Four effects of High temperature on Rice

The temperature requirements of rice are different in each growth and development stage, and there is an optimal temperature. If the critical temperature exceeds the upper or lower limit, the growth and development of rice will appear abnormal phenomenon, that is, physiological obstacles. Therefore, attention should be paid to the effect of high temperature on rice.

1. Effects of high temperature on different growth stages of rice

1. Heading and flowering stage. Generally, the temperature of 25-30 ℃ is suitable for rice at heading and flowering stage. A large number of empty grains will appear when the temperature is lower than 25 ℃ or higher than 30 ℃. At the same time, high temperature can also damage the male reproductive organs of rice, causing variety degradation or ovary unfertilized after flowering to form empty chaff grains.

2. Filling period. The optimum temperature of rice filling stage is 2125 ℃. If rice encounters high temperature of more than 35 ℃ during filling period, rice grain will easily stop developing and form semi-solid grain, resulting in loose grain texture, enlargement of abdominal white, decrease of 1000-grain weight and deterioration of rice quality, which is often called "high temperature forcing ripening" phenomenon.

Second, the effect of different location of paddy field on rice yield.

The fields located in flat and open terrain, long sunshine hours, good soil and fertilizer conditions and low groundwater level are the most affected by high temperature. in normal years, these fields are high-yield fields, but due to the rare influence of high temperature, they will turn benefit into harm. This is related to the number of hours absorbed by high temperature and strong light on this kind of paddy soil. On the other hand, most of the mountain ridge fields and high altitude fields are half overcast and half yang, which shortens the hours of sunshine, coupled with the drop of the fields and the flow of irrigation water, which makes it rise slowly in the daytime, cool down quickly at night, and increase the temperature difference between day and night. In some fields, the groundwater level is high, most fields are irrigated with mountain spring water, the soil and water temperature is relatively low, and the yield is relatively low over the years. Under this abnormal high temperature, the low temperature rises to just right, thus turning the harm into benefit. on the contrary, abnormal high temperature has become a factor to increase the yield of this kind of field.

Third, the influence of different variety combinations under the same temperature.

Because the origin of parents of each combination is different, the sensitivity to temperature is different between hybrid rice combinations and combinations. After hybrid combinations, due to genetic factors, these characteristics will show differences in the offspring, even if a series of combinations, one parent is the same, the other parent is different, the offspring are also different. For the late-maturing combinations with stable growth period, the chances of avoiding high temperature at heading stage and filling stage are increased, so the damage caused by high temperature is relatively light.

Improper cultivation and management to promote the harm of abnormal high temperature

The effects of improper cultivation and management on rice are mainly shown in two aspects:

1. Improper fertilization. In all fertile rice fields or fields with partial application of nitrogen fertilizer and late re-application, the seed setting rate was lower, the leaves were crimson at maturity, sheath blight and rice false smut were common, and stalk withering occurred just after rare. In the mature stage, the leaves are golden fields, the seed setting rate is relatively high, the burden of grain is heavier, and the disease is mild, which is the embodiment of proper fertilization. There are also some thin fields, in previous years, due to a variety of reasons, the effect of fertilization was not good, the fertilizer utilization rate was not high, and the yield was always difficult to increase, but under this condition of abnormal high temperature, it was possible to alleviate some restrictive factors, so as to accelerate the decomposition rate of nutrients in paddy fields and improve the utilization rate of nutrients, so as to obtain a rare good harvest.

2. The cause of moisture. This also includes both man-made and natural factors, the so-called man-made factors, that is, most farmers in accordance with the conventional practice of high yield, often irrigation in the middle and later stages, wet management, but in the abnormal high temperature conditions are not helpful, aggravating the high temperature raging. On the other hand, some farmers have always managed extensively and let them flood with irrigation, so they are less harmed by high temperature and get a better harvest luckily. The so-called natural factors are some reasons of low-lying terrain, high groundwater level or cold spring irrigation, which do a great favor to the cold pulp field and alleviate the harm of abnormal high temperature.