Evauatilon of Trap-plant Cultivars Potential on Reductions of Sugar Beet Soil-borne pathogens

Sugar beet cyst nematode (SBCN) is known as a nematode whose damages can be mitigated by rotation. Given the fact that oilseed radish (Raphanus sativus ssp. oleifera) and white mustard (Sinapis alba L.) is not widely included in crop rotations containing sugar beet in Iran, the present study was carried out to study the phenology and growth stages of oilseed radish (Adagio Cv.) under tempearte conditions (Karaj, 2010-2011), and the effect of sowing two commercial cultivars of oilseed radish (Adagio and Colonel) and white mustard (Luna and Accent) on the reduction of nematode population (in Isfahan and Jovein) in 2009-2011 and the infection to rhizomania (in Shiraz), and the subsequent response of sugar beets. It was found that 5-15 kg oilseed radish seeds should be sown from mid-July until early-August in order to harvest one cutting of forage (about 8-10 weeks before beginning of -6 C killing cold temperature) and incorporating the second-cutting with soil which would increase soil nitrate (NO3-N) at 0-30 cm depth by about 16.6 mg/kg. Under these conditions, about 3.4-5.5 t.ha-1 dry hay and 1.0-1.2 t.ha-1 protein would be produced. Different cultivars of oilseed radish and white mustard had different potential of fodder production in the studied regions. Also, the results of qualitative analysis of oilseed radish (Adagio Cv.) hay showed that it can produce forage with 49 3% dry matter digestibility (DMD), 13 2% water soluble carbohydrates (WSC), 14 3% crude protein (CP), 32 4% crude fiber (CF), 44 3% acid detergent fiber (ADF), 57 6% neutral detergent fiber (NDF), and 8 1% ash (ASH). Trap-plant cultivation significantly decrease the number of eggs+J2 of the nematode. However, trap-plant cultivars had different efficiency in reducing the number of nematodes in Isfahan and Shiraz. Relative coefficient of nematode population reduction (Pf/Pi) was 70, 53 and 82-93% in Isfahan, Shiraz and Jovein, respectively, although the cultivation of trap plant had no significant effect on the intensity of rhizominia in Shiraz. Sugar beet planting after incorporating oilseed radish and white mustard forage significantly increased sugar beet root yield by 30-91 and 21-37% in Isfahan and Jovein as compared to control, respectively. In Shiraz region too, white sugar yield of Accent plots (6.21 t.ha-1) exhibited significant difference with that of control plot (4.81 t.ha-1). Sugar beet cultivation in plots planted with Adagio, Colonel and Accent in Isfahan, with Colonel in Jovein and with Accent in Shiraz increased sugar content by 1.66-1.95, 1.23 and 1.93% as compared to control, respectively.