SPAD值与杂交狼尾草施氮水平和农艺性状的关系

采用盆栽试验探讨利用叶绿素计(Chlorophyll Meter SPAD-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0,100,200,300,400k9/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.

Relation of SPAD Reading with Traits and Protein Content of Pennisetum Hybrid Applied with Various Levels of Nitrogen

Pot experiments were conducted to investigate how to predict the crude protein content and the level of nitrogen application of Pennisetum Hybrid using the SPAD value by Chlorophyll Meter.The experiment included 5 treatments under different nitrogen levels(0 kg/hm2,100 kg/hm2,200 kg/hm2,300 kg/hm2,400 kg/hm2) with 3 replicates.The SPAD value of the third leaf from top of Pennisetum Hybrid was determined by using the Chlorophyll Meter under different nitrogen levels at different stages, and partial agro-traits and the crude protein content in stems and leaves were determined simultaneously. The results showed that the SPAD value and the crude protein content in stems and leaves decreased gradually, but the number of tillers, the plant height and the yield of Pennisetum Hybrid increased with their growth. The SPAD value had a positive correlation with the level of nitrogen application, the number of tillers, the plant height, the yield and the crude protein content in stems and leaves of Pennisetum Hybrid. In addition, the SPAD value had the lowest but not significant correlation with the plant height,had a higher correlation with the number of tillers and the yield at significant or almost significant level, and had the highest correlation with the crude protein content in stems and leaves at significant or highly significant level.Therefore,the SPAD value from the Chlorophyll Meter could be used to predict the crude protein content in stems and leaves of Pennisetum Hybrid, and could further be used indirectly to reflect the level of nitrogen of Pennisetum Hybrid in view of providing a scientific basis for proper application of N fertilizer.