滇中高原玉米吐丝后叶片衰老的特点

CHARACTERS OF MAIZE LEAF SENESCENCE AFTER SILKING IN YUNNAN PLATEAU

滇中高原玉米吐丝后叶片具有功能期长、衰老延缓的特点。成熟时９００００株／ｈｍ２，单株绿叶数平均在８片以上，ＬＡＩ达４．１。成熟前果三叶Ｃｈｌ含量仍保持在吐丝时的８５．７％～９５．２％，ＭＤＡ含量变化平缓，光合速率和籽粒干物质积累强度后期下降缓慢。温度处理进一步证实，当地温凉的气温（１８．４℃）是叶片衰老慢的主要原因。２０℃与３０℃处理相比，前者叶片衰老过程中Ｈ２Ｏ２、ＭＤＡ变化平缓，含量低，ＣＡＴ活动性随Ｈ２Ｏ２水平相应变化，但滞后１～２天。较低的温度可以改善叶片衰老过程中活性氧代谢，进而延缓衰老。

In Yunnan plateau,the senescence of maize(Ye dan No.6)leaves was retarded after silking and its functional period was prologed.In maturing,compared with silking,there were 8.75 green leaves per plant,LAI still remained 4.1,chlorophyll contents of three leaves(12th-14th)remained over 85.7%,photosynthetic activity and rate of dry matter accumulation of grain decreased gradually and remained a relative high level in the latter balf Period.Temperature treatment confirmed that moderate temperature in Yunnan plateau was the main cause of retard of the corn leaves senescence.Compared with 30℃,20℃ effectively retarded the senescence of corn leaves,because the balance of the of activated oxygen metabolism was improved.Contents of H2O2 and MDA were low and varied gradually and gently.But the level of MDA decreased in the latter half period,which is different from other reports.Similarly,the activity of catalase peak was low and varied gently its peak was behind H2O2's one or two days.