مطالعه اثر فراسنجه‌های اقلیمی بر جمعیت کنه‌ی زعفران و شکارگر آن در استان خراسان رضوی

Saffron (Crocus sativus L.; Iridaceae) is a perennial, corm-bearing, autotriploid (3n=24) plant that flowers in autumn. Its red and dry stigma is known as the most expensive spice in the world. Due to the expansion of cultivated areas of this strategic crop across various regions of the Iran with differing climatic conditions, the occurrence of physiological risks to the plant and an increase in pest populations are inevitable. The saffron mite (Rhizoglyphus robini Claparède, 1869), the most significant pest of saffron, causes both direct and indirect damage to the crop by feeding on healthy or damaged corms. Changes in environmental factors, like temperature and humidity, can influence the population dynamics of this pest and its predators. In this study, the effect of parameters of temperature, soil relative humidity and altitude on the fluctuations of the saffron mite population (adults and nymphs) and its predator (Gaeolaelaps aculeifer Canesterini, 1884) in five saffron fields (5-year-old) in Darghez, Qochan, Gonabad, Mashhad and Torbat Heydarieh cities were investigated. For this purpose, 200 grams of soil along with 200 grams of saffron corm were separately collected from five points in the field (once every two months throughout the year) and put into black plastic bags transferred. Mites were separated following the Fahti et al. (2024) and slide-mounted according to Evans (1992). Data analysis out using SPSS software (2007). The relationship between the population growth rates of adult and nymph bulb mites, as well as adult predatory mites throughout the year, was modeled using a third-degree nonlinear regression model. The highest growth rates for adult, nymph and predatory mite nymph were observed on 3 and 12 December and 3 January, respectively. The lowest growth rate for the adult mite population occurred on June 24, and for nymphs and predators, it was on August 5 and 9 respectively. The changes in ambient temperature and soil moisture, along with the population rates of adult mite in a total of five cities, were analyzed using simple linear regression. The effect of temperature on the increase in the adult bulb mite population was inverse, while the effect of humidity was direct. The impact of soil temperature and relative humidity on the nymph/adult mite population ratio was assessed through simple linear model fitting. The nymph/adult population ratio increased with rising temperatures and decreased with increasing relative humidity. The population fluctuations of adults, nymphs, and the total bulb mite population (nymphs + adults) were correlated with the elevation using a non-linear power model. The bulb mite population's fluctuations throughout the year decreased with an increase in altitude. Given the significance of this crop, the findings of this research could significantly contribute to advancing knowledge in the field of saffron cultivation and development.