جستجوی مقالات مرتبط با کلیدواژه "تغییرات جمعیت" در نشریات گروه "زراعت"

Legumes are a rich source of protein and dietary fiber. A good combination of legume protein with whole grains can eliminate malnutrition and amino acid deficiency in humans. Beans are one of the most important crops that are used in the nutrition of the people of the world and are very important due to their high nutritional value and relatively easy storage. Thrips is one of the pests that reduces bean yield. The different developmental stages of Thrips tabaci, by settling on underside of the bean leaves and feeding on the plant sap, cause silvery leaf spots which the black feces of the pest are visible inside them. These signs of damage indicate the presence of Thrips tabaci. This pest is active in bean fields in all season and cause damage. Onion thrips is the most well-known thrips in the world and causes significant damage to onion, cotton, lettuce, tomato and few other plants. It also carries some viral diseases.
 
Phaseolus vulgaris is one of the most important legumes cultivated in most countries of the world. This crop is attacked by various pests including onion thrips. This study was conducted in two years in field condition by planting cultivars Yaghut, Goli, Dadfar, Derakhshan, Ofogh and Akhtar (control) in a randomized complete block design with four replications in two experiments with spraying and non-spraying treatments, at Arak. To assess population changes, sampling was weekly done from the beginning to the end of the growing season. For sampling, five plants were randomly selected from each plot and scored based on the amount of damage and contaminated leaf area. Yield and yield components were also calculated. The results of this study were analyzed using SAS 9.1 statistical software and the means were compared by Tukey test in 1% and 5%.
 
In this study, Yaghoot and Dadfar cultivars had the highest yields with 2775.3 and 2735.3 kg/ha, respectively. On the other hand, Goli cultivar had a lower damage scale and a lower yield reduction percentage compared to other cultivars, but its yield (2110 kg/ha) was lower than other cultivars except the control. The two-year results of this study showed that the highest population of thrips in different stages of nymphs and adults were observed in Akhtar (7.01 and 2.15) and Derakhshan (5.93 and 1.65) cultivars. Population densities of onion thrips on seven cultivars and one soybean genotype were examined by Sedaratian et al. (2010). The results showed that the highest and the lowest population of thrips was observed on (Dpx and KS-3494 genotype) and on (L17 and Taller) respectively. This is not consistent with the results of the present study due to differences in the crop types studied. Kalafchi et al., (2002) examined the resistance of cultivars based on census of onion thrips population and evaluation of crop agronomic characteristics. These researchers evaluated nine onion varieties for damage. Red Azarshahr cultivar with the highest number of thrips and the highest damage to other cultivars was sensitive, and Sefid-Qom cultivar with the lowest number of thrips, was less contaminated. The results of this study are different from the results of recent studies due to differences in employed product and cultivars. The bean plant growth type has a significant effect on the resistance of the cultivars to the two spotted mite. Generalizing this result to the onion thrips needs to more researches. Compounds such as phytic acid, lectin and trypsin inhibitors can affect the biology of the onion thrips. This is similar to the results of the present study due to differences in populations studied as well as differences in yield and damage scale.
 
Based on the results of this study, Yaghut due to higher yield and Goli cultivars due to less damage scale priority for cultivation in the area.

According to statistics released by the Ministry of Agricultural Jahad, the area under cultivation of beans in Iran is 105,000 hectares, with an average yield of 2200 kg/ha. Thrips is one of the pests that reduce bean yield. The different developmental stages of Thrips tabaci, by settling under the bean leaves and feeding on the plant sap, cause colored silver spots, that the black feces of pest are visible inside these spots. These signs of damage indicate the presence of pests. Thrips is evident from the beginning to the end of its growing population of active beans in the fields and its damage. Onion thrips is the most well-known thrips in the world and causes significant damage to onion, cotton, lettuce, tomato. It also carries some viral diseases. 

