【作者】 李刚华；

【导师】 丁艳锋；

【作者基本信息】 南京农业大学 ， 作物栽培学与耕作学， 2005， 硕士

【摘要】 本研究以95-38、武育粳3号、镇稻5394、9915等4个粳型品种和1个籼型品种R161-10的盆播氮肥试验、宁粳2号盆栽¹⁵N穗肥试验及¹⁵N顶4叶标记试验、武育粳3号大田穗肥试验、宁粳2号大田基追肥试验,研究了提高SPAD计诊断水稻氮素营养水平的技术措施,分析了叶片氮素的吸收和转运规律,并探讨RSPAD值与施肥量间的关系。主要结果如下: （1）同一叶片不同测定位置的SPAD值差异很大,SPAD值呈开口向下的二次曲线变化模式或由叶尖向叶基增加的直线变化模式。穗分化前后距叶尖20～50%处附近的SPAD值与叶片氮含量相关系数较高,30～50%处的变异系数较低,同时距叶尖30%处的测定值最能代表该叶的平均水平。因此,距叶尖30%处是最合适的测定位置。 （2）下位叶比上位叶对土壤氮的供应状况更为敏感,随着施氮量的增加,水稻叶片氮素含量、叶绿素含量、SPAD值相应的增加,而下位叶的增幅更明显。整个生育期水稻各叶位叶片SPAD值与其氮素含量及总叶片全氮量和植株氮含量均呈极显著的指数相关,以顶3叶相关性最高。穗分化前后SPAD值与水稻总叶片全氮量和植株氮含量的指数相关系数大小依次为顶3叶>顶4叶>顶1叶>顶2叶。适宜氮素水平下,穗分化前后顶3叶SPAD值的变异系数较小,而顶1叶变异系数较大。从而认为,在高产条件下,以某一特定叶片的SPAD值指标或以叶色差的大小来诊断推荐水稻穗肥施用时,顶3叶是较为理想的指示叶或参照叶。 （3）水稻高氮与低氮条件下顶3叶与顶4叶氮浓度及SPAD值大小顺序不同,低氮条件时顶3叶高于顶4叶,高氮时相反。土壤供氮能力越强,水稻植株从土壤中吸收的¹⁵N分配到顶4叶的比率和量越高,而顶4叶向外输出的¹⁵N也越多。顶4叶与顶3叶氮浓度的大小变化不仅反映了植株的氮素营养状况,同时反映土壤的供氮能力,在实践应用中可以通过顶3叶与顶4叶的叶色比较来直观判断。因此,顶3叶与顶4叶的叶色比（RSPAD）可以作为水稻氮素营养水平和丰缺状况的诊断指标。 （4）水稻的RSPAD值随穗肥施用而呈规律性变化,利用倒4叶期的RSPAD值来诊断推荐穗肥施用是可行的。用聚类分析方法将水稻穗分化始期不同小区的RSPAD值分为RSPAD>0和RSPAD≤0两种类型,即顶3叶叶色深于或浅于顶4叶叶色两种实践中容易辨别的类型。当水稻穗分化始期的RSPAD≤0时,以120～135kg N ha^-1的穗肥处理可获得较高的产量和氮肥利用率。而当水稻穗分化始期更多还原

【Abstract】 In this study, different nitrogen (N) pot experiment involving four japonica rice varieties (95-38, Wuyujing3, zhendao5394, 9915) and 1 indica variety in 2003, pot experiment with N15 labelled urea applied to soil and 4th leaf from the top on rice ningjing2 in 2004, field experiment with different nitrogen rate at spike differentiation stage on wuyujing 3 and different basal-dressing ratio on ningjing2 in 2003 were carried out. The objectives of this study were to: (1) determine the optimum measuring leaf site and leaf position with leaf chlorophyll meter (SPAD-502) for diagnosing the nitrogen status; (2) analysis the translocation and distribution of N between different plant parts and different leaves; (3) investigate the relationship of spad value between third leaf and 4th leaf from the top under different N supply level and explore the feasibility of nitrogen spike-dressing rate recommendation based on RSPAD value (the ratio of SPAD value of third leaf to that of 4th leaf). Results showed as following:(1) SPAD value varied with the measuring position on the same leaf, and distribution pattern can be fitted by quadratic (y=ax2+bx+c, a<0) or linear (y=ax +b, a>0) curve very well. At spike differentiation stage, the SPAD value measured at about 20-50% from the tip of leaf blade correlated best with leaf nitrogen content, variation coefficient of SPAD value measured at 30-50% from the tip of leaf blade was lowest, and the average SPAD value was located at 30% from the tip of leaf blade regardless of the leaf and measuring date. Thus, 30% from the tip of leaf blade was the best measuring position.(2) Leaf N/ chlorophyll content and SPAD value increased with the increasing N fertilizer, and the lower leaves were more sensitive to the soil N supply than the upper leaves. N content of different leaf positions were exponentially related with the corresponding SPAD values during the whole growth cycle, the determinationcoefficient was as high as 0.919, significant at 0.01 level. The SPAD value of third leaf from the top was most correlated with the whole leaf and plant N concentration among the top four leaves at all growth stages. The CV of SPAD value of third leaf from the top was smallest at fore-and-aft spike differentiation under optimal N level. Thus, third leaf from the top was the most ideal indicator leaf when using SPAD value or leaf color difference to diagnose N status and make N fertilization suggestion for spike in rice.(3) Nitrogen concentration and SPAD value of third leaf and 4th leaf varied with nitrogen supply level, third leaf with higher value under low N supply level and vice versa. Stronger was the soil N supply level, higher was the amount and distribution ratio of N15 uptake from soil to 4th leaf from the top, and more output from the 4th leaf to other leaves. Relative change of nitrogen concentration or SPAD value of third and 4th leaf not only indicated the plant nitrogen status, but also reflected the soil nitrogen supply level, thus their ratio (RSPAD) can be used to diagnosis the rice nitrogen status.(4) RSPAD value changed in rule after nitrogen topdressing at spike differentiation stage. It is feasible for N topdressing rate recommendation based on the RSPAD value at n-4 stage. RSAPD can be divided into two types through clustering analysis, leaf SPAD value of third leaf from the top higher (RSAPD>0) or lower than the 4th leaf (RSPAD<0). In order to achieve high yield and high nitrogen use efficiency (NUE), the optimal N rate was 120-135 kg N ha-1 for RSPAD<0 and 180 kg N ha-1 for RSAPD>0.更多还原