氮肥与涝渍胁迫时间对抽雄期夏玉米叶片生理特性的影响

为了探究氮肥与涝渍胁迫时间对抽雄期夏玉米生理特性的影响，选用裕丰333为试验材料，采用盆栽试验，施氮量设置3个水平处理，分别为0、180和300 kg·hm^-2，记为N0、N1和N2。共设置3个胁迫时长处理，分别为3 d、5 d和7 d，记作S3、S5和S7；3个胁迫恢复时长2 d、4 d和6 d，记作R2、R4和R6。在涝渍胁迫-恢复期间分别测定夏玉米叶片的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和过氧化物酶(POD)的活性，丙二醛(MDA)以及叶绿素含量。研究表明，在涝渍胁迫期间，高氮素水平下，涝渍胁迫时长增加会减少SOD活性但会增加CAT活性。相同的施氮水平下，MDA和叶绿素含量没有显著性变化，说明涝渍胁迫对于玉米叶片MDA和叶绿素的含量影响较小。在涝渍胁迫与恢复期间，抗氧化酶活性随着氮素水平的提高而显著增大。在高氮素水平下，叶绿素含量在淹水3 d达到最大。高氮素水平有利于改善抽雄期夏玉米生理特性。

Effects of nitrogen fertilizer and waterlogging stress time on physiological characteristics of summer maize leaves at tasseling stage

In order to explore the effects of nitrogen fertilizer and waterlogging stress time on the physiological characteristics of summer maize in the asphyxiating stage, a pot experiment was adopted, selecting Yufeng 333 as the experimental material. Three levels of nitrogen application were set as 0, 180 and 300 kg·hm^-2, named as N0, N1 and N2, respectively. Three stress duration treatments were set, which were 3, 5 and 7 days, respectively, denoted as S3, S5 and S7, and three stress recovery durations were set as 2, 4 and 6 days, denoted as R2, R4 and R6, correspondingly. The activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD), malondialdehyde (MDA) and chlorophyll contents in the leaves of summer maize were measured during the waterlogging stress-recovery period. The results showed that during waterlogging stress, under high nitrogen level, the increase of waterlogging stress duration would reduce SOD activity, but it increased CAT activity. Under the same nitrogen application level, MDA and chlorophyll contents had no significant changes, indicating that waterlogging stress had little effect on MDA and chlorophyll contents in maize leaves. During the period of waterlogging stress and recovery, the activities of antioxidant enzymes increased significantly with the increase of nitrogen level. Under high nitrogen level, chlorophyll content reached the maximum at flooded day 3. High nitrogen level is beneficial to the improvement of the physiological characteristics of summer maize at tasseling stage.