Good seedlings, good semi-ripe rice seedlings, high yield

The seedling stage management of mechanized transplanting is the key to cultivate robust seedlings suitable for mechanical transplanting and the key to the success or failure of popularizing mechanized rice transplanting. "good semi-mature rice seedlings, good seedlings and high yield". The quality of seedlings plays an important role in the number of panicles, grains and grain weight of rice in the later growth stage. The basic requirements of mechanized transplanting seedlings are overall balance and individual health, and require that "a board of seedlings is not high or low, and a handful of seedlings is not thick or thin".

High temperature and high humidity to promote full seedling

After sprouting, it is necessary to go through a period of high temperature and humidity after sowing in order to ensure the neat emergence of rice seedlings. therefore, according to the different ways of raising seedlings and stubble, corresponding measures should be taken to increase temperature and keep moisture to ensure the safety of seedlings. At the same time, the seedling field should be open to a good level of water shortage to avoid rain flooding the seedling bed, resulting in stewed seeds rotten buds.

Seal the film, cover the grass and stand the seedlings. The seedling covered with plastic film is suitable for raising seedlings of wheat stubble rice when the temperature is high. It includes three types: double film seedling raising, floppy disk hand sowing and machine sowing. At the seedling stage, we should pay attention to two points: one is to grasp the thickness of the cover grass, thin and uniform, to avoid burning seedlings at noon in sunny days. The second is to remove the stagnant water on the cover film in time after rain, so as not to cause water in the film area, coupled with the wetting aggravation of the covered straw, local pressure "plaster", resulting in braised seeds rotten buds, affecting the whole seedling.

Seedlings are set up in the arch shed. Arch shed seedlings are suitable for raising seedlings in early spring and cold-prone areas in late spring when the temperature is low. After the seedlings are raised from the soil surface of the buds, the surface temperature in the greenhouse should be controlled below 35 ℃ at noon in sunny days, so as to prevent the seedlings from being burned by high temperature.

The stage from sowing to seedling is generally the sealing stage of greenhouse film, which is mainly heat preservation and moisturization. only when the temperature in the film exceeds 35 ℃, the two ends of the seedbed are opened at noon to cool down, and then sealed in time. During this time, if the bed soil is white and the seedlings should be watered with "horse racing water" when rolling leaves.

Timely seedling refinement

Uncover the film and refine the seedlings. The time of covering the film is not too long, and the time of uncovering the film is determined by the temperature at that time, generally when the seedling is unearthed about 2 cm, and when the incomplete leaf is pulled out from the first leaf (3-5 days after planting). If the covering time is too long, it is easy to burn the seedlings in the hot sun. Uncover the film principle: sunny evening, cloudy morning, before light rain, after heavy rain. In case of cold spell and low temperature, it is advisable to postpone the release of the film and cover it day and night.

The refined seedlings of the seedlings in the arch shed. After the seedlings are young, the time of dismantling the shed will be determined according to the temperature. The shed can only be removed when the minimum temperature is stable above 15 ℃, otherwise it can be managed by day-opening and night-cover method, and the pan soil (or bed soil) can be kept wet.

Scientific water management

Moisture management. That is, to adopt the way of intermittent irrigation, to give priority to dampness, to adjust air with water, to adjust fertilizer with water, to adjust temperature with water, and to protect seedlings with water.

Operation points: flat ditch water is irrigated when the film is opened, and then water is added after it dries naturally, so repeatedly. If the seedlings have rolled leaves at noon in sunny days, thin water should be irrigated to protect the seedlings, and dry ditch water should be released in rainy days; if the seedlings are attacked by strong cold air in early spring, they should be irrigated to protect the seedlings with waist water, and the seedlings should be protected by changing water after the temperature is stable, so as to prevent rotting and dead seedlings caused by root injury at low temperature and excessive changes in temperature difference; timely drainage and ventilation should be carried out when the temperature is normal, so as to improve the root activity of seedlings. Control water to refine seedlings 3-5 days before transplanting.

Water control management. It is basically similar to the conventional fertilizer bed dry seedling raising pipe water technology, that is, sufficient water is irrigated once (flat ditch water) when the film is opened, and discharged after drying through the bed soil (can also be sprayed to replenish water). At the same time, clean up the seedling ditch, keep the water system unblocked, ensure that there is no stagnant water in the seedling field in rainy days, prevent the flooding of dry seedlings, and lose the advantage of dry cultivation. After that, if the seedlings have curled leaves at noon, you can artificially spray water once in the evening or the next morning to make the soil moist. No leaves rolled, no water replenished. The water quality of replenished water should be clean, otherwise it is easy to cause dead seedlings.

Make good use of "weaning fertilizer"

The application of weaning fertilizer is carried out according to the specific conditions of bed soil fertility, seedling age and air temperature, and is generally applied in the period of one leaf and one heart (7-8 days after sowing). In each mu of seedling pond field, 500kg of rotten dung to 1000 kg of water or 5kg of urea (about 2g of urea per plate) to 500kg of water were applied in the evening when the seedling leaves were spitting forever. The fertile bed soil may not be applied, and the amount of fertilizer application can be appropriately reduced in order to prevent the seedlings from being too high in the wheat stubble field.

Deal with the cold in late spring at seedling stage

Protect seedlings in deep water, adjust temperature with water and adjust air with water. In case of low temperature and cold wave, pour deep water to the seedling fork to protect the seedlings, be careful not to drown the seedling center. If the weather suddenly clears up after the cold wave, do not immediately return to the water to dry the field, so as not to cause withered and rotten seedlings. The main danger of late spring cold is that the weather suddenly clears up and the temperature rises suddenly, resulting in physiological dehydration of seedlings, and the deep water layer can alleviate the drastic changes in the temperature of the seedling bed.

Sprinkle dimethazone in time. Before the low temperature or after the cold wave, 100,150 grams of dimethazone per mu can be used to pour 1000 times of the liquid to prevent rotten seedlings from dying. After a long period of rain and low temperature, Zhuangyangbao should be sprayed in time to control the occurrence of blight.

The arched shed is protected from freezing. If the cooling range is large and the time is long, if possible, we can combine the first two measures to build an arch shed for heat preservation and anti-freezing.

Avoid overweight too early. After low temperature, the stress resistance of seedlings is poor, if the early application of chemical fertilizer, for the weak growth of seedlings, it is tantamount to making things worse, accelerating the death of rotten seedlings. Therefore, topdressing should be carried out 3-4 days after low temperature.