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.