氮肥和多效唑对小麦茎秆木质素合成的影响及其与抗倒伏性的关系

 【目的】明确氮肥和多效唑对小麦茎秆木质素含量的影响，探讨氮肥和多效唑调节茎秆抗倒伏能力的机制。【方法】以小麦品种烟农21和藁城8901为材料，通过田间试验和室内分析，研究氮肥和多效唑对小麦不同时期茎秆抗折力、抗倒伏指数、木质素含量的影响以及木质素合成相关酶的活性变化。【结果】同品种条件下，与低施氮（225 kg?hm-2）处理相比，高施氮（300 kg?hm-2）处理降低了茎秆苯丙氨酸转氨酶（PAL）、酪氨酸解氨酶（TAL）、肉桂醇脱氢酶（CAD）和4-香豆酸:CoA连接酶（4CL）的活性，茎秆木质素含量、抗折力和抗倒伏指数降低。而喷施多效唑显著提高茎秆PAL、TAL和CAD的活性，木质素含量、茎秆抗折力和抗倒伏指数提高，倒伏面积和倒伏程度降低。相关分析表明，茎秆抗倒伏指数与木质素含量呈显著正相关（r=0.61，P＜0.05）；木质素含量与PAL、TAL和CAD酶活性呈显著正相关，与4CL酶活性相关不显著。【结论】高施氮量处理降低了茎秆木质素合成相关酶的活性和木质素含量，茎秆抗倒伏能力降低。而施用多效唑显著提高茎秆木质素合成相关酶的活性和木质素含量，进而增强了茎秆抗倒伏能力。

Effects of Nitrogen and PP333 Application on the Lignin Synthesis of Stem in Relation to Lodging Resistance of Wheat

【Objective】 This study was carried out to elucidate the effects of nitrogen and PP333 application on lignin content in culm of wheat, and discuss the physiological mechanism of nitrogen and PP333 in regulating the lodging resistance of wheat. 【Method】A field experiment was conducted with two nitrogen application rates and two PP333 levels to study the changes of snapping resistance, culm lodging resistance index (CLRI), lignin content and activities of phenylalanine ammonia-lyase (PAL), tyrosine ammonia-lyase (TAL), cinnamyl alcohol dehydrogenase (CAD) and 4-coumarate CoA ligase (4CL) of wheat, and the effect of nitrogen and spraying PP333 on the lignin content, related enzyme activities in the lignin biosynthesis of wheat and their relationships with lodging resistance.【Result】 Compared with the low N (225 kg?hm-2) rate, the high N (300 kg?hm-2) rate reduced the PAL, TAL, CAD and 4CL activities and lignin content, reduced snapping resistance and CLRI of the same cultivar. The application of PP333 improved the PAL, TAL and CAD activities, increased lignin content, snapping resistance and CLRI, thus reduced lodging area and lodging degree. Correlation analysis showed that the lignin content of basal stem had a significant and positive correlation with PAL, CAL and CAD activity and CLRI, respectively, yet had no significant correlation with 4CL activity.【Conclusion】The high N(300 kg?hm-2) rate reduced the PAL, TAL,CAD enzyme activities and lodging resistance. Spraying PP333 improved the PAL, TAL, CAD enzyme activities and lignin content, and thus enhanced the lodging resistance.