Abdul-Baki A, Baker J E
United States Department of Agriculture, Market Quality Research Division, Beltsville, Maryland 20705.
Plant Physiol. 1970 Jun;45(6):698-702. doi: 10.1104/pp.45.6.698.
The 6-week period of development and maturation of the barley (Hordeum vulgare L.) floret from anthesis to harvest is characterized by two phases: an early phase of rapid increase in respiration rate and dry weight, and a late phase during which respiration decreased rapidly whereas dry weight remained unchanged. Consumption of O(2) by the embryo changed little during the entire developmental period, whereas O(2) uptake by the endosperm and the lemma and palea decreased significantly during the late phase.Maximal inhibition of O(2) uptake by cyanide in whole florets and floret parts coincided with maximal respiration and growth rates. Differences in sensitivity of embryo and endosperm to cyanide, as the floret matured, appeared to be related to developmental differences between these two tissues. Electron micrographs of embryo and endosperm cells are presented to illustrate some of their ultrastructural features, both at early and late stages of development. Increases in O(2) uptake and cyanide sensitivity of the caryopsis after the lemma and palea were removed suggested that the lemma, palea, and pericarp contributed partly to the increased resistance of the mature floret to cyanide by acting as barriers to gas exchange, thus restricting the movement of both cyanide and oxygen into the caryopsis.
大麦（Hordeum vulgare L.）小花从开花到收获的6周发育和成熟时期具有两个阶段：早期呼吸速率和干重快速增加，后期呼吸迅速下降而干重保持不变。在整个发育期间，胚对O₂的消耗量变化不大，而在后期胚乳以及内外稃对O₂的吸收显著减少。全小花和小花各部分对氰化物抑制O₂吸收的最大值与最大呼吸速率和生长速率一致。随着小花成熟，胚和胚乳对氰化物敏感性的差异似乎与这两个组织之间的发育差异有关。文中呈现了胚和胚乳细胞的电子显微照片，以说明它们在发育早期和晚期的一些超微结构特征。去除内外稃后颖果对O₂的吸收和对氰化物敏感性增加，这表明内外稃和果皮通过作为气体交换的屏障，部分导致了成熟小花对氰化物抗性的增加，从而限制了氰化物和氧气进入颖果。
