**7.3. Cultural practices**

The cultural control generally depends on date and depth of sowing and manipulation of agronomic practices [68, 87]. It is reported that delay sowing usually lowers the wilt incidence whereas compared with early sowing (end of July), late sowing resulted in low yield [88]. The most suitable dates vary according to the different production regions. Use of clean seed for sowing and use of fungicidal seed treatment can reduce contaminating inoculum sources. To prevent the crop from various diseases a proper depth (10–12 cm) of seed planting should be used [89]. Intercropping/mixed cropping is being suggested for reduced wilt incidence and increased crop yield. Haware (1982) suggested that deep ploughing and removal of infected trash can reduce inoculum levels of Fusarium wilt of chickpea [90]. Soil solarization is another way to minimize the disease incidence [91]. In order to control the lentil wilt pathogen, chemical amendments (Mn and Zn) and foliar application on lentil wilt is also recommended. The study suggests that the application of Zn and Mn salts at 80 ppm concentration on presoaked seeds of lentil has shown promising results on the control of wilt disease [92].

pathotypes, it is difficult to develop the resistant cultivars. Hence, the knowledge of about the inheritance and genetics of wilt resistance is important to develop resistant or moderately resistant cultivars. The studies in genetics of resistance to Fusarium wilt will eventually help to produce more resistant lentil cultivars [104]. Resistant or moderately resistant lentil cultivars (OPL 58, DPL 61 and DPL 62) significantly reduced wilt incidence and severity of root rot, and increase grain yield [31]. Very limited studies are available on the genetics and inheritance pattern of wilt resistance in lentil. Kamboj et al. (1990) has reported five independent genes to confer resistance to Fusarium wilt in lentil [105]. Eujayl et al. (1998) has also recorded the monogenic inheritance in 'ILL 5588' for wilt resistance and designated the gene as Fw. A study based on allelism test, identified 2 genes each of duplicate genes and complementary genes imparting resistance in the variety PL 234, JL 446 and PL 286, respectively [104]. However, Abbas (1995) has reported that only one dominant gene is controlling the wilt

Fusarium Wilt: A Killer Disease of Lentil http://dx.doi.org/10.5772/intechopen.72508 127

Stevenson et al. (1995) has explained that the plant root exudates and the difference in resistance in genotypes depend on the amount of root exudates and their antifungal compound [107]. Another study reveals that the root exudates release considerable amounts of organic substance in soil including the amino acids and sugars and the amino acid (Glycine and phenylalanine) were found to have an inhibitory effect upon the spore germination of pathogen [108]. Iftikhar et al. (2005) analyzed the presence and involvement of antifungal compounds in wilt resistance. The result suggests that the phenolics have an important role in imparting resistance against wilt disease because only wilt-resistant lines produced this compound [109]. Similarly, in another study the potential of the lines to produce phytoalexins influences their resistance to fungal infections [73, 110]. Similarly, a peptide with a molecular mass of 11 kDa, was isolated from dry seeds of red lentil has exhibited antifungal activity against *Fusarium oxysporum* [111]. These selected lines serve as a reliable source of disease resistance

The classical plant breeding is based on recombination breeding approach by selecting the desirable plants on the basis of their phenotypic characters. However, this approach is less precise and time consuming when dealing with quantitative traits which are highly influenced by environment and genotype-environment (GE) interaction [112]. Therefore, it is important to integrate modern biotechnological tools such as genetic engineering and marker assisted selection (MAS) in lentil breeding program to mainstream new genetic variability in

In early 1980s, the first genetic linkage map of lentil was constructed using morphological and isozyme markers [113, 114]. Later, Eujayl et al. (1998) has reported first comprehensive linkage map with 177 RAPD, AFLP, RFLP, and morphological markers was developed using inter specific recombinant inbred lines (RIL) population of a single cross of *L. culinaris* × *L. orientalis* [104, 106]. Hamwieh et al. (2005) added 39 SSR and 50 AFLP markers to the comprehensive Lens map constructed by Eujayl et al. (1998), comprising 283 genetic markers covering 715 cM. They have constructed first genomic library from a cultivated accession, ILL5588 using the restriction enzyme Sau3AI (*Staphylococcus aureus* 3A) and screened with (GT)10, (GA)10, (GC)10, (GAA)8, (TA)10, and (TAA) probes. This study reveals that only SSR59-2B

resistance found in the crosses made at ICARDA [106].

and can be used in Fusarium wilt resistance breeding programs.

**7.6. Modern breeding approach**

the cultivated gene pool.

