Iran Agricultural Research
Volume:40 Issue: 2, Summer and Autumn 2021

A prevalent problem in pomegranate fruit (Punica granatum L.) is sunburn which reduces fruit quality. This study aimed to reduce the severity of sunburn during the growth of pomegranate fruit by covering them with colored netted bags. Kaolin (5%) as a traditional treatment to reduce sunburn was used to compare the efficiency of noble and traditional techniques. The netted bags were either white, green, yellow, gray or blue. The experiment was carried out on a commercial cultivar (‘Rabab-e-Neyriz’) over a period of two successive years. The colors of the netted bags affected the anthocyanin content of arils at harvest time. They also reduced sunburn damage. Fruit of the control group were damaged notably by sunburn (32.26%), compared to those covered with blue and white netted bags (0%). The highest amount of ascorbic acid and the minimum amount of anthocyanin were recorded in fruit covered with blue netted bags. The lowest degree of aril whitening (i.e. the discoloration of arils) was observed when fruit were covered with white bags. Covering the fruits with gray netted bags caused the highest antioxidant activity and the highest total phenolic content in the arils. Overall, covering fruit with netted bags is recommended to prevent sun burn and to increase fruit quality.

Today, due to increasing public awareness, the use of eggs as a source of essential amino acids in the human body has expanded. Since the egg is a packaged food, the quality and mechanical integrity of the shell are of great importance. In this study, a number of healthy eggs were selected and then exposed to ultraviolet (UV) and infrared (IR) radiation. After this step, half of the samples were smeared in sunflower oil and stored for 2 days. In the next step, the fracture force of the eggshell was obtained with the help of the Instron device. The results of this experiment showed that a number of levels of ultraviolet radiation factors were able to cause changes in the amount of fracture force of the eggshell. In the study of the effect of infrared light on the fracture force of the eggshell, it was observed that with increasing the number of bulbs and irradiation time, the amount of breaking force has also increased and this had a direct relationship with the factors of number of lamps and irradiation time. Also, in the study of the effect of infrared samples and impregnation of the shell with sunflower oil, it was concluded that impregnation of the eggshell with the oil reduces the amount of refractive force from 30.3 to 26.5 N. Finally, it was observed that the infrared samples had a higher average refractive index than the ultraviolet samples.

The most important coccinellid predator in pistachio orchards, feeding on aphids and psyllids, is Oenopia conglobata contaminata L. (Coleoptera: Coccinellidae). The aim of the present research was to evaluate the effects of a range of cold storage temperatures (4, 8 and 12ºC) in a seven-day cold storage period on some biological parameters of the newly emerged adults of O. conglobata contaminata reared on non-prey food. The replicates were 100, 32 and 30 one-day old adults for 4, 8 and 12ºC, respectively. Each couple of the coccinellids was put into an experimental unit and incubated at 26±1, 60±5% RH and a photoperiod of 16L:8D till death and some biological parameters of the beetle were estimated. The results elucidated that the percent vitality and longevity of the adults markedly increased at 12 and 8°C, respectively. In addition, the longest oviposition and post-oviposition periods were observed at 8°C. The total fecundity and fertility of females significantly had the maximum values at 8°C. Moreover, the number of egg clusters and days in which the oviposition happened significantly elevated at 8°C. The survival rate of the adult coccinellids declined after a seven-day cold storage at 4 and 12°C compared to that obtained at 8°C. The results highlighted the positive effects of the suitable cold temperature (8°C) on the storage of the efficient predator to improve long distance shipment. It could help to enhance the cold storage efficacy and quality of the predator reared to release for biological control programs.

Beauveria bassiana is an entomopathogenic fungus that acts as a biological control agent and attacks varieties of insects by degrading and penetrating their cuticles. The relevant molecular basis of this action was investigated by comparing the expression analyses of dipeptidyl peptidase and cytochrome P450 monooxygenase, candidate genes involved in fungal pathogenesis, via Real-Time PCR. B. bassiana was grown in an artificial medium and in the cuticle extract media isolated from four species belonging to different insect orders. The expression of the two genes in the fungus was examined in different culture media. The results showed that dipeptidyl peptidase was upregulated in media containing insect cuticular extracts compared to the control synthetic medium, while Cytochrome P450 monooxygenase showed reduced expression in abundance. The effect of cuticle types in inducing gene expression was compared and discussed. It seems likely; information from different reactions of this fungus against different insect cuticles can be helpful in producing specific pesticides.

