追施氮肥量对菘蓝根的外形品质、干物质积累及活性成分含量的影响

Effects of topdressing nitrogen on apparent quality,dry matter accumulation and contents of active components in the root of Isatis indigotica Fort.

采用田间小区试验,设5个处理,氮肥用量分别为225、450、675、900、1125 kg/hm2,每一个处理3个重复小区,研究不同追施氮肥量对菘蓝的光合参数、根的外形品质、干物质积累及活性成分含量的影响,探讨氮肥施用量对菘蓝植株地上部和地下部生长的生理影响,优选菘蓝最佳追施氮肥量。结果表明,追施氮肥有利于提高菘蓝叶片的净光合速率、气孔导度、胞间CO2浓度、蒸腾速率,可以显著增加菘蓝根主根直径和根长,有明显的壮根效应;而菘蓝总鲜重随着施氮量提高而增加,但超过900 kg/hm2后就不再增加;在450 kg/hm2下菘蓝根侧根数最少,低氮(225 kg/hm2)和高氮(900、1125 kg/hm2)水平下菘蓝根侧根数增加过多,影响了菘蓝根药材外形品质;随着施氮量增加,地上部和地下部干物质积累先增加后下降,而根冠比不断下降,氮肥量为675 kg/hm2时地上部干物质积累最大,氮肥量为900 kg/hm2的地下部干物质积累最大,追施氮肥对地上部的促进效应明显高于地下部。施氮量增加,多糖含量先增加后下降,施氮量为675 kg/hm2时菘蓝根中多糖含量最高为158.383 mg/g,而(R,S)-告依春含量没有明显的变化规律,氮肥量为900 kg/hm2时含量最高达到0.5655 mg/g。为保证菘蓝根产量和药用品质适宜的追施氮肥量是675 900 kg/hm2。

Effects of topdressing nitrogen on the photosynthetic parameters of lsatis indigotica Fort. , apparent quality, dry matter and active components of the root of Isatis indigotica Fort. was studied to explore the physiological effects of nitrogen fertilizer on the growth of shoots and roots, and to find the best preferred nitrogen fertilizer application rate. A field experiment was carried out using five processing nitrogen treatments with three repeats, and the amounts of nitrogen fertilizer were 225 kg/ha, 450 kg,/ha, 675 kg/ha, 900 kg/ha and 1125 kg/ha, respectively. The results show that the nitrogen fertilization has a strong root effect by improving the photosynthetic parameters（ Pn, Gs, Ci and Tr）, and significantly increases the main root diameter and root length. The total fresh weight increased with nitrogen rate, but no longer increasing with more than 900 kg/ha. The number of lateral roots was the least under 450 kg/ha. The numbers of lateral roots were increased significantly under the low nitrogen （225 kg/ha） and the high nitrogen （900 kg/ha and 1125 kg/ha）, which affected the medicinal appearance quality of the root of Isatis indigotica Fort.. With the increase of nitrogen rate, the dry matter accumulation amounts of leaves and roots were increased firstly, and then decreased, and the dry matter of leavesand dry matter of roots were maximum under the 900 kg/ha and 675 kg/ha, respectively. But the root-shoot ratio was declined with the increase of nitrogen rate. It indicates that the promotion effect of topdressing nitrogen fertilization on the leaves is larger than that of the roots. With the increase of nitrogen rate, the polysaccharide content was increased firstly, and then decreased, and the content of polysaccharide was the maximum （158. 383 mg/g） under the 675 kg/ha. The variation of the content of （ R, S） - epigoitrin was not very clear, which was the maximum （0. 5655 mg/g） under the 900 kg/ha. The suitable nitrogen application amount was 675 kg/ha - 900 kg/ha to ensure production and medicinal quality of the root of Isatis indigotica Fort..