Oxygen is essential for all aerobic organisms. Higher plants need oxygen to sustain metabolism and growth. After experiencing anaerobic stress for a period of time, most plant tissues will be damaged. This study examined the physiological characteristics and anatomical structures in the root tips of rice seedlings (cultivars Xiushui09 and Chunyou84) in response to different rhizosphere oxygen environments. The results showed that moderate oxygen (MO: 2.5–3.5 mg L⁻¹) increased the dry weight accumulation and formation of rice roots (including length, surface area, number of tips) in both genotypes. Compared to under normal conditions (NC), the magnitudes of increase in these four variables were 4.67, 66.40, 35.44 and 49.50% in Xiushui09 and 12.25, 15.59, 13.57 and 13.48% in Chunyou84, respectively. Low oxygen (LO: 0–1.0 mg L⁻¹) stress decreased the root surface area but increased root volume and average diameter. LO and high oxygen (HO: >6.8 ± 0.21 mg L⁻¹) stress each damaged the apical cells' ultrastructure, reduced the number of organelles, and increased electrical conductivity. Meanwhile, the root activity and respiration of rice seedlings decreased; the abscisic acid content increased compared to levels under NC. Under MO treatment, the cell membrane was not damaged, the root tip organelles were rich, the soluble protein content, root activity, respiration rate and gibberellic acid content increased compared to levels under NC; the magnitudes of these increases were 24.76, 36.00, 8.00 and 283.00% in Xiushui09 and 4.78, 40.00, 15.45 and 49.35% in Chunyou84, respectively. In conclusion, MO optimised rice root morphology and enhanced root physiological activity.

中文翻译：

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水稻分ing期根际氧浓度对根系生理特性和解剖结构的影响

氧气对于所有有氧生物都是必不可少的。高等植物需要氧气来维持新陈代谢和生长。经历了一段时间的厌氧胁迫后，大多数植物组织将受到破坏。本研究探讨了根际氧环境对水稻幼苗（品种秀水09和春优84）根尖的生理特性和解剖结构的影响。结果表明，中度氧气（MO：2.5–3.5 mg L ^-1）增加了两种基因型的水稻干重积累和水稻根系的形成（包括长度，表面积，叶尖数量）。与正常条件下相比，秀水09四个变量的增加幅度分别为4.67％，66.40、35.44和49.50％，而春油84分别为12.25、15.59、13.57和13.48％。低氧（LO：0–1.0 mg L ^-1）应力减少了根部表面积，但增加了根部体积和平均直径。LO和高氧（HO：> 6.8±0.21 mg L ^-1）应力会破坏根尖细胞的超微结构，减少细胞器的数量并增加电导率。同时，水稻幼苗的根系活力和呼吸作用降低。脱落酸含量与NC水平相比有所提高。MO处理后，细胞膜未受损，根尖细胞器丰富，可溶性蛋白含量，根系活力，呼吸频率和赤霉素含量均比常压水平提高。秀水09的增幅分别为24.76、36.00、8.00和283.00％，春油84的增幅分别为4.78、40.00、15.45和49.35％。总之，MO优化了水稻根系形态并增强了根系生理活性。