Compatibility of pesticides and biological control agents is the main concern of Integrated Pest Management (IPM) programs. The present study focused on the side effects of spirotetramat and chlorpyrifos on the demographic parameters of Aenasius bambawalei Hayat (Hym: Encyrtidae). Adult parasitoids were exposed to one ppm of chlorpyrifos and 7.5 ppm of spirotetramat for 24 hours. Then, they were released on the third instar nymphs of the mealybug Phenacoccus solenopsis Tinsley (Hem. Pseudococcidae) and their demography was investigated. The results showed that oviposition period, fecundity, and female and male longevities adversely were affected by both insecticides. However, the adult pre-oviposition period (APOP), the total pre-oviposition period (TPOP), and the number of daily eggs of insect females were not affected significantly. The intrinsic rate of increase (r) was calculated to be 0.16, 0.13, and 0.12 day-1 for control, spirotetramat, and chlorpyrifos treatments, respectively. The results of this study revealed that chlorpyrifos at sublethal concentrations have more negative effects on A. bamabawalei than spirotetramat and need to be applied with caution in IPM programs.

Rice (Oryza sativa L.) serves as the main food for more than half of the world's population. Salinity is one of the most important factors which limits rice yield. Eleven rice cultivars were evaluated in a randomized complete block design with three replications under salinity stress and normal conditions. The stress tolerance and sensitivity indices, including the mean productivity (MP), the geometric mean (GMP), the stress tolerance index (STI), the yield index, the yield stability index, the harmonic mean (HM), the stress susceptibility index, the tolerance index and yield loss rate, and principal component analysis were used to evaluate the variation and response of rice cultivars under salinity stress conditions, and to identify the tolerant cultivars. A significant variation was observed among the cultivars for grain yield and stress indices. Principal component analysis using grain yield and stress tolerance indices identified two components including “salinity tolerance component” and “salinity sensitivity index component” with eigenvalues greater than 1, which described a cumulative explanation of 99.39 percent of the variance among the cultivars. MP, GMP, and STI were found to be considered as the most suitable indices for selecting rice cultivars tolerant to salinity. The cluster analysis and the distribution of the cultivars in the biplot diagram obtained based on grain yield, and stress tolerance indices introduced Lenjan Askari, Yasouj, and Kamfirouz as tolerant, and Loudab Champa, Gharib, and Mamassani Domsiah as sensitive cultivars. These tolerant cultivars can be used in breeding programs to improve the salinity tolerance of rice.

This study was aimed to determine the effect of the geometry of a bent leg tillage implement on draft force and specific draft. This research designed as a split-split plot experiment with three replications. Treatments were three soil moisture content levels of 7-10, 10-13 and 13-16 % as main plots, three forward speeds of 5, 7.5 and 10 km h-1 as sub-plots and three lateral blade spacing of 12, 16 and 20 cm as sub-sub-plots. Results indicated that forward speed, lateral blade spacing and soil moisture content affected draft force and specific draft. Reducing soil moisture content from 13-16% to 7-10% increased draft force by 12% and reduced specific draft by 9%. Increasing forward speed from 5 to 10 km h-1 increased draft force and specific draft by 71.8% and 70.7%, respectively. The lateral blade spacing of 16 and 20 cm was recognized to be proper for tilling by the bent leg tillage implement. Other findings showed that the geometry and characteristics of the bent leg tillage have the potential to have reduced draft force at higher levels of the forward speed.

