The germination of turfgrass seeds was affected by hydrothermal conditions
The germination of turfgrass seeds is affected by water and heat conditions, and there are great differences in the speed of emergence and turf formation. How to select the most suitable sowing time and obtain the fastest turf formation speed with the most reasonable irrigation and other management measures has been the unremitting pursuit of the majority of users. In recent years, scholars have successfully used a model method to study the requirements of water and heat conditions in the germination process of grass seeds. These results can be used to guide the rational planting of lawn, reduce the risk of planting failure, and reasonably shorten the seedling period to reduce the cost of construction.
The temperature in this paper refers to the soil temperature. In the season when the air temperature is relatively stable, the surface soil temperature is close to the daily average temperature (the simplest algorithm is the average temperature measured at 2:00, 8:00, 14:00 and 20:00 every day). Because the specific heat capacity (buffering capacity of temperature change) of most cultivated soils is greater than that of air, the change of soil temperature will lag behind that of air temperature in spring and autumn, that is, soil temperature will be slightly lower than daily average temperature in spring and slightly higher than daily average temperature in autumn. It is not convenient for most users to measure the soil temperature, so we can refer to the air temperature and correct it according to the previous introduction to guide the production. Grass seeds belong to small seeds, sowing depth is shallow, and frequent watering is needed to maintain the surface soil moist at seedling stage. Large amount of watering will reduce soil temperature and slow down seedling emergence in many cases. Reasonable control of watering amount and interval at seedling stage is very helpful to speed up seedling emergence and turf formation. Soaking seeds in warm water for 24 hours before sowing is also a common method to accelerate seedling emergence, which can effectively reduce the water demand at the initial stage of seed germination and accelerate the germination process.
Some studies have proved that annual ryegrass and white clover are a few grass species that can germinate at low temperature. For example, Dannong's Mini White Clover still has a germination rate of more than 50% after 4-5 days at 10 ℃. However, annual ryegrass can be used in warm season turf in the south of China in late autumn or early winter.
The temperature indexes affecting seed germination mainly include the lowest germination temperature, the most suitable germination temperature (range), the highest germination temperature and the effective accumulated temperature (℃· day) for 50% germination. The lowest germination temperature of Festuca arundinacea and Poa pratensis was 2-3 ℃, perennial.
