Effects of N Application Rates and NO_3-N to NH_4-N Ratios on Yield and Quality of Flue-cured Tobacco Planted in Black Soil

A field experiment about effects of nitrogen application rates and different NO3-N to NH4-N ratios on agronomic, chemical and biological characteristics as well as yield and quality of flue-cured tobacco grown in a black soil was conducted from 2004 to 2005 in Heilongjiang Province. The results showed that the nitrogen application rates at 45 kg·hm^-2 with the ratio of 75% NO3-N to 25% NH4-N resulted in the highest potassium and reducing sugar contents in the flue-cured tobacco leaving with the highest quality grade and value. It is recommended that this ni- trogen application rate and NO3-N to NH4-N ratio should be widely applied on flue-cured tobacco grown in the black soil in Heilongjiang Province.

温度和盐度对虾夷马粪海胆耗氧率和排氨率的影响

采用封闭式呼吸器研究了虾夷马粪海胆（Ｓｔｒｏｎｇｙｌｏｃｅｎｔｒｏｔｕｓｉｎｔｅｒｍｅｄｉｕｓ）的耗氧率和排氨率与温度和盐度的关系。结果表明：在温度１５～２５℃的范围内，耗氧率和排氨率随温度的升高而增加；相同温度下，随个体重量的增加耗氧率和排氨率下降，呈负指数关系；虾夷马粪海胆的适宜盐度为３０左右，此时的耗氧率最大，为０．０９１ｍｇ／ｇ·ｈ，排氨率最低，为２３．６２μｇ／ｇ·ｈ。