A short period (240°C hr; Tb = 25°C) of heat stress (30°C day/25°C night) during forage rape (Brassica napus L.) seed development or at seed physiological maturity can reduce seed vigour, but the extent of oxidative damage associated with this short heat stress was not known. Heat‐stressed seeds were assessed for malondialdehyde (MDA) content, hydrogen peroxide (H₂O₂) accumulation, antioxidant enzyme activity, adenylate energy charge and seed ultrastructural integrity, and compared with that of non‐heat‐stressed seeds. Heat stress increased both MDA content and H₂O₂ accumulation by 35%–50%, reduced antioxidant enzyme activity by between 12% and 67%, and significantly reduced adenosine energy charge. Transmission electron microscope images showed clear evidence of seed deterioration in heat‐stressed seeds, including ruptures in cell wall and plasma membranes, fused lipid bodies and damaged mitochondria. Heat stress at physiological maturity caused more oxidative damage than the same heat stress during seed development. Seed vigour decreased as H₂O₂ accumulation increased and antioxidant enzyme activity decreased, but no direct relationship between lipid peroxidation and seed vigour was established. The extent of damage resulting from even shorter periods of heat stress (<240°C hr) before or at seed physiological maturity requires investigation.

中文翻译：

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种子发育过程中热胁迫后饲用油菜（甘蓝型油菜）种子的氧化损伤

在饲用油菜（甘蓝型油菜）种子发育过程中或在种子生理成熟期，短暂的一段时间（240°C hr； Tb = 25°C）的热胁迫（30°C白天/ 25°C夜间）会降低种子活力但是与这种短暂的热应力相关的氧化损伤的程度尚不清楚。评估热胁迫种子的丙二醛（MDA）含量，过氧化氢（H ₂ O ₂）积累，抗氧化酶活性，腺苷酸能电荷和种子超微结构完整性，并与非热胁迫种子进行比较。热应力增加了MDA含量和H ₂ O ₂含量积累了35％–50％，抗氧化酶活性降低了12％至67％，并显着降低了腺苷的能量消耗。透射电子显微镜图像清楚地表明了热胁迫种子的种子变质，包括细胞壁和质膜破裂，脂质体融合以及线粒体受损。与种子发育过程中相同的热胁迫相比，生理成熟时的热胁迫引起更多的氧化损伤。H ₂ O ₂积累增加，种子活力降低，抗氧化酶活性下降，但脂质过氧化与种子活力没有直接关系。在种子生理成熟之前或之前，甚至更短的热应激（<240°C hr）所造成的损害程度也需要进行调查。