Sixteen cultivars varieties of the following solanaceous vegetables; eggplant varieties. (Balady, Classic, Long white and Woman bag), pepper varieties. (Balady, Deer horn, Lamashiar, Mexican, Red sweet zoly, Saudi and Top star) and tomato varieties (Al-Basha 1077, Sama, Strain-B, Super Cristal and Tomato 935) were tested for their host response to Meloidogyne javanica. According to rating scale based on nematode reproduction, Classic, Long white & Woman bag varieties. of eggplant and Top star variety. of pepper were considered as highly susceptible hosts with (Rf) values 18.04, 15.24, 19.82 & 17.30 folds, respectively. While, Balady variety. of eggplant and Strain-B variety. of tomato were classified as moderately susceptible hosts to nematode infection with (Rf) values 5.28 and 5.07 folds. Lamashiar variety. of pepper and tomato varieties. Super Cristal, Al- Basha 1077 &Tomato 935were found less susceptible with (Rf) values ranged between 1.07 and 4.83 folds. On the other hand, M. javanica failed to reproduce and multiple on Deer horn variety. of pepper, which was ranked as highly resistant host with (Rf) value 0.59-fold. Whereas, Balady variety. of pepper and Sama variety. of tomato were ranked as resistant hosts. Nematodes could not reproduce, develop, or penetrate the roots of Mexican, Red sweet zoly and Saudi varieties. of pepper, which were ranked as immune hosts to M. javanica infection.

The family Solanaceae is an economically important family of flowering plants. The family ranges from annual and perennial herbs to vines, or either shrubs and trees, including a number of important vegetable crops like tomato, pepper, eggplant, white and red potato, and tomatillo. The family also contains several plants that are considered toxic to humans being such as the weeds jimsonweed, nightshade and mandrake. Many members of the family contain potent alkaloids that are having immense value by considering its nutritional value. The Solanaceae consists of approximately 98 genera and about 2,700 species, with a great diversity in their habitats, morphology and ecology. Solanaceous vegetable crops are important source of vitamin C, A, E, thiamine, niacin, pyridoxine, folacin, minerals and dietary fibers which play a significant role in human nutrition and helps to cope with malnutrition (Devi and Nagar 2017). 

Nematodes are one of the most diverse phyla in the kingdom of Animalia, probably exceeding all other animal species in sheer abundance (Chitwood & Chitwood 1974). Nematodes are found in almost all terrestrial, aquatic and marine environments. They can be either free-living or parasitic, feeding on plants, fungi, and animals (Decraemer & Hunt 2013). The species, which have adapted a plant-parasitic lifestyle, pose a significant threat to crop production worldwide (Sikora & Fernàndez 2005) and to solanaceous cultivated in soils of the Nile Valley and reclaimed sandy soils in the desert of Egypt (Mokbel et al., 2006; Abd-Elgawad et al., 2012; Abd-Elgawad, 2013 and Montasser et al., 2019). The root-knot nematodes consist of sedentary polyphagic root endoparasites (Sharon et al. 2007) and their species are the most destructive plant-parasitic nematodes causing large economic losses in crop production (Sasser 1980). More than 100 species of root-knot nematode have been reported worldwide (Karssen & Moens 2013). As a result, most solanaceous are invaded by the root-knot nematode Meloidogyne spp. infested. According to Mota et al. (2013) nematodes can also form complexes with other pathogens such as Fusarium oxysporum, Rhizoctonia solani and Thielaviopsis basicola. Nowadays, nematologists around the world are looking for alternative control measures to avoid soil pollution with chemical nematicides and the resulting hazardous effects due to its residues. Farmers use resistant rootstocks to manage the nematodes of genus Meloidogyne in modern agricultural trends. Currently, cultivars resistant to M. incognita or M. javanica are species identified by Pinheiro et al., (2014) as the most important for vegetable crops. However, other species have gained prominence; They have been found to infect materials resistant to the above species (Pinheiro et al., 2014). Other species pose a major threat to vegetable production due to their high harmful potential, wide range of hosts, and lack of resistant commercial material. Genetic resistance has been considered the best alternative to control phytonematodes due to the low efficiency of chemical control and the search for sources of vital resistance in breeding programs (Hussain et al., 2014 and Liu et al., 2015). Therefore, the aim of the present study is to evaluate the genotypes of some solanaceous vegetables in terms of their response to M. javanica infection.

