Iran Agricultural Research
Volume:41 Issue: 2, Summer and Autumn 2022

The family Geminiviridae with fourteen accepted genera and an increasing number of unassigned species is currently identified as the largest family of plant‐infecting viruses. Their twinned icosahedral particles contain single-stranded genomic DNAs that are naturally transmitted by Hemiptera insects including whitefly (Bemisia tabaci), several species of leafhoppers, treehoppers and one species of aphid in a wide range of host plants. Also, some geminiviruses are transmitted by seeds in certain hosts. In addition to climate changes, industrial cultivations, and the development of global trade, the genetic flexibility of geminiviruses has led to an increase in the rate of their distribution. Diseases caused by geminiviruses constitute a serious constraint to tropical and sub-tropical agroecosystems worldwide. The economic losses caused by geminivirus infections have grown especially in open fields and greenhouses in Iran during the last years. Defining two distinct genera by having unique molecular and biological characteristics, Becurtovirus and Turncurtovirus, and the presence of different species and strains of other geminiviruses introduces Iran as a putative origin of diversification for old-world monopartite geminiviruses. This review presents the occurrence and diversity of the members of Geminiviridae in Iran. Moreover, some applicable control measures have been proposed based on compatibility with the Iran agroecosystem which would also be recommended for other tropical and subtropical regions  of the world.

Agriculture is an essential instrument for development, poverty alleviation, and food security in developing countries, such as Iran. The agricultural sector of Iran is dominated by small-scale farming, and the yield of most crops is low. A well-designed and well-functioning agricultural extension system can facilitate the transition toward productive, profitable, and sustainable agriculture. However, the top-down agricultural extension system of Iran has left most smallholder and resource-poor farmers with no access to advisory services, and their problems have remained unresolved. The new agricultural extension system (NAES) was initiated in 2014 to better respond to the problems of smallholder farmers. However, there is still no definite reflection on the influences of the NAES on agricultural development. Therefore, this study aimed to evaluate the performance of the NAES. Also, it purposed to identify the blocking mechanisms hindering the NAES’ function. In this regard, qualitative research was planned and conducted in Fars Province, Southern Iran. The findings revealed that NAES has managed to enhance the availability of extension services for smallholder farmers, improve the productivity and profitability of agriculture, and reduce livelihood vulnerability. However, it has failed in facilitating access to remunerative markets, mobilizing sustainable financial and human resources, and being entirely demand-driven because of financial, physical, institutional, market, natural, informational, capability, and psychological constraints. Some recommendations and implications are offered to improve the effectiveness of the NAES.

The present study was conducted to investigate the effects of micronutrient elements (Fe, Cu, Zn and Mn) application on the content and composition of essential oil of Damask rose (Rosa damascena Mill.) flowers in southwestern Iran (Shahrekord) in 2019 and 2020. Four foliar fertilizers including Librel Fe-Lo, Librel Cu, Librel Zn and Librel Mn were applied as mineral fertilizers. Librel Fe-Lo contains 13.2% chelated iron, Librel Zn is a foliar fertilizer with 14% Zinc in chelated form, Librel Cu has 14% copper in chelated form, and Librel Mn is comprised of 13% Mn chelated with EDTA. Results obtained from gas chromatography/mass spectrometry (GC-MS) showed 36 essential oil components. The highest (0.11-0.14%) and lowest (0.03-0.05%) levels of essential oil content were obtained from combined Fe, Cu, Zn and Mn treatment and control treatment, respectively. Plants treated by the combinations of 40 ppm of micronutrients (Fe3Cu3Zn3Mn3 treatment) and control produced the greatest and lowest amounts in most essential oil components, respectively. The predominant components of the essential oil included oxygenated monoterpenes including beta-citronellol (22.5-28.1%), geraniol (15.1-23.1%), camphor (0.86-2.3%), citronellol (0.4-1.9%), trans-geraniol (0.5-2.1%), together with aliphatic hydrocarbons  including nonadecane (11.1-13.3%), pentadecane (3.55-8.9%), and heneicosane (4.5-8.7%). Application higher than 40 ppm of micronutrients, most possibly due to toxicity, lowered both content and composition of essential oil.

