氮肥水平和刈割间隔对杂交狼尾草根系活力和粗蛋白含量的影响

Effect of nitrogen fertilizer application and defoliation intervals on root vigour and crude protein in hybrid Pennisetum

为探明氮肥和刈割间隔对杂交狼尾草根系活力和粗蛋白含量的影响,在杂交狼尾草第1次刈割后,采用裂区设计(主区为4个N肥水平0,33.75,67.50和101.25kg/hm2,副区为4个刈割间隔21,28,35和42d)进行试验,结果表明,1)根系伤流液强度、伤流液中氨基酸总量平均值均以施肥水平33.75kg/hm2显著高于其他处理,硝态氮总量平均值随施肥水平提高而增加,不同处理间差异均显著。根系伤流液强度、伤流液中氨基酸总量平均值刈割间隔为28d时显著高于刈割间隔21,35和42d,硝态氮总量平均值刈割间隔35d时显著高于刈割间隔21,28和42d;2)植株粗蛋白含量N肥水平间差异显著,N肥水平101.25kg/hm2时平均粗蛋白含量达到13.34%,显著高于氮肥水平33.75kg/hm2和不施N处理,而与N肥水平67.50kg/hm2的平均粗蛋白含量12.59%无显著差异,刈割间隔28d时平均粗蛋白含量为13.83%,显著高于刈割间隔21,35和42d的粗蛋白含量11.86%,11.83%和11.05%;3)植株粗蛋白含量与根系伤流液中的氨基酸总量呈二次曲线关系;4)根系伤流液强度及其氮素形态变化规律为杂交狼尾草适宜施肥技术和刈割间隔的确定提供了依据。

The experiment was conducted to determine the effects of N fertilizer (NF) and defoliation interval (DI) on root vigor and crude protein in hybrid Pennisetum (Pennisetum americanum×P.purpureum). After the first harvest, complete random block split-split was designed. Main-block was four NF application level[0(CK),33.75(N_1), 67.50(N_2),101.25 kg/hm^2(N_3), subplot was DI(21,28,35,42 d). The results indicated that: 1) The average exudates intensity and total AA under 33.75 kg/hm^2 N fertilization rate were the highest among the four nitrogen fertilizer levels; The average total NO_3^--N increased and existed significant difference under four N fertilization rate; The average exudates intensity and total AA were significant highest at defoliate intervals of 28 d; The average total NO_3^--N was highest at 35 d defoliation intervals. 2)Content of crude protein in dry matter of Pennisetum had significant difference under different N fertilizer application. Crude protein averaged 13.34% in N_3 which was significant higher than 12.59% in N_1 and CK, and wasn't significantly different in N_2. Crude protein averaged 13.83% at 28 d DI, which was significantly higher than (11.86%), 11.83%, and 11.05% at 21,35 and 42 d separately. 3)The relationships between crude protein content in plant and AA in root exudates were quadratic equation.4)The physiological evidence for suitable N fertilizer rate and defoliation interval in Hybrid Pennisetum was supplied through regulation of exudates intensity and N formation.