Relationship Between Heterogeneity in Germination and Growth and Structure of Soil and Soil Layr in Large-sized Direct Sown Paddy Field

1995财政年度的研究活动是对蒸渗仪发芽和生长的异质性、土壤和土层的结构以及发芽和生长的试验的继续。在千叶县樱田市的稻田地区进行了田间调查。喷雾机的种子密度的不均一性较小，而喷雾机的种子密度的异质性较大。密度的平均值很容易控制，但密度的标准差很难控制。但标准差的不均一性对空间的可能性至关重要，从而导致产量下降。在土壤和油层上，土壤物理性质，对土壤化学(肥力)和平整条件进行了调查，结果表明，土壤硬度是影响根系和植物生长的重要因素。蒸渗仪试验明确了个体密度与生长的关系；当种子间距为2~20 cm时，生长速度基本不变。因此，在随机苗直播的情况下，避免过多的稀疏部位是最重要的方法。为了保证种子的均匀萌发和生长，土壤和土层的管理与均匀育苗方法一样重要。

The research activity in the fiscal year of 1995 is the continuation of field survey on heterogeneity of germination and growth, structure of soil and soil layr and experiment of germination and growth in lysimeters.The field survey was done in the paddy field area in Sakura city, Chiba prefecture.Heterogeneity of seed density is smaller in the case of mist machine and larger in the case of hericopter.The average of density is easy for controling but standard deviation of density is difficult for controling.But the heterogeneity in standard deviation is critical for the possibility of spacity, which decreases the yield.On the soil and aoil layr, characteristics of soil physics, soil chemistry(fertility)and levelling conditins are surveyed.As a result, it became clear that soil hardness is the important factor for growth of roots and plant.Lysimeter experiment has made clear of the relationship between individual density and growth ; i.e.when the distance between seeds are 2 to 20 cm, the rates of growth does not changed.As the result, in the case of direct seeding by random seedling, to avoid too much sparce places is the most important method.And for ensuring homogenerous germination and growth, the management of soil and soil layr is very important as wall as homogenerous seedling method.