reproduction factor

Tomato is attacked by root-knot nematodes (Meloidogyne spp.), reducing crop yield. The negative consequences on the environment and the high cost of producing chemical nematicides limit their application. The use of chemical fertilizers with a direct and indirect effect on the population of nematodes is considered as an environmentally friendly alternative solution. In this research, the effect of recommended minimum and maximum concentrations of Zima (soil conditioner), Nemo (growth enhancer) and Bonza (root growth stimulant) fertilizers was investigated in reducing the damage caused by M. javanica in tomato plants under greenhouse conditions. For this purpose, four-leaf stage tomato seedlings were treated with the concentrations 0.5% and 1% of Zima fertilizer, 0.1% and 0.3% of Nemo fertilizer, and 0.1% and 0.3% of Bonza fertilizer and simultaneously inoculated with 6000 nematode eggs and kept in greenhouse conditions. Sixty days after nematode inoculation, the results showed that nemo at the rate of 0.3% significantly increased the vegetative indices of healthy and infected plants. Also, the concentration of 0.5% Zima fertilizer decreased the number of eggs, galls and eggmasses in the root system, and the reproduction factor of nematode by 57.4, 34.6, 43.7, and 56.9%, respectively, compared to the control. The results of the research showed the importance of modifying the soil structure and compensating essential nutrients to reduce the damage of root-knot nematodes in tomato plants.

Root-knot nematodes (Meloidogyne spp.) are considered among the most important pathogens leading to great damage to agricultural products. So far, different practices such as crop rotation, resistant cultivars, and chemical compounds have been used for controlling these nematodes. High cost of chemical compounds and their environmental problems has attracted the researchers’ attention for using non-chemical methods for nematode management. The exploitation of resistant varieties is one of the most important approaches to managing plant-parasitic nematodes. The present study aims to evaluate the reaction of 15 different varieties of pomegranate to RKN, M. incognita race 2.

The morphological characters of isolated nematodes were evaluated after sampling, along with identifying the nematode species. The experiment was conducted in greenhouse conditions with a temperature ranging from 22-26°C based on the completely randomized design with factorial arrangement. First, pomegranate cuttings were rooted and inoculated with 2000 eggs and second-stage juveniles of the nematode per kg of soil. Then, host plant growth traits such as length, fresh and dry weight of stems, and roots, as well as developmental stages of the nematodes including the number of galls, egg mass, and reproduction factor were evaluated in different cultivars of pomegranate 90 days after inoculation. The final rating was conducted based on the Canto-Saenz system (1985). Finally, the data were analyzed by using SPSS 24 software, and Duncan test and t-test were used for comparing the means.

Based on the results, Malas-e Torsh cultivar was tolerant (GI≤2, RF>1), Malas-e Shirin and Tabestani were hypersusceptible (GI>2, RF≤1), and Agha Mohammad Ali, Alak-e Torsh, Bahabadi, Berit-e Poust Ghermez, Golnar, Naderi, Bihasteh-e Ravar, Pous Sefeed-e Shirin, Bihasteh-e Shomal, Poust siah, Souski-e Taft and Shahsavavar-e Yazdi were evaluated as susceptible (GI>2, RF>1).

Based on the results,tolerance of only one cultivar against root-knot nematodes should be considered by experts and farmers.

The Root-knot nematodes (Meloidogyne spp.) are one of the most damaging plant pathogens with a wide host range and cause major losses to agricultural crops. The use of resistant cultivars is considered a safe, economical, and effective method to control these nematodes.

In the present study, eight melon cultivars namely Ahlam, 105, Tracey, Ronak, Deltagrin, Mac, Holar, and Veno were evaluated for their response to M. javanica. The seeds were planted in 2 kg pots and maintained under natural conditions in Khormuj city, Bushehr province. Seedlings at the four-leaf stage were inoculated with 5000 eggs and second-stage juveniles. The factorial experiment was conducted in a completely randomized design with five replicates. Sixty days after nematode inoculation, the plants were harvested and the plant growth and nematode population indices were evaluated.

The results showed that the nematode reproduction factor was significantly lower in Ronak, Deltagrin, and Veno than in the other cultivars. No significant difference was observed in shoot fresh weight of nematode inoculated and non-inoculated plants of Ronak cultivar.

Ronak, Delta-green and Veno cultivars are less susceptible to M. javanica.

Plant-parasitic nematodes significantly reduce crop production. The stem and bulb nematode (Ditylenchus dipsaci) is one of the important pathogen of several ornamental and field crops including alfalfa. In this study, the reactions of seven alfalfa ecotypes to the nematode were investigated under greenhouse conditions. The experiment was conducted based on completely randomized design with three replicates. The results showed significant differences (p < 0.05) among inoculated ecotypes with the nematode in all morphological traits (except of root length) compared to the control. The nematode reproduced in all studied alfalfa ecotypes, but the rate of reproduction was different. The highest reproduction factor (RF) was observed on the ecotype Neishabouri (RF = 7.14) and the lowest on Feiz and Hamedani with reproduction factors of 1.24 and 1.85, respectively. The highest number of the nematode was observed in stems, rhizosphere and buds. The results showed that none of these ecotypes were resistant or tolerant to the stem and bulb nematode.

