Maize requires more water, in addition to the seedling period should be appropriate water control, and then must meet the water requirements of maize in order to obtain high yields. Corn water demand by the region, climate, soil and cultivation conditions. According to the data proved that mu yield 500 kg of summer corn water consumption 300-370 cubic meters, the formation of l kg of kernels about 700 kg of water. It is also proved that water consumption increases with yield. There are large differences in water consumption among the various reproductive periods of maize. Due to the differences in the length of the fertility period of spring and summer maize and the climatic changes during the fertility period, the water consumption of spring and summer maize varies in each fertility period. The general trend is that less water is needed from sowing to seedling emergence. Tests have proved that the maximum soil field water holding capacity should be maintained at 60% to 70% when sowing, in order to maintain the whole seedling; seedling to jointing, water demand increases, soil moisture should be controlled in the field of the maximum water holding capacity of 60% for the corn seedling to promote the conditions for the growth of the root; jointing to the male water demand dramatically increased, the male to the peak of the water demand for grouting, from the bloom of the first 8 to 10 days before the beginning of the 30 days of water consumption accounted for about half of the total water consumption. Half of the total water consumption. The period of field water status of corn flowering, pollination and kernel formation has an important impact, the soil is required to maintain the maximum field water holding capacity of about 80% is appropriate, is the critical period of corn water; grouting to maturity is still consuming more water, milk ripening gradually reduced. Therefore, the requirement in the milk ripening before the soil still maintains the field maximum water holding capacity of 80%, after milk ripening to keep

Holding 60% is appropriate. Tianjin is located in the eastern coastal area of the North China Plain, maize fertility period precipitation

characterized by the two ends of the less, more in the middle. That is, less in April and May, more in June, July and August, and less in September, the total precipitation is slightly higher than the corn water demand, but variable, uneven distribution. Therefore, irrigation and drainage should be carried out according to specific conditions. Usually, before sowing to pour bottom moisture water; large trumpet period and about 20 days after the male pumping, respectively, watering tapping ears and tapping grain water; when the moisture is insufficient, leaf curl, and no rain in the near future, should be immediately watered, and vice versa can not be watered. If there is a lot of rain and the field is waterlogged, it should be drained in time to prevent the root system from suffocating and dying. Germination and seedling emergence, seedling period, should pay attention to the dispersal of moisture, to prevent rotting seeds bud flooding.

Temperature requirements of maize

Maize is a temperature-loving crop with a sensitive response to temperature. Currently applied corn varieties require a total cumulative temperature of 1800-

2800 ℃ during the reproductive period. Different reproductive period of different temperature requirements, in the case of soil water, gas conditions are appropriate, corn seeds at 10 ℃ can be normal germination, to 24 ℃ germination fastest. The minimum temperature of nodulation is 18℃, the optimum temperature is 20℃, and the maximum temperature is 25℃. Flowering is the highest temperature requirements in the life of corn, the most sensitive response period, the optimal temperature of 25-28 ℃. Temperature higher than 32-35 ℃, the relative humidity of the atmosphere is less than 30%, pollen grains due to loss of water loss of vitality, styles are easy to wither, difficult to pollination, fertilization. Therefore, only the adjustment of the sowing period and timely watering and cooling to improve the relative humidity of the atmosphere to ensure pollination, fertilization, the formation of grains. Requirements for the average daily temperature in the

20-24 ℃, such as the case of lower than 16 ℃ or higher than 25 ℃, affecting amylase activity, nutrient synthesis, transfer slowed down, the accumulation of reduced, delayed maturity, grain weight reduction in yield.