| Abstract: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. |
