Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years
Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years
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发表时间：
2002
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通讯作者：
Liu He
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作者：
Liu He
三个冬小麦品种（Triticum aestivum L.），以北京地区近60年来广泛栽培的代表品种为材料，在相同的环境条件下栽培，并对其生理特性进行了研究。测定了不同生育期叶片净光合速率（Pn）、蒸腾速率（Tr）的日变化，探讨了叶片光合作用与产量的关系。根据Pn/Tr计算叶片瞬时水分利用效率（WUE）。说明光合速率与产量的关系随小麦生育期的不同而变化。90年代育成的高产小麦品种京冬8号在拔节期白天的光合速率（Pn最大值提高77%）和蒸腾速率（Tr最大值提高69%）高于低产小麦品种烟大1817（40年代育成），但WUE低于烟大1817。但不同品种间的Pn差异随小麦生育进程而变化。3个品种叶片的Pn在10时以前通常以京东8号最高，而烟大1817的Pn在10时以后最高。在面团成熟期，烟大1817叶片的Pn在全天内最高。3个小麦品种蒸腾速率变化趋势的差异与Pn变化趋势的差异基本一致，但水分利用效率均以烟大1817最高，说明京冬8号的高产是通过消耗较多的水分实现的。烟大1817的光合午休现象与后期育成品种相反，表现为光合午休现象较小，说明烟大1817具有较强的抗光抑制能力。这可能是由于近60年来小麦品种的改良，使叶片光合势提高。然而，它变得不耐光抑制。
Three winter wheat cultivars ( Triticum aestivum L.), representatives of those widely cultivated in Beijing over the past six decades, were grown in the same environmental condition, and their physiological features were investigated. Daily changes of net photosynthetic rate ( P n ), transpiration ( T r ) in different growth stages were measured in order to find the relationship between leaf photosynthesis and yield. Instantaneous water use efficiency ( WUE ) of leaf was calculated from P n / T r . It is suggested that relationship between photosynthetic rate and yield changed with the developing stages of wheat. High yield wheat cultivar Jingdong 8 (released in the 1990s) had a higher photosynthetic rate (the maximal P n increased by 77%) and transpiration rate (the maximal T r increased by 69%), but a lower WUE than the low yield cultivar Yanda 1817 (released in the 1940s) during the day time at stem elongation stage. However, difference of P n among the three cultivars changed with wheat growth process. Before 10 o'clock P n in leaves of Jingdong 8 usually was the highest of the three cultivars, but P n of Yanda 1817 was the highest after 10 o'clock. At dough ripe stage, P n in leaves of Yanda 1817 was the highest among the three cultivars during the whole day. The difference of changing trend of transpiration in three wheat cultivars was similar to P n , but WUE of Yanda 1817 was the highest in those three cultivars, indicating that the higher yield of Jingdong 8 was achieved via a greater consumption of water. Contrary to the cultivars released in the later period, midday depression of photosynthesis was small in Yanda 1817, which might suggest that Yanda 1817 was resistant to photoinhibition. It is possible that photosynthetic potential in leaves of wheat increased as wheat cultivars was improved over the past six decades. However, it became less resistant to photoinhibition.