Showing 10 results for Pear
A. M. Maskouki, A. Mortazavi,
Volume 8, Issue 2 (7-2004)
Abstract
The inhibitory effects of thyme and ajowan oils on growth of A. parasiticus on pear during cold storage were studied. The main components of the two essential oils are phenolic compounds such as thymol and carvacrol with antimicrobial properties. Pear samples were inoculated by suspension ( 106 spor/ml) of A. parasitcus spores and sprayed by thyme (200 p.p.m) and ajowan (300p.p.m) separately and kept in cold storage (0 ±10C and relative humidity of 85%). Organoleptic test for evaluating oil odor residue was studied after 3 months. The amount of spoilage and contamination of pear fruit in 1st, 2nd, and 3nd month after cold storage was determined and were data the statistically analyzed. The results showed that in spite of the higher thymol content in ajowan oil constituent, which is well known as an antimicrobial agent Stronger than thyme oil, thyme oil at 200 p.p.m was more effective than ajowan oil in controlling and preventing, A.parasiticus growth in pear. It seems this is due to synergistic effects of other phenolic compounds such as carvacrol which does not exist in ajowan oil. The results of organoleptic test showed that the samples treated with ajowan oil have more acceptance than those treated with thyme oil thie applied even to the control sample. According to the results, thyme and ajowan oils are good promising natural antifungal agents without any hazardous effects on human health and can be successfully use as chemical fungicides.
A. Davoodee, E. Majidi, H. Rahimian, M. Valizadeh,
Volume 9, Issue 2 (7-2005)
Abstract
The fire blight with the bacterial causal agent, Erwinia amylovora (Burrill) winslow etal. is one of the most important diseases of the pome fruits that causes the economical losses to quince, pear and apple productions, respectively, in some parts of country. To determine the infection severity of the 43 raturally infected pear cultivars in collection of karaj horticulture research division and also for studing the reaction of these cultivars against disease, the evaluation was performed by the USDA standard system for these cultivars in collection. In this study, although the most of cultivars had been infected on the natural conditions, but disease severity was significantly different between them. By the USDA system, pear cultivars were divided in the 2 classes. Percentage of pear cultivars in very susceptible and moderately susceptible classes were 81.4 and 18.6 respectively. Also for dividing the pear cultivars, beside of USDA method, SPSS software and the cluster analysis were also by the UPGMA method and cultivars were divided into 3 clusters, but it seems that the classification of cluster analysis did not conform with USDA system. Correlation of I.V.S in the artificial tests and the disease severity by natural infection was very significant (r= -0.83).
M. Niknejad Kazempour, E. Kamran, B. Ali,
Volume 11, Issue 40 (7-2007)
Abstract
Fire blight caused by Erwinia amylovora, is a serious disease of pome fruits in many areas in the world which causes evaluative necrosis. Indeed, E. amylovora can invade the whole tree solely by internal progression through the host tissues. In this research, symptoms of necrotic shoots and exudates production on infected pear trees in different areas of Guilan province (Astaneh Ashrafieh, Lahijan and Kiashahr) were surveyed. Samples were taken from infected tissues of diseased trees. For isolation of bacterial causal agent, the infected tissues were crushed in pepton water, then 100µl of the extracts were cultured on Sucrose Nutrient Agar (SNA) and Luria Berthani (LB) containing Cyclohexamid antibiotic (50 µg / ml). The isolated bacteria were rod-shaped , gram negative and facultatively an-aerobic. The bacteria produced Levan on media including sucrose , but could not produce fluorescent pigments on King’s B medium. All strains made hypersensitive reaction on tobacco leaves. All isolates were oxidase , nitrate, urease and indole negative and were not able to rot potato tuber slices, produce H2S and grow in 36 °C. The isolates could use citrate, acetoin, sorbitol and trehalose and their gelatin test was positive. Based on morphological, biochemical, physiological characteristics and production of a 937 bp with specific primer Ea1 and Ea2 in PCR method, the strains were identified as E. amylovora. This is the first report of the existence of this bacterium on pear fruit trees in Guilan province.