#### **7.4. Fusarium wilt resistant cultivars**

The initial step in managing the disease is to develop a reliable and reproducible disease screening techniques, so that a large number of germplasm (cultivated and wild relatives) can be evaluated in wilt sick plot and in greenhouse. The varietal resistance is a major goal of lentil improvement programme currently running at the International Centre for Agricultural Research in the Dry Areas (ICARDA). In order to identify the resistant variety of Fusarium wilt, screening under field and controlled conditions (green house and laboratory conditions) has been suggested [93, 94]. The systematic utilization of resistant source for wilt from cultivated accessions such as 'ILL 5883', 'ILL 5588', 'ILL 4400' and 'ILL 590' has resulted in the development of a wide spectrum of Fusarium wilt resistant varieties at ICARDA. Some of the prominent wilt resistant varieties in Syria ('Idleb 2', 'Idleb 3', 'Idleb 4' and 'Ebla 1'), Lebanon ('Talya 2', 'Rachayya' and 'Hala'), Turkey ('Firat 87' and 'Syran 96'), Ethiopia ('Adaa', 'Alemaya', 'Assano', 'Alemtena' and 'Teshale'), Iran ('Kimiya') and Iraq ('IPA 98') [95]. In India, several wilt resistant varieties are released such as 'L 4147', 'Pant L 406', 'Pant L 4', 'Pant L 639', 'Priya', 'Seri', 'JL 3', 'Noori', and 'VL 507' under national program [65, 96, 97].

The lentil germplasm can be screened under natural condition with natural inoculum of *Fol* in field. Wilt sick plot (WSP) is the most common method used to screen disease resistant plants under natural conditions. The WSPs have been developed by ICARDA, and NARS. The advantage of this method is that, large number of genotypes can be screened. Bayaa et al. (1997) has screened a core collection of 577 lentil germplasm accessions from 33 countries. The result reveals that the most resistant accessions came from Chile, Egypt, India, Iran and Romania and also emphasize the relative uniformity of disease pressure in WSPs [19].

Different inoculation methods have been used to for the infectivity of wilt in chickpea but in lentil very limited work has been conducted [12, 98, 99]. The inoculum density of about 106 conidia ml−1 is generally been used to establish the pathogen [100]. Wild species are an invaluable source for disease resistance. The wild germplasm of lentil was evaluated for resistance against biotic and abiotic stresses was done at ICARDA [101]. The crosses were made between the wild lentil (*L. culinaris* ssp. *orientalis*) and the cultigen has resulted in highyielding selections under dryland conditions. Similarly, another study was done to screen the 221 accessions representing five species/subspecies, showed resistance in ILWL 113 (*L. culinaris* ssp. *orientalis*) from Turkey and ILWL 138 (*L. ervoides*) from Syria [102]. In India, seventy accessions representing four wild species/sub-species were evaluated and the donors for *Fol* resistance were identified in all species. The wild accessions of lentil (one of *L. culinaris* ssp. *orientalis* (ILWL76), five of *L. odemensis* (ILWLs 35, 39, 153, 237, 300), eleven of *L. ervoides* (ILWLs 40, 41, 42, 133, 204, 251, 258, 261, 271, 280 and 299) and six of *L. nigricans* (ILWLs 22, 26, 31, 37, 38, 430) can provide an important source of alien genes for disease resistance [103].

#### **7.5. Genetic of Fusarium wilt resistance**

The most economical means to control the Fusarium wilt of lentil is through the development of resistant varieties [12]. Due to the evolution of new races and co-existence of more than one pathotypes, it is difficult to develop the resistant cultivars. Hence, the knowledge of about the inheritance and genetics of wilt resistance is important to develop resistant or moderately resistant cultivars. The studies in genetics of resistance to Fusarium wilt will eventually help to produce more resistant lentil cultivars [104]. Resistant or moderately resistant lentil cultivars (OPL 58, DPL 61 and DPL 62) significantly reduced wilt incidence and severity of root rot, and increase grain yield [31]. Very limited studies are available on the genetics and inheritance pattern of wilt resistance in lentil. Kamboj et al. (1990) has reported five independent genes to confer resistance to Fusarium wilt in lentil [105]. Eujayl et al. (1998) has also recorded the monogenic inheritance in 'ILL 5588' for wilt resistance and designated the gene as Fw. A study based on allelism test, identified 2 genes each of duplicate genes and complementary genes imparting resistance in the variety PL 234, JL 446 and PL 286, respectively [104]. However, Abbas (1995) has reported that only one dominant gene is controlling the wilt resistance found in the crosses made at ICARDA [106].

Stevenson et al. (1995) has explained that the plant root exudates and the difference in resistance in genotypes depend on the amount of root exudates and their antifungal compound [107]. Another study reveals that the root exudates release considerable amounts of organic substance in soil including the amino acids and sugars and the amino acid (Glycine and phenylalanine) were found to have an inhibitory effect upon the spore germination of pathogen [108]. Iftikhar et al. (2005) analyzed the presence and involvement of antifungal compounds in wilt resistance. The result suggests that the phenolics have an important role in imparting resistance against wilt disease because only wilt-resistant lines produced this compound [109]. Similarly, in another study the potential of the lines to produce phytoalexins influences their resistance to fungal infections [73, 110]. Similarly, a peptide with a molecular mass of 11 kDa, was isolated from dry seeds of red lentil has exhibited antifungal activity against *Fusarium oxysporum* [111]. These selected lines serve as a reliable source of disease resistance and can be used in Fusarium wilt resistance breeding programs.
