滇中高原高产玉米的产量形成

YIELD FORMATION OF HIGH YIELD CORN IN THE MIDDLE YUNNAN PLATEAU

分析了滇中高产玉米的产量形成特点及其与高原气候生态环境的关系。滇中高产田块（１３．５～１６．６ｔ／ｈｍ２）的产量结构为：每公顷株数６７５００～１０５０００，每穗粒数５５０～６７０，千粒重２５０～３２０ｇ，穗粒重０．１８～０．２ｋｇ。滇中低纬度、高海拔的地理条件和受季风影响，形成了高原独特的气候生态环境，玉米生长期降水集中，气候温和平稳，夏无酷暑，太阳辐射强，日较差大。玉米的生育期特别是生殖生长期显著延长，有利于小花分化和大穗形成。株型紧凑，整齐度高，有利于增加种植密度。籽粒灌浆期处于高原雨季，日照时数偏少，气温偏低，光合速率和灌浆速度处于中等水平，但滇中玉米的灌浆期长，叶面积稳定期长，干物质总的积累水平较高，其千粒重偏低与籽粒总库容大有关。

This paper analyses the characteristics of the yield formation of high yield corn and the relationship between the corn and the climatic ecological environment in the Middle Yunnan Plateau. The yield composition of the high-yielding fields with yields from 13. 5 to 16. 5 t/hm2 is: 67 500-105 000 plants per hm2, 550-670 grains per ear, 250-320 grams per 1000 grains and 0.18-0. 2 kg per ear. The geographic condition of low latitude, high elevation and the impact of monsoon form a unique climatic ecological environment in the Middle Yunnan Plateau, where precipitation is concentrative, the climate is temperate and stable, with no intense heat in summer, and with strong solar radiation and great temperature variation between day and night in the corn growing season. The corn's growth period, especially the reproductive stage, is significantly elongated, which is favorable to the differentiation of florets and the formation of big ears. The compact plant type and even crop stands are also beneficial to the increase of planting density. The grain filling stage occurs in the rainy season of the Plateau with less sunshine and lower temperature. Therefore the rate of photosynthesis and grain filling are at medium level. But the grain filling stage and the stable leaf area stage of the corn are longer in the Middle Yunnan Plateau, and the total dry matter accumulation is comparatively higher, though the grain weight is lower, because the total grain sink per area is bigger.