1, seedling stage: refers to the period from emergence to jointing, with vegetative growth as the main focus and root completion as the center. Emergence is the period from sowing to seed germination. The field emergence rate is 50% and the seedling height is 2 cm.
2. Heading stage: refers to jointing stage to heading stage. This period is the most vigorous period of growth, and vegetative growth and reproductive growth go hand in hand. This period can be divided into jointing stage, big bell mouth stage and small bell mouth stage. The jointing stage is the period of young panicle differentiation, and the stems of 2~3 cm can be felt by hand near the ground.
The big trumpet stage is the stage when the leaves of the stick begin to be pulled out, but they have not yet spread out, forming clustered, flat, hollow and trumpet-shaped new leaves. The female spike enters the floret differentiation stage, and elastic spikelets can be felt between the spread leaves and the unexpanded leaves.
3. Flower-grain stage: refers to the stage from heading to fruiting, which is the stage of constructing seeds with reproductive growth as the center. Include tasseling stage, pollen dispersal stage and fruiting stage.
Extended data:
Corn is a thermophilic crop, which needs higher temperature during the whole growing period.
The biologically effective temperature of maize is 65438 00℃. Seeds germinate at 6- 10℃, germinate slowly below 10℃, germinate vigorously at 16-2 1℃, and the optimum germination temperature is 28-35℃, and stop germination above 40℃. The seedling stage can withstand short-term temperature dependence of -2-3℃. It needs 15-27℃ at jointing stage, 25-26℃ at flowering stage and 20-24℃ at filling stage.
Different corn varieties have different requirements for temperature, and the early-maturing varieties in China require a cumulative temperature of 2000-2200℃; Medium-mature varieties are 2300-2600℃; Late-maturing products and 25OO-28OO (3000)℃. Most corn producing areas in the world are concentrated in July 2 1-27℃, and the frost-free period is 120- 180 days.
Baidu encyclopedia-corn