在试验大田，利用Li-Cor6200光合测定系统，以中秆大穗型品种鲁谷10号和矮秆紧凑型品种矮88为材料，初步研究了夏谷群体光合作用特性及其影响因素。结果表明，夏谷光合日变化呈单峰曲线，上午11时前后群体光合达最大值，其趋势与光照强度的变化基本吻合。两品种的群体光补偿点为180～190μE.m-2.s-1，鲁谷10号对高光强的利用率高于矮88。矮88的CO2补偿点为45μL.L-1，低于鲁谷10号(65μL.L-1)。土壤呼吸释放的CO2对群体光合有较大的贡献，平均所占比重达25.96%。%The study was conducted in the experimental field during1994～1995 to investigate the traits of canopy photosynthesis (CAP) and its influencing factors of summer-sowing millet. Two varieties of middle height Lugu No.10 and dwarf compact type Ai88 were tested using Li-Cor 6200 photosynthetic analysis system. Main results are as follows: the diurnal changes of CAP was a single peak curve. The highest CAP was at 11 o′clock and the diurnal change of CAP was basically coincided with the change in solar radiation. The canopy light compensate points of two varieties were from 180 to 190 μE.m-2.s-1. Utilization efficiency for higher intense solar radiation of Lugu No.10 was higher than that of Ai88. The CO2 compensate point of compact type variety Ai88 was 45 μL.L-1, which was lower than that of Lugu No.10 (65 μL.L-1). CO2 released from soil accounted for a big part in the CAP, about 26%.
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