EFFECTS OF STRAW MULCHING AND TILLAGE MEASURES ON THE PHOTOSYNTHETIC CHARACTERISTICS OF MAIZE LEAVES

摘要

This study investigated the response mechanisms of maize leaf photosynthetic characteristics to straw mulching and tillage measures in the black soil region of northeast China. Five treatments were established based on tillage and the average straw mulch yield from prior years (6500 kg ha(-1)): conventional tillage with no straw mulching (CK), conventional tillage with 1.0-fold (6500 kg ha(-1)) mulching (CM1), no tillage with 0.5-fold (3250 kg ha(-1)) mulching (NM0.5), no tillage with 1.0-fold (6500 kg ha(-1)) mulching (NM1), and no tillage with 1.5-fold (9750 kg ha(-1)) mulching (NM1.5). The net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and light response curves of maize leaves were determined and compared between the treatments with different straw mulching amounts and farming methods and between different growth stages. The photosynthetic capacity of maize leaves was greater under NM1.5 than under the other treatments except at the V6 growth stage, and the increase in yield was the most obvious effect. The photosynthetic capacity of maize leaves can be improved by increasing the quantity of straw mulch. The photosynthesis of maize was affected by nonstomatal factors at different growth stages, and straw mulching reduced the negative effects of nonstomatal factors on the photosynthesis of maize leaves. Based on a light response model of the photosynthetic rate, the maximum net photosynthetic rate, light saturation point, and apparent quantum efficiency increased as the straw mulch quantity increased, and the magnitude of the increase was greatest between the 1.0-fold and 0.5-fold straw mulching treatments. This finding indicated that straw mulching can increase the adaptability of maize to strong light and improve the efficiency of maize under weak light; moreover, the NM1.5 treatment led to the greatest improvement in the light response characteristics of maize leaves.