H. Khoshghalb, K. Arzani, M. J. Malakouti, M. Barzegar,
Volume 12, Issue 45 (10-2008)
Abstract
Changes of the main sugars and organic acids content in Asian pear (Pyrus serotina Rehd.) Cultivars ‘KS’9 and ‘KS’13 grown in Tehran were studied from fruit set to maturity. The main sugars and organic acids content in fruits were determined 1 and 2 months before harvest, at the time of harvest and 1, 2 months after harvest time using High Performance Liquid Chromatography (HPLC). Fruits were stored at 2˚C and 80-85% relative humidity (RH). There were significant differences between cultivars and time of fruit harvest in terms of sugars and organic acids content. In both studied cultivars, fructose, glucose and sorbitol increased from the first fruit sampling to one month after harvest (1 to 9% FW) and then decreased. Sucrose content decreased from 2 months before harvest to 2 months after harvest time (3 to 0.75% FW). In both studied cultivars organic acids content increased at the time of pick-up and then decreased. The highest organic acids contents in the studied cultivars were malic and ascorbic acids (345 and 41.1mg 100g-1FW in ‘KS’9 and control, respectively). The relationship between low sugar and organic acid content in fruits showed the highest correlation (0.8 to 1) in both cultivars among low flesh firmness, low total soluble solid (TSS), low dry weight and high internal browning determined in this study. Results indicated that high content of sugars and organic acids in fruit led to delayed internal browning. Asian pears with a low ascorbic acid concentration are probably more susceptible to internal browning. High correlation was observed between high sugars content and high fruit colour.
S. Mirbagheri, M. Naderi, M. H. Salehi, J. Mohammadi,
Volume 23, Issue 3 (12-2019)
Abstract
Rivers are one of the most important source of water supply for drinking and farming purposes. Zard River is one of the surface water resources of Khuzestan province. The purpose of this study is to evaluate the quality of the river water and to observe the trend of changes in the water quality of this river in the Mashin station during the period of 1997-2015 by using the Man-Kendal, Spearman, variance analysis statistical methods and the least significant difference (LSD) and cluster analysis. LSD test shows SAR, Na, Cl, pH parameters up to 2010 (before Jare dam construction) were significant at 95% confidence level compared to 2015 (year of control). No changes were made after dam construction. According to Mann-Kendal non-parametric test, pH, Ca and SO4 have a significant upward trend to the 0.037, 0.393 and 0.376 respectively, the variables Cl, SAR, Na and temperature have a significant decreasing trend to the -0.387, -0.417, -0.386 and -0.1 respectively. Also Spearman test shows that the dam improved the quality of river water regarding to salinity. Variance analysis show that pH, SAR, Na, Cl, Ca and SO4 have significant difference. Cluster analysis classified the qualitative data before the construction of the dam in three clusters and after the construction of the dam were divided into two clusters where TDS variable was less distant than other variables. As a result, the quality of the irrigation water is changed downward and the TDS is more similar to the other variables compared.
L. Neisi, P. Tishehzan,
Volume 23, Issue 3 (12-2019)
Abstract
Rivers are one of the most important source of water supply for drinking and farming purposes. Zard River is one of the surface water resources of Khuzestan province. The purpose of this study is to evaluate the quality of the river water and to observe the trend of changes in the water quality of this river in the Mashin station during the period of 1997-2015 by using the Man-Kendal, Spearman, variance analysis statistical methods and the least significant difference (LSD) and cluster analysis. LSD test shows SAR, Na, Cl, pH parameters up to 2010 (before Jare dam construction) were significant at 95% confidence level compared to 2015 (year of control). No changes were made after dam construction. According to Mann-Kendal non-parametric test, pH, Ca and SO4 have a significant upward trend to the 0.037, 0.393 and 0.376 respectively, the variables Cl, SAR, Na and temperature have a significant decreasing trend to the -0.387, -0.417, -0.386 and -0.1 respectively. Also Spearman test shows that the dam improved the quality of river water regarding to salinity. Variance analysis show that pH, SAR, Na, Cl, Ca and SO4 have significant difference. Cluster analysis classified the qualitative data before the construction of the dam in three clusters and after the construction of the dam were divided into two clusters where TDS variable was less distant than other variables. As a result, the quality of the irrigation water is changed downward and the TDS is more similar to the other variables compared.
