• Korean journal of applied entomology
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• v.55 no.4
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• pp.439-444
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• 2016

Maruca vitrata is a main insect pest against crops of Vigna species (V. angularis and V. radiata) and Sesbania sesban in Fabaceae, but the life cycle of the insect is unclear in Korea. In order to know over-wintering possibility, its stage of the insect, over-wintering entry season, and the first adult emergence season of the next year, we investigated over-wintering rates of the insect in outdoor conditions in Suwon ($37^{\circ}16^{\prime}N$ $126^{\circ}59^{\prime}E$ 35ASL). In all colonies which the rearing for larvae, pupae and eggs started after mid-September, adults did not emerge within the year, and all insects died before next June. In several trials for over-wintering of larvae and pupae in soil, all insects died, too. Larvae stored during specified periods at low temperatures (10 and $13^{\circ}C$) did not emerge. From the results, it was postulated that M. vitrata does not have an adaptability to temperature below zero, and cannot over-winter in Suwon area.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.1
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• pp.16-24
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• 2010

Effect of flooding on the desalting efficiency and the growth of sudan grass, barnyard grass, sesbania and corn was studied in a sandy soil of the Iweon reclaimed tidal land. Flooding plots were treated by 400 (one time flooding), 800 (two times flooding), and 1,200 mm(three times flooding) of water, respectively, and then soil salinities of the treated plots were compared with salinity of the control plot (not flooded) for estimation of desalting effect. Desalting ratio of 1,200 mm treatment was 78.3% for depth 0-20 cm, 70.5% for depth 20-40 cm and 60.8% for depth 40-60 cm, and then the soil salinity reached at 3~6 dS $m^{-1}$. Consequently, it was considered that sandy saline soil was satisfactorily desalted for upland crops to be cultivated by 1,200 mm flooding, but insufficiently desalted by 400 mm and 800 mm flooding because of high salinity ranged 5~14 dS $m^{-1}$ even after flooding treatment. In addition, it was estimated that soil salinity should be controled lower than 7.7 dS $m^{-1}$ in order to obtain more than 80%of crop emergence when four crops are simultaneously cultivated by inter- or mixed cropping in a field. Dry matter yields (kg $10a^{-1}$) was 1,068 for sudan grass, 696for barnyard grass, 1,426 for sesbania, and 1,164 for corn by 1,200 mm flooding treatment, but only 46.8~74.3% by 800 mm flooding treatment and 2.9~25.5% by 400 mm flooding treatment. Therefore, it is concluded that the flooding treatment more than 1,200 mm is necessary for satisfactory desalinization in order for the low salt tolerance crops to be cultivated in the sandy reclaimed tidal land.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.54 no.3
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• pp.299-306
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• 2009

In nitrogen-limited conditions, rhizobia lead to formation of nitrogen-fixing nodules on the roots of leguminous plants. The process of nodulation is autoregulated by pre-existing nodules in the same root system. The altered profile of sap proteins by inoculation with B. japonicum may indicate presence of a signal responsible for autoregulation transferred through stem. The 20 kDa protein enhanced by innoculation significantly decreased in intensity from 2.5 to 7 days after inoculation (DAI). However 6 kDa protein did increase during such a transition period. Western blot analysis showed that both 20 kDa and 6 kDa were cross-reacted with the SKTI antiserum. This suggests that SKTI may be involved in soybean nodulation by specific induction and degradation in stem sap during early stage of nodulation. RNAi technique and Agrobacterium rhizogenes-mediated transformation were applied to investigate the function of SKTI in nodulation. We have found that the number of rhizobium-induced nodule was much less in SKTIi-silenced hairy roots than the non-silenced. Indeed the quantitative RT-PCR showed that the expression level of SKTI gene was reduced over 40% in the transgenic hairy roots compared to the non-transgenic. It appears that the observed early induction of SKTI and degradation into small peptide in a specific time manner may be involved in autoregulation of nodulation in soybean and the specific mechanism of such regulation remains to be investigated.