The application of molecular methods as complementary or alternative methods can help identifying the plants containing the resistance gene at genotypic level. Therefore, DNA markers can be useful tools for selecting resistant genotypes and can save the evaluation time and improve the precisions. Selection takes productive and genetic lines resistant to nematodes have been known in sugar beet genotypes by Polymerase chain reaction (PCR). Sugar beet (Beta vulgaris L.) is the greatest vital crops that standing following to sugar cane as sugar crop in the world, later it produces about 20 % of sucrose production annually in the world. In Egypt, Sugar beet is cultivated in 523188 faddans with an average production of 20.7 tons per faddan. Recently, reclaimed desert irrigated lands at West Nubaryia and El-Bostan regions has shown that sugar beet can be successfully grown under sandy soil area condition and its considered as the extended area for sugar beet production in Egypt. The most serious problem against sugar beet extension in new lands is root-knot nematode, Meloidogyne incognita and Meloidogyne javanica which were reported as major nematode pests of sugar beet in Egypt. Importance of employed resistance nematode sugar beet genotypes (cultivars/hybrids) in infested areas has a great concern.The present study was carried out during the growing season 2015 -2016 at pots experiment in Sabahia Agricultural Research Station, Alexandria, Egypt, for evaluating the reaction of seventeen sugar beet genotypes against the most serious nematode, (Meloidogyne incognita). The seventeen sugar beet genotypes tested in this test were twelve sugar beet commercial varieties, three sugar beet inbred lines and two sugar beet breeding materials. Computed damage index classified the seventeen sugar beet genotypes into five categories according to the varietal assessment. (Four were resistant(R), three were moderately resistant (MR), six were tolerant (T), two were susceptible (S) and two were hyper susceptible (HYS)). The results for conventional PCR indicated that genes of Hs1pro-1and HSPRO2 shows resistance to, (Meloidogyne incognita) beside the known function of these genes as resistant against cyst nematode (Heterodera schachtii). Mi-1.2 gene consider resistance to root knot nematode (Meloidogyne incognita) was found in (Mi-3) inbred line.
Filtrates of several fungi (Arthrobotry oligospora, Dactylella brochopage, Nematochomus concurrence, Fusarium exsporium, Trichoderma harzianum and Varticillium chlamydosporium) and bacteria (Bacills cereus, B. thuringiensis, Psendornonas fluorescens and Serratia odorifera) as biocontrol agents were tested for their nematicidal against the root-knot nematode, M. javanica infecting sugarbeet plants, as well as for their effects on yield and quality parameters. These microbial filtrates were applied as soil drench at the three concentrates (50, 75 and 1000%). Results showed that all fungi and bacteria filtrates significantly reduced the numbers of nematode population and reproduction factor comparing to the check treatment. The reduction percentage of nematode counts and reproduction factor was affected by microbial filtrate type and concentration used. Enhanced reduction followed increased concentration in each microbial filtrate. Moreover, root, leaves and sugar yields, as well as quality characters (i.e. T.S.S., sucrose and purity %) were also significantly increased. Among the fungi filtrates, V. chamydosporiusm filtrate at the highest concentration recorded the maximum effect in reducing number of nematode population and reproduction factor. Also, the highest increase percentages of leaves, root, sugar yields and sucrose, T.S.S and purity% were obtained at the highest concentrations of V. chlamydosporium. In case bacteria filtrates, the highest reduction of nematode population and reproduction factor as well as, the greatest root and sugar yields increases were achieved at the highest concentration of B. cereus and S. odorifera, filtrates. Generally, the plants treated with V. chlamydosporium, B. cereus and S. odorifera filtrates had less nematode population and higher productivity of sugarbeet than those plants treated with the other tested microbial agents. In addition, these filtrates had nearly the same effect of the nematicide, Oxamyl on root-knot nematode, M. javanica. Also, these biocontrol agents are ecological sound, economical viable and partial substitutes for costly and pollution causing chemical nematicides and have been a successful instead of these chemical nematicides management strategy when used alone or in combination with other strategies.
Four amino and organic acids, L-arginine, L-glutamic (as amino acids), ascorbic and salicylic (as organic acids) solution applied as soil drench in three concentration levels to evaluate for nematicidal effects against root-knot nematode, Meloidogyne javanica infecting sugarbeet. Their effects on sugarbeet yield and its components and quality parameters were determined. All of the tested compounds reduced the number of juvenile larvae in soil, immature stages, mature females in root, final nematode population as well as reproduction factor, comparison to the check treatment. These compounds were mostly variable in their effectiveness in reducing nematode infesting or reproduction factor and enhancing plant yield and quality according to compounds type and concentration level used. Then, the percentage of reduction in nematode parameters or/and the increases in crop parameters increased by increasing the concentration level of each tested compound. The ascorbic acid was more effective in reducing nematode fecundity, final nematode population and reproduction factor followed by salicylic acid, L-arginine acid and L-glutamic acid in a descending order. Also, the ascorbic acid component showed the best results in improving leaves, roots, sugar yields and quality parameters of sugarbeet in comparison with the other tested compounds. In comparing between the effects of both ascorbic acid and nematicide, Oxamyl on nematode development and reproduction factors as well as productivity of sugarbeet, the ascorbic acid recorded reduction in juveniles larvae in soil, final population number and reproduction factor with values of 76.3, 71.6% and 2.1 fold, respectively as well as increases in root yield and sugar yield with values of 65.73 and 126.51%, respectively, however, Oxamyl recorded reduction to 73.6, 77.3% and 1.9 fold in juveniles in soil, final population number and reproduction factor, respectively as well as increases to 68.09 and 124.12% in root and sugar yield, respectively. The problems associated with nematicides application turned the workers view to focus on new strategies or use new safe components or chemicals for nematode management program. On the other hand, it was obvious from the obtain data, the
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