【摘要】 甜菜群体光合速率日变化属于中午降低型，其中午降低是受多种生理生态因子相互作用的结果，但主要来自中午大气相对湿度的降低和叶片气孔阻力的增加所造成的不利作用。更多还原

【Abstract】 篛ne Sugarbeet Cultivar was planted in a well-Cultured field to study the diurnal variation of canopy apparent photosynthesis (CAP) as well as the relationship between it and main physiologlcal ahd ecological factors.The results indicted that the diurnal variation of CAP belongs to the type of midnap. The midnap of CAP results from the common effect of many physiological and ecological factors but the main reason was from the atomosphere relative humidity decrease and leaves stomotal resistance increase in the midday.更多还原