Weeds are the most important limiting factors in agricultural systems and the use of mulch is considered as a suitable solution in the ecological management of weeds. In order to evaluate the coriander yield and its weed control, a factorial experiment was conducted at the research farm of the Faculty of Agriculture, University of Zanjan in 2020. The first factor was the types of mulches including ratios of 100 % (40.0 kg ha-1), 66 % (26.4 kg ha-1), and 33 % (13.2 kg ha-1) of clover (Trifolium alexandrinum L.) and 100 % (20.0 kg ha-1), 66 % (13.2 kg ha-1), and 33 % (6.6 kg ha-1) of alfalfa (Medicago scutellate L.) as living mulches, wheat straw (Triticum aestivum L.) (one kg m-2) as a non-living mulch, and a non-mulched treatment and the second factor was weed control including complete weed control, once-weed control and non-weed control. The results showed that the effects of the treatments of mulch type and weed control were statistically significant on the components of yield and yield of coriander. The highest grain yield (1601.4 kg ha-1), biomass yield (3901.0 kg ha-1) and essential oil yield (3.35 kg ha-1) were recorded in wheat straw mulch under complete weed control conditions. Clover at densities of 100 % and 66 % caused suffocation and complete destruction of coriander plants. Therefore, the grain yield and biomass production of coriander in these treatments were equal to zero. Alfalfa at low densities had no significant effect on weed control. Complete control of weeds caused a significant increase in all evaluated traits in coriander. The results of the present study showed that wheat straw mulch is a suitable solution for controlling coriander weeds, which not only does not interfere with the growth of coriander but also causes effective control of its weeds. Therefore, considering the importance of integrated control of weeds in sustainable agricultural systems, the use of wheat straw mulch can be introduced as one of the strategies to reduce the use of chemical pesticides and reduce environmental pollution.

Land-use change from forest to arable lands may have a major significance on soil processes, properties, and functioning. This research investigated the influence of long-term land-use change from untouched forests to arable lands under northern and southern slope aspects on soil physical and chemical properties. Six regions of the Zagros area in the west of Iran, where the increasing trend of forest to agricultural land conversion has occurred during the last decades, were selected for this study. Composite soil samples were collected from the 0-20 cm depth in both the northern and southern slopes of native forests and their related cultivated areas. The highest dispersible clay and soil bulk density and the lowest aggregate stability were observed in cultivated areas. Soil organic carbon and total N declined in response to the land-use change from forest to cultivated areas in all study areas. The highest amounts of soil organic carbon, total N, C/N ratio, and available P were observed in northern slopes compared with southern slopes in some studied regions. In general, the conversion of natural forests to agricultural cropping systems resulted in soil quality declining. However, the deterioration intensity in the northern and southern slope aspects was similar approximately.

Plant growth and yield are influenced by many production parameters such as the amount of irrigation water, fertilization, plant density, etc. Due to the limitation of resources and agricultural inputs, increased production costs, food demand, population growth, and environmental problems, the development of scheduling approaches to use production parameters is necessary. In this study, firstly, crop yield and net benefit responses to variation of production parameters and secondly, economic-mathematical analysis of production parameters such as irrigation water were reviewed. Presented analyses in this study were categorized into four cases including 1) constant or variable crop price, 2) single, two, or multiple variables production functions, 3) limited land area and water or not limited, and 4) variable water price. The economic-mathematical analysis presented about deficit irrigation in this study was extended to determine the optimum value of other production parameters such as fertilizer rate, plant density, seed density, corm planting intensity, etc.

Microcerotermes diversus Silvestri, is an important termite in Khuzestan province with a broad range of foraging. In recent years, control of underground termites has been more based on the application of chemicals which has increased pest insecticide resistance. In this study, the resistance of different populations of termites to chlorpyrifos was investigated using estimated LC50 and measuring the activity of two acetylcholinesterase (AChE) and glutathione-s-transferase enzymes. Four populations of M. diversus with different histories of organophosphorus insecticide spraying were studied. Populations A (Am Altamir1), B (Am Altamir2), and C (Mollasani) were collected from date palm groves with 30 and 10-year histories of organophosphorus insecticide spraying, as well as without spraying history, respectively. Population D (Ramin University) was collected from orange trees, three weeks after spraying with chlorpyrifos. The bioassay results showed that the highest and lowest LC50 values were observed in populations A and C, respectively. Moreover, the activity of AChE using acetylthiocholine iodide, propionylthiocholine iodide, and butyrylthiocholine iodide substrates was higher in the populations with chlorpyrifos spraying history, with the highest activity in population A. It was also demonstrated that the AChE activity with acetylthiocholine iodide substrate was higher than the activity of this enzyme with butyrylthiocholine iodide and the propionyl choline substrates in the populations with 30 and 10-year history of spraying. The Michaelis constant (Km) and maximum velocity (Vmax) values of AChE as two important kinetic factors, indicated the highest affinity of this enzyme to the substrate in population A.