In recent years, non-chemical control of common species of the root-knot nematodes (Meloidogyne spp.), including soil enrichments by organic matters, animal manures and chemical fertilizers has received considerable attention. In 2014, in an experiment, effects of two levels (10 and 25 mg/kg) of sulfur fertilizers viz. ammonium sulfate, calcium sulfate, potassium sulfate, magnesium sulfate and zinc sulfate, and the levels of 25 and 50 mg/kg of elemental sulfur on the activity of the root-knot nematode M. incognita, in pasteurized soil were studied in greenhouse. Seedlings of cucumber cv. Negin at three or four-leaf stages were inoculated with two eggs or second stage juveniles of the nematode/g of soil. The results of two trials showed that magnesium sulfate 10 mg/kg caused 179% increase in the yield on average. The highest reduction was recorded in the number of eggs/g of root and reproductive factor in 25 mg/kg level of calcium sulfate with 71.6% and 58.6%, decrease followed by 25 mg/kg sulfur with 69.1% and 57.0% decrease respectively. The treatment of 50 mg/kg of sulfur was also in the next rank.

Root-knot nematodes (Meloidogyne spp.) are one of the main pests of cucumber production in greenhouses and farms. Applications of chemical and organic fertilizers are effective in reducing the damages caused by these nematodes. For this purpose, during 2013-2014, in an experiment, effects of 25, 50 and 100 mg/kg of elemental sulfur at planting time and 45 days before planting, in sterilized and non-sterilized soil were studied in two turns in greenhouse. First, two eggs or second stage juveniles of the nematode/g of soil and sulfur levels were mixed with the soil. Then cucumber seeds cv. Negin were sown immediately in the half of the pots and in the other half after 45 days. In order to evaluate the effect of sulfur evaporates on the initial nematode population, one half of 45 days pots were placed in plastic bags. The results of two trails showed that sulfur 50 mg/kg of soil in 45 days pots, filled with non-sterilized soil and placed inside plastic bags caused 36% increase in the shoot dry weight and 114% in the yield, on average. In addition, sulfur 100 mg/kg of soil caused 70% and 69% decreases in the final population and reproduction factor of the nematode, respectively.

Host preference of Helicotylenchus digitiformis Ivanova, 1967 on 10 common field crops including cantaloupe (Samsuri), canola (Golden), clover, corn (704-Hybrid), cotton (Deltapine 16), lucerne (Hamedani), sugar beet (Pb8), tomato (Rutgers), turf grass (Sport) and wheat (Shiraz) was studied in two separate trials. Tests were performed in randomized complete block designs, with initial field populations of 1.49 and 4.33 nematodes/g of soil, under greenhouse conditions. The results showed that all plants are hosts for the nematode but the highest final population and reproduction factor were happened on the cotton (Deltapine 16) and corn (hybrid 704). In addition, to determine the damaging levels of the nematode on corn (hybrid 704) and cotton (Deltapine 16), two tests were conducted in randomized complete block designs with initial field population, ½ field population and control (4.33, 2.16 and Zero nematodes/g of soil, respectively) and six replicates, under greenhouse and microplot conditions. The results showed that all of the field populations under greenhouse conditions and treatments with nematode under microplot conditions caused significantly decreases in most of growth indices of corn plants. Nevertheless, the nematode population has not any significant effect on the growth indices of cotton, although the nematode multiplied on it and reproduction factor was more than one. Also, similar tests were carried out on two local wheat cultivars (Shiraz and Pishtaz), with field population, ½ field population, 1/3 field population and control (1.49, 0.75, 0.50 and Zero nematodes/g of soil, respectively) in a randomized complete block design with five replicates, under microplot conditions. Results showed that only the field population significantly caused decreases in most of growth indices of wheat (Pishtaz).

Root-knot nemaode which causes extensive damage to legumes and cereals has been reported in many countries. The nematods has been observed on legumes، roots in many regions of the world، causing swollen root and yield reduction. In order to evaluate the effect of irrigation interval on reproductive traits of root-knot nematode، and the damage inflicted upon navy bean، a study was conducted in 2011 in the research greenhouses of Shiraz Islamic Azad University. The factorial experiment was arranged in an RCB design of three replications. Three factors، including- variety at two levels; irrigation interval at three levels، and infestation at two levels were considered. Nematode inoculation was conducted at the seedling stage of navy bean by a number of 2000 eggs plus second stage juveniles per kg of soil in each pot. Plant growth and nematode reproduction trends were started to be assessed two months following inoculation. On the basis of the recorded results the effect of irrigation interval on the whole traits، related to nematode، was significant at a 1% level of probability. The highest and the lowest number of galls per root، egg mass per root، nematode final population as well as reproduction traits were recorded for the 48 and 96 hour irrigation intervals respectively. The two irrigation treatments significantly differed at 5% level as regards the four tested traits. The results also revealed that varieties at different irrigation intervals responded differently to nematode damage. As much as the soil moisture content was less، the nematode was more disabled and plants grew with more vigor. So، maybe one can retard the growth of nematodes by management of irrigation interval especially when the probability of damage of the nematode is high، although the economic performance of the crop should also be put into consideration.