黄土塬区不同品种玉米间作群体生长特征的动态变化

不同玉米品种间作,品种间的竞争对群体结构和产量可能有促进作用.为了明确不同密度下品种间作对不同生育期群体生长特征的影响,以及在不同生育期的变化规律,选用郑单958和沈单16两个不同株型的玉米品种在中、高两种密度条件下进行隔行间作田间试验.研究结果表明:不同密度间作群体叶面积指数(Leaf Area Index,LAI)显著增加,同密度不同品种间作LAI在生育后期显著增加,有利于形成合理的冠层结构以获得更多的光照；中等密度下品种间作单株叶面积较单作显著增加,而高密度间作显著降低了单株叶面积；中等密度下,品种间作地上部干物质积累量显著增加,郑单958尤为突出,但高密度间作时的增加幅度较小,这与高密度下株高、茎粗相对减小有关.品种株高、茎粗随间作密度的增加而有所增加,对间作竞争的响应与品种特性密切相关；在不同生育期,郑单958和沈单16号表现不同的生长规律,前者在整个营养生长过程中对间作竞争的响应明显、持续和稳定,而进入生殖期后,间作的生长优势逐渐消失；后者在营养生长期干物质积累量大,但持续时间较短,表现出较弱的竞争性.品种间作可有效改善群体冠层结构,增加群体物质生产力,更好的为增产鉴定基础.

The dynamic variation of maize (Sea mays L.) population growth characteristics under cultivars-intercropped on the Loess Plateau

To improve maize (Zea mays L.) yield on the Loess Plateau many researches focused on high density, the water and fertilizer use efficiency, however, increasing productivity by high density is limited, because the influence of population characteristics is various. The corn production is a population process, optimized corn group structure can be helpful to augment production. The objectives of this study were to understand that the effects of maize cultivars intercropping on population growth characteristics in the field, and the dynamic changes of them during different growth stages. The experiment conducted on intercropping cultivation which interlaced with the same row spacing and mulch covered, used the two maize cultivars (zhengdan 958 and shendan 16) and two kinds of densities. Leaf area index (LAI), individual leaf area, plant height, stem diameter and dry matter accumulation were measured as growth characteristics. In contrast with monoculture, LAI of intercropping population showed significant increased when higher density. This may because a reasonable canopy compound structure is helpful for photosynthesis and dry matter production. Low-low density intercropping dramatically increased leaf area per plant. In the model of high-low density intercropping, leaf area per plant of the low density cultivar increased significantly, but high density varieties leaf grew less. High-high density intercropping reduced the individual leaf area significantly, compared with monoculture plants. Plant height and stem diameter of varieties increased slightly with the high intercropping density. The response of competition was correlated to the cultivars characteristics significantly, but the influence of intercropping density was insignificant. Intercropping has significant increase in dry matter accumulation, especially in zhengdan 958. With the increase of density intercropping, the plant height and stem diameter reduced and the quantity of accumulation decreased. The morphological characteristics of zhengdan 958 at the vegetation stage and reproduction stage performed an obvious, sustainable, and stable response to intercropping-competition, but shendan 16 did not. The differences of growth between the intercropping and monoculture minimized gradually at the reproduction stage. Dry matter accumulation of shendan 16 was faster at the vegetation stage but only for a short time, indicated an unstable competitive performance. It is concluded that cultivars-intercropping improves the population's canopy structure and increases the productivity of dry matter effectively, lays the great foundation for the maize yield.