---

Modified atmosphere packaging is one of the recommended methods to increase the shelf time and quality of fruits and vegetables. To design a good packaging, accurate respiration rate is necessary. In this research, selection of the proper mathematical equation in determining the respiration rate is investigated and respiration rate of peeled and ready to use carrots were measured at laboratory temperature (21±1°C) and refrigerator temperature (7±1°C) in the closed system. In addition, effects of temperature and slicing were studied on respiration rate were studied. It was found both increase in temperature and slicing, increase the respiration rate. Results of this research are necessary to design of modified atmosphere packaging.   

---

Intra-specific variation in responses of diurnal and long-term photosynthesis, stomatal conductance, chlorophyll fluorescence, and respiration in spring wheat (Triticum aestivum L.) to salinity was investigated using two tolerant cultivars (CR and Kharchia-65) and a sensitive one (Ghods). Plants were grown in sand culture in controlled environment at selected levels of salinity (5 as control, 100, 200, and 300 mol m-3 NaCl and CaCl2 in 5:1 molar ratios). Photosynthesis was markedly reduced in the saline conditions, but there were no significant differences observed amongst cultivars. Stomatal conductance of both upper and lower leaf surfaces was the main factor limiting photosynthesis in the presence of salinity. However, non-stomatal limitations as indicated by reduction in variable to maximum fluorescence (Fv/Fm) showed that plants might experience some degree of photoinhibition at the highest level of salinity. Gas exchange in control and 100 mol m-3 did not change throughout the day in either the salt-sensitive or the salt tolerant cultivars but in the last hours of the day photosynthesis in the sensitive cultivar was markedly reduced. Respiration remained unchanged up to 200 mol m-3 salinity but at 300 mol m-3 it decreased as compared with the lower salinity levels. The most remarkable change in respiration rate was that at seven hours after light when CO2 production was much higher than at the other times of the day. The results indicated that although photosynthesis is well correlated with stomatal conductance, wheat genotypes show different responses as regards other such aspects of photosynthesis, in different salt concentrations, as growth stage, time of the day and duration of salt exposure.

---

Blood orange has high nutritional value due to high concentrations of vitamin C, fiber, folate, minerals and phytochemical compounds, such as flavonoids, amino acids, triterpenes, phenolic acids and carotenoids. The blood oranges contain greater amounts of antioxidants than other oranges. Orange fruit continue to respire, after harvest so there are probability changes of bioactive compounds that present in this fruit. The aim of this study was to investigatethe changes of the bioactive compounds, antioxidant activity and their relationship with respiration rate of blood orange during storage. Blood oranges var. sangria was purchased from the Citrus Research Institute of Iran. The fruits were transported to the laboratory immediately after harvesting and were stored at 5-4°C and 85-90% relative humidity for 50 days. Changes of concentration of vitamin C, flavonoid compounds, total carotenoids, antioxidant activity and respiration rate were evaluated once a week during storage. The concentration of vitamin C decreased, but the concentration of flavonoid, total carotenoids, antioxidant activity and respiration rate of blood orange increased during storage. The concentration of vitamin C, flavonoid, total carotenoid, antioxidant activity and respiration rate of blood orange changed during storage. With attendance to nutritional value and the functional compounds of orange fruit, use of appropriate actions are recommended to better maintenance of the bioactive compounds and antioxidant activity. Also, considering effects of respiration rate on the bioactive compounds and antioxidant activity, decrease of respiration rate of blood orange during storage could lead to be better preservation of the functional compounds.  

---

Application of edible coating as a way of prolonging the shelf-life of perishable fruits and vegetables is promising. Two plum cultivars (Stanley and Giant) were treated with 1% Chitosan and then stored at 0-1^oC and relative humidity of 90±5% for 40 days. Changes in weight loss, respiration rate, fruit firmness, soluble solid content, titrable acidity, pH, ascorbic acid as well as decay rate were periodically recorded. The results indicated that Chitosan coating was effective in reducing weight loss, respiration rate as well as decay rate. A parallel trend in weight loss and decay rate was observed for both cultivars. Comparing the two cultivars, ‘Giant’ exhibited higher weight loss and respiration rate. Weight loss was mitigated through Chitosan application due to its positive effect in reducing respiration. In addition, Chitosan coating resulted in the retainment of a higher content of titrable acid, pH as well as firmness in either cultivar. However, total soluble solids and ascorbic acid contents were not significantly affected by the coating. The results finally indicated that Chitosan treatment is an effective strategy for maintaining organoleptic characteristics and as well for the prolonging of postharvest life in plums.

