• ISSN 1008-505X
  • CN 11-3996/S
徐国伟, 孙会忠, 陆大克, 王贺正, 李友军. 不同水氮条件下水稻根系超微结构及根系活力差异[J]. 植物营养与肥料学报, 2017, 23(3): 811-820. DOI: 10.11674/zwyf.16291
引用本文: 徐国伟, 孙会忠, 陆大克, 王贺正, 李友军. 不同水氮条件下水稻根系超微结构及根系活力差异[J]. 植物营养与肥料学报, 2017, 23(3): 811-820. DOI: 10.11674/zwyf.16291
XU Guo-wei, SUN Hui-zhong, LU Da-ke, WANG He-zheng, LI You-jun. Differences in ultrastructure and activity of rice roots under different irrigation and nitrogen supply levels[J]. Journal of Plant Nutrition and Fertilizers, 2017, 23(3): 811-820. DOI: 10.11674/zwyf.16291
Citation: XU Guo-wei, SUN Hui-zhong, LU Da-ke, WANG He-zheng, LI You-jun. Differences in ultrastructure and activity of rice roots under different irrigation and nitrogen supply levels[J]. Journal of Plant Nutrition and Fertilizers, 2017, 23(3): 811-820. DOI: 10.11674/zwyf.16291

不同水氮条件下水稻根系超微结构及根系活力差异

Differences in ultrastructure and activity of rice roots under different irrigation and nitrogen supply levels

  • 摘要:
    目的探讨不同水氮耦合对水稻根系超微结构及根系代谢特性的影响,从根尖细胞超微结构及根系活力方面阐明不同水氮组合处理在根际环境间的差异。
    方法以新稻 20 号为材料,进行盆栽试验,设置浅水层灌溉、轻度水分胁迫 (灌 1~2 cm 水层,至土壤水势降到 –20 kPa 再灌浅水层,如此反复) 和重度水分胁迫 (灌 1~2 cm 水层,至土壤水势降到 –40 kPa 再灌浅水层,如此反复) 3 种灌溉方式及不施氮肥,适量氮 (N 240 kg/hm2) 和高量氮 (N 360 kg/hm2) 3 种氮肥水平,测定了不同处理水稻根系氧化力、根系伤流量及根系分泌有机酸总量,并观测了根系细胞超微结构。
    结果随着生育进程,根系氧化力表现为先增加后降低的趋势,在幼穗分化期达到峰值,根系伤流液及根系分泌物中有机酸总量先增加后降低,在抽穗期达到峰值。在同一氮肥水平下,轻度水分胁迫后根系细胞完整,核膜界限清晰,结构特征典型;与保持水层相比,根系氧化力及根系伤流量在分蘖盛期分别增加 25.6%~32.0% 及 9.1%~18.8%,根系分泌有机酸总量在抽穗期前平均增加 16.4%。重度水分胁迫后嗜锇体和淀粉体较多,后期细胞完全扭曲变形,细胞间隙明显增多增大、细胞器出现断裂降解,细胞基质中仅存细胞器碎片,细胞壁较完整,未出现断裂情况;与保持水层相比较,根系氧化力及根系伤流量在幼穗分化始期平均降低 8.8% 及 25.6%,根系分泌有机酸总量平均降低 22.8%。在同一灌溉方式下,适量氮处理根系细胞结构较完整,核膜较清楚,有利于根系活力的提高及根系有机酸的分泌;重施氮处理根系细胞壁和核膜降解加速。与适量氮相比,高氮处理下根系氧化力及根系伤流量在分蘖盛期至幼穗分化始期分别降低了 6.6%~9.8% 及 7.7%~15.4%,根系分泌物中有机酸总量在抽穗前平均降低 11.6%,整体上根系活力降低、有机酸的分泌量显著减少。
    结论轻度水分胁迫耦合适量氮处理的水稻根系超微结构最优,细胞结构特征典型,核膜最为清晰,细胞完整,根系代谢能力最强。表明通过适宜的水氮耦合调控,能够提高根尖细胞的生理功能,增强根系活力、促进根系有机酸的分泌,能为水稻的生长创造良好的根际环境。

     

    Abstract:
    ObjectivesThis study observed root ultrastructure and measured metabolism of japonica rice under different irrigation and nitrogen supply levels to help understanding the mechanism of suitable irrigation and nitrogen fertilization coupling in yield increase of rice.
    MethodsA pot experiment was conducted using a mid-season japonica rice cultivar of Xindao 20 as tested material in 2014 and 2015. Three nitrogen levels of 0, 240 and 360 kg/hm2 and three irrigation regimes, including submerged irrigation, alternative wetting and moderate drying (–20 kPa) and alternative wetting and severe drying (–40 kPa) were designed. The root activity, root bleeding and total organic acid content in roots were measured, and root tip ultrastructure was scanned.
    ResultsWith the elongation of rice growth, the root oxidation was increased firstly and then decreased with the peak at the panicle initial (PI) stage, the same trend was observed with the index of root exudates, and total organic acids in root exudates with the peak appeared at the heading stage. There was a significant interaction between irrigation regimes and nitrogen levels. At the same nitrogen level, the boundaries of nuclear membrane in root cells at the mid-tillering and PI stages were clear, and typical structure was found under the condition of moderate water stress. Compared with the submerged irrigation, the root activity was also increased at the main stages, the total contents of organic acid were enhanced significantly, such as root oxidative ability and the root exudates were increased by 25.6%–32.0% and 9.1%–18.8% at the mid-tillering stage, respectively, and the total organic acid production was improved by 16.4% at the pre-heading stage. The opposite results were observed under the condition of severe water stress, the number of organelles was reduced, osmiophilic bodies and amyloplast were increased, cells twisted and wrinkled at the later stages, organelles were broken and degraded, cell debris was remained in the cell matrix. Compared with the submerged irrigation, the root activity and root secretion of total organic acid were significantly decreased, such as the root oxidative ability and the root exudates were decreased by 8.8% and 25.6% at the PI stage respectively, and the total organic acids secretion was reduced by 22.8% at the whole stage. In the same irrigation regime, nuclear membrane at the main growth stages was clear and typical structure could be found under the condition of moderate N treatment, when compared with no nitrogen applied, meanwhile root activity and the total content of organic acid were enhanced significantly. The opposite result was observed under the condition of high N treatment, cells twisted and wrinkled in the later stage, organelles was broken and degraded, cell wall and membrane degradation was accelerated and cell debris was destroyed in the cell matrix, which indicated that heavy nitrogen application was not conducive to the maintenance of function of organelles, and root metabolic function declined. Compared with the moderate N treatment, the root oxidative ability and root exudates were reduced by 6.6%–9.8% and 7.7%–15.4% from the mid-tillering to PI stage respectively, meanwhile the content of organic acid in root exudates was reduced by an average of 11.6% under the condition of high N treatment before the heading. Overall, the root activity and the amount of organic acid secretion were significantly reduced.
    ConclusionsThe nuclear envelope was most clear and root metabolism ability was strongest under the condition of moderate water stress and moderate N interaction. These results suggested increasing physiological function of root tip cells, enhancing root activity and improving root secretion of organic acids through the appropriate regulation of water and nitrogen will create a good rhizosphere environment for the growth of rice.

     

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