Early rice is often damaged due to high temperature during heading and flowering to the grain filling stage, resulting in reduced production. High temperature damage to this period is mainly in two stages: First, before and after flowering, the viability of pollen is weakened, so that pollination is poor, empty grains increase, and the rate of setting is reduced. The second is the grouting period, which slows down or even stops the grouting speed, resulting in an increase in grain size and a decrease in grain weight. This causes premature aging and early maturing, which is called high-temperature ripening. The indicators of high-temperature heat damage are as follows: The maximum daily temperature is more than 3 days consecutively â‰¥ 35Â°C, and the sensitive period is at the flowering stage of rice. Practice has proved that in the flowering period, a high temperature above 35 Â°C for 1 hour will cause high inflorescence of spikelets, of which the flowers that have been open will suffer the most. About 10% is generally lost, and up to 20% is serious. This is an important reason that affects the high yield and quality of early rice. The following measures can be taken for prevention. Field irrigation deep water temperature and high temperature hot air conditions irrigation, can improve the microclimate in the field, so that the air temperature between the rice plant population decreased by 1 Â°C - 3 Â°C, the ear temperature decreased by 1 Â°C -1.5 Â°C. It is advisable to carry out day-night irrigation at places with convenient water sources. Poor conditions, can be deep-water irrigation for 2-3 days in a short period of time, but avoid deep-seated long-term, so as to avoid premature aging of oxygen depleted rot. Foliar water spray cooling can significantly reduce the temperature and increase the humidity. After the sprinkler irrigation, the field temperature can be reduced by more than 2Â°C, the relative humidity is increased by 10%-20%, and the seed setting rate is increased by about 2.6%. It is advisable to spray irrigation before and after flowering, and the water consumption per mu is 200-250 kg. To control the late-stage fertilization of nitrogen fertilizer in early rice, we must be cautiously engaged in, especially pay attention to strictly control the amount of nitrogen fertilizer. Because of the excessive supply of nitrogen in the later period, it is easy to cause the lodging of the seedlings, and weaken the resistance of the plants to high temperatures. If it is necessary to supplement nitrogen fertilizer, it is only suitable for top dressing. Outside the root topdressing fertilizer can reduce the temperature and humidity, but also to add water and nutrients. In combination with irrigation and cooling, at the same time, 150 grams of potassium dihydrogen phosphate per acre and 50 kg of water were sprayed on a sunny day at 4 pm to maintain the function of the leaves and enhance the high temperature resistance of rice plants. Pay attention not to be sprayed on rainy days so as to avoid being lost. Spray chemical agents with 100 grams of zinc sulfate per acre, 250 grams of salt or 100 grams of potassium dihydrogen phosphate, 60-75 kg of water sprayed foliar. Conditions can be sprayed with some light vitamin C or 3% superphosphate solution, which has a certain effect of reducing high temperature damage.
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