5个苜蓿品种群体光合生产特征比较
Canopy Apparent Photosynthetic Characteristics of Five Alfalfa Varieties

为探讨绿洲区不同苜蓿品种群体光合生产特征，选择5个苜蓿品种，在苜蓿生长第2年对冠层群体辐射透过系数及群体光合速率进行测定与分析。结果表明，随着苜蓿植株生长发育进程的推进，各苜蓿品种的散射和直接辐射透过系数均呈下降的趋势，散射辐射透过系数从分枝前期到初花期下降了31.6%～55.7%，直接辐射透过系数从天顶角7.5°～67.5°呈逐渐变小的趋势。苜蓿群体光合速率的日变化呈单峰曲线，且无“午休”现象，各品种苜蓿群体光合速率的峰值均出现在13:30，‘胖多’的群体光合速率日均值最大，为3.39 g·m-2·h-1，‘阿尔冈金’最小，为2.85 g·m-2·h-1。不同品种苜蓿的群体光合速率在初花期达到峰值，均在4.0 g·m-2·h-1以上。整个生育期，各苜蓿品种的群体光合速率大小顺序为：‘胖多’＞‘金皇后’＞‘WL-323’＞‘阿尔冈金’＞‘新牧1号’。各品种苜蓿干草产量均为第1茬最高，占全年总产量权重的33.82%～34.88%，第4茬产量最低，其权重为15.81%～16.51%。不同品种之间，‘胖多’的总干草产量最高，为22 997 kg·hm-2，其次分别为‘阿尔冈金’‘金皇后’‘WL-323’和‘新牧1号’。从群体光合速率及产量的角度考虑，‘胖多’优于其他4个品种，但其生产性能的稳定性较差。
To explore the characteristics of canopy photosynthesis production of different alfalfa varieties in oasis, five alfalfa varieties were chosen, and canopy radiation transmission coefficient and canopy apparent photosynthetic were measured and analyzed in the second growth year of alfalfa. The results showed that, with the growth and development of alfalfa plant, the transmission coefficient of diffuse penetration (TCDP) and transmission coefficient of radiation penetration (TCRP) of different alfalfa varieties showed a downward trend, and TCDP decreased by 31.6%-55.7% from the early branching stage to the beginning stage of flowering, and TCRP showed a downward trend from zenith angle 7.5 °-67.5 °. Diurnal variation of photosynthetic rate of ‘alfalfa’ population photosynthetic rate showed a single peak curve, without midday depression. The peak of canopy apparent photosynthetic rate of different alfalfa varieties occurred at 13:30, and the biggest daily mean value of canopy apparent photosynthesis rate was 3.39 g·m-2·h-1 detected in ‘Pangduo’, and the lowest value was 2.85 g·m-2·h-1 detected in Algonquin. The canopy photosynthetic rate of different alfalfa varieties reached the peak, more than 4.0 g·m-2·h-1, in the early flowering period. The order of canopy apparent photosynthetic rate of different alfalfa varieties was ‘Pangduo’ > ‘Golden Empress’> ‘WL-323’> ‘Algonquin’>‘Xinmu No.1’. The hey yield of first cut of different alfalfa varieties was the highest during the whole growth period, accounted for 15.81%-16.51% of total mass, and the fourth cut was the lowest, accounted for 33.82%-34.88% of total mass. ‘Pangduo’ had the highest total hay yield for 22 997 kg·hm-2, then followed by ‘Algonquin’, ‘Golden Empress’, ‘WL-323’, and ‘Xinmu No.1’, respectively. Considering canopy apparent photosynthetic rate and hay yield, ‘Pangduo’ was better than the other four varieties, even though it had poor stability of production performance.