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从开花期到衰老后期测定了一个硬粒小麦品种和软质小麦品种旗叶的净光合,CO_2补偿点和RuBpcase(1.5—二磷酸核桐糖羧化酶)活性。二者的净光合没有显著差异。净光合和RuBpCase活性之间的线性关系可归因于相对低的酶活性。两个品种酶活性的直线斜率相近,说明二者的羟化效率相似。在210mlO_2L~(-1)气体中,两个品种的CO_2补偿点没有差异,而在22mlO_2L~(-1)气体中,两个品种的CO_2补偿点没有差异,而在22mlO_2L~(-1)气体中,仅定型叶片之间CO_2补偿点略有差异。将CO_2补偿点外推为零时,氧浓度为正值说明线粒体的呼吸作用没有完全被抑制。根据叶子光合作用的新模型,计算了两个品种呼吸作用的近似值。叶子从定型到衰老暗呼吸(测定叶圆片O_2的吸收)变化很小。在定型的叶片中,软质小麦品种的暗呼吸显著提高,而在衰老的叶片中,这种差异消失。由于其它因素如同化物的分配,呼吸消耗在生物产量的形成中也十分重要,高光合效率与高产并不总是相关关系,但高等植物叶子的光合作用仍是决定生物产量的主要因素。(Rawson etal.,1983),然而,为了寻找同一种群内光合效率的变异,已经进行了大量的研究。在调查小麦栽培品种时,Rawson等(1983)发现穗重与旗叶面积、灌浆期间的光合效率有关,而与叶子在个体发育中最大的光合效率无关。他们观察到不同叶子的最大光合效率是没有关系的,这或许是因为在发育期间接受的辐照度不同而引起的。并提出筛选高光效品种的时期不能在幼苗期,而只能在成株期。本文报道一个研究大田栽培的两个小麦品种从籽粒灌浆期到衰老末期旗叶光合作用过程的试验。这项研究的主要目的是为了寻找旗叶衰老期间两种基因型之间光合效率的可能差异,以及这些差异的生理学基础。测定项目包括净光合速率(Pn),CO_2补偿点(r)和RwBP-Case的活性。虽然CO_2补偿点只是一个假定的参数,但测定它仍可找到限制叶子净同化率的有关因子。(charles-Edwards 1978;Ticha等1981)。RuBpCase是固定碳素的关键酶,也许是控制CO_2吸收的最重要的生化因素,暗呼吸也要测定,因为它影响整个生育期间植株的净同化率。测定品种为在意大利种植适应范围很广的软质小麦品种Marzotto和硬粒小麦品种Cre 80.测定部位为旗叶叶片。
Net photosynthesis, CO 2 compensation points and RuBpcase (1.5-phosphodiestearic acid carboxylase) activity in the flag leaves of a durum wheat variety and a soft wheat variety were measured from anthesis to late senescence. There was no significant difference in net photosynthesis between the two. The linear relationship between net photosynthesis and RuBpCase activity can be attributed to relatively low enzyme activity. The slope of the straight line of the two varieties of enzyme activity is similar, indicating that the hydroxylation efficiency of the two are similar. There was no difference in CO 2 compensation points between the two cultivars in 210 ml O 2 L -1 gas, while in 22 ml O 2 L -1 gas, there was no difference in CO 2 compensation points between the two cultivars. In 22 ml O 2 L -1 gas, , There is a slight difference between the CO2 compensation points only for the fixed blades. When the CO 2 compensation point is extrapolated to zero, a positive oxygen concentration indicates that mitochondrial respiration is not completely suppressed. According to the new model of leaf photosynthesis, the approximate values of respiration of two species were calculated. Leaves from setting to aging dark breathing (measured leaves O 2 absorption) changed little. In stereotyped leaves, the soft respiration of dark wheat varieties significantly increased, while in aged leaves, the difference disappeared. Because of other factors such as assimilate allocation, respiration consumption is also very important in the formation of biomass, photosynthesis efficiency is not always related to high yield, but the photosynthesis of higher plant leaves is still the main factor determining the biomass yield. (Rawson et al., 1983). However, a large number of studies have been conducted to find variations in photosynthetic efficiency within the same population. When investigating wheat cultivars, Rawson et al. (1983) found that panicle weight was related to the leaf photosynthetic efficiency of flag leaves and grain filling, but not to the maximum photosynthetic efficiency of the leaves in their development. They observed that the maximum photosynthetic efficiency of different leaves was irrelevant, perhaps because of the differences in irradiance they received during development. And put forward the selection of high light efficiency of the species can not be in the seedling stage, but only in adult stage. In this paper, we report a pilot study on the photosynthesis of flag leaves in two wheat cultivars ranging from grain filling stage to end of senescence. The main purpose of this study was to find possible differences in photosynthetic efficiency between the two genotypes during flag leaf senescence and the physiological basis for these differences. Measurements include net photosynthetic rate (Pn), CO 2 compensation point (r) and RwBP-Case activity. Although the CO 2 compensation point is only a hypothetical parameter, it is still possible to find the relevant factor that limits the net assimilation rate of leaves. (charles-Edwards 1978; Ticha et al 1981). RuBpCase is a key enzyme that fixes carbon and may be the most important biochemical factor that controls CO 2 uptake. Dark respiratory should also be determined because it affects the net assimilation rate of plants throughout their growth. The cultivars were planted in Italy with a wide range of adaptable varieties of wheat, Marzotto and durum wheat, Cre 80. The test site was flag leaf.