不同氮素水平下水稻叶片及相邻叶位SPAD值变化特征

通过大田试验,研究在3种不同施肥方案和6个施氮水平下,水稻植株整个生长周期SPAD值的变化情况以及水稻分蘖、孕穗和抽穗3个重要时期主茎顶1叶至顶4叶的SPAD值分布变化特征。结果表明:水稻整个生长期叶色呈现"黑黄"交替的变化规律,而主茎顶4叶对氮素供应盈缺的反应最为敏感,可作为反映水稻N素营养状况的理想指示叶;对水稻主茎上各个相邻叶位的SPAD差值与施氮水平之间的相关性比较发现,顶4叶和顶3叶的SPAD差值(SPADL4-L3)与施氮水平之间存在明显的相关性,随着施氮水平的提高,顶4叶与顶3叶间的SPAD值差异逐渐缩小,且这一结果不受施肥条件和水稻生长时期的影响,因此,也可以利用SPADL4-L3值作为水稻整个生育期N素营养状况实时诊断的指标。

Dynamic characteristics of SPAD value of rice leaf and adjacent leaf under different N application rates

A field experiment was conducted to investigate the dynamic characteristics of SPAD reading during growth stage of rice and the spatial distribution of SPAD value of four leaves from the top on main stem of rice using the chlorophyll meter SPAD under three different fertilization programs and six different N application rates at tillering stage,booting stage and heading stage of rice.The results showed that the greenness of rice leaf was regularly changed as "black-yellow" alternation ways through the whole growth period of rice,and the sensitivity of the fourth leaf from the top to N was highest,giving it as the most ideal indicator of rice leaf position when using SPAD value to diagnose N status.Furthermore,the difference between SPAD values of the adjacent leaf and nitrogen application rates showed that SPADL4-L3 was highly related to the plant nitrogen content.With the increasing plant nitrogen content,the difference in SPAD value between the fourth leaf and the third leaf decreased,regardless of fertilizer application condition and development stage.Thus,SPADL4-L3 value could be used as a suitable indicator for rice plant nutrition status at whole stage.