辽河三角洲稻区施氮水平对水稻生长发育及产量的影响

Effects of Nitrogen Application Rate on Rice Growth and Yield in Liaohe Delta

辽河三角洲单季稻区属于辽河平原水稻的主产区、高产区。长期以来,该地区主要以追加化肥来提高水稻产量,导致氮肥投入过高,利用率较低。根据水稻生育周期内对氮素的生物学响应,分析了辽河三角洲代表性水稻产区内不同氮素条件下水稻的生长发育及产量表现,以期获得适合该地区的合理氮肥推荐用量。研究表明,水稻的株高、功能叶片的SPAD值、茎蘖总量与氮素用量呈显著正相关,同时分蘖期的长短也受氮素水平的控制,即施氮量越高分蘖期越长。从产量及构成因子来看,有效穗数、穗粒数、千粒重对籽粒产量有显著贡献,中高氮处理(N210、N260、N315)的产量构成因子都处于较优水平,因此产量最高;低氮处理(N160)与极高氮处理(N420)的产量构成因子指标较差,产量显著低于中高氮处理。产量与施氮量符合线性加平台的肥料效应方程,基于该方程得出辽河三角洲地区最佳氮肥推荐用量为225kg/hm^2。由于土壤-水稻系统是一个整体,基于系统内的氮素平衡理论估算出辽河三角洲地区推荐氮素用量为221~235kg/hm^2。鉴于以上研究结果,推荐辽河三角洲地区合理氮素施用阈值为225~235kg/hm^2。

The Liaohe Delta, single-cropping rice region belongs to the main rice-producing area in Liaohe Plain. The local farmers rely too much on additional chemical fertilizers to improve rice yield, resulting in high input of nitrogen fertilizer and low use efficiency. Based on the biological response of rice to nitrogen in the growth cycle, the agronomic characteristics of rice including plant height, SPAD value, tillering number, and yield parameters of rice under different nitrogen fertilizer rates were investigated. The results showed that plant height, SPAD value of flag leaves and tiller numbers were positively correlated with the amount of nitrogen fertilizer. Higher Nitrogen treatment results in prolonged tillering period, which could lead to the late maturity of rice shoot. In terms of yield factors, the yields of medium and high nitrogen treatments(N210, N260 and N315) was the highest, compared to low nitrogen treatment(N160) and(N420) treatment. decreased significantly compared to them due to lack of nitrogen and nitrogen excess. The yield components of N420 treatment, including grain number per ear, rate of grain filling and 1000-grain weight, were significantly lower than those of the three treatments with higher yield. The yield and nitrogen application rate accorded with the yield-response curve of linear plus platform. According to the equation, the optimum nitrogen application rate in this area was 225 kg/ha. Although nitrogen use efficiency of N210 treatment was the highest(42%), considering the nitrogen balance of soil-plant system, it was suggested that the nitrogen application rate should be between 221-235 kg/ha in Liaohe River Delta. In the view of the above results, it is recommended that the reasonable threshold of nitrogen fertilizer application rate in Liaohe River Delta should be 225-235 kg/ha.