Propagation of Meloidogyne javanica in pure culture:

A pure stock culture of the root-knot nematode M. javanica was prepared from naturally infected tomato roots collected from an infested field in Assiut province. Individual egg-masse with their mature females removed from root tissue. Each egg-mass placed in a small glass capsule containing fresh water. The females from which egg-masses were taken preserved in 4 % formaldehyde solution in glass capsules for nematode identification. Each egg-mass was transferred to a 25 cm pot filled with-steam sterilized sandy loam soil and grown with a seedling of eggplant variety. Balady. Inoculated pots were placed in a greenhouse and watered when needed. After two months of inoculation, infected roots were then chopped and used as sources of inoculation for other series of clean cv. Strain-B tomato seedling. By repeating this procedure, enough quantities of inoculation from stock cultures were obtained on eggplant variety. Balady.

Identification of Meloidogyne species: 

Species of Meloidogyne were identified on basis of perineal pattern system of mature females. It was achieved by transferring individual mature females on a slide in a drop of hot lacto-phenol solution. The posterior end of each mature female was cut off by using a sharp razor blade and trimmed down to the area showing the pattern. Slides were gently covered with a clean cover slip and sealed with finger nail-polish, (Taylor and Netscher, 1974). All preparations were examined microscopically using an oil immersion lens. Identification of Meloidogyne sp. was established after referring to morphological characteristics given by Chitwood (1949); Taylor & Sasser (1978); Sasser & Carter (1982) and Hartman & Sasser (1985).

Greenhouse screening tests

Seeds of the following solanaceous vegetables, four eggplant (Solanum melongena) cultivars; (Balady, Classic, Long white and Woman bag, seven pepper (Capsicum annuum L.) cultivars; Balady, Deer horn, Lamashiar, Mexican, Red sweet zoly, Saudi and Top star), andfive tomato (Solanum lycopersicum L.) cultivars; (Al-Basha 1077, Sama, Strain-B, Super Cristal and Tomato 935)were plantedin 30 cm diameter pots containing mixture of clay and sand soil (1:1 v:v) for two weeks. Pots were then inoculated with approximately 3000 newly hatched juveniles (J2) of M. javanica per plant by pipetting the nematode suspension in five holes around the root system. Each treatment was replicated three times. Non-inoculated plants served as a control. All pots were arranged in a randomized block design in a greenhouse. All plants were grown during the normal growing seasons at greenhouse temperature of30 ± 5 Co, for 60 days after planting or 30 ± 5 Co, for 45 days after inoculation , all plants were harvested and removed gently, washed in water and the root of each plant was stained in lacto-phenol acid fuchsine (Goodey 1957). Number of juveniles in soil per pot, galls, nematode developmental stages on root, egg-masses per root was counted. Eggs of ten randomly selected egg-masses of each root system were also counted by sodium hypochlorite. The rate of nematode reproduction was calculated. Plant growth criteria involving length and fresh weight of both roots and shoots were calculated. The percentages of reduction of such parameters of each plant were also determined. The host category of the tested crop cultivars plants infected with the root-knot nematode, based to the nematode reproduction (Rf = Pf / Pi) was determined according to Montasser et al. (2017), as follow: (Pf / Pi = 0.0) I = Immune host, (Pf / Pi < 0 xss=removed xss=removed xss=removed xss=removed> 15.0) HS = Highly susceptible host. 