---

In this study effect of temperature, O₂ concentration and storage time were investigated on respiration rate of uncoated and coated pear (Dargazi Cultivar) using Sclerorhachis platyrachis essential oil of 0, 125, 250, and 500 ppm. Mathematical model using Michaelis–Menten’s equation, with the model constants described by means of an Arrhenius-type relationship was applied to predict respiration rate at various temperatures (4, 10, and 25 ºC) and O₂ concentrations to design modified atmosphere packaging (MAP) of pear in order to extend its shelf-life. Results showed that all factors affected respiration rate of the pears but the influence of temperature was most pronounced. Increase in temperature led to increase of respiration rate and reduction of positive effect of essential oil on this parameter reduction. Moreover, after about 100 hours, respiration reached equilibrium. Respiratory quotient of Pears at 4 and 10 °C was on aerobic limit. However, at 25 °C, after 110 hours, and reaching CO₂ to 23%, respiratory quotient passed the critical point. Finally, package containing 3.7% O₂ + 8.1% CO₂ + 88.2% N₂ was suggested as an appropriate MAP for storing the pears (Dargazi cultivar).
 

---

Zero tillage practices have a direct effect on soil microbial communities modifying soil productivity and sustainability. The crop sequences used can change the aforementioned properties, too. In this study, we evaluated the effect of crop sequences under zero tillage management on soil biological and chemical properties including vertical distribution of soil organic carbon, soil basal respiration, and dehydrogenase, acid phosphatase, and urease activity along a seasonal year and at different soil depths. The sequences included in this study were: (I) Single crop per year (sunflower-wheat-sorghum-soybean); (II) Mixed agriculture/livestock with pastures, without using winter or summer forages (wheat sorghum/soybean-canola-pasture); (III) Winter management (wheat-canola-barley-late soybean); (IV) Mixed with annual feed crop (wheat-oat/Vicia sativa- soybean or sunflower), and (V) Intensive management (wheat-barley-canola, with alternation of soybean or late soybean). Soil organic carbon decreased with increasing depth, depending on sequences (P_seq×depth= 0.0173). Soil basal respiration was higher in the 0-5 cm layer than in the 10-20 cm layer of the topsoil irrespective of the crop sequences (P_depth= 0.0062). Dehydrogenase, acid phosphatase and urease activity were affected by crop sequences, sampling season, and depth. Mixed sequences (sequences II and IV), including perennial pastures or annual feed crop could favor dehydrogenase and phosphatase activity. Sequences with cover crops (sequences II and IV) could favor microbial activity and, therefore, improve soil quality.

---

In this study, 23 local genotypes of sour cherry from collection in Meshkin Dasht-Karaj in terms of physical and chemical characteristics including weight, flesh to core ratio, firmness, total soluble solids, dry matter content, titratable acidity, pH, flavour index, respiration rate, color indices of fruits and juices (L*, b*, a*, Hue and Chroma) and their correlations were examined. The results showed that all genotypes had significant differences (p ≤ 0.05) in terms of the studied characteristics. Based on the correlations in the color indices, a* index alone can be used to evaluate the red color differences of various genotypes. According to the results, genotypes of KB-100, KB-450, and KB-213 with suitable characteristics such as weight (>2.8 g), flesh to core ratio (>8.5), flavour index (>9.5) and acidity (<1.75%) are more suitable for fresh consumption and genotypes of KB-232 and KB-247 with suitable weight (>3.7 g), dry matter content (>15%) and respiration rate (<9000 mg CO₂/kg.hr) are more applicable for processing. Also, genotypes with high acidity (>3%) such as KB-157, KB-121, KB-234, and KB-152 are more suitable for pickling and fruit roll-up processing. Genotypes with high dry matter content (>21%) and intense redness (a*<9 for skin and a*<16 for fruit juice) such as KB-136 and KB-449 are more suitable for the production of powder, dried sour cherries, syrup and nectar. Late harvested genotypes with firmness (>6N) such as KB-343 and KB-353 are also recommended for compote and jam processing, respectively.

---

In this study some physical and geometrical properties of 11 superior apricot genotypes were determined. These properties such as respiration rate, fruit dimensions, perimeter, surface area, volume, compact factor, geometric mean diameter, projected area, shape factor, circularity, length to width ratio, length to thickness ratio, and length to mass ratio were measured at harvesting moisture content ranging from 75.19 to 87.67 %. Then the correlation among average values of the attributes was performed and the genotypes were classified using principal component analysis (PCA). The results showed that all the genotypes had significant differences in terms of all the studied attributes (P<0.01). There was a significant and positive correlation between fruit length and weight and fruit length and moisture content. Fruit shape factor and compression factor showed a positive and significant correlation, while these attributes had negative and significant correlations with circularity. This study showed that Iranian apricot genotypes could be discriminated by differences in their geometrical characteristics using principal component analysis. Based on the PCA results, the first two components account for the most of the variation in the data (91%) and five distinct groups were observed. Overall, the results of this study can be beneficial for the design of equipment for harvesting, transportation, separating, packaging, and processing of apricot fruit.
 

