Aspectos da biologia e manejo do nematoide de cisto da soja
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2013-07-04
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Universidade Federal de Goiás
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Soybean is the most important oilseed crop grown in the world and Brazil is the second largest producer. Many pest problems can affect soybean, including the soybean cyst nematode, Heterodera glycines. The search for efficient management alternatives of this nematode and understanding of their biology have been largely studied, but still lacking information. Experiments were conducted under greenhouse conditions and naturally infested field aiming to better understand the behavior of H. glycines and to propose management alternatives. The first study had the purpose to evaluate the penetration and life cycle of H. glycines, race 3 (HG Type 0 -) in soybean cultivars resistant (BRSGO 8860RR) and susceptible (BRS Valiosa RR) under greenhouse conditions. Evaluations in stained roots were made at 2, 4, 6, 9, 12, 15, 18, 21, 24 and 30 days after inoculation (DAI). The penetration of H glycines occurred throughout the period of evaluation in both cultivars. The H. glycines life cycle was completed in 15 days, both in the susceptible and resistant cultivars. Resistant cultivar had the peak period of formation of J3, J4 and females delayed in comparison with the susceptible cultivar. The second study aimed to evaluate effectiveness of the resistance to H. glycines under high inoculum concentration, and the effect of increasing inoculum rates on the penetration of juveniles and H. glycines survival. Two experiments were conducted using three soybean cultivars (BRS Valiosa RR, susceptible to H. glycines; BRSGO Chapadoes and BRSGO 8860RR, both resistant to H. glycines) under four inoculum concentrations (1.000, 2.500, 5.000 and 10.000 eggs and J2 per plant). The increase in the H. glycines inoculum concentration increased the final nematode population in the susceptible cultivar. The cultivar resistance was not affected by high inoculum concentration. The root penetration of J2 increased as the inoculum concentration increased regardless the cultivar. The survival rate was higher in the susceptible cultivar decreasing with increasing of inoculum concentration. The third study evaluated the effect of seed treatment two soybean cultivars (resistant BRSGO 8860RR and susceptible BRS Valiosa RR). Two experiments were conducted, one in a naturally infested field and other under greenhouse conditions. The seed treatments did not affect the stand and the plant height of the resistant soybean cultivar. There was no effect of seed treatments on the nematode population in the field experiment. Under greenhouse, seeds treated with abamectin (50 and 75 mL a.i. 100 kg seed-1) + thiamethoxam (70 mL a.i.), imidacloprid + thiodicarb (105+315 mL a.i.) and thiodicarb + imidacloprid with carbendazim + thiram (75+225 e 30+70 mL a.i.) reduced the number of females per gram of roots on the susceptible cultivar. Seed treatment with imidacloprid + thiodicarb (75+225 mL a.i.) also reduced the number of eggs per female on the resistant cultivar BRSGO 8860RR.
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ARAÚJO, Fernando Godinho de. Aspectos da biologia e manejo do nematoide de cisto da soja. 2013. 89 f. Tese (Doutorado em Agronomia) - Universidade Federal de Goiás, Goiânia, 2013.