苗期地温对棉花前期生育进程的影响研究

为研究苗期地温变化对棉花出苗和生长状况的影响，采用田间试验，设置3个不同播期，调查地温与棉花生长变化的关系。结果表明，苗期5 cm地温受气温影响波动要比10 cm和15 cm土层大，且地温相对较高，随播期推后，不同土层温差变化减小；不同播期约4~5天可见苗，受积温影响不大，但随播期推后，进入苗期时间增长；从第一真叶到见蕾一、二播期仅差1天，出叶时间间隔变短，而二、三播期的间隔则变长；不同播期中第三播期棉花株高最高，高出其他播期达20 cm，差异显著，株宽和始节高度差值也达5.5 cm和5.3 cm，且随播期推迟这种差异增大。本试验认为，不论播期怎样变化，只有地温变化趋缓，才利于棉花出苗和稳健生长，构建理想群体结构。

Soil Temperature at Seedling Stage: Effect on Early Growth Process of Cotton

To study the effect of soil temperature change on seedling emergence and growth of cotton, a field experiment is conducted and 3 different sowing dates are set up, and then the relationship between soil temperature and cotton growth is investigated. The results showed that at the seedling stage, the fluctuation affected by temperature at 5 cm soil layer was larger than that of 10 cm and 15 cm soil layer, and the ground temperature was relatively higher, with the delay of sowing time, the temperature difference in different soil layers decreased. The seedling could be seen on the 4th-5th days under different sowing time, and they were affected by the accumulated temperature slightly. But with the delay of sowing time, the entering time to seedling growth increased. From the first real leaf to showing one or two buds, there was only 1 day difference between the first and the second sowing time. The interval of leafing became short, but the interval of the second and the third sowing time became long. The plant height of the third sowing time was the tallest, 20 cm higher than that of the other sowing time, and the difference was significant. The difference of plant width and height of the first node was up to 5.5 cm and 5.3 cm, respectively, and the difference increased with the delay of sowing time. The experiment suggests that no matter how the sowing time changes, only the slow-down of the ground temperature change could benefit the seedling emergence and growth of the cotton, and the construction of an ideal structure.