---

Micro-propagated potato plantlets (cvs. Agria and Fontane) were grown in growth chambers under controlled conditions to determine the effect of different levels of CO₂ concentrations (400 vs. 800 µmol mol⁻¹) on physiological and biochemical traits and yield of minitubers, at the Ferdowsi University of Mashhad, in 2015. Irrespective of the cultivar, the elevated CO₂ significantly increased Net photosynthesis (Np) and leaf Dark Respiration (R_D) compared to the control at 34 and 57 days after transplanting. Higher Np under the elevated CO₂ resulted in a higher accumulation of leaflet starch and soluble sugar content. The elevated CO₂, compared to the ambient, induced allocation of more dry matter to the underground parts, especially tubers. CO₂ Enrichment did not significantly affect the number of tubers and mean tuber weight, however, the elevated CO₂ increased yield of Agria and Fontane by 17 and 39%, respectively. The yield of Fontane was increased more than Agria when exposed to elevated CO₂, mainly due to greater mean tuber weight than tuber number. The number of large size tubers increased under elevated CO₂. The results showed that the greater mean tuber weight might affect tuber yield more than the number of tubers. Our findings suggest that rising levels of CO₂ in minituber production systems could be beneficial to improve productivity and tuber yield.

---

The aim of this study was to determine the effects of different concentrations (0, 100, 200 and 300 mg L^-1) of postharvest AminoethoxyVinylGlycine (AVG) on fruit quality, chilling injury, and bioactive compounds in cold-stored plum fruit (Prunus salicina L. cv Friar). Fruit were stored at 0-1°C with 90±5% Relative Humidity (RH) for 60 days. Weight loss, flesh firmness, Soluble Solids Content (SSC), titratable acidity, total anthocyanin content, total phenolic content, antioxidant capacity, respiration rate, and chilling injury were determined at the harvest and during the storage period at 15-day intervals. As compared to the control, AVG treatment delayed ripening and prolonged storage life, as indicated by prevented fruit softening, and retarded the increase in SSC. The 200 and 300 mg L^-1 AVG treatments considerably reduced respiration rate and maintained higher bioactive compounds contents than other treatments. The severity of the chilling injury was reduced by AVG treatments compared to the control during storage. The results indicated that postharvest 200 and 300 mg L^-1 AVG treatments could be an effective tool for prolonging storage of 'Friar' plums.
 

---

Having a short postharvest life, cucumber undergoes rapid loss of quality. In this research, the effects of temperature, oxygen, and postharvest storage time on the respiration rate of Royal cucumbers were investigated. To design a Modified Atmosphere Packaging (MAP) for cucumber in order to extend its shelf-life, a mathematical model using Michaelis–Menten’s equation, with the model constants described by means of an Arrhenius-type relationship, was applied to predict respiration rate at various temperatures (4, 10, and 20ºC) and O₂ concentrations. Results revealed that all three factors affected respiration rate of the cucumbers, but the influence of temperature was most pronounced. The model was validated in a commercial passive and active MAP. The model could well predict the O₂ change in the package but the modeling of CO₂ change, mainly at 20ºC, was not satisfactory, which might be due to occurrence of anaerobic condition. The mathematical model was verified as long as the O₂ concentration did not reach anaerobic levels at 20°C. Applying the corresponding respiration, the model will also be applicable for other variety of cucumbers with similar metabolic and respiratory behavior to design the optimal MAP conditions.

---

To investigate the response of soil microbial populations to different doses of glyphosate and sulfosulfuron, a factorial experiment based on a complete block design was conducted at Shiraz University, Iran. The factors included different herbicides and dose rates (glyphosate at 0, 540, 1,080, and 4,320 g ae ha^-1 and sulfosulfuron at 0, 12.5, 25, and 50 g ai ha^-1), and time of measurements (4, 15, 45, and 65 days after herbicides spray). Microbial respiration, microbial biomass carbon, metabolic quotient, dehydrogenase activity, and aerobic heterotrophic bacteria were measured in soil samples. The results showed that microbial respiration, microbial biomass carbon and metabolic quotient were highest for glyphosate 1,080 g ae ha^-1 at 4 days after herbicide application. Dehydrogenase activity had a decreasing trend in all herbicide treatments in comparison with the control treatment in all measuring times, except 4 days after spraying. There was no significant difference in dehydrogenase activity between herbicide treatments. The effect of sulfosulfuron on microbial respiration and metabolic quotient was not significant, whereas time and its interaction with herbicide dose rate affected these two variables significantly. Generally, all the measured indices for sulfosulfuron and glyphosate treatments decreased with time after herbicide application. Sulfosulfuron at 50 g ha-1 and glyphosate at 4,320 g ha-1 had the lowest amounts of aerobic heterotrophic bacteria after 65 days, decreased by 23.7 and 50%, respectively compared with the control. Our results demonstrate that the effects of herbicides on soil microbial communities are strongly related to the herbicide dose and the time after herbicide spray. In conclusions, the herbicides at doses more than the recommended doses showed inhibitory effects on soil microbial communities in the alkaline soil, where the inhibitory effect was more at 4,320 g ae ha^-1 glyphosate.