Abstract: To elucidate varietal difference in photosynthetic response to different light intensity in rice, photosynthetic capability and RuBPC activity and PEPC activity in rice leaves were determined by using ¹⁴C-tracer techniques under continued high light and low light. The results showed that photosynthetic rate and RuBPC activity in indica-japonica hybrid rice Yayou 2 were inhibited lesser and appeared to be a property of photosynthetic stability as compared with that in indica hybrid rice Shanyou 63. It was worthy of being noted that PEPC activity was induced to increase remarkably under photoinhibitory condition in the rice variety Yayon 2. Meanwhile, photosynthetic performances of indica-japonica hybrid rice and their parents were studied. Photosynthetic characteristics in indica-japonica hybrid rice Yayou 2 based on japonica rice 02428, which is a valuabled germplasm in the breeding of indica-japonica hybrids.

Key words: tracer techniques, Indica-japonica hybrid rice, PEPCase, Photoinhibition, photosynthesis, RuBPCase, Light intensity response

摘要： 报道了水稻光合对不同光强的响应能力及品种间差异。应用14C同位素示踪技术在连续强光和遮荫条件下，测定了籼粳杂交稻亚优2号及其亲本粳稻02428，籼稻3O37和籼型杂交稻汕优63的光合速率，双磷酸核酮糖羧化酶(RuBPC)和磷酸烯醇式丙酮酸羧化酶(PEPC)活性。结果表明：籼粳杂交稻亚优2号在强光和弱光下光合速率和C3光合酶RuBPC活性比籼型杂交稻汕优63抑制较少，表现有比较稳定的光合特性。值得注意的是在光抑制条件下，耐光抑制水稻品种的C4光合酶PEPC有诱导增加活性的现象。与其两个亲本相比较，籼粳杂交稻亚优2号的光合特性更相似于粳稻02428。因此，在配组具有优良光合性状的籼粳杂交稻品种时，广亲和高光效种质02428是一个值得利用的材料。

关键词: 水稻, 光合作用, 光强响应, 品种, 光抑制, 双磷酸核酮糖羧化酶, 磷酸烯醇式丙酮酸羧化酶