J Integr Plant Biol. ›› 2002, Vol. 44 ›› Issue (8): 913-919.

• Research Articles •

Changes of Gas Exchanges in Leaves of Different Cultivars of Winter Wheat Released in Different Years

LIU He-Qin, JIANG Gao-Ming, ZHANG Qi-De, SUN Jia-Zhu, QU Chun-Mei, GUO Ren-Jun, GAO Lei-Ming, BAI Ke-Zhi and KUANG Ting-Yun

• Published:2002-08-21

Abstract:

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 (Pn), transpiration (Tr) 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 Pn/Tr. 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 Pn increased by 77%) and transpiration rate (the maximal Tr 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 Pn among the three cultivars changed with wheat growth process. Before 10 o'clock Pn in leaves of Jingdong 8 usually was the highest of the three cultivars, but Pn of Yanda 1817 was the highest after 10 o'clock. At doughripe stage, Pn 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 Pn, 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.

（1.中国科学院植物研究所植被数量生态实验室，北京100093；
2. 中国科学院植物研究所光合作用基础研究开放实验室，北京10093；
3. 北京市农林科学院作物研究所，北京100098）

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