| Budget Amount *help |
¥12,400,000 (Direct Cost: ¥12,400,000)
Fiscal Year 2004: ¥3,700,000 (Direct Cost: ¥3,700,000)
Fiscal Year 2003: ¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2002: ¥5,400,000 (Direct Cost: ¥5,400,000)
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| Research Abstract |
We focused on the bleeding rate as an index of root-system vitality of soybean, and made its dynamics through the plant growth and its diurnal change clear. With the bleeding rate, it was shown that the treatment of soil molding enhanced the root-system vitality all through the plant growth, resulting in higher shoot dry matter production and yields in both dry and wet years. The promoted development of adventitious roots, which are newer than (i.e., not so aged as) taproot, contributed to this enhancement of the root-system vitality. In an experiment on waterlogging, the growth of taproot was severely inhibited by the excessive soil moisture. and, instead, adventitious root were formed from the hypocotyl and basal part of the stem, which distributed and crawled around the soil surface. Thus, the effects of soil molding, which promotes adventitious roots formation and offer them the soil space for distribution and functioning, on the tolerance against waterlogging in soybean. The molding did not alleviate the inhibition of shoot growth (leaf area, leaf color, dry weight) during the 20-day waterlogging treatment, but remarkably enhanced the recovery after the treatment. The final shoot dry biomass and yield of waterlogged soybean was significantly enlarged by the molding. The root system of the molded and waterlogged soybean was very shallow but maintained large total root length by the development of adventitious roots in the molded part of the soil. The results indicated that soil molding can be a good management to avoid the excessive water stress that often occurs in paddy-fielded-originated soybean fields in Japan.
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