Abstract:

Chlorophyll and soluble protein break down and reactive oxygen species metabolism is maladjustment in the process of leaf aging. The damage action of reactive oxygen species is one of the reasons for plant leaf aging. Superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) are important defending enzymes that can eliminate reactive oxygen species and inhibit plant aging. The experiment was carried out to study the effects of three cultivation modes (flat planting, straw mulching, plastic film-mulching) with the 120 kg N ha^-1 application and planting density of 130–150×10⁴ plants ha^-1 on leaf aging of the winter wheat (Triticum aestivum L.) cultivar Xiaoyan 22. The results showed that leaf aging and reactive oxygen species metabolism varied with the cultivation modes. Compared with flat farming, straw mulching could increase leaf chlorophyll, slow the speed of leaf aging and the extent of declining metabolism. At the early filling stage, plastic film-mulching could increase leaf chlorophyll, enhance POD, CAT activities, and lower the malondialdehyde (MDA) content. At the late filling stage, there were a remarkable decline of leaf chlorophyll, a quick leaf aging and a marked increase of MDA. The POD and CAT were involved in leaf aging regulation, synergistically protecting the leaves by reducing the damage from reactive oxygen species, prolonging the functional period of leaves and increasing the yield. We can use straw mulching to regulate the leaf aging of winter wheat, and improve the yield and quality of winter wheat in the south of Loess Plateau.

Key words: Cultivation mode, Winter wheat, Leaf senescence, Activate oxygen metabolism