黍气体交换对异质养分环境的反应

GAS EXCHANGE VARIATION IN RESPONSE TO HETEROGENEOUS NUTRIENT ENVIRONMENTS IN PANICUM MILIACEUM

比较了异质养分环境中黍 (Panicum miliaceum)叶片气体交换和光合养分利用效率。异质养分环境显著影响黍叶片气体交换 ;繁殖前期叶片光合速率、蒸腾速率、气孔导度和水分利用效率随环境中总养分水平变化的趋势与种子成熟期恰好相反 ;光合速率、蒸腾速率和气孔导度与叶氮含量成显著相关 ,而与叶磷含量和叶钾含量无显著相关 ;光合磷利用效率和光合钾利用效率受异质养分环境的显著影响 ,而光合氮利用效率对异质养分环境无显著反应。

Gas exchange and photosynthesis nutrient use efficiency were studied in leaves of Panicum miliaceum grown in heterogeneous (patchy) nutrient environments (HNEs). HNEs had a significant influence on gas exchange in the leaves of this species, but this effect varied among growth stages. In pre reproductive stage individuals, photosynthetic rate ( P n ), transpiration rate (E) , and stomatal conductance (g s) decreased with increasing total nutrient availability in HNEs, while water use efficiency increased. These trends were reversed in the seed maturation stage. There was a significant correlation between gas exchange ( P n, E, g s) and leaf nitrogen (N). However, no such correlation was found between gas exchange and leaf phosphorus (P) or leaf potassium (K). Both P and K use efficiency were significantly affected by HNEs, but photosynthetic N use efficiency was not.