This research aimed to compare the effect of two sources of fat and three levels of a pellet binder on pellet quality, growth performance, prececal nutrient digestibility, carcass, and economic traits in Ross 308 broilers. Two hundred and forty-day-old broiler chickens were applied in a 2 × 3 factorial arrangement in a completely randomized design with four replicates and ten birds in each replicate. The dietary treatments were two fat sources (soybean oil and fat powder) and three levels of a commercial binder named Glomatin® (0, 2, and, 4% in grower and 0, 3, and 6% in finisher diets). The data were subjected to the procedure of General Linear Models (GLM) of SAS, version 9.4 (P ≤ 0.05). Birds fed the soybean oil-containing diet with the second level of Glomatin® binder (2% in grower and 3% in finisher diets respectively) showed the best feed conversion ratio (FCR) in the whole period, and the highest prececal dry matter digestibility, ether extract digestibility, and economic profit. It concluded that increasing the physical quality of the pellet diet by adding a binder in soybean oil-containing diets had an optimum level (2% in grower and 3% in finisher diets respectively). Over that optimum level, it could harm FCR, prececal nutrient digestibility, and finally, profitability.

The water crisis is a major challenge for water resources managers in semi-arid regions of Iran. Most of the policies to deal with this crisis have been to contain surface water behind dams. Changing the national approach from dam construction to watershed management is inevitable to conserve groundwater resources in Iran. The effects of flood water spreading (FWS) and artificial recharge of groundwater (ARG) were investigated in a large area in southern Iran during the 151 hours of historic flooding in 2017. The study area was two basins in the Gareh Bygone Plain (GBP) including the Bisheh Zard Basin (192 km2) and Tchah Qootch Basin (171 km2). The water budget equation was used to evaluate the inflow and outflow of the flood spreading system.  Six installed piezometers in the GBP measured the water recession level. The inflow and outflow were continuously measured by a water-level recorder and five broad-crested weirs, respectively. The soil water content of 30 m depth was recorded by the Time Domain Reflectometry (TDR) sensors. The total volume of water retained by the system on 17 January 2017 was 19,160,951 m3. Net replenishment of the aquifer was 6,677,301 m3. The total recharge of the ARG was 8,332,916 m3 in the study duration. The flood water system retained 70% of the total diverted flow to the system and increased the water level wells in the study area from 1.03 to 2.74 m. Therefore, it can be concluded that FWS and ARG restrained the rare flood event in Iran .Consequently; they can be the logical processes to avoid flood damage and conserve groundwater resources.

The guava fruit has a relatively short storage life due to its physicochemical properties. Despite many studies to maintain the quality and increase the storage life of guava fruits, no optimal method is currently available in this regard. To reduce the chilling injury of guava fruits, this study focused on the postharvest application of Aloe vera gel and hot water treatments on guava fruits based on a factorial experiment in a completely randomized design. The applied treatments were storage times at five levels (0, 7, 14, 21, and 28 days), hot water treatments at three levels (no hot water, 40, and 50 °C,) for 10 min, A. vera gel at three levels (0, 5, and 10%), and a control treatment (distilled water, A. vera-free + no hot water). Samples were stored at 7±1 °C with 95% relative humidity for 28 days and then at 24 °C for 24 h for adaptation to market conditions. According to the results, the values of the a* color index increased but the values of the L* and b* color indices decreased over storage time. Among the experimental treatments, the 5% A. vera gel was more effective for maintaining guava fruit quality by increasing the total sugar content and lowering the ion leakage percentage. The interaction of 40 °C hot water + 10% A. vera gel led to positive effects by reducing the respiration rate and better-preserving fruit firmness. The total chlorophyll values of all treatments in the 4th week were the lowest compared to the same treatments in weeks 1-3. An increase in the storage period resulted in a downward trend in ascorbic acid index. The minimum peel carotenoid and flavonoid content were observed in 40 °C hot water + 10% A. vera gel treatment. Treatments with no hot water + 5% A. vera gel, no hot water + 10% A. vera gel, and 40 °C water + 5% A. vera gel resulted in the highest levels of peel antioxidants, ion leakage, and malondialdehyde, respectively. The results of this study demonstrated that the use of A. vera gel and hot water treatments reduces the chilling injury of guava fruits, leading to a better storage life of fruits during the storage time.

