Quebedeaux B, Hardy R W
Central Research Department, Experimental Station, E. I. Dupont de Nemours and Co., Wilmington, Delaware 19898.
Plant Physiol. 1975 Jan;55(1):102-7. doi: 10.1104/pp.55.1.102.
Reproductive as well as vegetative parameters of mature soybean (Glycine max [L.] Merr. cv. Wye) plants grown in chambers in which the aerial portion was exposed to altered pO(2) during all or part of the growth cycle were measured. Oxygen concentration was found to be a key factor controlling all phases of reproductive development. Exposure to 5% O(2) from early seedling stage to senescence increased leaf, stem, and root dry weights and reduced seed yields when compared to 21% O(2); exposure to low O(2) during the vegetative growth stage from early seedling to mid-flowering arrested pod but not seed development; exposure from mid-flowering to mid-pod filling almost completely arrested seed but not pod development; exposure from mid-pod filling to senescence arrested seed development at the mid-filling stage.Exposures to 5% O(2) initiated at mid-flowering for 1, 2, 3, 5, 10, and 15 days had no effect on seed development when the exposure was up to 3 days and produced almost total arrest when the exposure was 10 or more days, suggesting reversibility. The requirement for O(2) in seed development is independent of CO(2) concentration with similar results produced by subambient O(2) combined with ambient CO(2), elevated CO(2) up to 2000 mul/l or depressed levels of CO(2) with the CO(2)/O(2) ratio as in air. An elevated O(2) atmosphere containing 40% O(2) and ambient or elevated CO(2) inhibited total growth but did not affect the balance of vegetative to reproductive growth.We conclude that an unknown reaction or process requiring at least atmospheric concentrations of O(2) but independent of CO(2) in contrast to photorespiration is necessary for optimization of all phases of reproductive growth and the effect is reversible for exposures of up to 3 days but not for exposures of 10 days or more. We propose that this O(2) phenomenon may be the result of a unique physical process or chemical reaction associated with translocation and accumulation of assimilates in reproductive structures.
对在生长箱中种植的成熟大豆（Glycine max [L.] Merr. cv. Wye）植株的生殖和营养参数进行了测量，在整个或部分生长周期中，其地上部分暴露于变化的pO₂环境。结果发现，氧浓度是控制生殖发育各阶段的关键因素。与21% O₂相比，从幼苗早期到衰老期暴露于5% O₂会增加叶片、茎和根的干重，但会降低种子产量；在营养生长阶段（从幼苗早期到开花中期）暴露于低氧环境会抑制豆荚发育，但不影响种子发育；从开花中期到豆荚充实中期暴露于低氧环境几乎完全抑制种子发育，但不影响豆荚发育；从豆荚充实中期到衰老期暴露于低氧环境会使种子发育在充实中期停滞。在开花中期开始暴露于5% O₂ 1、2、3、5、10和15天，暴露3天及以下对种子发育没有影响，暴露10天及以上则几乎完全抑制种子发育，表明具有可逆性。种子发育对O₂的需求与CO₂浓度无关，亚环境O₂与环境CO₂、高达2000 μl/l的升高CO₂或与空气中CO₂/O₂比值相同的降低CO₂水平相结合，都会产生类似结果。含有40% O₂和环境或升高CO₂的高氧环境会抑制总体生长，但不影响营养生长与生殖生长的平衡。我们得出结论，与光呼吸相反，生殖生长各阶段的优化需要一种未知的反应或过程，该过程至少需要大气浓度的O₂且与CO₂无关，暴露3天及以下这种影响是可逆的，但暴露10天及以上则不可逆。我们提出，这种O₂现象可能是与同化物在生殖结构中的转运和积累相关的独特物理过程或化学反应的结果。