Phaseolus vulgaris is one of the most important legumes cultivated in most countries of the world. This crop is attacked by various pests including onion thrips. This study was conducted in two years in field condition by planting cultivars Ghaffar, Sadri, Koosha, talash, local chiti of Khomein (control) and KS-21492 genotype in a randomized complete block design with four replications in two experiments with spraying and non-spraying treatments, at the National Bean Research of Khomein Station. Sampling was also conducted weekly to evaluate changes in pest populations (separately from larvae, nymph and adult) from the beginning of infestation to the end of infestation was performed. For sampling, five plants were randomly selected from each plot and scored based on the amount of damage and contaminated leaf area. Yield and yield components were also calculated. The results of this study were analyzed using SAS 9.1 statistical software and the means were compared by Tukey test in 1% and 5%. 

The two-year results of this study showed that Ghaffar and Koosha cultivars had the highest average yield of 3749.88 and 3602.25 kg/ha, respectively. Chiti of Khomein and sadri had the highest of population. On the other hand, KS-21492 genotype had less damage scale than Sadri and control, but its yield (2212.50) was lower than other cultivars. Given that this genotype had the lowest yield loss and population among cultivars. Sedaratian et al, (2010) also studied the population density of thrips onion on seven cultivars and one soybean genotype and reported the highest density of thrips on Dpx and genotype KS-3494 and the lowest population density on two cultivars L17 and Tellar. This is not consistent with the results of the present study due to differences in the product studied. Cultivars resistance based on population count of onion thrips and evaluation of crop yield characteristics were also used by Kalafchi et al, (2002). These researchers evaluated nine onion varieties for damage. Red Azarshahr cultivar with the highest number of thrips and the highest damage to other cultivars was sensitive, and Sefid-Qom cultivar with the lowest number of thrips, it is less contaminated than this pest. The results of this study are different from the results of recent research due to differences in product and cultivars tested. The results of the research (Mohiseni & Kushki, 2016) showed that the plant growth type had a significant effect on the resistance of cultivars to two spotted mites, which requires further investigation on the impact of the plant growth type on the onion population. Research has shown that different varieties of common beans contain anti-nutritional compounds such as phytic acid, lectin and trypsin inhibitors that can influence the biology of herbivorous pests such as onion thrips. This is similar to the results of the present study due to differences in populations studied as well as differences in yield and damage scale. Studies have shown that the levels of these anti-growth factors in different bean genotypes are different. 

Based on the results of this study Koosha and Ghaffar cultivars due to higher yield Priority for cultivation in the area.

Responses of ten pomegranate cultivars Malas Torsh Saveh, Malas Shirin Saveh, Agha Mohammad Ali Shirin, Alk Torsh Saveh, Alk Shirin Saveh, Poost Sefid Shirin, Poost Sefid Torsh, Poost Siyah Shirin, Tabestani Torsh Saveh and Poost Sefid Bihasteh Shomal to population density of Tenuipalpus punicae were evaluated during 2001-2002 in Saveh region. A Randomized Complete block design in three replications was used for analysing the data collected from forthnightly sampling of mites onset from mid. May up to mid. November. Maximum number of mites on both sides of leaves was recorded 67.66 and 24.33 at the middle and end of August on Poost Sefid Shirin cultivar during two years of sampling, respectively. Maximum (13.47) and minimum (0.4) mites densities were recorded on Poost Sefid Shirin and Malas Torsh cultivars in the first year and rather similar densities in the second year determined them as susceptible and resistance cultivars to the mite density respectively, but in general no significant difference was observed among the cultivars with population density of mite. Analysis of data from eleven sampling intervals indicated only peak of mite population during September which can be related to the high temperature occurred during this period. Population of mite was highly affected by color and taste of pomegranate cultivars. Cultivar Poost Sefid and local cultivars with white color and sweet taste attracted higher populations of mite. Maximum mite-days (225 days) was also observed on Poost sefid Torsh cultivar. These findings indicate that white colored pomegranate cultivars accepting higher populations of mites and longer time of activity, seems to be more sensitive to the mite.