氮素水平对萝卜干物质累积特征及源库活性的影响

Effects of Nitrogen Levels on Characteristics of Dry Matter Accumulation and Source-Sink Activities of Radish

【目的】了解不同氮素供应水平对萝卜干物质累积特征及源库活性的影响,为萝卜生产的最佳氮肥管理提供理论依据。【方法】采用田间小区试验方法,以冀西北高寒半干旱区的萝卜主产区张家口市尚义县为研究区域,以当地主栽萝卜品种春雷为供试材料,设置0(N0)、84(N1)、126(N2)、168(N3)、252(N4)、和336(N5)kg·hm-2共6个施氮水平,分析不同施氮水平下萝卜干物质累积特征和源库活性的差异。【结果】在当地土壤肥力条件下,与未施氮处理相比,氮肥的施用可显著提高萝卜产量达35.69%—64.59%;苗期、莲座期、膨大期和成熟期总干物质累积量分别增加29.15%—94.85%、10.73%—101.31%、22.86%—33.57%和30.33%—66.47%,不同施氮水平之间的萝卜产量及干物质累积量总体表现出随施氮量的增加先增加后降低的趋势。对适宜施氮量有利于萝卜产量和干物质累积的主要原因进行分析,发现适宜的氮素供应水平下总干物质和肉质根干物质的快速累积持续期延长,最大累积速率提高,肉质根最大干物质累积速率和总干物质快速累积出现的时间提前;同时萝卜生育前期的库活性以及叶片的干物质累积速率提高,而且整个生育期的源活性、整株及肉质根的干物质累积速率也保持了明显优势。【结论】适宜的氮素供应可以有效地协调萝卜干物质的累积特征参数与源库活性的关系,从而影响萝卜干物质的累积,并最终影响肉质根的产量。

[Objective] The purpose of this study was to investigate the effects of different nitrogen levels on the characteristics of dry matter accumulation and source-sink activities of radish to provide a theoretical basis for the best technique of nitrogen management in radish production.[Method] A field experiment was conducted in Shangyi county of Zhangjiakou city, the main production area of radish in semiarid cold region of Hebei province with a variety of Chunlei suitable for this local area. Six nitrogen levels at 0 （N0）, 84 （N1）, 126 （N2）, 168 （N3）, 252 （N4） and 336 （N5） kg·hm-2 were set to analyze the differences between the dry matter accumulation characteristics and source-sink activities of radish.[Result] Results indicated that, compared to the control, nitrogen fertilization significantly increased the radish yield by 35.69%-64.59%, and increased the dry matter accumulations of radish by 29.15%-94.85%, 10.73%-101.31%, 22.86%-33.57% and 30.33%-66.47% at the stages of seeding, rosette, root development and maturity, respectively. The yields and dry matter accumulation of radish leaves and fleshy roots all increased firstly and then decreased with the increase of nitrogen application rates. Results also showed that the optimal nitrogen fertilization lengthened the fleetly accumulation duration of dry matter of whole plants and fleshy roots, and enhanced the maximum accumulation rate. Meanwhile, the time of reaching maximum dry matter accumulation rate of fleshy root and the starting time of＆amp;nbsp;fleetly accumulation of total dry matter were also both advanced. Furthermore, the optimal nitrogen fertilization increased the sink activities and the dry matter accumulation rates of leaves at earlier stage, and enhanced the source activities and the dry matter accumulation rates of whole plants and fleshy roots during the whole growing period.[Conclusion] Optimal nitrogen supply effectively coordinated the characteristics of dry matter accumulation and source-sink relationship of radish, and ultimately enhanced the yield of fleshy root .