Salinity and water stresses and also low fertile soils are the main constraints in the agricultural production of Iran. The purposes of this study were to examine whether the application of wheat straw biochar (with EC of 9.3 dS/m) can enhance faba bean’s physiological characteristics and growth under greenhouse conditions. Hence, three levels of biochar (0, 1.25 and 2.5 % w/w), irrigation regimes (50, 75 and 100 % of crop water requirement) and irrigation water salinities (0.6, 4 and 8 dS/m) were applied using the factorial arrangement in a complete randomized design with four replications. The application of 2.5 % biochar under 0.6 dS/m saline water and 50 % deficit irrigation significantly increased crop height, leaf area index, stomatal conductance by 12, 14 and 11 %, respectively, and declined leaf temperature by 3 % in comparison with that obtained at no biochar application. The addition of 2.5 % w/w biochar under 8 dS/m and 50 % deficit irrigation significantly decreased crop height and stomatal conductance by 21 and 29 %, respectively, in comparison with that obtained at no biochar application, 8 dS/m and 50 % deficit irrigation. Moreover, the application of 2.5 % w/w biochar together with 0.6 dS/m saline water and 100% irrigation water led to having maximum fresh seed yield and 100-seed dry weight. In conclusion, the application of 2.5 % w/w biochar with high electrical conductivity was not appropriate for faba bean under saline conditions at any water regimes.

The need for sustainable resource management is increasingly urgent. A prerequisite for achieving sustainable agriculture is the use of production resources more efficiently. In this study, by combining Data Envelopment Analysis (DEA) using environmental and economic indices, the effect of optimal farm scale on the improvement of these indices was investigated. Data were obtained from 136 farmers using a questionnaire and face-to-face interviews. The mean technical efficiency, pure technical efficiency and scale efficiency were estimated to be 0.76, 0.89 and 0.85; respectively, while the benefit-to-cost ratio was found to be 1.22. Results indicated that if the resources were used efficiently on an optimum scale, the emission and energy use could be reduced to 976.33 kg CO2eq ha-1 and 15391 MJ ha-1. 37.73 % of the energy savings, respectively. Also, 35.6% of greenhouse gas emission reductions were related to the optimal farm scale. Furthermore, the contribution of the optimal scale in improving the benefit-to-cost ratio and energy use efficiency was found to be 12.5 and 16.23%, respectively. The results showed that the optimum scale of agricultural activities was a crucial factor in saving energy and reducing greenhouse gas emissions in wheat production in eastern Iran. Therefore, as local farms in the studied region mostly were small-scale, fragmented and scattered, land integration and promotion of activities at the optimal production scale are recommended as important steps in reducing environmental side-effects and increasing farmers’ profitability.

Lemon balm (Melissa officinalis L.) is known as one of the most important hormonal plants (anti-thyroid), sedative, wound healing agents, and flavorings in the food industry. The present work aimed to determine the effect of different zinc (Zn) sources on the natural product composition, and antioxidant activity of lemon balm. The experiments were performed in a greenhouse in Eram Garden (Shiraz, Iran) with three replications and five different treatments including T1: No zinc (control(, T2: EDTA-chelated Zn, T3: nano Zn, T4: Zn sulfate, and T5: citrate-chelated Zn. The results showed that all Zn resources improved the chemical composition of the lemon balm essential oil (EO), such as geranial, caryophyllene oxide, and phthalic acid. The highest amount of geranial (40.8%) was achieved in the plants treated with citrate-chelated Zn. The highest total content of caryophyllene oxide (8.8%) was achieved when Zn sulfate was applied. The highest phthalic acid (2.24%) was obtained in the plants treated with Zn sulfate and nano Zn. The highest antioxidant activity (162.86 mg L-1) was found when nano Zn was applied. The results revealed that the application of Zn to therapeutic plants like lemon balm could be very useful for the production of active natural compounds such as geranial, phthalic acid, and caryophyllene oxide for use in drug industries and medical materials.

