI)، Elvise cultivar was identified as the most tolerant cultivar under dehydration stress in the pod formation stage onwards.

Awareness of the ecological characteristics and habitat needs of Tecomella undulata (Roxb.) Seem as a rare، valuable and multipurpose plant is of utmost importance in utilizing its diverse functions، especially at the local scale. For this purpose، due to the massive structure of habitats of this important species in Iran، the largest habitat in the world، which is located in the Dalfard region of Jiroft، was considered for this study. First، the habitat area was marked with a GPS device based on field operations and considered as an information layer in 2020. Then، topographic factors including altitude، slope and geographical directions were extracted in Arc-GIS 10.4.1 software. Variables as rainfall indices، freezing days، temperature indices including average temperature، maximum temperature، minimum temperature، absolute maximum temperature and absolute minimum temperature were examined based on the nearest meteorological station including Miandeh station. Geological characteristics were investigated based on lithological units. The circular plots of 1000 square meters (based on the canopy size of tree species) with 5 numbers were sampled to evaluate the components of canopy cover and associated species. The results showed that this valuable species can grow in the altitude range between 1289 to 1404 meters، slope range from 0 to 26% and all geographical directions. Existence of granite lithological units in the upstream and severe fluctuations of habitat environmental factors including high dry period، highly variable annual rainfall range of 39.5 to 578، presence of freezing days، temperature range of -4 to 49 °C are the unique habitat characteristics of this species.

The aim of this study was to investigate the effects of using different combinations of waste water and well water with the approach of using unconventional water on some physical and chemical properties of soil. For this purpose، a factorial experiment was conducted in a completely randomized design with three factors. The main factors include irrigation with waste water to well water ratio in 5 levels including I1 (control: irrigation with well water)، I2 (75% well water and 25% waste water)، I3 (50% well water and 50% waste water)، I4 (25% well water and 75% waste water) and I5 (irrigation with 100% waste water)، the second factor includes two soil depths (0-30 and 30-60 cm) and the third factor includes the duration of irrigation in 5 levels (zero، 1، 2، 3 and 4 months). The results showed that soil salinity، pH and organic carbon increased with increasing irrigation time. The highest increase in salinity was observed after 4 months in I5 treatment with about 37% increase compared to the control treatment. The amount of organic carbon in treatments I4 and I5 in the surface layer increased by about 60% compared to the subsurface layer. However، waste water consumption improved hydraulic conductivity compared to well water، so that its amount increased in I5 treatment، at surface and subsurface depth by 76.7% and 80%، respectively، compared to the control treatment. The findings of this study showed that the use of treated wastewater as one of the unconventional water sources، despite increasing soil salinity، can increase organic carbon and improve soil permeability.

The water crisis in the agricultural sector is one of the main challenges، and wastewater recycling is one of the ways to control this crisis. One of the limitations of using effluents in the agricultural sector is water pollution with heavy metals. Among the various methods used to remove heavy metals، biological methods are of great interest. Therefore، in this study، the ability of three microalgae of the genus Sandsmus، Scenedesmus acutus، Scendesmus incrassatulus، and Scenedesmus obliquus to remove cadmium from industrial effluents was studied. To investigate the effect of different parameters on the adsorption rate of microalgae، adsorption rate in different values of pH (3 to 7)، temperature (15 to 35 ° C)، amount of biosorbent (0.25 to 2 g)، metal concentration (20 to 200 mg/L and adsorbent contact time (30 to 150 minutes) were tested. The effect of all these parameters on the absorption rate was significant. The highest rate of cadmium (99%) uptake by microalgae occurred at pH 6، temperature 25 °C ، 1.5 g of biosorbent، the metal concentration of 150 mg /l and contact time of 150 minutes. But the amount of cadmium uptake by different species of microalgae was not significantly different.

Today، in developed countries، using specialized machines for agricultural products processing، is one of the most common ways to reduce the final price of these products. For this purpose، firstly، henna leaf separator was designed in the SolidWorks software and then constructed. In order to evaluate the performance of this prototype، three factors include the speed of rollers at two levels of 1550 and 750 rpm، the distance between the rollers at three levels of 2، 3 and 4 mm، and moisture content at three levels of 14%, 45% and 87% in the form of a factorial design of experiment with three replications was conducted. The success rate in leaf separation was considered as the evaluation index of the machine. Analysis of the results showed that the effect of roller speed، moisture content and rollers distance as well as the dual and triple effect of these factors on the success rate in leaf separation were meaningful. The results showed that the best performance of the roller separator was achieved at the rollers speed of 1550 rpm، distance of 2 mm between the rollers and moisture content of 14%.

The purpose of this study is to estimate the economic value of carbon sequestration by wheat species in wheat fields of Sistan plain and to provide a solution to increase carbon sequestration capacity. For this purpose، sampling was done by systematic random method and the amount of organic carbon was determined by Walkie-Black method in wheat species. Then، by multiplying the conversion factor of organic carbon in plant biomass، the total weight of precipitated carbon per hectare of the study area was calculated. The results showed that the value of absorption per ton of carbon dioxide from the alternative cost method in the study area was estimated at 22775200 thousand Rials and the total value of carbon sequestration is estimated at 73746723.918 million Rials. It is suggested that due to the economics of carbon sequestration by plants and the simplicity of the method of measuring the amount of production and carbon sequestration, especially in wheat cultivation as a strategic and essential crop that occupies a large area of land each year، a kind of database Create and take into account the necessary incentives to promote sustainable agriculture and increase carbon sequestration capacity in agricultural ecosystems.

In recent years، conservation agriculture has emerged as a multidimensional approach to the sustainable use of water and soil resources and the achievement of sustainable development goals. Despite the efforts، development process of this approach is slow and faces many obstacles. In the present study، an attempt was made to examine the obstacles to the development of conservation agriculture from the mental dimension of the experts of the Research Center. The target population was the experts of Sararud Research Center in Kermanshah in 2019-2020 who were studied purposefully. In this regard, Q methodology was used. This method is one of the mixed research methods. Based on the findings of the Q-factor results، the number and manner of groupings show that the range of mindsets and opinions of experts regarding barriers to conservation agriculture have differences and similarities. Therefore، according to the purpose of studying Q and the criterion of interpretability of factors or groups, 5 categories (technology-centric، tradition-oriented، knowledge-centered, cognitive-centric, institution-centered) of the mentality and beliefs of experts in Sararud Research Center Kermanshah has been obtained. Each group had different mindsets and attitudes about barriers to the development of conservation agriculture. Given the prevailing mental model identified (central institution)، it is recommended that the government provide incentives and grants (loans، etc) to beneficiaries so that they can apply the method conservation agricultural farms.