Sixteen local and important solanaceous cultivars belonging to three crop species were tested for their susceptibility and resistance to the infection of the root knot nematode, M. javanica infection Table (1). Eggplant cultivars Classic, Long white & Woman bagand Top star cultivar of pepper were highly susceptible as these cultivars gained the highest values of number of galls, adult female, egg-masses per root, eggs per egg-mass and rate of nematode reproduction. No significant differences were found on such nematode criteria on such root cultivars when compared with those of the other tested cultivars. Therefore, the calculated values of rates of nematode reproduction were 18.04, 15.24, 19.82 & 17.30 folds, respectively. On Balady cultivar of eggplant and Strain-B cultivar of tomato supported the moderately values of nematode criteria, however, the calculated numbers of galls per root and values of rates of nematode reproduction (Rf) were 81 & 69 galls and 5.28 & 5.07 folds, respectively. Also, M. javanica reproduced and multiplied low on Lamashiar cultivar of pepper and tomato cultivar Super Cristal, Al- Basha 1077 &Tomato 935 with the number of galls per root and rates of nematode reproduction (Rf) values ranged between 20 & 54 galls and 1.07 & 4.83 folds, respectively. On the other hand, M. javanica failed to reproduce and multiply on Balady cultivar of pepper and Sama cultivar of tomato. The nematode final population per plant was less than its initial population in these plant cultivars. There upon, the calculated number of galls and rates of nematode reproduction (Rf) on such cultivars were 2 & 9 galls and 0.04 & 0.31folds, respectively. In addition, theevaluation revealed Mexican, Red sweet zoly and Saudi cultivars of pepper as immune (non-host) with zero, number of galls per root, nematode juveniles in soil, nematode developmental stages per root, egg-masses per root, eggs per egg-mass, nematode final population and rate of nematode reproduction.

Table (1): Susceptibility of some eggplant, pepper and tomato cultivars to root-knot nematode, M. javanica infection under greenhouse conditions.

Means in each column followed by the same letter′s are not significantly different by (p≥0.05) according to Duncan's multiple range test.

* Significant at 0.05 level of probability ** highly significant at 0.01 level of probability.

The influence of the root-knot nematode, M. javanica on plant growth of fresh weights of shoots and roots of the same cultivars as well as percentage reductions when compared with healthy once were recorded. Plants Fresh weights of Classic, Long white & Woman bag cultivars of eggplant and Top star cultivar of pepper were highly significantly affected by the nematode infection when compared with their controls. The percentage of reductions in plants weights on such cultivars were 44.44, 33.74, 61.85 & 48.29%, respectively. Whereas, the lowest reductions in plants fresh weights were recorded on Mexican, Red sweet zoly and Saudi cultivars of pepper. The collected plant growth parameters (decreased percentage) on such cultivars were 3.25, 1.48 &1.43 %, respectively. Thereby, according to rating scale based on nematode reproduction as plant damage, the host category as shown in Table 1. 

Generally, these results are in accordance with findings of Oka et al., (2004); Gharabadiyan et al. (2012) and Cole et al., (2014). Several authors have studied the inheritance of the resistance reactions of C. annuum lines to root-knot nematodes. Hare (1956, 1957) demonstrated that a dominant gene (N) present in cv. Santaka controlled resistance to three different Meloidogyne species, but its efficiency depended upon the nematode isolate and the amount of inoculum (Hare, 1957). Hazarika, (1990); Khan et al. (2002); Basappa, (2005); Buena et al. (2006) and Devi et al. (2015) reported that, if a cultivar is listed as resistant to a species ofroot-knot nematode, this does not necessarily mean that the cultivar is resistant to all races of this species and the response of cultivars in some case, may also, very due to environmental factors. Resistance to one species or one race of root-knot nematodes may be independent of resistance to other species, races or biotypes (Bommalinga et al., (2013); Okorley et al., (2018) and Rabelo et al., (2018). For example, the genotypes of Capsicum annuum L. var. annuum are resistant based on the reproduction factor, and highly resistant based on the reproduction index to M. javanica while for the M. incognita race 3, six genotypes are resistant and/or highly resistant. No evaluated C. annuum genotype is resistant to M. enterolobii (Soares et al., 2018).