Introducing new sweet cherry cultivars with different ripening times is one of the most important goals of cherry breeding programs in Iran. ‘Zoshk’ cultivar was selected from the native sweet cherry genotypes of Khorasan Razavi Province by implementing eight research projects for 21 years since 1998. The results of this study showed that this cultivar had semi-spreading tree habits and a moderate degree of branching. The time of the first flowering of the ‘Zoshk’ cultivar was in the second week of April. A pollination study demonstrated that this cultivar was self-incompatible. ‘Sefid-90’, ‘Surati-e-Lavasan’, and ‘Dovomras-e-Mashhad’ cultivars were suitable pollinizer cultivars for ‘Zoshk’. In addition, the harvesting time of this cultivar was in the third week of June. The average fruit weight of the ‘Zoshk’ cultivar (10.17 g) was higher than those of ‘Shandiz’ (7.23 g), ‘Toos’ (6.87 g), and ‘Siah-e-Mashhad’ (7.80 g). Further, the total soluble solid was higher in ‘Zoshk’ (19.66%) compared to ‘Shandiz’ (16.63%) and ‘Toos’ (17.13%) cultivars. Moreover, the yield of ‘Zoshk’ in the economic fruiting stage was 33.67 kg per tree, higher than those of ‘Shandiz’ (22.43 kg) and ‘Toos’ (12.67 kg) cultivars. Regarding the high yield, average fruit weight, percentage of soluble solids, and extended ripening time of the ‘Zoshk’ cultivar, the expansion of this cultivar is recommended in some sweet cherry orchards in Iran.

Planting crops with less vulnerability to environmental stresses, especially drought in semi-arid areas, can remarkably improve irrigation water use efficiency (IWUE). Therefore, in this study, planting quinoa (Chenopodium quinoa) under different irrigation regimes and planting dates was investigated. Irrigation regimes included full irrigation (FI) and 50% of full irrigation (0.5FI), where planting dates consisted of six planting dates in the early spring and six planting dates in the early fall. Results indicated that the highest grain yield, dry matter, root dry weight, leaf area index, harvest index, and yield components were obtained in early spring cultivation on February 19 and in the early fall on August 23 planting dates. The maximum leaf area index on the planting date of August 23 was 21% higher than that on the planting date of February 19 under FI conditions. The highest harvest index was 0.32 in FI and the planting date of August 23. The planting date of August 23 increased water use efficiency for grain (IWUEG) by 30% compared to planting on February 19 under FI conditions. There was no significant difference in specific root length between planting dates on February 19 and August 23. Applying 0.5FI compared to FI increased root dry weight to shoot dry weight ratio to 142% on the planting date of August 23. Generally, the planting date of August 23 is suggested as the best planting time for quinoa in the study area with no water scarcity, while planting on February 19 is recommended in the conditions of scarce water resources by applying 0.5FI.

Quinoa (Chenopodium quinoa) is world-renowned for its nutritional and health benefits and its adaptability to different environments. Despite some research on quinoa cultivation, determining the appropriate planting date and density for different genotypes and regions needs to be studied. The main objective of this study was to determine the effects of planting date and planting density on quinoa seed yield in climatic conditions of Kermanshah. In this regard, field experiments were conducted during two growing seasons (2019-2020) at the research farm of Razi University, Kermanshah, Iran. The experiments were conducted as split-plot factorial in randomized complete blocks design with three replications. Three sowing dates (March 15th, April 15th, and May 15th) were assigned to the main plots, two planting densities (40 and 60 plants m-2), and three genotypes including Titicaca, Q29, and Red Carina as subplots. The results showed that the highest seed yield (2179.72 and 2267.39 kg ha-1) were achieved on April 15th, 2019 and May 15th, 2020, respectively. Sowing dates of April 15th in 2019 and May 15th in 2020 with a plant density of 60 plants m-2 and Titicaca genotype had the highest seed yield for quinoa in Kermanshah climatic conditions. The results showed that panicle length and biological yield had a positive and significant correlation with grain yield in all studied planting dates. There was a positive and significant correlation between grain yield and grain weight per plant, 1000-grain weight, and biological yield at both densities. The path analysis revealed that panicle length had the highest positive direct effect on seed yield followed by 1000-seed weight on the first sowing date in 2019 and 2020, while biological yield and panicle length had the highest positive direct effect on seed yield on the second and third sowing dates, respectively. This experiment showed that genotypes and planting dates are the most determining factors affecting quinoa growth, development, and yield compared with planting densities.