Munjangbyeo' is a japonica rice cultivar developed from a cross between Sangsanbyeo and Suweon 397 by Sangju Substation of National Yeongnam Agricultural Experiment Station, RDA in 1999. The cultivar is early matured with heading date of Aug. 2 in ordinar

Nonghobyeo', was derived from a mutant of Milyang 95, by pure line selection method, which was developed from the single cross between Chukei 1016 and Milyang 79, by the rice breeding team of National Yeongnam Agricultural Experiment Station (NYAES) in 19

Sangmibyeo' is a japonica rice cultivar developed from a cross between Sambaegbyeo and Ou 316 by Sangju Substation of National Yeongnam Agricultural Experiment Station, R.D.A. in 1998. The cultivar is early maturing with heading date of August 7 in ordina

To obtain a basic information on the development of effective control strategies for weedy rice in direct seeding rice cultivation, occurrence patterns of weedy rice as influenced by different cultural practices such as cultivation method, water management, seeding time, and tillage were investigated in field or pot experiments. High occurrence of weedy rice was observed in a continuous direct seeding paddy field as compared to machine transplanted one. Based on the percent of weedy rice panicle over three years trial, high ridged dry seeding was highest with 36.9%, followed by wet seeding with 30.9%, water seeding with 14.6% and machine transplanting rice with 0.8%, indicating 97.8% reduction in weedy rice occurrence by machine transplanting rice as compared with high ridged dry seeding. Germination of weedy rice was promoted to 83-94 % when rice panicle was flooded from September 30 to October 10 for 6 days and 74-88% for 9 days on October 20. Weedy rice occurrence was also substantially reduced by delayed seeding on June 10 and intensive tillage. The results suggest that machine transplanting rice be more effective cultural practice than flooding treatment, delayed seeding and intensive tillage when weedy rice problem occurs in direct seeded paddy field.

Occurrence of Weedy Rice as Affected by Cultural Practices

The effects of plant hormones (NAA, GA3 and BA) and light qualities (white, red, green and blue light) on the changes of reducing sugar contents and invertase isozyme activities in leaves of maize (Zea mays L.) and mung bean (Phaseolus radiatus L.) seedlings were investigated. NAA accelerated the increase of reducing sugar contents and invertase isozyme activities, on the contrary, GA3 had little effect in the accumulation of reducing sugar and in the increase of enzyme activities from the leaves of maize and mung bean seedlings. On the other hand, BA accelerated an increase in the activities of the invertase isozyme from the leaves of mung bean seedlings whereas it had little effect in the increase of the enzyme activities from those of maize seedlings. The accumulation of reducing sugar in leaves of both seedlings was promoted by red light irradiation compared to white light irradiation, while the activities of the enzyme were little affected by various light qualities. In the simultaneous applications of plant hormone and light quality, NAA with white light was very effective in the increase of reducing sugar contents and the enzyme activities from the leaves of mung bean seedlings, whereas NAA application with blue light showed a prominent enhancement in the reducing sugar contents and the enzyme activities from those of maize seedlings. These results suggest that plant hormone, particularly NAA, may be a more important factor than various light qualities in the stimulation of invertase activity.

Light qualities and three kinds of plant hormones, NAA, GA_3 and BA were treated on maize seedlings to investigate the effect on formation of the chlorophyll-protein complexes. Each three kinds of plant hormones accelerated the chlorophyll proteins formation, particularly LHCP-1 and LHCP-3, but two kinds of hormonal combinations didn`t promote these proteins accumulation under sun light condition. The formation of chlorophyll proteins of LHCP-1, CPA and LHCP-3 associated with PSⅡ was promoted under red light compared to sun light, on the contrary the formation of chlorophyll proteins was not affected by white light. Plant hormones under red light induced chlorophyll proteins formation associated with PSⅡ at early state of chloroplast development and two kinds of hormonal combinations under red light were very effective in accumulation of chlorophyll proteins of PSⅡ in contrast to sun light. The results obtained suggest that light may play an important role compared to plant hormones in the formation of chlorophyll proteins.