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采用盆栽试验探讨利用叶绿素计(Chlorophyll MeterSPAD—502)预测杂交狼尾草粗蛋白含量和牧草的施氮水平。试验设5个氮肥水平(纯氮量0,100,200,300,400kg/hm2)和3次重复,利用叶绿素计读取不同氮水平不同时期杂交狼尾草倒数第3片叶子的SPAD值,同时测定部分农艺性状和茎叶粗蛋白含量。结果表明,杂交狼尾草的SPAD值和粗蛋白含量是随着牧草的生长而逐渐降低,分蘖数、株高和生物产量随着牧草的生长而提高;杂交狼尾草的SPAD值与其施氮水平、分蘖数、株高、产量和茎叶粗蛋白含量都成正相关,与牧草的株高相关性最小且都不显著;与牧草的分蘖数和产量相关性大,接近或达显著水平;与牧草的茎叶粗蛋白含量相关性最大,均达显著或极显著水平。因此,利用SPAD值可用来预测杂交狼尾草茎叶粗蛋白含量,进而诊断杂交狼尾草的氮素营养水平,为牧草的合理施肥提供依据。
Pot experiments were conducted to determine the crude protein content of Pennisetum chongqing (Hance) and the nitrogen application rate of forage grass using Chlorophyll MeterSPAD-502. Five nitrogenous fertilizers (0,100,200,300,400kg / hm2 pure nitrogen) and three replications were tested in this experiment. The SPAD value of the third penultimate hybrid P. philoxeroides leaf was measured by chlorophyll meter, and some agronomic traits and stems Leaf crude protein content. The results showed that the SPAD value and crude protein content of hybrid Pennisetum decreased with the growth of forage grass, tiller number, plant height and biomass increased with the growth of forage grass. The SPAD value of hybrid Pennisetum was similar to that of nitrogen applied There was a positive correlation between the tillering number, plant height, yield and crude protein content of stems and leaves, and no significant correlation with the plant height of forage grass. The correlation between tiller number and yield of forage was close to or reached a significant level. Forage grass stems and leaves crude protein content of the most relevant, reached significant or very significant level. Therefore, the use of SPAD value can be used to predict the crude protein content of Pennisetum hybrids, and then diagnose the nitrogen nutrition level of hybrid Pennisetum, providing the basis for rational forage fertilization.