缺锰降低大豆叶片叶绿素荧光的高能态猝灭

缺锰大豆叶片光合速率比对照低 5 0 %左右。缺锰叶片的Fv/Fm较对照低约 30 %～ 40 % ,而Fo比对照高 2～ 3倍左右。强光下 ,缺锰叶片的qP为对照的5 0 %。缺锰降低了叶片的高能态猝灭 (qE) ,仅占其NPQ的 6 0 %左右 ;而对照 qE组分占NPQ的 90 %左右。对照和缺锰叶片叶黄素库的脱环氧化程度分别为36 %和 2 1%左右。认为缺锰叶片 qE的降低可能是由于叶黄素脱环氧化程度减少所致

Energy-dependent Quenching of Chlorophyll Fluorescence is Depressed in Mn-starved Soybean Leaves

Photosynthesis and chlorophyll fluorescence dynamic were investigated in Mn-starved leaves. Photosynthetic rate in Mn-starved leaves was about 50% lower than to that in control leaves (Fig.1). Fv/Fm was 30%-40% lower in Mn-starved leaves, but Fo was about 2-3 times higher than that in control leaves (Fig.2). Under high irradiance, qP in Mn-starved leaves was about 50% lower than that in control leaves (Figs.4, 5). qE was about 60% of the total fluorescence quenching in Mn-starved leaves, but 90% in control leaves (Fig.5). The de-epoxidation state in control and Mn-starved leaves were 36% and 21% respectively, and it was 15% lower in Mn-starved leaves (Fig.6). It is suggested that energy-dependent quenching of chlorophyll fluorescence may be depressed due to the limitation of xanthophyll cycle, thus serious photoinhibition was observed in Mn-starved leaves (Fig.3). The causes of the inhibition of energy dissipation depending on xanthophyll cycle were also discussed.