M. Noshadi, A. Ahadi,
Volume 23, Issue 4 (2-2020)
Abstract
Groundwater supplies a major portion of two basic human needs: drinking and agricultural water. Forecasting, monitoring, evaluating the performance and planning of this vital resource require modelling. The lag time of the groundwater level fluctuations against the rainfall is one of the essential data of the models. The purpose of the present study was to evaluate the piezometers behaviour by using the Pearson cross-correlation method between SPI and GRI indices in the Shiraz alluvial plain in order to determine the mentioned lag time. The results showed a similar behaviour for 86.2% of the piezometers. In 79.3% of the piezometers, groundwater level was declined one month after the rainfall event. The best correlation coefficient between the aforementioned indices was observed along the southwestern to the northeastern axis of the plain. The northern alluvial plain has a better correlation, as compared to the southern section because of the northern-southern slope of the plain. The central area of the plain had the highest correlation coefficient. The maximum correlation coefficients occurred at a time scale of 48 months. Also, since 2004, due to the decline in the atmospheric precipitation in the Shiraz plain, the SPI index has surpassed the drought level, although the trend has not been significant. However, the GRI does not follow this trend, showing a significant hydrological drought. The reason can be the disproportionate water extraction to recharge ratio in the alluvial aquifer of the plain.
M. H. Nasserzadeh, B. Alijani, M. Paydari,
Volume 24, Issue 2 (7-2020)
Abstract
Given the climatic changes and threats to food security in recent years, they have have become a major issue in agricultural climatology. The present study aimed to investigate the status of agricultural climate suitable for the cultivation of rice in the light of the influential climatic conditions in the past. Given the effect of temperature and the amount of precipitations on rice growth and the sensitivity of rice to these two variables, the study examined the predicted future temperature and rainfall and their effects on rice. Data related to the temperature and rainfalls were obtained from the Meteorological Organization. Additionally, the temperature and agricultural potential of the region were considered. By preparing the agricultural calendar for the cultivation of rice, the correlation between temperature, precipitation and rice productivity was calculated using the Spearman Correlation coefficient. By using the SDSM model, future data and temperature and precipitation return period were determined in the SMADA software. The results demonstrated that minimum spring temperature tended to be late spring. The minimum temperature had the highest impact in April, the maximum temperature had the highest impact in July and the maximum rainfall had the highest effect in both June and July. Based on the results of the prediction models, the studied region would experience an increase in temperature and rainfall by providing favorable conditions for the cultivation of rice. However, delays in the cold season and shortness of the growth period increased the risks associated with the cultivation of rice in this period.
S. Esmailian, M. Pajouhesh, N. Gharahi, Kh. Abdollahi, Gh. Shams,
Volume 28, Issue 2 (8-2024)
Abstract
Studying the process of soil erosion and evaluating its effective factors is one of the most important prerequisites for proper management of soil and water resources. This study was conducted to investigate the production of surface and pipe runoff and sediment using artificial rainfall on silt loam soil in the laboratory. So, the soil was collected from the study area and transported to the laboratory. Laboratory experiments were performed on a soil bed in a rectangular flume with three pipes, at slopes of 2%, 6%, 10%, 14%, and 18% under simulated rain (30 mm/h) for one hour. Related graphs were drawn in Excel to analyze the results, and Spearman's correlation test was used in SPSS software to check the correlation between runoff and sediment values in each slope. The results showed that with the increase in slope, the sum of surface and pipe runoff and sediment increased over time. For example, in a slope of 2%, the runoff and sediment in the initial moments of the experiment increased from 0 to 1.3 liters and 26.2 g m-2 at the end of the experiment. Also, the correlation coefficient between runoff and sediment in the slopes was 0.98, 0.62, 0.4, 0.93, and 0.15, respectively, which was significant in some, but in others, it was not significant because of soil loss.
V. Rezaei, S. S. Eslamian, J. Abedi Koupai, A. R. Gohari,
Volume 28, Issue 2 (8-2024)
Abstract
The relationship between intensity-duration-frequency of rainfall is a significant tool for estimating flood discharge. According to the sparsely available rain gauge stations and the development of technology, it is possible to use satellite rainfall data with different temporal and spatial resolutions. PERSIANN rainfall data with a time resolution of 1 and 6 hours were used in this research. Also, the spatial resolution of these data is 0.04 x 0.04 degrees. Rainfall data from synoptic stations around the Kan basin were also used. Three common continuous probability distributions of Gamble, Pearson type 3, and Log Pearson type 3 with return periods of 2, 5, 10, 25, 50, and 100 years were investigated to calculate and check the IDF curve. In general, the precipitation intensity obtained from Gumble's method was more than Pearson Type 3's method. Log Pearson type 3 distribution did not provide acceptable results in this research. The two interpolation methods of inverse distance weighting and empirical Bayesian kriging were used to generalize the frequency intensity curves to the entire Kan basin. The results showed little difference between these two methods, except for Pearson type 3 probability distribution.
