آلودگی نهالستان‌های هسته‌دار به نماتدهای خانواده کریکونماتیده در منطقه کرج

Horticulture is an inseparable and very important part of the country's agricultural economy. The foundation of a healthy and high-quality seedling is grown in the nursery. Any lack of nutrients, poor nutrition and low growth of seedlings in the nursery will cause the growth, weakness and suffering of the resulting trees in the garden. Therefore, nurseries, as the primary focus of all types of pollution, play a very important role in the correct and economic development of the country's gardens. Plant parasitic nematodes, as one of the most important damaging factors, can be transferred to the main land through infected seedlings. Criconematids are one of the important groups of ectoparasitic nematodes and in high populations they cause damage to all kinds of agricultural products. Today, the direct relationship between the population of criconematids (especially the species Mesocriconema xenoplax) with the increase of canker disease and sensitivity to frost is well known. This group of nematodes is very sensitive to lack of moisture, and in the development of newly constructed gardens, the contamination of the main land (without previous cultivation) with this group of nematodes is usually very low. Therefore, one of the main ways to transfer this group of nematodes to new gardens is with seedlings. During the sampling of the soil and roots of a number of stone fruit nurseries in Karaj region, 18 samples were infected to Criconematidae family (population density from 10 to 480 in 200 cubic centimeters of soil). The highest frequency percentage is related to the genus, Mesocriconema with two species: M. xenoplax (72/5%) and M. antipolitanum (11%). The other genera, Criconema mutabile (5.5%) and Criconemoides informis (11%) are also reported. Variation range of morphometric data of M. xenoplax with the highest frequency percentage are presented as follows: body length 489-690 micrometers, stylet length 65-84 micrometers, R=75-110, V=92.4-96.5% and VL/VB=0.6-1.4. According to the results of this survey, one of the factors causing the decline in stone fruit trees in gardens can be caused by the infection of seedlings with criconematids. Because these nematodes are ectoparasite, it is recommended to prepare seedlings without soil if possible.