遮光对玉米品种株型及光合速率的影响OA

In order to clarify differences in plant morphological characteristics and photosynthetic responses to shading among high-yielding maize cultivars from different release eras,it compared Yedan 13 and Denghai 618 in a field experiment with two light regimes:30%shading throughout the entire growth period(S)and no shading(CK),under a uniform plant density of 75,000 plants/hm2.The results showed that after shading,Denghai 18 outperformed Yedan 13 in grain yield,dry matter at maturity,post-silking dry matter accumulation,and harvest index.The yield reduction was greater in Yedan 13(49.25%)than in Denghai 618(42.23%).In contrast,the reductions in dry matter at maturity(21.88%vs 34.30%),post-silking dry matter accumulation(34.10%vs 45.59%),and harvest index(7.99%vs 10.50%)were smaller in Yedan 13 than in Denghai 618.Under the control treatment,plant height,ear height,ear height ratio,and aboveground stem internode length were all greater in Yedan 13 than in Denghai 618.Shading increased plant height,ear height,ear height ration,and inernode length in both cultivars.The pattern of internode elongation differed between cultivars:elongation was more pronounced at and above the ear in Yedan 13,whereas it was concentrated in the middle internodes in Denghai 618.Under the control,Yedan 13 had higher leaf area index(LAI),total leaf area,and leaf area density(LAD)both above and below the ear,but a lower net photosynthetic rate(Pn),compared with Denghai 618.Shading increased leaf length and LAI in both cultivars,while significantly decreasing total LAD,above-ear LAD,and leaf Pn.Overall,season-ong low light markedly altered maize plant architecture and reduced grain yield.Denghai 618 exhibited a more suitable LAI and canopy leaf area distribution(LAD),and stronger adaptability under low-light conditions.