Sand dunes cover more than half a million hectares of Khuzestan Province in Iran. These areas are a serious threat to agricultural lands, buildings, and industrial facilities. Knowing the characteristics of these lands helps a lot to manage and control this threat. This research was done to determine the characteristics of sand dunes of Khuzestan Province and their management. The results showed that the dynamic characteristics of sand dunes, such as salinity, are different depending on the location and direction of the prevailing wind. However, the organic carbon, cation exchange capacity, and acidity (pH) were similar in all regions. Soluble K was inversely related to salinity. In the western regions, carbonates (lime and dolomite) along with quartz, kaolinite, chlorite, and illite were the dominant minerals, and smectite, palygorskite, and vermiculite were in the next order. The southeastern parts had a similar composition, but the proportion of minerals was different based on the location, especially for polygorskite. The proportion of smectite, polygorskite, and sepiolite minerals was high in the direction of prevailing winds, but their amount decreased in the inner parts. Sepiolite was observed only in the southeastern regions, which was related to the origin of gypsum soils in the neighborhood areas. A similar composition of these minerals and their proportion was also seen in the deeper parts. The similarity of the sand dunes minerals shows that they have the same origin and their similarity with the composition of soil minerals in the plains of Khuzestan indicating that these sands were formed from the wind erosion of the plain during different dry periods.

Canna indica (canna) a species in the Cannaceae family, is a perennial ornamental plant widely used in landscape designing. Different species of plant viruses have been reported which infect this plant and act as a significant threat to canna plants, leading to a range of symptoms and a decrease in their decorative values, as well as lower quality propagated materials and significant financial losses. Canna cultivars that are extensively cultivated for their ornamental values are susceptible to a recently discovered Potyvirus known as canna yellow streak virus (CaYSV). This virus has infected many canna cultivars found in gardens, leading to significant impact and concern in horticultural settings. During a survey conducted in the summer of 2022, severe veinal chlorosis and veinal streaking symptoms were observed on the leaves of canna plants in the green space of Yazd City, Iran. Total genomic RNA was extracted from symptomatic leaves of 20 canna samples and one symptomless sample (negative control), and subjected to RT-PCR using a potyvirus degenerate primer pair (NIb3R, NIb2F). RT-PCR resulted in the amplification of a DNA fragment with the expected size of approximately 350 bp in all of the symptomatic samples, whereas no DNA fragment was obtained from a symptomless plant. The amplified DNA fragment was subjected to the Sanger sequencing method, and its size was confirmed to be exactly 350 bp. Sequence analysis of the nucleotide sequence of this amplicon with the same region of other corresponding CaYSV isolates in the GenBank revealed that the Iranian CaYSV isolate was the most similar (99.05%) to an isolate from Russia (Acc. No.  MG_545919.1) and the less similar (89.59%) to a CaYSV isolate from United Kingdom (Acc. No.  EF_466139.1).

Most soils close to urban centers are often degraded due to intensive cultivation, resulting in low organic matter content and low plant nutrients. Remnants of vegetable materials are frequently abandoned in urban markets in Nigeria and their disposal by local councils is expensive; these materials therefore constitute a nuisance to the environment. However, these materials can be composted and used as soil amendment. A field experiment was conducted at the Teaching and Research Farm of the University of Ilorin, Ilorin, Nigeria during the 2018 and 2019 cropping growing seasons to evaluate the effects of urban wastes as compost on the growth, yield and nutritional composition of lettuce. The experiment was laid out in a randomized complete block design replicated four times. The rates of compost application were as follows; 0, 5, 10, 15, 20 Mg/ha and NPK at the rate of 300 kg ha-1. Data were collected on vegetative parameters (plant height, number of leaves, leaf area index), yield parameters (yield per net plot, yield per hectare), and the vitamin composition (Vitamins A and C). The results showed that the application of compost manure improved the soil physical and chemical properties such as the water holding capacity, which was improved by 27.77% and 29.43% in the first and second growing seasons respectively. The application of 20 Mg ha-1 produced superior growth and yield (34.93 and 33.64 Mg ha-1) in the first and second growing seasons, respectively. Farmers are therefore encouraged to plant their lettuce crop using compost manure especially in urban areas.