Never ignore the effect of high temperature on rice
In the summer of 2003, there were rare high-temperature weathers in the northwestern Jiangxi Province, and during the entire July, August, and early September, they were all in sunny days with little rain. Most of the weather temperatures were between 35 and 40°C, resulting in most of the night. Rice headings are advanced and the growth period is greatly shortened. In response to this phenomenon, we conducted the following analysis. First, the impact of high temperature on rice growth and development stage According to rice cultivation theory, rice in each growth and development stage of the different temperature requirements, there is an optimum temperature, if the upper or lower limit of the critical temperature, rice growth and development Abnormal phenomena will occur, that is, physical disorders. In the heading and flowering period, the rice should be at an optimum temperature of 25-30°C. Below 25°C or above 30°C, a large amount of empty pods will appear. The 32-degree-C will cause 1000-grain weight drop, and 35°C will cause empty grain. High temperatures can damage the male reproductive organs and cause degeneration or emptying of the ovary after flowering. The optimum temperature during the grain filling period is 21 to 25°C. In the event of a high temperature above 35°C, the rice grains will easily stop developing and form semi-solid grains, which will result in the loosening of grain texture, the increase of belly whiteness, the reduction of grain weight, and the deterioration of rice quality. This is the "high temperature Fatigue phenomenon. From the end of June in 2003, the whole July, August, and early September were in the sunny heat of 35-40 degrees Celsius, which caused most of the late varieties to have early heading, and the growth period was greatly shortened. In early August, the heading varieties all headed early in August and were 10 to 15 days earlier than normal years. Second, the influence of different locations of paddy fields on rice yield The dry winter fields that are located on the flat terrain, long sunshine hours, good soil and fertility conditions, and low groundwater level are most affected by high temperatures. In normal years, these fields belong to high-yield fields. The rare high-temperature effects turned "profit" into "harm". This is due to the fact that high temperature and strong light is responsible for the absorption of such paddy soils. The mountains, ridge fields, and most of the high-altitude fields are half-cast and half-yang, shortening the number of sunshine hours, adding the gap between the fields, and the flow of irrigation water, allowing the temperature to rise slowly during the day, cooling at night, and increasing the temperature difference between day and night; Fields have high groundwater levels, most springs in irrigation springs or irrigation in winter, water and soil temperatures are relatively low, and the annual output is low. Under this abnormally high temperature, the low temperature rises to “just rightâ€, thus turning “harm†into “profitâ€. "The abnormally high temperature has become an increase in the yield of this type of field. Third, under the same temperature conditions under different combinations of varieties of hybrid rice combinations and combinations, because each combination of parents of different parents, the sensitivity of different temperature responses. After crossing the hybrid combination, due to genetic factors, these characteristics will show differences in offspring. Even if it is a series of combinations, one parent is the same, the other parent is different, and their offspring are different. From the perspective of the effects of high temperatures in 2003, the late-maturing combination with a stable growth period has an increased chance of avoiding high temperatures at the heading stage and the grouting period, and thus the degree of damage caused by high temperature is relatively light. Fourth, improper management of cultivation has played a role in boosting the abnormal high-temperature hazards. This is mainly manifested in two aspects: First, improper fertilization. For fertile rice fields or partial nitrogenous fertilizers, and late replanting, the seed setting rate is relatively low. The mature leaves exhibit reddish-red color, and sheath blight and rice smut are more common. Dry stalk phenomenon. In the mature period, the leaves show a golden yellow field, and the seed setting rate is relatively high. The valley's head is heavy and the disease is slight. This is an appropriate embodiment of fertilization. There is also a part of the thin field, in previous years because of many reasons, the fertilization effect is not good, the utilization of fertilizer is not high, the output is always difficult to increase, and under such abnormal high temperature conditions may ease some of the constraints, so that the paddy field nutrients The decomposition rate is accelerated, and the utilization of nutrients is increased, resulting in a rare good harvest. The second is the cause of moisture. This includes two factors, man-made and natural. The so-called man-made factor is that most farmers follow the conventional practice of high yields. They often have constant exposure and moist management in the middle and later stages, but under the abnormally high temperature conditions, they have helped “disheartenâ€. , has exacerbated the high temperature raging. However, some farmers have always been extensively managed and allowed to infuse it with water, so they are less harmed by high temperatures, and they are lucky to obtain a better harvest. The so-called natural factors are the causes of low-lying terrain, high groundwater levels, or cold spring irrigation, which have helped the cold paddy field and alleviated the danger of abnormal high temperatures.