Reproduction of <i>Meloidogyne incognita </i>on eggplant rootstock cultivars and effect of eggplant rootstock cultivation on nematode population density

Abstract

The southern root-knot nematode Meloidogyne incognita is an important pathogen of solanaceous plants worldwide. To assess resistance and suppressiveness to the nematode of the Japanese cultivars of eggplant rootstocks, we conducted greenhouse experiments. Numbers of nematode egg masses were significantly lower on Solanum tor vum rootstock cultivars, Tonashimu, Torero, and Torvum vigor, than the cultivars of the other Solanum species after 45 days of cultivation. Next, we examined the effect of Tonashimu on the population density of the nematode in soil. After 116 days of cultivation, the second-stage juvenile density of the nematode in soil was reduced, and was significantly lower in pots of Tonashimu, than in those of Solanum melongena cultivars. These results suggest that the Japanese rootstock cultivars of S. torvum are resistant to the nematode, and could suppress nematode density in soil. Nematol. Res. 46(2), 87-90 (2016).Key words: grafting, resistance, root-knot nematode, Solanum torvum INTRODUCTIONEggplant (Solanum melongena) is cultivated worldwide and is especially popular in Asian countries such as China and India. Eggplant was introduced into Japan during the Nara period (AD 710 to 794) and today is an important domestically produced vegetable (Saito, 2004). Many crops, including eggplant, are attacked by the southern root-knot nematode Meloidogyne incognita, resulting in yield losses. In eggplant, 20-29% of total yield is estimated to be lost because of Melodogyne spp. (M. incognita is dominant) in the tropics (Sasser, 1979) and the economic threshold level of eggplant is reported to be 5.4 M. incognita second-stage juveniles (J2) per 100 g soil (Netcher and Sikora, 1990). Recently, Watanabe et al. (2013) reported that soil densities of two J2 per 20 g soil or greater with the Baermann technique have been shown to significantly reduce eggplant yield (cultivar Senryo 2go) at 50 days after planting.Most plant nematode control methods rely on chemical agents. Although soil fumigants such as 1,3-dichloropropene are commonly used, the use of such chemicals is likely to be subject to increasing restriction owing to environmental and safety concerns. The exploitation of resistant cultivars is the most effective and environmentally benign method to reduce nematodeinduced crop loss. However, no eggplant cultivar resistant to M. incognita has been found.Eggplant cultivars grafted onto resistant rootstocks are used to prevent various diseases, including bacterial wilt (caused by Ralstonia solanacearum), and Fusarium wilt (caused by Fusarium oxysporum) (Yoshida, 2004). Solanum torvum has a poor germination rate and slow seedling development but is employed as rootstock for eggplant cultivation because of its vigor and resistance to serious soil-borne diseases as described above (Gousset et al., 2005;Miceli et al., 2014). Moreover, S. torvum has been found to exhibit resistance to M. incognita in several studies conducted in Japan and abroad (Ali et al., 1992; Daunay and Dalmasso, 1985; Dhivya et al., 2014;Ha...

Response of eggplant genotypes to avirulent and virulent populations of Meloidogyne incognita (Kofoid & White, 1919) Chitwood, 1949 (Tylenchida: Meloidogynidae)

“…Y8 and Y7 genotypes were resistant to S6 and V14 according to the egg mass index but were susceptible according to the gall index. Several studies have shown that S. integrifolium is susceptible to M. incognita (Daunay & Dalmasso, 1985;Ali et al, 1992;Rahman et al, 2002;Uehara et al, 2016). In the present study, Solanum aethiopicum L. Y14 and Y30 genotypes were susceptible to both the avirulent and virulent populations of M. incognita.…”

“…The cultivated eggplant cv. Senryo 2 gou was susceptible to populations of M. incognita (Uehera et al, 2016;2017), while the rootstock cultivar Daitaro was susceptible to the virulent M. incognita Chiba and Niigata populations (Uehara et al, 2016). In another study, S. melongena cultivars, including Pusa Purple Long, Purple Cluster and Purple Round, were susceptible to M. incognita (Alam et al, 1974;Dhawan & Sethi, 1976;Ravichandra et al, 1988;Nayak & Sharma, 2013).…”

“…Eggplants cultivated are susceptible to RKNs; however, some wild eggplant species are resistant to some RKN species (Daunay & Dalmasso, 1985;Hebert, 1985;Ali et al, 1992;Boiteux & Charchar, 1996;Rahman et al, 2002;Uehara et al, 2016;2017;Öçal et al, 2018). At present, Solanum torvum (Sw.) is commonly used as a rootstock (Uehara et al, 2017).…”

Differences in parasitism of Meloidogyne incognita and two genotypes of M. arenaria on Solanum torvum in Japan

“…(Ali et al., ; Boiteux & Charchar, ; Daunay & Dalmasso, ; Dhivya et al., ; Gonzalez et al., ; Hara et al., ; Ryu, ; Shetty & Reddy, ). In addition, our previous study showed that S. torvum is resistant to M. incognita in Japan (Uehara et al., ). Moreover, S. torvum is resistant to M. arenaria in areas outside Japan (Daunay & Dalmasso, ; Gonzalez et al., ; Ryu, ).…”

“…Moreover, several studies in Japan and elsewhere have shown that S. torvum is resistant to root-knot nematodes, including Meloidogyne incognita, Meloidogyne javanica and Meloidogyne arenaria (Ali, Matsuzoe, Okubo, & Fujieda, 1992;Boiteux & Charchar, 1996;Daunay & Dalmasso, 1985;Dhivya, Sadasakthi, & Sivakumar, 2014;Gonzalez et al, 2010;Hara, Momota, Kusakari, Abe, & Yamada, 1983;Ryu, 2012;Shetty & Reddy, 1985). Previously, we have demonstrated that S. torvum rootstock is unlikely to cause sudden increases in M. incognita population density, in contrast to the other rootstock cultivars used for eggplant cultivation (Uehara et al, 2016).…”